Belled End Fittings - Surve Jitendra.

Create a spark to reduce labor, welding costs

For 70 years, factory-made, wrought butt-welding fittings were the choice for pressure piping systems, in shapes defined by ASME B16.9. However, in recent years, new metal forming processes have enabled the development of wrought socket-welding fittings.

By Ray Stubbs Jr., Bestweld Inc. -- Plant Engineering, 6/15/2008

For 70 years, factory-made, wrought butt-welding fittings were the choice for pressure piping systems, in shapes defined by ASME B16.9. However, in recent years, new metal forming processes have enabled the development of wrought socket-welding fittings. In 1996, those fittings were standardized in “MSS Standard Practice SP-119, Belled End Socket Welding Fittings, Stainless Steel and Copper Nickel” – more familiarly known as “belled-end pipe fittings.” The bodies of these are essentially the same as those in ASME B16.9, but the welding skill, materials and labor time to join them are far less extensive.

According to the American Welding Society and the Bureau of Export Administration, in their May 2002 report entitled Welding Related Expenditures, Investments and Productivity Measurement in U.S. Manufacturing, Construction and Mining Industries, labor typically accounts for 76% of total welding cost. Given the amount of welding involved in a typical piping system, simplifying the process can amount to considerable savings.

This simple change in pipe fitting specification can save 50% to 70% of the labor time needed in joint preparation and welding. Multiply that by each joint throughout the piping system, and this can amount to huge savings to the plant budget. And while significant economic advantages are realized, no sacrifice is made in piping system performance – and in some cases system reliability is improved.

Easing the fit and the weld

Cold-formed, wrought belled-end pipe fittings have expanded ends, creating a socket to receive the connecting pipe. This design allows them to be joined by fillet welds rather than the butt welds needed to join traditional pipe fittings. Both the type of weld and the shape of the parts make good welds easier to achieve.

Fillet welds can be done four to seven times faster and require fewer steps than butt welds. Much less joint preparation goes into a fillet weld, with no machining of parts onsite needed to ensure fit. Butt-welded joints require both pieces to be beveled at the point of installation for a precise fit of root geometry.

Pre-weld fit time is virtually eliminated with belled-end fittings, where butt-welded joints take a significant amount of time to fit. Belled-end fittings joined with fillet welds are more forgiving: where the shape and alignment of the two pieces may vary just a slight amount, welds can still be done successfully. With butt-welding, “out of round” situations, misalignment and mismatched wall thicknesses can cause problems in achieving a good weld.

In butt-welding, an interior backing ring may sometimes be needed to support the welded seam and provide a good surface on which to weld the two beveled edges together. The backing ring is tacked in place, and then weld material is deposited into the groove created by the two machined parts. Where a backing ring is not used, the two parts still must be fit into a jig and tack-weld before being final-welded into place. Joining belled-end fittings with fillet welds eliminates these preliminary steps. In addition, back-side weld joint gas inerting is often required for butt joints but is seldom needed for socket welds.

The ability to use a fillet weld at a lap joint between the fitting and the pipe instead of a butt weld also reduces the chance for burn through – a contributor to internal deformities such as craters, fissures and icicles that can affect process flow. Fillet welds are much easier to do and much less expensive to inspect. Most fillet welds are accomplished in one root pass and one finish pass, whereas comparable strength butt-welded joints require multiple passes. Fillet welds are inspected visually for size and slope, but butt welds are inspected radiographically in order to ensure proper joint preparation and root pass penetration.

Belled-end fittings perform

Today, B31.3, the piping designer’s most significant specification, recognizes the MSS SP119 fillet weld fittings as a cost-reducing alternative to standard butt welding fittings. The current edition of ASME B31 Code for Pressure Piping lays out design requirements for effective, safe and insurable systems. B31.3 Process Piping is “piping typically found in petroleum refineries, chemical, pharmaceutical, textile, paper, semiconductor and cryogenic plants, and related processing plants and terminals.”

But how does performance stack up? Fillet welds in themselves are strong, reliable joints; in piping systems using belled-end pipe fittings, the performance meets or exceeds standard pipe fittings. The fittings provide the same pressure and temperature limits as the corresponding butt-weld fittings. Manufacturers’ design-proof burst testing confirms that MSS-SP119 fittings have burst capacities matching those of ASME B16.9 rated butt-welded fittings.

The fillet-welded joint is stronger than the pipe alone. The cold-formed wrought fittings also better match the wall thicknesses of piping systems than cast or forged fittings, which tend to be rigid and oversized. That properly enables systems with belled-end fittings to flex more uniformly, distributing the stress into the sidewalls rather than the joints. This extends system life where fatigue is a concern.

U.S. Navy testing of the fittings discovered that the fitting bell contributed a significant reinforcement value to elbows. In fatigue testing of angular displacement large enough to produce B16.9 elbow failures in 1,000 cycles, belled-end elbow fittings lasted two to four times longer, the testing found.

Belled end fittings have Piping Code recognition: the current standard MSS SP-119 is referenced by B31.3, Code for Chemical Piping. Standard Practice SP-119 currently is being revised to include belled-end fittings in more materials and with thicker walls, broadening the application possibilities.

Belled end fittings can be used with standard wall and light wall pipe, and commonly are supplied in several alloys of stainless steel, copper nickel, titanium and aluminum. In today’s economy, labor cost outweighs component cost; even where special materials are used, installation and performance issues still make belled-end fittings a preferred choice.

Consideration of welding requirements during piping design will yield impressive benefits. Using belled-end fittings can help a manufacturing facility cut welding labor costs, reduce inspection costs and welding rework and build stronger piping systems.

---

Author Information

Ray Stubbs has been in the welded piping industry for more than 30 years, serving since 1984 as a founding partner and vice president of sales at Bestweld Inc. A producer of stainless steel and higher nickel alloy welding fittings for high-pressure, high-temperature and severe corrosion applications, Bestweld is a U.S. Navy ship parts supplier. Bestweld was named 2004 Supplier of the Year by Northrop Grumman Newport News and Northrop Grumman Ship Systems.

 

Use of fittings can help combat the loss of skilled welders Choosing belled-end pipe fittings also can help plants address a major problem in industry today: the lack of highly skilled welders. Besides enabling faster production of good joints, belled-end pipe fittings benefit plant engineering departments because less advanced welding skills are needed than for comparable strength, butt-welded systems. As experienced welders retire, a broad range of welding knowledge is leaving the workplace. New graduates show low interest in welding, while technology creates more uses for the skill. In a May 2002 survey by the American Welding Society and The Bureau of Export Administration, almost 50% of companies studied said the numbers of their welding trainees were not adequate to meet replacement requirements. More than 40% of heavy industrial manufacturing firms indicated that a shortage of qualified welders affects productivity either “moderately” or “extensively,” and approximately 30% of the firms in the automotive and construction industrial sectors indicated similar levels of impact, the survey indicated. Lack of skilled welders also can inhibit manufacturing expansion plans, affecting the economy as a whole. Welders with advanced skills command premium wages. According to an August 2006 Wall Street Journal report, graduates of welding technical programs can receive annual salaries in excess of $50,000. By specifying belled-end pipe fittings, the productivity of welding professionals, whether on staff or outside, can be maximized and costs can be minimized.

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Pipe Span Factors - a note by Hassan Hajitabar.

In general Pipe span is limited by pipe material (allowable stress),
sectional modulus (nominal size and Sch. of pipe) and weight of its content
and insulation and design temperature of the pipe system which affects
allowable stress in calculation of pipe span. In general pipe span is
limited by allowable deflection and allowable bending and shear stress. To
simplify pipe support spacing calculation MSS- SP69 has provided recommended
practice for support spacing which has been accepted by ASME. These spans
are limited to max. combined stress(bending and shear) to 1500 PSI and max.
pipe sag of 0.1 inch we use allowable pipe span as a general and primary
solution for supporting but some points should be considered in supporting:
1- All span should be adjusted based on available structure for supporting.
2- In case of change of direction in horizontal pipes you should reduce pipe
span. as a good practice you can use 0.75 of span.
3- Span should be decreased based on concentrated weight and load in piping
system such as valve and flange. As a good practice you can use 0.75 of span
for one element and 0.6 of span for two elements in piping system.
4- finally you should consider maintenance requirement(for example for valve
maintenance and removal) you should consider supports as possible as near to
valves).
Also I should note hear that occasional loads such as wind and earthquake do
not concern span of weight support because using span is used for dead
loads. For this loads stress analyzer engineer should use proper guide and
other dynamic supports such as rigid strut and shock absorber with careful
attention to thermal expansion and load.
When you see various recommended span for a same size it may means using of
various safety factor, various fluid content, various design temp. Various
pipe materials and other design objects in calculation of max. allowable
span.

In general we have:

L < (10 * Z* F * S/W)^0.5
In which
L= Max. allowable span(mm)
Z= Pipe sectional modulus(mm3)
F= Safety factor
S=Allowable stress in design temp(N/mm2).
W=Weight per linear unit of pipe(N/mm)
I hope these all are useful for you.

