HIC test on a valve 2

[ElenaN]

Hi,
Im new in this industry and I work for quality assurance job in our company.
Our company makes carbon, stainless and high alloy castings for industrial valves, pumps and other flanges.
Currently, our customer required a valve made A216 WCB and also HIC, SSC test on that valve.
As I know, HIC does not occur in castings, regardless of the material.

Is that necessary for the valve?
or is this not matter because the test will be works on specimen of the product not product itself?
On the NACE there is no specification about this directily.
What is HIC test? How does the HIC test works on the product exactly?
If the customer wants..do we have to do this test on our porduct regardless of spcecifications like NACE or others?

Im sorry about my english skills. I think maybe you cannot understand my words accurately.
But If you answer my questions, I will thank you.

 

[SJones]

HIC does not occur in castings, rehardless (sic) of the material

HIC is specific to carbon and low alloy steel. It would be more advisable to state 'there is a low likelihood of HIC occurring in carbon and low alloy steel castings.'

Regarding the HIC test itself, the standard is NACE TM0284 as directed by ISO 15156-2, Annex B. One thing that both of these standards come up short on is actually indicating that the test pieces are to be taken from a product in the final supply condition. The omission is generally compounded by purchasers' specifications also failing to clarify the requirement. A further issue is that ISO 15156-2 is predicated on HIC only occurring in flat rolled steel, and products made from it, whereas the NACE document also deals with forgings and the like. So, who is right?

As a supplier, you contract with the purchaser to provide an agreed product. Thus, if your company has accepted the purchase order on the basis that HIC testing is to be performed, then it is to be performed unless waived by the purchaser.

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.

 

[Chumpes]

hi
HIC damage is a SCC mechanism in wet H2S environment where the entry of atomic hydrogen produced by corrosion reaction is favoured by presence of wet H2S. hydrogen diffuses in metal and recombines at sites of lowest energy, i.e. at the interface between intermetallic particles and bulk metal. That is why the shape and size of the particle-bulk interface area is of great influence on occurrence of HIC, and it is known that CS metallic products not originated form plates (castings, forgings,...) are less sensitive to HIC than flat rolled CS plates, but not necessarily immune Under severe conditions.

The test method for HIC NACE TM0284 consists in sampling metal specimen in the original material (destructive), then testing in a normalized aqueous solution deaerated and saturated with H2S gas (refer to NACE std). All product forms can be sampled but it is up to you to decide whether the HIC test is necessary for cast valves because NACE TM0284 is only a testing method and does not give information on whether the material shall be tested or not.

With regard to our experience in our fiel of application, our philosophy is to consider small limitations of the steel chemistry (S, P) is sufficient to provide resistance to HIC for castings and forgings without any HIC test (more or less in line with MR0175) in our service fluids. But HIC testing remain mandatory for HIC plates in our point of view. Other service fluid may ask for HIC test of castings too.