I have problem in reviewing QC document for Pressure reducing desuperheating valve (PRDS)

material: A216 WCC
rating : ASME 600#
Plug and seat ring material: 410 SS (ANSI 410)

my question:
1. i asked for NDE liquid penetrant (PT) test form hard facing area form plu(plugvalve) and seat ring material.

but our contractor said NDE (PT) test is not required since the material is 410 SS, if the material is 316 SS (A276-316) then it is required.

I am confused why plug and seat ring does not require NDE (PT) test if the material 410 SS??

My suggestion is that you should ask the contractor in writing for the reason, as you have at least two possible reasons for the answer:

1. Commercial /contractual reasons: the contractor sees extra costs or commercial complications for complying with your demand.

2. The contractor sees (as you presume) some technical reasons bound to either standards or common practice elswhere not to do this test.

.. or a combination of both.

Technically you want a thoroughly tested product. If you look at the detailed properties of 410SS this is a product that normally are hardened by annealing, and if annealed at wrong temperatures can alter properties away from the target properties from your purpose ( lower yield-strength or more suspectible to corrosion).

A dye penetration test could tell you something about the result of the production process of the piece regarding surface exposed properties (either walzing, barstock or casting cutting, annealing, grinding and welding -if any).

The yield strength something about the overall result.

I do not see why there should be a problem giving you a price for any sensible test, or do them, if you think the cost /benifit postive for ensuring a critical component's quality.

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