Best Regards
Hassan Hajitabar

Piping Engineer
Engineering Department
Iranian Offshore Engineering & Construction Company (IOEC)
E-mail: Hajitabar@Ioec.com

A 197 cupola malleable iron.(The missing picture)

A 197 cupola malleable iron.

"Bathula Raghuram \(Mumbai - PIPING\)" <r.bathula@ticb.com> Sent by: piping_valves@yahoogroups.com 17/06/2008 13:02 Please respond to piping_valves@yahoogroups.com

To <piping_valves@yahoogroups.com> cc Subject RE: [piping_valves] A 197 cupola malleable iron.

Cupola malleable iron is a blackheart malleable iron that is produced by cupola melting and is used for pipe fittings (probably in ANSI G49.1 I think) and similar thin-section castings.

 

The essential purpose of melting is to produce molten iron of the desired composition and temperature. For gray iron, this can be accomplished with various types of melting equipment. Cupolas and induction furnaces tend to be the types most commonly found in the gray iron foundry. The cupola was traditionally the major source of molten iron. However, gradual acceptance of electric melting has reduced the dominance of the cupola.

 

The following are the Grades of malleable iron specified according to minimum tensile properties (Source: ASM Handbook)

 

 Jitendra Surve Wrote:

Please enlighten me with your analysis of Cupola malleable iron A 197.
 
It seems to have low carbon content for malleability.
 
 
Regards,
Jitendra

Autofrettage of piping

The subject is more familiar to Stress engineers. Thought of sharing the basics with others.

The link below gives the basics behind the Autofrettage.
http://www.interlaken.com/legacysite/pdf/Autofrettage_ABCs.pdf

Though widely popular in other industries, in petrochemical field, the lines subject to high pressure piping such as LLDPE plants of Borestar technology of Borealis and LDPE of Lupotech technology of Basell have very high pressure piping which are in most cases licensor engineered items. General recommendation in such piping is to ensure that the piping does not fail under fatique loads. To arrive the pre compression stress equivalent autofrettage pressure limit, the pipe is analysed and plotted for various thickness percentage segments and how the stresses peak and drop, so that to arrive the optimum residual stress and the equivalent autofrettage pressure.

The pipe and fittings are subject to that resultant pressure and pre stressed before installation. Thus it is ensured that the piping can withstand higher fatigue loads and shock pressures of very high pressure services. Also observe the various stress curves on the attached snap of a sample analysis.

Stress engineers in the group are requested to share more of thier experience and views.

With regards,
Kannan.

Fugitive emission in valves [Second part]

In continuation of the subject, also look into the uploaded files on the subjects by Piet de Later of Dow chemicals.

http://tech.groups.yahoo.com/group/piping_valves/files/

Secondly,  this regulation is to have strict control and leak resistance on the hazardous emission of dust, steam or gas happening due to the external leakages for the safety reasons and long term reliability of the valves.

For instance: Cd, Hg, Ti, CO, NOx  < 0.2 mg/m3.
                   As, Co, Ni, Se             < 1.0 mg/m3.
                   Pb, Sb, F, CN           < 5.0 mg/m3.

For ball valves max. leakage rates of 0.03 g.h-1 are allowed for substances involving a risk potential. The maximum emission rate of He = 4.99x10-2 bars cm3s-1 is deemed to be permissible after a 100,000 operational cycles with Helium test medium at room temperature under a 55 bars pressure. This could be achieved for example, by means of specific design of packing or by means of bellows and a subsequent safety stuffing bushing and with PTFE sealing, if permitted for the service condition.

With regards,
Kannan.

17-4PH cracking.

People involved in the valve application, take care before placing order to know the component materials of the valve. The 17-4PH usually used in the stem construction have failed like the below. Tyco valves has observed similar failures in thier inhouse research and has reported the same on using 17-4PH. And are not recommending this material unless specifically asked for.

As all suppliers and buyers do not take much interest in the small components of the valve, it will be the responsibility of the buyer to take note of these before ordering and the complete knowledge of the service involved. Alternatives would be FXM19, F51, F6a Cl4 depending on temp. and service.(17-4PH is 17Cr-4Ni-Pricipatation Hardened)

http://www.hghouston.com/x/25.html

(Photo attached for members not having net access.)



Nomarski intereference contrast photograph of the microstructure of a 17-4PH stainless steel sleeve bearing overlayed with sintered tungsten carbide. A hydrogen embrittlement crack has initiated at the overlay/base metal interface. A mechanical crack in the overlay permitted access of a corrosive downhole environment to the 17-4PH stainless steel base metal. Vilellla's etch. (~65X)

With regards,
Kannan.

Fugitive emission in valves.

Ta-Luft - Technical instruction on air quality directive item 5.2.6. VDI 2440, has set the creteria under which leakage rate the packing of valve (any type) can be accepted using helium as the medium for the test. Helium has been choosen as it is the best inert gas and excellent sensors are availabe to smell it. The creteria also includes the application temp. range.

The test can be performed only once on the prototype design of the packing in the presence of a TPI like TUV inspector. And they witness and issue the certificate which can be accepted by a purchaser as a base reference for a type of valve, particular size range and temp. range for that design of packing or a spectrum of different designs of packing.

Now coming to your question, by packing I mean the stem packing of any valve. This act Ta-Luft was enacted to reduce the fugitive emmision of the plant. Most of the valve packing are degraded after certain cylces of operation and the service starts leaking. The Ta-Luft mentioned above is for only valve packing and includes the no. of cycle of operation where mechanical arrangement during testing, strokes the valve stem from close to open position automatically with a counter.

There are other Ta-Luft laws which dictates many other different type of emmisions other than the valve packing.

Helium leak test specific to individual manufacturer's own standard, as such is not accepted in the current market. Widely  accepted are the Ta-Luft and the Shell's SPE 77/312 which calls for more stringent creteria as the individual manufacturer's testing procedure are not much reliable without any reference scale.

Just for your information, nowadays most of the well known manufacturer's have adapted the Ta-Luft as a default design and offer it, even if you don't call for it.

Though this law is applicable only for Germany, it has been informally adapted by most of the European and Asian country plant owners. In USA the equivalent law is Called as Clean Air act. The approach is different in the testing and creteria but the end result emmision is slightly less stringent than the Ta-Luft requirements. The more stringent to follow is the Shell SPE 77/312. BP in US has its own standard like the shell in line with Clean Air act.

VDI is like the Institution of Engineers of India of Germany, The association of German Engineers but very active and creactive group having strong lobby in the government even today, which is responsible in bringing the Ta-Luft law more than two decades back well before the Clean Air act.

With regards,
Kannan
Linde, Germany.

**********************************************
http://piping-valves.blogspot.com/
http://materials-welding.blogspot.com/
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Sandesh Mane wrote:
 
Just a query...
Where are the low emmission valve used and is it related only to stem packing or some other design criteria is also there.
 
Do all low emission valves shall be helium leak tested /TALUF certified....
 
what is difference between taluf cert valves and helium leak test ??...which one is more stringent.
 
regards,
Sandesh Mane

What is Galvanizing...?

What is corrosion?
How do you protect iron and steel from corrosion?
How do you galvanize?
Surface PreparationGalvanizing Inspection
What is the resulting metallurgical bond?
Service Life Expectations for Galvanized Steel


What is corrosion?
Corrosion is the reaction between a material and its environment that produces a deterioration of the material and alters its mechanical properties. The actual corrosion process that takes place on a piece of bare mild steel is very complex due to factors such as variations in the composition/structure of the steel, presence of impurities due to the higher instance of recycled steel, uneven internal stress, or exposure to a non-uniform environment.
It is very easy for microscopic areas of the exposed metal to become relatively anodic or cathodic. A large number of such areas can develop in a small section of the exposed metal. Further, it is highly possible that several different types of galvanic corrosion cells are present in the same small area of the actively corroding piece of steel.
As the corrosion process progresses, the electrolyte may change due to materials dissolving in or precipitating from the solution. Additionally, corrosion products might tend to build up on certain areas of the metal. These corrosion products do not occupy the same position in the given galvanic series as the metallic component of their constituent element. As time goes by, there may be a change in the location of relatively cathodic or anodic areas and previously uncorroded areas of the metal are attacked and corrode. This eventually will result in uniform corrosion of the area.
The rate at which metals corrode is controlled by factors such as electrical potential and resistance between anodic and cathodic areas, pH of the electrolyte, temperature and humidity.
How do you protect iron and steel from corrosion?
Barrier protection is perhaps the oldest and most widely used method of corrosion protection. It acts by isolating the metal from the electrolytes in the environment. Two important properties of barrier protection are adhesion to the base metal and abrasion resistance.
Cathodic protection is an equally important method for preventing corrosion. Cathodic protection requires changing an element of the corrosion circuit, introducing a new corrosion element, and ensuring that the base metal becomes the cathodic element of the circuit. Hot-dip galvanizing provides excellent barrier and cathodic protection. The sacrificial anode method, in which a metal or alloy that is anodic to the metal to be protected is placed in the circuit and becomes the anode. The protected metal becomes the cathode and does not corrode. The anode corrodes, thereby providing the desired sacrificial protection. In nearly all electrolytes encountered in everyday use, zinc is anodic to iron and steel. Thus, the galvanized coating provides cathodic corrosion protection as well as barrier protection.




