Strip check test and wedge material

Two possibilities

1) Copper strip test for LPG gases. check the link.

http://symp15.nist.gov/pdf/p153.pdf
http://www.onyxnet.co.uk/clients/mastrad/copper.htm

The COS impurity can form H2S which comes under NACE. So is why the copper strip test is done. In your case it has no meaning as it is relevant in the msd activity of basic engg.

Other metal strip tests are existing like the silver etc.

2) It is corrosion test.(By coupons as in NACE)

http://www.freepatentsonline.com/4338097.html

Also check perry's handbook 28-10 on testing methods.

This test gives the measurement of rate of corrosion simulating the actual process condition. Like the background of nelson curves. This is not the job of the EPC contractor but the job of the Basic engg company and licensor to define what choice of material to withstand the life of the plant and define the required corrosion allowance. Detail engg. is NOT basic engg. In detail engg. we can just ask the vendor to comply with NACE std. for the ITB material prescription. Such corrosion test is very expensive and time consuming as it takes weeks to corrode the metal and measure the reduction of thickness. Calling the vendor to do such test is nonsense. If he can stamp NACE compliance, it is understood he has done such a sample test to get the accreditation for a few years period.

The third possibility I am waiting for the vendor's reply latest by tomorrow and it seems it was done few years ago for a project by one of his colleague.
 
On acceptance of forged and casting, in general till 4" the forging is offered by default. It is better not to define it in your datasheet. If required you can use the same breakup of the body(forged/cast). If you have not defined and vendor offers all in casting reject and ask him to follow the body size break as a min. However there are some good cast materials used for stem against barstock. Such castings can be accepted depending on the process area and your overall understanding and judgement of the frequency of operation and the operating pressures.

The above is applicable for all kinds of obstructer.

With regards,
Kannan

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One more query..
Whether to accept cast material for disc/plug/wedge instead of forged.I m really confused ,becaus all our vendors have offered cast material.


-Strip check test is required for 1% of total ordered quantity of valves (min. 1 no) for all valves in process / NACE / Hydrogen application
 
This is our ITB requirement.& vendor has regretted to give the same.
I have searched on net....but didnt get exact test procedure, related to valves.

Regards,
Sheetal Patil

Aker Solutions