Plate 516 gr 70 Segregations 1

[Makun]

Hi, I'm analyzing inspection's results of a vessel. We found a some indications in the middle of the thickness. The vessel is a Freewater KO and the operative pressure is 3 kg/cm2. I search in API 571, and said that it may be susceptible to HIC. Should I analyse by API 579? We didn't found a crack during the inspection, just segregations.

Regards

 

[metengr]

You are probably referring to inclusions.

 

[Makun]

Yes, I'm referring to inclusions (non metallic)

Thanks

 

[metengr]

If you had not found cracking leave it alone. Perform periodic inspections for cracks.

 

[Makun]

Do you have any bibliography to justify? I look in API 579 but is not clear at that point

Regards

 

[pradipgoswami]

Hi Makun,

If the service involves Hydrogen, especially wet H2S service, then definitely it's concern.Or else as suggested by Metengr "periodic/regular inspection so as to monitor the areas around the segregation would be advisable. Segregation in wet H2S service could be the initiating factors for SOHIC(please see the link below).
Segregation is similar to inclusions and may lead to worst case scenario.Look under chapter 7 in 579.

Thanks.

http://www.twi-global.com/technical...teels-review-of-current-knowledge-march-2007/

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
All provided answer are personal opinions or personal judgements only. It's not connected with any employers by any means.

 

[Makun]

Thanks, we began evaluating the vessel taking the group segregations as a lamination. With this premise, the indication would not comply with the requirements of API 579 part 13. As you indicate, would not be the most appropriate evaluation procedure. The vessel has inner lining, for this reason, it can be considered as susceptible to SOHIC?