How do you galvanize?
The galvanizing process consists of three basic steps: surface preparation, galvanizing and inspection.




Surface Preparation
Surface Preparation is the most important step in the application of any coating. In most instances where a coating fails before the end of its expected service life, it is due to incorrect or inadequate surface preparation.
The surface preparation step in the galvanizing process has its own built-in means of quality control in that zinc simply will not react with a steel surface that is not perfectly clean. Any failures or inadequacies in surface preparation will be immediately apparent when the steel is withdrawn from the molten zinc. Any areas that were not properly prepared will remain uncoated. Immediate corrective action is taken.
Surface preparation for galvanizing typically consists of three steps: caustic cleaning, acid pickling and fluxing.
Caustic Cleaning – A hot alkali solution often is used to remove organic contaminants such as dirt, paint markings, grease and oil from the metal surface. Epoxies, vinyls, asphalt or welding slag must be removed before galvanizing by grit-blasting, sandblasting or other mechanical means.
Pickling – Scale and rust normally are removed from the steel surface by pickling in a dilute solution of hot sulfuric acid or ambient temperature hydrochloric acid.
Fluxing – Fluxing is the final surface preparation step in the galvanizing process. Fluxing removes oxides and prevents further oxides from forming on the surface of the metal prior to galvanizing and promotes bonding of the zinc to the steel or iron surface. The method for applying the flux depends upon whether the particular galvanizing plant uses the wet or dry galvanizing process.
In the dry galvanizing process, the steel or iron materials are dipped or pre-fluxed in an aqueous solution of zinc ammonium chloride. The material is then thoroughly dried prior to immersion in molten zinc.




Galvanizing
In this step, the material is completely immersed in a bath consisting of a minimum 98% pure molten zinc. The bath chemistry is specified by the American Society for Testing and Materials (ASTM) in Specification B 6. The bath temperature is maintained at about 850 F (454 C).
Fabricated items are immersed in the bath long enough to reach bath temperature. The articles are withdrawn slowly from the galvanizing bath and the excess zinc is removed by draining, vibrating and/or centrifuging.
The chemical reactions that result in the formation and structure of the galvanized coating continue after the articles are withdrawn from the bath as long as these articles are near the bath temperature. The articles are cooled in either water or ambient air immediately after withdrawal from the bath.




Inspection
The two properties of the hot-dip galvanized coating that are closely scrutinized after galvanizing are coating thickness and coating appearance. A variety of simple physical and laboratory tests may be performed to determine thickness, uniformity, adherence and appearance.
Products are galvanized according to long-established, well-accepted and approved standards of the ASTM, the Canadian Standards Association (CSA), and the American Association of State Highway and Transportation Officials (AASHTO). These standards cover everything from the minimum required coating thicknesses for various categories of galvanized items to the composition of the zinc metal used in the process.




What is the resulting metallurgical bond?
Galvanizing forms a metallurgical bond between the zinc and the underlying steel or iron, creating a barrier that is part of the metal itself. During galvanizing the molten zinc reacts with the surface of the steel or iron article to form a series of zinc/iron alloy layers. The photomicrograph below shows a typical galvanized coating microstructure consisting of three alloy layers and a layer of pure metallic zinc. Moving from the underlying steel surface outward, these are:
The thin Gamma layer composed of an alloy that is 75% zinc and 25% iron,
The Delta layer composed of an alloy that is 90% zinc and 10% iron,
The Zeta layer composed of an alloy that is 94% zinc and 6% iron, and
The outer Eta layer that is composed of pure zinc.




































Service Life Expectations for Galvanized Steel
The graph below is a plot of the thickness of the galvanized coating against the expected service life of the galvanized coating under outdoor exposure conditions. Most galvanized applications are 4 mils of thickness minimum per surface.
The expected service life is defined as the life until 5% of the surface is showing iron oxide (rust). At this stage, it is unlikely that the underlying steel or iron has been weakened or the integrity of the structures protected by the galvanized coating otherwise compromised through corrosion.




Graph – “Life of Protection”


















Painting Over Hot-Dip Galvanized Steel
For years, protecting steel from corrosion typically involved either the use of hot dip galvanizing or some type of paint system. However, more and more corrosion specialists are utilizing both methods of corrosion protection in what is commonly referred to as a duplex system. A duplex system is simply painting or powder coating steel that has been hot dip galvanized after fabrication. When paint and galvanized steel are used together, the corrosion protection is superior to either protection system used alone.

Painting galvanized steel requires careful preparation and a good understanding of both painting and galvanizing. Many products have been galvanized and painted successfully for decades, including automobiles and utility towers. Past experience provides excellent historical data for how best to achieve good adhesion. By studying past adhesion failures and successes, galvanizers, paint companies, researchers, paint contractors, and other sources have created an ASTM specification detailing the process and procedures for preparing hot dip galvanized steel for painting. When the galvanized surface is prepared correctly, paint adhesion is excellent and the duplex system becomes an even more successful method of corrosion protection.

How a Duplex System Works
Before deciding how to protect steel from corrosion, it is important to understand how steel corrodes. Corrosion of steel takes place because of differences in electrical potential between small areas on the steel surface which become anodic and cathodic. When an electrolyte connects the anodes to the cathodes, a corrosion cell is created. Moisture in the air forming condensation on the steel surface is the most common electrolyte. In the electrolyte, a small electrical current begins to flow. The iron ions produced at the anode combine with the environment to form the loose, flaky iron oxide known as rust.In order to protect steel from corrosion, something must interfere with the corrosion cell, either by blocking the electrolyte or becoming the anode. Two common methods of corrosion protection are cathodic protection (the fonnation of another anode) and barrier protection (blocking the electrolyte from the steel surface). Hot dip galvanizing alone affords both types of protection.

Aging Characteristics of Galvanized Coatings
Galvanized steel can be divided into three categories: newly galvanized steel, partially weathered galvanized steel and fully weathered galvanized steel. Each type of galvanized steel must be prepared slightly different because the galvanized surface has different characteristics at each stage of weathering. It is important to know the age of the galvanized steel that will be painted.

Newly Galvanized Steel
Newly galvanized steel is zinccoated steel which has been hot dip galvanized after fabrication within the past 48 hours. The newly galvanized steel should not be water or chromate quenched, nor should it be oiled. This type of galvanized surface is typically very smooth and the surface may need to be slightly roughened, using one of the profiling methods described in this publication, to improve paint adhesion. A newly galvanized surface has little or no zinc oxides or zinc hydroxides, so no major cleaning is necessary.

Partially Weathered Galvanized Steel
Partially weathered galvanized steel has begun to form the protective zinc patina, but has not completed the process. Before painting partially weathered galvanized steel, it is important to know if the coating was chromate quenched. The presence of chromateconversion coatings can be determined by spot testing the galvanized steel according to ASTM B 201. If a chromate coating is detected the chromate layer must be removed, either by brushing off by abrasive blast cleaning, abrading the steel by sanding or allowing the steel to weather for six months.
Partially weathered galvanized steel should also be inspected for wet storage stain. Since wet storage stain is hygroscopic and has a larger volume than the zinc metal, paint adhesion can be seriously affected when this stain is painted. Wet storage stain is a whitish zinc corrosion byproduct. If the surface to be painted has wet storage stain, it should be carefully removed by brushing the stain with a mild ammonia solution, such as diluted household ammonia. Severe cases of wet storage stain should be brushed with a mild acidic solution, such as one part acetic acid mixed with 25 parts water. Follow these cleaning procedures with a clean, warm water rinse.
Partially weathered galvanized steel also should be slightly roughened to improve paint adhesion. Any of the surface profiling methods described in this publication can be used to prepare the surface.

Fully Weathered Galvanized Steel
Fully weathered galvanized steel has a completely formed zinc patina. The patina has a very stable and finely etched surface, which provides excellent paint adhesion. The only surface preparation needed is a warm water power wash to remove loose particles from the surface. In order to protect the surface, the power wash should not exceed 1450 psi. Allow the surface to completely dry before application of the paint system.

Profiling
In order to provide a good adhesion profile for the paint, the galvanized surface must be flat with no protrusions and slightly roughened to provide an anchor profile for the paint system. Filing high spots, sweep blasting, phosphating, and using wash primers or acrylic passivations are the most common methods of increasing the profile of a galvanized surface. Again, care must be taken not to damage the galvanized coating.

High Spots
Any high spots or rough edges should be removed and smoothed out in order to provide a level surface for paint. Use hand or power tools to grind down the high spots. Care should be taken to remove as little zinc as possible.

Sweep Blasting
In order to roughen the typically smooth galvanized surface after cleaning, an abrasive sweep or brush blast may be used. Care should be taken to prevent removing too much of the zinc coating. Particle size for a sweep blast of galvanized steel should range between 200 and 500 microns (8 to 20 mils). Aluminum/magnesium silicate has been used successfully in the sweep blasting of galvanized steel. Organic media such as corn cobs, walnut shells, corundum, limestone, and mineral sands with a Mobs hardness of five or less may also be used. The temperature of the galvanized part when blasting can have a Significant affect on the finished surface profile. Sweep blasting while the galvanized part is still warm, 175 to 390 degrees F, provides an excellent profile. Ambient conditions for sweep blasting are recommended to be less than 50 percent relative humidity and a minimum of 70 degrees F.

