Hydrogen Embrittlement on metals.

Though the subject is quit huge to discuss, I would like add few morepoints though not all.

1) The purity level of the Hydrogen is also categorised as less than 99% ormore than 99%.
2) The pressure is one important element(hardly addressed during designphase by material engineers), for less than 99% purity which means amixture, the partial pressure should be >1bar for the hydrogen to have itsshow.
3) Limits are present for Carbon monoxide and Oxygen and other elements aswell, which induces the phenomenon described by you(Owen).
4) Whether the system is under cyclic condition or not which applies to PSA and likes.
5) Materials are defined by their yield and tensile strengths limitations.Take note the equipment material prescription varies differently frompiping material for the same conditions.
6) Not the least though, Hydrogen embrittlement should not be equated withHydrogen induced cracking.

Coming to the point of temperature, linked to materials, considering carbonsteel as the material of constr., for eg. A well known refinerylicensor prescribes the temp. limitation at 260 deg.C, A German company holding numerous technologies in the subject of Hydrogen limits the use of Carbon steel to 200 deg.C, A UK Engg. company having H2 licenses, limits it to 240 deg.C. As I had seen lab test reports andfound H2 effects above 200 deg.C, such variation of 200 to 260 is quit abig gap under standard test procedures.

Let me know the thoughts of our groups on the temperature factor, what could be the reasoning behind such broader limits.

Some useful links for members interested further study.
http://www.uni-saarland.de/fak8/wwm/research/phd_barnoush/hydrogen.pdf
Some site generalises the subject which cannot be put into practice or inyour engg. Take caution, in your understanding of the subject.
http://octane.nmt.edu/waterquality/corrosion/hdamage.htm
http://www.corrosionist.com/Corrosion_Control_Offshore_Oil_Gas.htm
http://hrc.nevada.edu/qa/SIP/SIP-UNR-018R0D0.pdfhttp://www.hydrogen.energy.gov/pdfs/progress05/v_a_4_adams.pdf

With regards,
Kannan Sundaram

"Owen Jenkins" <owen@osjl.co.uk> Sent by: Tomaterials-welding@googleg <materials-welding@googlegroups.com>roups.com cc
Subject21/04/2009 20:49 [MW:2002]
Re: effect of H on notch strengthPlease respond to materials-welding@googleg roups.com

Ali,The name is Owen, not oven. An oven is something in which you heat food, oroccasionally heat-treat metals!

For hydrogen embrittlement to occur, you must have monatomic hydrogendiffusing through the metal and gathering in grain boundaries. Monatoms ofhydrogen are small enough to diffuse through grains of steel. Theembrittlement occurs as a result of monatomic hydrogen atoms diffusing intothe grain boundaries, reacting to form molecules of hydrogen gas, whichthen force the grains apart. Diffusion and reaction rates both slow withdecreasing temperature, hence the effect of hydrogen embrittlementdecreases below a certain temperature. The effect of the ductile-brittletransition then becomes more important with decreasing temperature. It isalso worth remembering that, at constant pressure, the volume of a givenmass of hydrogen will decrease with temperature, or, at constant volume,the pressure will decrease with decreasing temperature, hence the drivingforce pushing the grains apart will be reduced. If it is too cold for thehydrogen atoms to diffuse through the steel, HE can't occur.

The monatomic hydrogen is commonly formed as a result of acid/metalcorrosion reactions (e.g. pickling steel prior to painting) or otherreactions in which hydrogen is liberated as a cathodic reaction (e.g.fusion welding where water is present or there are hydrogen compounds inthe flux). The hydroxonium (or hydrogen) ions are reduced to monatomichydrogen by electrons from the dissolving (corroding) metal or the weldingcurrent flow. The monatomic gas can diffuse through metal grains - thediatomic gas molecules can't.

2H+ + e- ® 2H.2H. ® H2

Some steels are much more prone to hydrogen embrittlement than others. HSLAand high strength carbon steels tend to be more problematic than others.Hydrogen embrittlement can be prevented by suitable heating to anappropriate temperature after the process which generated the hydrogen (oneof the functions of post-weld heat treatment), to allow the hydrogen todiffuse out of the steel. If you have a properly qualified weld procedure,the PWHT should be designed to mitigate the effects of hydrogenembrittlement.

When HE is suspected in cases of failure, there is never any sign of thehydrogen - it has all long gone, so it is usually inferred from thecircumstances and the nature of the cracks.

