PMI Testing on valves pipes and fittings

[deepuvarghese]

Hi All,

I like to know Positive metal identification testing requirement for valves and fittings.which standard ask for it and how can we determine the extend of testing.
Deepu

 

[stanweld]

PMI requirements must be determined by criticallity issues. What will happen if the wrong alloy material is installed in the piping system? Does the valve manufacturer or submanufacturers have their own PMI requirements? If the items are off the shelf, small bore valves, you may only wish to test on a lot basis. You may wish to test each pressure part or additional componenets of the valve should a failure prove catastophic.

 

[SJones]

API RP 578 or EEMUA 149

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[deepuvarghese]

Thanks Steve and stanweld for reply.
Is PMI testing recomended for trim materials of valves.The quality document ask for PMI testing for all presure containing ,pressure controlling and parts exposed to process fluids.
Doesnt this covers every thing.
Is in standard does it specifies what is pressure containing, pressure controlling parts.
Even for CS valves the trim material is SS.Does normally the PMI testing is done on this.
Does some one has extract from standard or sections from standard.I donot have a copy of API RP578 or EEMUA 149

How can I argue that PMI is not required for CS Valves.

Please clarify.

Thanks
Deepu

 

[Metaljon]

It is worth doing PMI as it surprising how common it detects material mismatch. If you I going to do PMI then you might as well do the lot. The Niton and Innov X-delta are very quick. By the time you have mobilised a tech to site the costs will be about the same whether you do 5 or 10 parts. For carbon steel components, PMI wouldn't tell you much as there is nothing to detect unless there are minor/trace alloying elements in the steel which are critical to component corrosion resistance or mechanical, creep properties etc. Final point PMI is used to confirm the basic steel composition is correct and not to verify the accurate composition.

http://nz.linkedin.com/pub/jonathan-smith/39/25/589