Repair of Damaged Galvanized Surfaces
Sometimes hot-dip galvanized coatings are damaged by excessively rough handling during shipping or erection. Welding or flame cutting may also result in coating damage.
When limited areas are damaged, the use of low melting-point zinc alloy repair rods or powders, the use of organic zinc-rich paints or metallizing is recommended to protect the area.
We would like to express our appreciation to The American Galvanizing Association for supplying material and photographs for our web site.
For additional information on the topics listed above please contact The American Galvanizing Association or Ben Pletcher, Sales Manager, Ohio Galvanizing Corp.

Specifications
The primary specification that government organizations, engineering firms, specifiers, and fabricators desire is ASTM A123. This specification is defined by the American Society for Testing and Materials. Items such as coating thickness, guidelines for acceptance, and testing methods are documented.
Additional specifications for areas such as the galvanizing of steel hardware and fasteners (ASTM A153) and the allowable practices for repair of galvanized steel (ASTM A7890) are also listed.
A 123
Standard for Specification of Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products
A 153
Standard for Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware
A 780
Standard for Specification for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings
Ohio Galvanizing is a member of the American Galvanizing Association and galvanizes all material to the ASTM A123 specification. We will provide the proper documentation for those jobs requiring certification to the specifications of ASTM A123.

With regards,
Kannan.

One reason for Inner ring and outer ring in Spiral wound gaskets.

As everybody know that in spiral wound gasket the outer ring is meant to be as a centering ring for assembly and is being called for by default. The inner ring is to remove the potential for the spot weld joint on the spiral ring to corrode or crack leading to the metallic spiral ring unwinding. The result of this failure may cause an obstruction in the pipe bore, breakdown of the gasket and ultimately reduce the sealing integrity of the joint. So it is advisable to prescribe SPW gaskets with inner and outer rings of suitable material compatable with the service in category M as prescribed in B31.3.

With regards,
Kannan.
Linde, Germany.

Why a Butterfly valve

Why A Butterfly Valve

I. Introduction
The basic concept of the butterfly valve can perhaps be best illustrated by comparison with a damper in a flue pipe: a round disc, of essentially the same diameter as the pipe, rotating on an axis at a right angle to the pipe centerline. When closed, the disc is positioned at a right angle to the fluid flow; when open, the disc is parallel to the fluid flow. The butterfly valve is thus a rotary, quarter-turn valve. The name "butterfly" derives perhaps from the appearance of the stem-disc assembly, which bears some resemblance to the body and outstretched wings of a butterfly.

II. Development History
Butterfly valves, in the form of dampers, have been used as flow control devices for centuries. In these early devices, the disc had no seating surface as such. The edge of the disc merely swept the inner diameter of the pipe to alter flow without ever achieving tight shutoff. The devices were very inexpensive to manufacture since the only parts nedded were a stem and disc, using the pipe itself as the valve body.
With the advent of rubber liners, which closed the gap between the disc edge and the pipe or valve body, the damper became a tightsealing valve. While natural rubber liners were not successful in this application, the development of synthetic rubbers in the 1950's offered the non-sticking, non-swelling characteristics required for acceptable long-term sealing.
Soft rubber liners seal by allowing the edge of the disc to compress the rubber, producing a local contact pressure higher than the line pressure. Typically, tight shut-off with soft rubber liners is limited to pressure differentials on the order of 150 to 250 psi.
To seal against higher pressures, the edge of the disc would have to severly compress the rubber liner, resulting in high operating torque and destructive wear on the liner.
Left in the closed position for an extended period of time under higher pressures, the rubber tends to deform permanently, bulging out on both sides of the disc edge and making it difficult or impossible to open the valve.
The rubber liner is also limited to temperatures below about 300°F and to fluids that will not have an adverse chemical reaction on the rubber.
The development of tetrafluoroethylene (TFE) offered a material that has many desirable properties for valve seals and seats. Since TFE is not nearly as resilient as rubber, it could not be directly substituted for rubber in order to upgrade the performance of rubber-lined valves. In fact, much development work had to occur before seats were designed that could exploit the capabilities of TFE and similar plastics in the areas of pressure, temperature, chemical inertness and low operational torque.
The result of these develpments transformed the butterfly valve into today's high-performance butterfly valves for pressure up to 1480 psi and beyond.

III. Economic Factors
The single most important reason for selecting a butterfly valve is its low cost compared to other types of valves on the market today. A related advantage is the compact size and light weight of a butterfly valve, which results from its smaller end-to-end dimensions.
Installation costs, like initial costs, are equally attractive. A small maintenance crew, for example, can easily intall or replace a 1 6-inch butterfly valve without using mechanical lifting equipment. Economies are also possible with pipe hanger supports and other installation and preparation expenses.
Seat replacement, particularly in high-performance butterfly valves is relatively simple. Stem packing can be replaced without disassembling stem and disc and, in many installations, without even removing the valve actuator.
Butterfly valves are often specified for throttling and flow regulating service because of the inherent approximately "equal percentage" flow characteristics, as differentiated from the linear or quick-opening flow characteristics of some other valve type.

IV. Types and Codes
While there is a great diversity of butterfly valves on the market today, there are three primary groups, each of which is defined by applicable industry codes and standards.
Industrial Rubber-Lined Butterfly Valves

Applicable Standards:
MSS-SP67, API 609

This type makes up the largest segment of the total butterfly valve market and is generally offered at the lowest price. While limited in its applications, as noted below, current models of this type of butterfly valve are much improved over earlier models. In those models, the stem on which the disc was mounted passed through the centerline of the valve body - and through the top and bottom of the rubber liner. The two points where the stem passed through the liner were difficult to seal and through leakage at these points was a common problem.
In the early 1960's, the problem was corrected by off-setting the stem from the valve centerline so that it did not pass through the sealing area of the rubber liner. The liner thus provided a continuous, uninterrupted seal area through a full 360°.
Despite improved sealing, however, the use of a rubber liner generally limits maximum differential pressure to around 285 psi, the maximum rating of ANSI 150. Resistance of the rubber liner to various fluid media and higher temperatures imposes further limits on applications.

Water Works (AWWA) Butterfly Valves
Applicable Standards:
Rubber lined - ANSI/AWWA C504
Metal seated - AWWA C505

Though usually limited to water and sewage, these valves are occasionally specified for other services. They are supplid in smaller sizes as rubber-lined valves with extra heavy stems and in large sizes - up to 72 inces - with adjustable seats. The rubber-seated valves are generally limited to 150 psi differential pressure. So-called metalseated valves of this type (which have no seat except for the close proximity of the disc to the wall of the flow passage) are generally limited to 200 psi pressure differential.
The American Waterworks Association (AWWA) specifies end-to-end dimensions, body materials, minimum shaft diameters and stem materials as well as several other design parameters.

High-Performance Butterfly Valves
Applicable Standards:
API 609 and MSS-SP68

As mentioned earlier, this is the latest type of butterfly valve on the market today. It was not until October of 1983, in fact, theat an industry standard was produced indicating its acceptance in the valve market. Other industry standards are expected to follow shortly.
High-Performance butterfly valves (HPBV's) are rather sophisticated valves designed for tight shut-off at relatively high tempertures and pressure (as compared to other types of butterfly valves.) They have dynamic (pressure assisted) TFE sealing and have full ANSI pressure ratings in classes 150, 300 and 600 (1480 psi) or higher at ambient temperatures.
Temperature capability ranges up to 450°-500°F, although pressure ratings are significantly reduced at the higher temperatures.
The inherent cost advantages of a flangeless or wafer-type butterfly valve (designed to be bolted between pipe flanges,) when combined with higher pressure/temperature capability, has created an enourmous market for HPBV's where gate and glove valves were previously used. Further developments with the HPBV have resulted in versions which are fire-tested for flammable liquid service, versions for cryogenic services at -320°F and, most recently, versions with metal seats which push teh capability of the valves into applications which had been exclusively held by gate, globe and plug valves.

V. HPBV Design
The performance of a HPBV is dependent on the seat design, along with several other design considerations. All HPBV's presently on the market are designed with an offset seat, the seat is set off to one side of the stem to provide an uninterrupted circular seal ring against which the disc seats when closed. The TFE seats can be designed so that fluid line pressure acts upon the seat to increase the contact pressure between seat and disc very similar to an O-ring sealing concept. This results in a leak tight valve at all rated pressures.
A properly designed seat should provide bi-directional, tight shutoff, sealing drop-tight at high as well as low pressure differentials. It should also produce a low operating torque, should be self-cleaning (not become packed with suspended solids in the fluid media,) and should perform all of its required functions within the normal pressure/temperature ratings of the valve.
All these requirements for good seat design can be achieved only with an extremely flexible and resilient seat. The Bray/McCannalok Series 40 HPBV seat meets these design requirements as illustrated below.
Most high-performance butterfly valves on the market today employ a second, almost imperceptible offset of the disc. These valves are sometimes referred to as "double offset" high-performance butterfly valves.
When the stem of such a valve is rotated (see illustration below,) the second offset provides a camming action whech, in the fully open position, completely removes the disc from any any contact with the seat. Without this offset, the disc would stay in constant compressive contact with the seat in the two areas where the plane of the disc intersects the plane of the seat. In this situation, after the valve has remained open for a long time - and especially after a few temperature cycles - the compressive contact of the disc with the TFE seat should result in a permanent indentation of the seat in these two areas. When the valve is then closed, these two indentations in the TFE seat would not resume their former shape and leakage would eventually be experienced in the two areas. The "double-offset" design eliminates this problem.
Recent improvements in HPBV's have also been made in bearings and stem seals - all of which have made it possible to achieve reliable valve operation through 100,000 or more valve cycles. And the use of exotic body and trim materials - such as Stainless Steel 316, 17-4PH, Alloy 20, Monel and aluminum bronze - have extended use of these valves into a great many corrosive applications.