Regards,
Owen

New in Piping field

Welcome Sanjay.

I do not know of any ebook as such to cover the big subject of piping. However you should start with OP Nair's Piping Handbook. And you can also have a read of the B31.3 lite in the below page.

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

Good luck.
Kannan

--- In piping_valves@yahoogroups.com, "sskukade007" <sskukade007@> wrote:
>
> Dear All,
> I have joined new in piping.
> can you recommend me e books for theory of piping and allied components
> (valves/flanges etc),reference tables,diagrams etc.
> Thanks.
> Sanjay.

Double offset butterfly valve with metal seat

Pl. read catalogs for more understanding.

The subject of seating in double ot triple offset butterfly is litte bigger than other valves due to the emphasis given to the application and operating conditions.

There are quit a few proprietary seat designs. For eg. the graphite layers gets eroded in few weeks to months due to operating condition resulting in big leak and pressure drops. The profile of the seat and disc is also important which developes the cavitation effect and pitting of the seat. So in the selection of a seat the operating condition such as the opening angle, pressure, which in turn will affect the operating pressure in turn the system design itself. So a well thought process is essential in the butterfly valve type and seat selection.

In solid seat the cost makes the big difference.

Regards,
Kannan

--- In piping_valves@yahoogroups.com, "ashoksiva1982" <ashoksiva1982@> wrote:
>
> Dear all,
>
> I have an enquiry for Double offset butterfly with metal seat. The design pressure shall be 40 bar. Can any one know the seating arrangement of competitor valves.
>
> I got some information from the below link. I need some more arrangement for the above requirements.
>
> http://www.sz-yll.cn/upload/814/200631485558638680174.pdf
>

--- End forwarded message ---

US Equivalent of Workstoff Nrs.

The official Beuth's listed equivalent are

1.8963 - ASTM A618 GR.II
1.7218 - ASTM A 29 /A 322 / A 519 GR.4130
1.0037 - ASTM A 36, A 109, A570 GR. 30

Regards,
Kannan.

On 1/12/09, Darji Nilesh (Mumbai - Machinery) <N.Darji@ticb.com> wrote:
 
Dear Friends,
 
Requesting you help to furnish Eq. ASTM Grades for the following material: -
 
1.        1.8963 (Is it better than SA 242 Gr.2 ??)
2.        1.7218 (Required material by Process data sheet is A 1045. Material 1.7218 is better than A 1045 ??)
3.        1.0037 (Required material by Process data sheet is CS-Epoxy painted. Selected material by Vendor is 1.0037, Is it better option ??).
 
Matter is little bit urgent so, kindly furnish your response before noon.
 
With regards,
 
Nilesh.

Branch components.

Firstly, I would like to highlight the word latrolet, weldolet are proprietary names of BF. However it has become synonym in the industry to use those names which is not correct. It is also referred as branch-olets prefixed by 45 deg, 90 deg, etc. not to confuse with proprietary name. Even the ANSI codes do not refer BF names.

Coming to the question, no doubt it is a seamless pipe made reinforced branch fittings. The beveling also looks fine for the profile of the pipe. Being a non standard size, the dimensions have to be verified  with the manufacturer only. But if you ask if forging or pipe made item is acceptable, the answer would be...both can be accepted as the subject is the reinforcing area and cross section thickness.

Additionally, the general opinion is that the BW Reinf.branch fittings has to be used within the available STD, XS, XXS, 160 is not correct. Though being standardized by manufacturer's, we can prescribe actual thickness requirement within B36.10/19 and to std plate thickness. As per my verification all the manufacturer's facility has the flexibility to manufacture the same.
For eg. MEGA a reputed manufacturer in Bergamo, near Milano, Italy is on such vendor. I would say apart from BF, they are the best company with the know-how of  reinforced branch fittings and any other forged components. Their catalog gives a detailed dimension of all types of Rienf. branch fittings for all thickness and diameters of B16.10/19, including the 32".

http://www.mega-spa.com/index.php?option=com_content&task=view&id=28&Itemid=43

Moreover some forging manufacturers like MAWO fittings in Germany do make special designed branch components which are not really looking like a 'olet nor a coupling and not always forged. Such components have been tested and proved at site and has less material and flexibility in mass manufacturing and of course cheaper than the so called weldolets or sockolets or flangolets etc. And the good part is the B31.3 code do not pose any restriction in such configurations. Pl. take note these components are proprietary of their customers such as BASF, Linde for example.

