Intergranular Corrosion Testing for Cast, Bar and Forge Materials

[nickypaliwal]

We have an Alloy 825 valve. Our client has asked for IGC testing of all Alloy 825 materials in the valve.

However MESC SPE 76/213 (Nickel Forged Alloys) and MESC 77/203 (Valve General Requirements) only tells about IGC of Forged Alloy 825.

They do not comment on the testing required for Cast and Bar ALloy 825 materials.

Vendor is requesting to accept the valve with IGC test of only forged parts and not for cast and bar parts.

Please advise if there is any code which talks about IGC requirement of Cast and Bar 825. Also comment if it affects whether the material is forged, cast or bar.

 

[SJones]

Of course 76/213, by its very title, is only going to address forged material. The first paragraph in 2.4.2 of 77/302 (not 203) refers to a requirement for statistical process control of corrosion testing for forged and cast nickel alloys. In the same sub-subclause, it goes on to ask for ASTM A262 Practice C testing for 825 forgings only.

Clearly, someone needs to provide a bit of clarification.

Steve Jones
Corrosion Management Consultant

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

All answers are personal opinions only and are in no way connected with any employer.

 

[jwhit]

ASTM A494, which is the usual material spec for cast 825 (Alloy Cu5MCuC)does not pick up corrosion testing of these alloys either. It is up to the customer to tell you which corrosion test to use and the acceptance criteria they need. Considering that you are referencing Shell Specs. there may be a Shell casting specification that they have not provided you with that will cover the testing. I would be going back to them about this one. Personal experience has been that the required information isn't always relayed to or passed on by the buyers.

 

[nickypaliwal]

MESC SPE 77/302 (Thanks Steve for correction) is a general requirement for valves and not specific to forged materials. It also talks about IGC of forged materials.

The valve datasheet additional specification also refers to above specification. I have reviewed all other specs mentioned in the valve datasheet but have not found anything about IGC test for cast and bar.

 

[EdStainless]

There is nothing that prevents applying the same IGC test to other product forms.
It just isn't required in the other product specifications.
One would (should) expect that all material of the same grade, regardless of process would meet the same metallurgical criteria.
If your client has this written into their spec, then price it in.
If they are asking after the fact, then well those horses have left the barn.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[SJones]

Ed - spot on. The fault lies with the poor wording of the Owner's specification which gives manufacturers a belief that the testing is only to be applied to forged products. What is tending to happen is that instead of simply accepting the Owner's clarification to test all product forms and making a corresponding compensation claim for the unclarity, 825 casting suppliers hide behind the text of G28, which states that it is 'not applicable to cast products,' and just flatly refuse to perform the test (even when told to change it to A262). What have they got to hide?

Steve Jones
Corrosion Management Consultant

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

All answers are personal opinions only and are in no way connected with any employer.

 

[OGMetEngr]

A262 Practice C is an acceptable test method for alloy 825, and acceptance criteria and test variables that demonstrate resistance to intergranular corrosion are available in literature. As others have stated, product form should not make a difference if resistance to intergranular attack is desired.

 

[nickypaliwal]

Thanks to all for your kind suggestions !!

 

[jwhit]

It isn't necessarily a matter of having something to hide. I usually suggest going back to the customer and asking for clarification of the specification and do they really need it. If the answer is yes, then they usually get what they need. However, I have also seen cases where somebody with more authority than I have, will say that it does not apply, therefore we aren't doing it. Normally,it gets done after much debate. The issue is that they don't want to understand or else don't have the basic technical knowledge to realize that for this or that application it is necessary to measure a particular set of properties. People don't like change or variation from the norm. Some are also just plain ignorant and wish to remain that way. As is the case here, there is also a failure to clearly communicate the requirements to the vendor. If the PO reads cast components shall receive IGC in accordance with MESC SPE 76/213 there is no question that it is needed.