VI. Conclusion
All butterfly valves in today's market are not alike. There are several distinct types, each having its own performance characteristics and preferred applications. It is anticipated that continuing advances in technology will further enhance butterfly valve performance and broaden applications. Even so, no single type can fully satisfy every application. There will always be need for all types of butterfly valves mentioned in this article.
As industries strive to reduce construction and operating costs, however, butterfly valves seem certain to appear more frequently in the notebooks of applications engineers. And continuing favorable user experience will no doubt open many new applicatoins for high performance butterfly valves. Source: Bray controls. Friends the topic is not exhaustive though and does not cover triple eccentric and trim butterfly valves. Also check out this page for economical disck/seat material selection

http://www.bray.com/apps/braymat/braymat.cfm?color=white&site=web

With regards,
Kannan.

VITON GLT SEALS FOR Valves for 16000 PPM H2S ( 1.6% )and 6% CO2

Dear Rana,

As most of the FKM (Fluorocarbon rubbers) and Viton GLT is also the proprietary materials of Dupont, Dupont's recommendation is the best to follow. Especially also of considering the sealing requirement. Also check ASTM D1330. For sealing check ASTM F607. Also check at the this link for more info and guidance. This supplier is quit well know in the valve industry.

http://o-ring.info/en/compounds/viton-fkm/#tab-2137

Personally I will not prefer to go for Viton GLT for your application. Lastly, it would be advicable to remove your company internal communications. OR could be trimmed out to avoid uneasy situations to you in your company on possible misuse of the same. Pl. take it in the right spirit.

With regards,
Kannan.

"Ranasaria Shivanand Rajendra" ranasr@npcc.ae

BackgroundSpecification: Seals suitable for 16000 PPM H2S (1.6% ) and 6% CO2 tosuit temp -40 to 204 Deg CSome vendors have indicated that VITON GLT is not suitable for this environment. But One vendor is recommending to use the VITON GLT seals by OLDRATI (tested by Bodycote ) as per attached test certificates.Some recommendations regarding acceptance criteria are given in attachede-mail extracted from one Dupont site Questions. Experts are requested to kindly guide and give their opinion VITON GLT could be a acceptable choice.Also please if this forum is not for such kind of questions then pleasetell me so that questions I would not post any questions related valves& its internals.

Regards,
Rana

Running torque

The closing, opening, breakaways, running torques are all applicable in all valve operations. And is significant to understand the operating force required to operate the valve with ease. Also in selecting the actuators. These values are to be analysed especially in valves of very large diameters. Shell prescribes a max. of 350N operating force. Most vendors are not interested in giving these data in the bidding stage. My suggestion is to make it a mandatory requirement to submitt these data in the bidding stage. Plant operational personnel can aprreciate the importance of these torques. Member's views are highly appreciated.

Running Torque.

The running torque of a gearhead is the amount of torque needed to drive the gearhead under a no load condition. This is separate and different from starting torque, which is the torque required to start the gearhead in motion (often referred to as 'breakaway torque'). The running torque is a constant amount of torque needed to overcome the accumulated friction, inertia and resistance of the gearhead. Friction comes from many areas, including the seals, bearings, and somewhat from the limited sliding action of the gears themselves. Inertia is primarily a function of the diameters of the gears themselves. The primary cause of resistance is the lubricant, as it impedes the rotary motion of the gears.Friction and inertia require a constant running torque to overcome, which does not vary by speed. Resistance, however, varies with speed, as it takes increasing amounts of torques for the gears to move through the lubricant itself. This can be displayed as a formula, with a constant running torque, and a variable torque which is a function of speed.

With regards,Kannan.

Stem lip seals.

The lipseal are being widely used b almost all the valve manufactures in the stem sealing. Some ball valve manufactures have developed the trend of offering extended bonnet in ball valves due to the use of such sealing to move the sealing element away from the body to have reduced temp. exposure. Another reason for the extended bonnet is usage of the PTFE materials in the bushing. These solutions give better efficient sealing in stems. But the stem size gets changed and other counter piping arrangement problem occurs. However alternative graphite packing with fillers are new combinations and still available in market. Engineers evaluating the valves should take note of the these materials to avoid the inconvenience for piping layout engineering and in the aesthetics of the plant in overall.

Flexible restraints in PE piping system.

--- In piping_valves@yahoogroups.com, kannan.sundaram@... wrote:

Felt this may of interest to support engineers.

The PE piping is gaining popularity among clients due to longer life
something from 25 to 50 years and even 100 years in case of urban
potable
water, Natural gas supply systems. All in the context of undersoil
constructions. Due to its flexibility it is layed down in underground
pits
without much care to be taken compared with GRE or metal or cement lined
pipes. Also sizes upto 1400mm are being manufactured by few
manufacturers. However this PE still has not reached India to my
knowledge, except Reliance - Jamnager. The attached file shows the
flexible restraint used in these piping systems to prevent axial
movement.

For information, EN12201-1/2/3/4, ISO9080 is a better method compared to
ASME 31.3M, ASTM2837 because EN recognises the RCP-Rapid crack
propagation
and SCG-slow crack growth in the long term application.

Regards,
Kannan.

ATEX - including valve actuators and mechanically operated valves.

What is ATEX ?

On 1 July 2003 the ATEX Directive will become mandatory for all
electrical
and mechanical equipment used in potentially explosive atmospheres.
After this date, products without ATEX certification will be illegal on
the European market, and cannot feature the new CE mark.

Most manufacturing and process industries generate potentially explosive
atmospheres using substances from solvents to flour. Under the CE mark
regime, the onus is on the manufacturer, authorised representative or
importer to ensure products meet the requirements of ATEX, and keeping
up-to-date documentation to demonstrate compliance is essential - before
and after the CE mark declaration of conformity has been signed.

Despite an eight-year transition period, there is still a large group of
manufacturers completely unaware of the new directive and how it will
affect their operations.

ATEX - What Does it Mean ?
Designed to open up free trade across Europe, the ATEX Directive 94/9/EC
(ATmosphere EXplosive) sets out to align technical and legal
requirements
across member states for equipment and protective systems used in
potentially explosive atmospheres.

From 1 July 2003 it will be mandatory for all electrical and mechanical
equipment used in potentially explosive atmospheres to be compliant with
the ATEX Directive 94/9/EC. The burden also falls on the end user with a
second ATEX Directive 1999/92/EC and its requirement to assess an area
for explosion risk.

Previously there has been no obligation to use certified equipment or to
grade an area as potentially explosive, merely to conform to the Health
And Safety At Work Act and satisfy the Health and Safety Executive.
Users requested third party certification on any equipment specification
to show safety requirements were met.

ATEX Directive (1999/92/EC)
There are also new requirements for users. ATEX Directive (1999/92/EC) -
also known as European Directive 137 or the "ATEX Use Directive" -
covers
the health and safety of workers at risk in these areas and makes it
mandatory under European law to assess for an explosion risk and
classify
accordingly. Once an area is classified, the 'Use Directive' requires
only equipment
suitable for safe operation under those risk conditions to be used. This
will
increase the amount of 'Classified or Zoned' areas and, in turn,
increase the
demand for ATEX certified equipment -an obvious opportunity for
manufacturers to
develop equipment to satisfy this increased demand.

ATEX Directive (94/9/EC)
Also known as ATEX 100a and ATEX 95, this directive allows movement
throughout the European Union and has been in existence through
statutory
regulations in the UK since March 1996, since when manufacturers have
been in a transitional period.

Forcing manufacturers to gain certification of electrical and/or
mechanical products to be used in potentially explosive atmospheres
created by
flammable gases, vapours, mists or dusts, the directive applies to
equipment and protective systems in potentially explosive areas below
ground, on
the surface and on offshore fixed facilities.

ATEX 94/9EC does not affect equipment which is already installed and in
use. Products 'not placed in the market' are exempt - this can be
products or
equipment made by companies for their own use or by a manufacturer
specifically for markets outside of the European Economic Area.
The new directive brings under control three types of equipment.
These are: non-electrical equipment (eg. mechanical equipment);
equipment for use in dust atmospheres (eg. equipment for flour or
saw mills) and safety related devices (eg. vent systems, flame
arrestors,
suppression systems) and safe area equipment.