So I would suggest to use the freedom of the code to invent and design your own new, cheap and economical and ease in welding with reduced fabrication and testing costs by avoiding the cumbersome welding process involved in the BW branch fitting. The best would be as Raghu suggested, the RF pads, but that also has its disadvantages in the operation life span.

Regards,
Kannan.

On Fri, Dec 12, 2008 at 11:19 AM, Bathula Raghuram (Mumbai - PIPING) <R.Bathula@ticb.com> wrote:
Can any one pl. share their experience on large size latrolets? I have not seen latrolet like this shape before, it looks like the vendor has taken a higher thickness pipe and machined to suite the curvature on run pipe. It s 32" x 28" latrolet weighing almost 670 Kg. in absence of catalogue for this size or any dimensional standard really it's impractical to judge whether it is a correct type fitting or not?

KAMOS RTJ Gaskets

I have not used this gasket but heard of this from one of the vendors. To what I understand from him and later discussing after your email, it seems it does reduce the time as you mentioned due to the difference in the method of testing. And as per the vendor this gasket does not have any disadvantage compared with the conventional ones from the operation experience point of view. But the concept is not new as other companies like kroll and Zieller are attempting on such variations.

Another special design gasket is available and being used by some companies like BASF and Statoil. The company is Jungtec, probably a more unfaimliar company. But they have good ideas and working design concepts and good long experience in field, on gaskets. On the subject of leakage after maintenance Jungtec is quit good.
Thier site is http://www.jungtec.de/en/productsoverview.html

For our friends to know more about the subject gasket... http://www.karmsund.no/2.1_kamos_rtj.htm

With regards,
Kannan.

Mohamed Ibrahim <mibrahim_ak@yahoo.com> Sent by: piping_valves@yahoogroups.com 20/11/2008 15:13 Please respond to piping_valves@yahoogroups.com

To piping_valves@yahoogroups.com cc kannan.sundaram@linde-le.com Subject [piping_valves] KAMOS RTJ Gaskets

Dear Friends,

 
Can you anyone please advise as you have ever used KAMOS RTJ Gaskets in your project as our client TOTAL asked us to see the feasibility to use such Gaskets in our Pipeline Project. Normally these gaskets will allow us to skip the standard leak test,cost reduction and can reduce down-time connected with testing.
 
Best Regards,
 
Ibrahim.

Design standard for ball valve

Dear Nitin,

Unofurtunately I was on leave and took sometime clearing all my personal emails. However it is disappointing our dear members have become more reluctant and lethargic to have discussions mutually benificial.

Coming to the query, to my knowledge of American standards, this size and rating is not covered for the obvious reason being unusual and are yet to be standardised. The solution in your case is to indicate the design to be in acc. with API 6D and F/F to manuf. std. I also have doubt if any manuf. will make a RB valve in that size. So you may have to consider only FB type. For testing of such valves ensure you mix API598 and API 6D to suit the design and service condition as many suppliers practically are unable to meet API 6D creteria for such large size. This is from my inspection experience.

If alternate valve type can be thought about in your application, definitely you should take that change. The key reasons being the maintenance of seats, back flushing, stem packing overhauling is going to be more complicated than any other on/off valve or even a flow control valve. Last but not the least, cost varies in the region of 25 to 40% more. for valves above 32".

So use of ball valves above 28" should have the right reasons.

Regards,
Kannan.

"Hanamapure Nitin \(Mumbai - Piping\)" <N.Hanamapure@ticb.com> Sent by: piping_valves@yahoogroups.com 07/11/2008 06:55

To <piping_valves@yahoogroups.com> cc Subject [piping_valves] Design standard for ball valve

Dear all,

I am looking for design standard for 600#, 42” LTCS reduced bore ball valve used in sour service.

Could anyone suggest me the design standard?

Thank you.

Best regards,

Nitin Hanamapure_._,___

AISI 307 reference.

Dear friends,

Atlast after pushing the sales manager and contacting the design manager directly, I found that the AISI 307 was wrongly indicated in their drawings and that it is a welding wire used for dissimilar welding to be designated as 'AVESTA 307-si'. It is being adapted by these manufacturers for cutting cost on the price of such valves in overall, by a welding overlay on the valve body itself. And having good hardness of 220 BHN and with the usual trim of 13Cr/316/304 the seating/disc hardness difference is taken care of. Incase of maintenance the welding is lapped onsite. No seat rings, threading, seal welding of the rings needed...looks a good idea and it does depend on the type and constructional design aspect of the valve and the fluid system.

The link provide by the Design manager of one of the valve company.

http://www.avestawelding.com/2813.epibrw

Also I found that the AWS designates as 'A 5.2 E 307' of the solid wire type with slight difference in the composition as per AJ Marshall's manganese steel welding info. And another one called 'super 307 / AWS E307-16' from SuperTech, Germany. Looks a lot of variations are available under 307.

The subject valves involved in my case was conventional check valves & NS check valves.

With regards,
Kannan Sundaram.

   
Dear members,

I would like to know more about AISI 307 which is being used by certain
suppliers as a seating of valves. The suppliers are not able to give the
exact ASTM references, but they say it is ...more or less....equivalent to
X15CrNiMn188(1.4370) of DIN. However I found this DIN material being used
generally to make check valve pins. I am having doubt if it is a
precipitation hardened steel category(which is usually prescribed for
stem/disc/ball/blade/diffuser materials requiring high strength) or a
something related to welding rods.

From my search it looks more of a welding overlay material. However I
could not find any ASTM specification reference of it. Can somebody
specify the same for me to check out the details.

With regards,
Kannan Sundaram.

Valve Datasheet templates

Dear members, sorry to forward this email quit late as I was on vacation.

 

This link looks quit informative.

----- Forwarded Message ----
From: Goran <goran_maaspers@hotmail.com>
To: kannan_cit@yahoo.com; ahmedeissa16@yahoo.com
Sent: Friday, November 21, 2008 6:43:42 PM
Subject: Valve Datasheet templates

Hi guys,

 

I stumbled across your correspondence at piping-valves.blogspot.com regarding Valve Datasheet templates.

 

This link may come handy: http://www.standard.no/acrobat/L-001/VDS/index.htm. These data sheets are used as is or customized to specific requirement by the norwegians. Use with sound engineering practice.

 

 

Best regards,

Goran Maspers

Sweden

Hydro test-max holding period

The holding period depends on the time needed for inspecting the system thoroughly. Minimum is 10 minutes. Especially the gas tests calls for 100% weld and mechanical joints being examined.
Also we have to ensure the limits of test pressure defined by individual components also to be taken care not to damage the components for eg. the soft seating or lining or to replace them with pipe spools.

To my info the repeated call for Hydrostatic test on the same system, the pressure need not be changed from the code to its design pressure as most of the case if any major leaks are identified, the test is performed again at the same pressure and not to reduced pressure. It is independent of the holding time. Holding time risk are purely defined by inspecting time and the in-line components and not of the piping components. It is a usual practice to remove all in-line components which has reduced testing pressure conditions.

The maximum test pressure is the pressure at which the pipe reaches its yield stress. In most of the cases the problems can be tracked back to the original thickness calc of the piping system where in somecases you may find the thickness not sufficient to take the test pressures but will suit the design pressure. When you design the piping class for rating condition you may have some margins to accommodate the test pressure but not always especially in the larger size range above 24". This makes the site testing team to reduce the test pressure adjusting to actual pipes purchased and being used and of the elevation impact of the system. Also piping connected with vessels pose a diff. situation and defining the test pressures requires a different judgement as the approach differs from company to company.

Most important thing is to question the need of hydrotest for a system to process dept. who defines the requirement.

Regards,
Kannan.

Aarpee <ramprasad.chari@gmail.com> Sent by: materials-welding@googlegroups.com 24/10/2008 08:29 Please respond to materials-welding@googlegroups.com

To "Materials & Welding" <materials-welding@googlegroups.com> cc Subject [MW:1236] Hydro test-max holding period

As per B31.3 Hydro test is carried out at 1.5X Design Pressure.Holding
time for Piping spools is normally 30 minutes but at times 4-6 hours
for Gas applications.Can this be held for 24 hours?What is the
potential risk?It is normally indicated that after Hydro inspection
for 10-30 minutes at 1.5X Design Pressure,if you intend doing further
inspection then same can be done at a pressure not more than the
design pressure.Opinion of the group is being sought thro this mail
Regards
Aarpee