From July 2003, all equipment and protective systems for use in higher
risk areas must be marked legibly and indelibly with the name and
address
of the manufacturer, CE mark and number of Notified Body, designation
of series or type of equipment, specific explosive protection 'Ex'
hexagon
logo, year of manufacture and serial number. It may also need to carry
the EC Type Examination Certificate details.

For CE marking, as well as compliance with ATEX, all hazardous area
equipment must comply with any other applicable directives. Currently,
the CE mark does not prove ATEX compliance as some hazardous area
equipment may be CE marked through compliance with other mandatory
directives.

Under ATEX, manufacturers must design and test components to prevent
or minimise the risk of explosion due to the production or release of
explosive atmospheres. Essentially, manufacturers must consider every
possible electrical or non-electrical source of ignition. And, at the
same
time, consider all potentially hazardous environments a product could
operate in; the different ways it could be applied and the technical
ability of the person using the product.

Product Approval
As with all new regulations, all new products must be assessed and all
existing products reassessed. There are two elements to gaining product
approval - Product Type Approval (testing and assessment) and Production
Control (quality systems in manufacture).

The former involves compliance with the Essential Health and Safety
Requirements (EHSRs) described in Annex II of the directive. Electrical
equipment is well covered, but few standards cover non-electrical
equipment. Production Control involves a Quality Assurance type
procedure often with the responsible manufacturer being audited by
a Notified Body for compliance with the relevant annex dependent on
the type of equipment and QA system currently in place.

The route to compliance with EHSRs will see most manufacturers choosing
to prove conformity with the latest edition of the harmonised standards
for electrical equipment for use in potentially explosive atmospheres.
For all
equipment this will require testing and production of test reports. For
the higher risk equipment - electrical categories I and 2 and mechanical
category I - this testing must be conducted by a Notified Body, normally
culminating with the issue of an EC Type Examination Certificate. The
details of this certificate must also be marked on the equipment.

Manufacturers must also supply other evidence of compliance such as
proof
of a consideration of issues including general electrical safety and
EMC.
New standards are currently being introduced almost every month, so
working with a chosen Notified Body at each stage of the process will
help manufacturers keep abreast of current methodology and standards.

Protection Zones and Categories
Under ATEX, all products must be categorised by the level of protection
they offer against the risk of becoming a potential source of ignition
in
an explosive atmosphere. Defined categories for equipment conformity
are divided between surface and mining applications. The 'Use Directive'
describes zones to reflect the explosion risk.

The ATEX Directive makes Notified Body involvement mandatory in both
equipment assessment and monitoring of production for equipment for
use in Zone 0 areas (highest risk) and for equipment to be used in Zone
1 areas (medium risk). For equipment to be used in Zone 2 areas only
(least risk) the manufacturer has to maintain technical documentation
which includes evidence of testing and production control, although
a Notified Body is not necessarily involved.

To simplify the route to ATEX compliance, the CE mark regime allows
manufacturers to pick and choose a Notified Body to suit their
requirements.
Careful planning and working with a testing organisation with direct
experience of the CEmark regime will help speed up time to market.
__________________________________________________

ATEX Certification coding example...
CE - Ex - II - 2 - G - EEx - d - IIC - T4 - T amb

CE
This means CE mark permitted by the European Commission to show
compliance
with all EU directives applicable to a product.

Ex
Distinctive community mark to show suitability for explosive atmospheres

II
Group II - surface industries
Group I - for use in mines

2
Equipment category

G
G = tested for gases
D = tested for dusts

EEx
EEx means equipment tested under the latest European Harmonised Standard
for use in Explosive atmospheres

d
Certification Production concept
e.g. d(flameproof) to EN50018

IIC
Apparatus Group

T4
Temperature classification
T1 = 450 Deg.C
T2 = 300 Deg.C
T3 = 200 Deg.C
T4 = 135 Deg.C
T5 = 100 Deg.C
T6 = 85 Deg.C.

T amb
Ambient temperature range in service
(Standard between -20 and +40 Deg.C)

A further Directive covers the minimum requirements for improving the
safety and health protection of workers potentially at risk from
explosive
atmospheres, requiring risk assessments by effected employers, but this
article will concentrate on the equipment aspect of ATEX.

The Directive applies to equipment and protective systems in potentially
explosive areas below ground, on the surface and on offshore fixed
facilities.
Manufacturers need to design and test components to prevent or minimise
the risk of explosion, and must consider every possible electrical or
non-electrical source of ignition.

There are two distinct elements to gaining product approval Product Type
Approval (testing and assessment) and Production Control (quality
systems
in manufacture). Notified body involvement is mandatory in both
equipment
assessment and monitoring of production, for equipment for use in Zone 0
areas (highest risk) and for equipment used in Zone 1 areas (medium
risk).

For equipment used in Zone 2 areas only (least risk), the manufacturer
has
to maintain technical documentation that includes evidence of their own
testing and production control. This latter type of equipment may appear
to meet the requirements without having been subjected to full test or
certification procedures, hence users of category 3 equipment should
check with the supplier to ensure that evidence of conformity is
acceptable.

The definitions of the terms Category and Zone are interrelated.
Category 1 equipment may be used in Zones 0,1 and 2. Category 2
equipment
may only be used in Zones 1 and 2, whilst category 3 equipment may only
be used in Zone 2. The Certification coding (see coding example) defines
the hazardous conditions in which a particular type of equipment may be
used
and should be clearly shown on the certification. It may also be
necessary
to use an IS barrier with a sensor. If in doubt ask the supplier. The
ATEX
Directive is also a CE mark directive, so all equipment must be CE
marked, which
also means that it must conform with all other relevant directives such
as the
EMC and Low Voltage Directives.

With regards,
Kannan.

Bolt torque calculations.

--- In piping_valves@yahoogroups.com, kannan.sundaram@... wrote:

In continuation of one of the earlier mails on the subject, I would like
to add the below simple approach also.

What is the Proper Torque to Use on a Given Bolt
by Joe Greenslade

"What torque should I use to tighten my bolts?" is a question suppliers
of
bolts are frequently asked by end user customers. Many times I have been
asked if a chart is published on the recommended tightening torque for
various bolt grades and sizes. I do not know of any. This article
provides
such a chart for "Initial Target Tightening Torque. It See Figure 1. The
formula for generating these values is explained below.

The widely recognized engineering formula, T= K x D x P (to be explained
later in this article), was used to provide the chart's values, but it
must be understood that every bolted joint is unique and the optimum
tightening torque should be determined for each application by careful
experimentation. A properly tightened bolt is one that is stretched such
that it acts like a very ridged spring pulling mating surfaces together.
The rotation of a bolt (torque) at some point causes it to stretch
(tension). Several factors affect how much tension occurs when a given
amount of tightening torque is applied. The first factor is the bolt's
diameter. It takes more force to tighten a 3/4-10 bolt than to tighten a
318-16 bolt because it is larger in diameter. The second factor is the
bolt's grade. It takes more force to stretch an SAE Grade 8 bolt than it
does to stretch an SAE Grade 5 bolt because of the greater material
strength. The third factor is the coefficient of friction, frequently
referred to as the "nut factor." The value of this factor indicates that
harder, smoother, and/or slicker bolting surfaces, such as threads and
bearing surfaces, require less rotational force (torque) to stretch
(tension) a bolt than do softer, rougher, and stickier surfaces. The
basic
formula T = K x D x P stated earlier takes these factors into account
and
provides users with a starting point for establishing an initial target
tightening torque.

? T Target tighten torque (the result of this formula is in inch pounds,
dividing by 12 yields foot pounds
? K Coefficient of friction (nut factor), always an estimation in this
formula
? D Bolts nominal diameter in inches
? P Bolt's desired tensile load in pounds (generally 75% of yield
strength)

The reason all applications should be evaluated to determine the optimum
tightening torque is that the K factor in this formula is always an
estimate. The most commonly used bolting K factors arc 0.20 for plain
finished bolts, 0.22 for zinc plated bolts, and 0.10 for waxed or highly
lubricated bolts.

The only way to properly determine the optimum tightening torque for a
given application is to simulate the exact application. This should be
done with a tension indicating device of some type on the bolt in the
application. The bolt is tightened until the desired P (load) is
indicated
by the tension indicating device. The tightening torque required to
achieve the desired tension is the actual tightening torque that should
be
used for that given application. It is extremely important to realize
that
this tightening value is valid only so long as all of the aspects of the
application remain constant Bolt suppliers sometimes have customers say
that their bolts are no good because they have started breaking while
being installed. Thorough investigation commonly reveals that the
customer
has started lubricating the bolts to make assembly easier, but
maintained
to same torque as was used when the were plain finished

The table in this article shows that by using this formula a 1/2-13
Grade
5 plain bolt should be tightened to 82 foot pounds, but the same bolt
that
is waxed only requires 41 foot pounds to tighten the same tension. A
perfect 1/2-13 Grade 5 waxed bolt will break if it is tightened to 81
foot
pounds because the K factor is drastically lower. The bolts are fine,
but
the application changed. Suppliers need to understand this and be able
to
educate their customers to resolve this common customer complaint about
breaking bolts.

The chart is provided for quick reference by fastener suppliers and
users
for selecting an initial target tightening torque. This chart was
derived
by using the formula shown earlier. An example of the calculation is as
follows:

Product: 3/4-10 Grade 5 zinc plated bolt
Formula: T= K x D x P

? K= 0.22 (zinc plated)
? D= .750 (3/4-10 nominal diameter
? P= 23.046 pounds

Hopefully the chart will help suppliers with an initial answer to the
customer's question, "What torque should I use to tighten my bolts?"
Keep
in mind this is only an estimated value. It may provide satisfactory
performance, but it also may not. Every application should be evaluated
on
its own to determine the optimum torque value for each application.
Major
bolt suppliers should have tension indicating equipment necessary to
help
their customers determine the appropriate tightening values for their
specific applications. Keep in mind that if the lubricant on a bolt and
nut combination is changed, the tightening torque value must be altered
to
achieve the desired amount of bolt tension.

****************
Joe Greenslade is President of Greenslade and Company, Inc. located in
Rockford, Illinois. His firm specializes in providing manufacturing
tooling and inspection equipment to suppliers of screws, bolts, rivets,
and nuts throughout the world.

Joe is an inventor, author, and lecturer. He holds eleven US Patents.
Has
written over 80 technical articles for industrial trade journals, and
has
spoken frequently at trade association meetings and technical
conferences
on issues related to industrial quality for the past ten years.

He is an Associate Member of the Industrial Fastener Institute and a
member of the American Society of Mechanical Engineers B1 Thread
Specification Committee. In 1992, Joe was recognized for his technical
and
innovative contributions to the fastener industry when, at age 44, he
became the youngest person to be inducted into the National Industrial
Fastener Show "Hall of Fame. "

Flame Spray

Yes infact it is an interesting area. To go in detail my mail was indication of the possible HVOF-High Velocity Oxy Fuel flame spray application method. With regard to your query, I would suggest you to have a look into http://www.finishing.com/ a technical forum which is dedicated for specialists in this coating & polishing industry including the ENP and other varieties of polishing. Aluminium is an expensive choice, and has high resistance to acidic and neutral environment / atmospheres. But is considered to of high risk in explosion due to Aluminium itself. And it is generally not a preferance for high temperature. I am aware of two monopolistic companies in the major valve market -Italy, one is flame spray, and the other is Praxair. If you are procuring your subject materials from this market, you can avail the service of these companies. Praxair in India, does not do this coating service to my knowledge. With regard to flamespray, the link below gives the basic list of coating nos. but it is a small list and you have to check with them for more information, they give these technical information only to thier regular customers on a limited info basis, as the detailed info of the individual coating material is not shared in the website and kept as an 'internal distribution copy'. It gives specific information on Application, mechanical, chemical, application procedure, hardness and life expectancy etc. being properiatary to them. But as a customer you can get this info for deciding on the exact coat you require for your application.
http://www.flamesprayusa.com/materials.php
http://www.twi.co.uk/j32k/protected/band_3/ksrdh001.html

With regards,
Kannan

"M K Malhotra" mk.malhotra@eil.co.in

Dear Kannan You have given a very elaborative and informative response. Many thanks for that. The last para is of interest to me in the manner that in one of our high temperature pipeline, we were considering to use Thermally Sprayed Aluminium as external corrosion coating to withstand high temperature. If you have further informatio on this subject please share.

Kind Regards.
Manoj K Malhotra Engg. Manager Pipelines, EIL New Delhi.

Just to highlight though known to many, B 16.5 spells as....

5.4.1 General. Ring joint gasket materials shall conform to ASME B16.20. Materials for other gaskets are described in Annex C. The user is responsible for selection of gasket materials which will withstand the expected bolt loading without injurious crushing, and which are suitable for the service conditions. Particular attention should be given to gasket selection if a system hydrostatic test approaches or exceeds the test pressure specified in para. 2.6. 6.4.5.2 Ring Joint. The side wall surface finish of the gasket groove shall not exceed 1.6 micro-m (63 micro-in.) roughness. (This finish is applicable for the gasket surface also.)

Secondly B16.20 lists .......

The hardness of few gasket material Soft iron is 90 BHN Low carbon steel is 120BHN F5 grade(4to6Cr-0.5Mo) is 130BHN SS410 is 170BHN SS304 is 160BHN SS316 is 160BHN SS321 is 160BHN SS347 is 160BHN

Thirdly .....

As the whole purpose of the hardness concern is not to crush the gasket or damage the damage the groove and to have the right leakage proofness. As any other joint, in these high rating class joints, I would recommend you to check the torquing requirement of these bolting in your project, which I suppose are having bolt dia >=2". Accordingly do the leakage check and consult the stress engineer to recommend the prefered hardness level of the gasket. The hardness difference is very important and linked to the torquing. Then choose your gasket material...again....suitable for the service though some may claim that the service will never be in contact with the gasket but it is not true in practical situation. For these reasons the B 16.5 leaves it to the design engineer.

Check this link for online bolt torque calculation
http://www.zerofast.com/torque.htm and http://tech.groups.yahoo.com/group/piping_valves/message/73

Irrespective of all these rules and approaches ...do qualify from your end if the contract is correct. Sometimes, does mistakes happen on either side(Contractor or Owner or PMC) That is why the big weapon called Concession request / Deviation request with different names.....is available, and....if you are sure of your method of qualification.

Finally......

Although it is recommended that the rings are to be of hardness lower than the flanges to assure tight joints when gaskets are replaced or renewed, this feature may not be possible to obtain in the case of various alloys. Stainless steel alloy flanges heat-treated for optimum corrosion resistance will have the same range of hardness as the ring gaskets of the same material annealed to minimum hardness. Setting hardness as a minimum does not mean to have any technical reasons except for gasket renewals. Nace materials are a different subject altogether. Pl. check it out. Also verify if this hardness is linked to specific gasket predefined by client/pmc. If so, do go for alternative gasket like soft iron as it is steam service in your case should not be a problem. Also check if the hardness issue, same incase of other flanges in the stream.

Else you have the alternative and expensive solution - Metal spray used for hardfacing of seats and balls of all type of valves. This technology came for the carbide coating in the glass industry. Technology came from LindeGas called 'Carboflam' was adopted by valve industry for the W-Carbide, Cr-carbide coatings which usually starts from 15 microns in thickness. The metal composition defines the temp resistance, corrosion, porosity,adhesiveness and the hardness, usually selected by the company which specialises in this kind of coating which are few in number and has become a highly controlled knowhow industry. However this is not the only technology available in the market.

http://www.linde-gas.com/international/web/lg/com/likelgcom30.nsf/repositorybyalias/glass_carboflam_new/$file/Carboflam_43491235.pdf

With regards,
Kannan.

desaid@toyoindia.com Sent by: piping_valves@yahoogroups.com
28/11/2007 04:49
Subject [piping_valves] Increase the Hardness of RTJ groove?

Dears, Can any one give suggestion / opinion on below situation. We have flanged valve having RTJ flanges as end connection. The requirement is to have the min. hardness of groove as 160 BHN. Vendor is offering quite less hardness than 160. (Valves already manufactured.) How can we increase this hardness?
By overlaying or cladding ?
Or by any special treatment?

Please help.

Thanks in advance,
Dhwani Desai.

Bolt coating.

In addition to Raghu's email, sorry that I forgot to mention that the
multilayer polymer coated bolts are being recommended for service
temperatures of less than 200 deg.c and for all material bolting
assemblies in highly corrosive atmospheric seashore site locations.

Just to pointout, additionally the zinc reacting with SS being
refered as the LME-Liquid Metal Embrittlement effect. Which is true
for metal coated SS bolting and painting material having zinc as an
ingredient which can possible spill over during site painting
acitivity and during fabrication or erection welds crossing the
melting temp. of zinc which will lead to LME. Accidents of failure of
massive pressure equipments have occured due to this minor mistake of
paint spray on SS vessels before going for heat treatment in shops.
Moreover this embrittlement moves across the thickness.

With regards,
Kannan.

Bathula Raghuram wrote

Zinc- or cadmium-coated steel fasteners shall not be used for
applications above 400°F: these coatings may cause hydrogen embrittlement.
Especially avoid mixing zinc- and cadmium-coated nuts, bolts, or washers at
temperatures above 300°F: the zinc and cadmium will melt and mix. The
resulting mixture is known to cause intergranular cracking, with subsequent failure of the fasteners in a short time. Failure of fasteners as described above can result in serious injury to personnel and damage to equipment. Cadmium or zinc is not permitted where it would be in
contact with fuel oil, lubricating oil, grease, or petroleum-based hydraulic fluid. This restriction does not prohibit the use of cadmium or zinc plated fasteners in locations that are external to these systems if there is no danger of contaminating the working fluid. For example, cadmium
or zinc plated fasteners could be safely used as hold down or mounting bolts for a hydraulic control valve since there is no danger of contact between the external fasteners and the fluid inside the valve. Personnel should wash their hands after handling cadmium plated fasteners to avoid ingesting cadmium.

Kannan Sundaram wrote:

Felt to caution people who prescribe the bolt coating.

In an inhouse test of Polymer coated bolt of of a reputed Japanese vendor, which was to perform 4000 hours of salt spray test as per B 117, did not meet the requirement though the vendor's test certificates prooved so. The inhouse test was performed as in one of the plant it was used and has peeled off while normal wrenching and never stood even 1/4 of the life period gauranteed by the supplier. Literally all bolting of the plant had to be replaced by the client.

The final recommendation is that it is ideal to have a phosphating coat and a galvanizing or zinc coat and the final coat to be fluorocarbon polymer coat which really stood well in acc. with B117 in the inhouse test and has been proven in few operational plants.

So as a caution note, it would be a good practice to go for multiple coat rather than single coat for the general call for such coating requirements.

I do not want to name the companies explicity in this list for obvious reason.

Readers' experienced views are welcome.

With regards,
Kannan.

Industrial hoses and connecting fittings.

One more important design note. Some process engineers forget to
specify the depressurizing vent in the utility stations. It is
mandatory to have depressurizing vent in utility station just before
the hose coupling in the inlet piping. After the application of the
service the operators will dismantle the hose assembly and the
contained pressure of the service in hose may cause injury and it has
to released first for safe removal, so is why the venting required, so
is for the steam also.

With regards,
Kannan.

Industrial hoses and connecting fittings.

This mail is to update some news on Nitrogen hose incidents and
recommendations in specifying the same in utility stations. Take note
of the importance of specifying the NRV / Check valve in nitrogen
hose assembly. This is true for steam also for the reason that these
two utilities are used for chemical and alkaline and acidic purging
and cleansing. Also the importance of the right class of jacket to be
worn during such U-station operation.

http://www.csctc.org/TBT04-17.pdf

http://www.pdo.co.om/hseforcontractors/online_library/downloads/200702
25092604.pdf

You can find more hose stories by searching for 'hose rupture'
or 'hose failure'.

Additional the crowfoot or the clawtype coupler is being recommended
for Air and water services rather than the past camlever couplings due to
the flexibility and tightness in its design and without any rubber
sealing element.

Secondly, some supplier links which may give some good insight to
members who may be involved in specifying the same.

http://www.alfagomma.com/index.aspx?Lang=INGLESE&Branch_Code=99999
http://www.hydroscand.se/gb/catalogue/hosefittings.htm
http://www.hydrasun.com/catalogue/ (popular in Gulf region)
http://www.flexiblehose.co.uk/
Matec
http://www.par-group.co.uk/coupling.aspx?page=454
http://www.hosecoupling.com/products.htm
http://www.gates.com/europe/index.cfm?location_id=5377
http://www.ducting.com/Products.html
Dixon Europe

Emco wheaton has an interesting product suitable for mobile tankers
upload/download for hazardous fluids.
http://www.emcowheatoncanada.com/main.cfm?id=ED58215C-1372-5A65-
3B73B6624C2CA4A0

If anyone has interesting and useful info on the subject pl. share.

With regards,
Kannan.

Intergraph PDS model interface

Sajit, the MDP as written earlier, is a seperate database schema in PDS
where the complete model data is replicated by means of running a seperate
batch process by the admin. Pl. refer the PDS manual which has a graphical
layout of all the tables and field names and the relationship between
them. The MDP has been provided so that the user can generate any kind of
report they may require of the model, including mto, tonnage, linelists,
valve lists, etc. anything you may like to report.

In simple terms...the other DB schema contains all the live graphical data
of the model in encrypted form which is the graphical technology of
intergraph. For developers access to this data the MDL language was
created to talk with this DB and to extract information and to create
graphical components. For eg. if you want to place a pipe, you can write
in MDL language and can see in it in the 3D model space. PDS has objects
written in MDL language, where all the basic elements like, pipe, elbow
etc...have been made available ready made which are variable driven, so
when the length and dia is defined by the modeler the system runs the MDL
objects and creates the 3D component and user places the labels like line
no. area code etc.. Same for any other objects modeled. All these
graphical information is stored in the DB in encrypted form which is
another important technogy. User can also access these info using MDL
language to report the same. As specialist of MDL are not many in the
market, MDP batch was made available for broader userbase, which is simple
to query and report.

Now coming to your question of being a simple task,.....the DB records of
a simple 2000 line project goes nearly a million all put together. Which
is why MDP is not online but a need based batch processing. However there
is possibility to run the batch for a partial data, sections etc. Consult
your admin to know more on MDP batching options.

So you have two choice, either to write a MDL procedure and dump ascii and
compile in ms-access or to access from MDP directly thro' ms-access. As
nowadays companies are growingly standardising the so called assemblies( I
know few companies who call a complete system of lines as an assembly and
other companies a pressure tap as an assembly) to more broader level,
like the 'modular piping', there should be people who create these
assemblies...which is possible only by MDL experts.

With regards,
Kannan.
----------------------------------------------------------

sviswan@technip.com
Sent by: PipingDesign@yahoogroups.com
03/06/2008 11:15
Please respond to
PipingDesign@yahoogroups.com

To
PipingDesign@yahoogroups.com
cc

Subject
Re: [PipingDesign] Intergraph PDS model interface

Kannan,

I understand general Databases Access, SQL server or Oracle, how they
work.
I do not know how the MDP works. Therefore it is hard for me to imagine
why
such an update is required at all. Since this is a seemingly simple task
and one that is not so resource intensive.

Sajit

kannan.sundaram@l
inde-le.com
Sent by: To
PipingDesign@yaho PipingDesign@yahoogroups.com
ogroups.com cc
Sandiveloo@technip.com
Subject
02/06/08 07:09 PM Re: [PipingDesign] Intergraph PDS
model interface

Please respond to
PipingDesign@yaho
ogroups.com

One additional point. The MDP is not an online info, but is a procedure
option of PDS.
In the beginning phase of a project the process takes few minutes to
generate/populate the
MDP databank. As the project data size grows, it has to be schedule by the
admin for overnight
process. Especially when multiple big projects are on....then the server
power will be sucked
by the system and sometimes the MDP batch may crash... So depending on the
server
resource limitation and real project needs like yours the pds admin may
have to manage
the MDP creating batch.

But in overall the daily batch is not really required as the modeling
progress of one day
is insignificant in a one year project schedule, but may have significance
during the IFC.

With regards,
Kannan

sviswan@technip.com
Sent by: PipingDesign@yahoogroups.com
02/06/2008 16:47
Please respond to
PipingDesign@yahoogroups.com

To
PipingDesign@yahoogroups.com
cc
sandiveloo@technip.com
Subject
Re: [PipingDesign] Intergraph PDS model interface

Kannan,

Thanks for your input, Pls. see my replies within your mail below.

Siddharthan,

Can you pls. provide an input to this discussion.

Sajit

kannan.sundaram@l
inde-le.com
Sent by: To
PipingDesign@yaho PipingDesign@yahoogroups.com
ogroups.com cc

Subject
02/06/08 04:04 PM Re: [PipingDesign] Intergraph PDS
model interface

Please respond to
PipingDesign@yaho
ogroups.com

The DB is not hidden by Intergraph but restricted by your PDS admin to
prevent people accessing
the information and possible damage the data cause model corruption and
etc. which is a nightmare
to them.

Sajit-----------------
I hope it is so. I am talking of only a read only link, which is the view
as I have said. This cannot do any corruption.
Anyway I will ask again.
-----------------------

Only the graphical information is encrypted in the DB. Even that can be
exploited if you know MDL language.
So nothing is really hidden in PDS for the right person.

The MDP-Material data publisher chart of PDS gives the complete data model
of the model. If you have
simple SQL (Query language) knowledge, and having simple read only access
of this MDP, you can
have any kind of reports generated where only your imagination is your
limits. Sometimes MS Access may
be slow due to the size of model data in projects having higher than
10,000 lines.

Sajit----------------

That is very encouraging.
I should be able to manage the SQL and Access, if this link was available.
---------------------
Another solution is to ask your PDS admin to make some standard queries
made available to you
to have on-line reports.

Another point to mention. You cannot have real status of lines being
modeled. Reason being, even if a
pipe is placed with the attributes, the MDP will account the line is
modeled. The completion of the line
cannot be known unless the modeler does maintain a modeling status
personal log.

Sajit----------------
There is an application called PPMS within PDS to which the designer
enters
the modelling progress %. Nevertheless that is also, as you say, not much
reliable.
--------------------

With regards,
Kannan
Linde, Germany.

sviswan@technip.com
Sent by: PipingDesign@yahoogroups.com
01/06/2008 17:19
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PipingDesign@yahoogroups.com

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Subject
[PipingDesign] Intergraph PDS model interface

I was wanting to extract information regarding the modelling status of
lines from PDS. This is for use with an Access database to do Isometric
production tracking.

This is currently done by exporting the information as a text file and
then
reading it from the text file into Access table. This is a static method
requiring an export each time one wants an update.

In Oracle / SQL Server database parlance, this is done by creating a view
(query in Access).

I am told by the PDS Admin group that such external links to the model
data
are hidden, intentionally. The reason is that Intergraph does not want
someone to figure out how the data flow happens within and come up with a
competing application.

Sajit

.

__,_._,___