SSC, SZC, SOHIC- ISO15156-2 2

[nickypaliwal]

NACE-MR0175/ISO 15156 - 2:Lab Test Qualification

1) Above document states that material needs to be qualified for SSC to test it for SOHIC/SZC. Does that mean that a material can be SSC resistant and not SOHIC/SZC resistant but not viceversa ?

2) Also the test method for HIC/SWC is mentioned only for flat products. Is this only applicable for particular product forms ?

3) SSC resistance is not mandated for testing of HIC/SWC cracking however the test environment for HIC/SWC and SOHIC/SZC looks same. Although acceptance criteria and the product forms may not be same. Please explain.

Experts may please add details they would like to highlight for better understanding of difference in acceptance of SSC, SOHIC/SZC and HIC/SWC.

 

[OGMetEngr]

1) Each mechanisms needs to be addressed separately. That being said, Section 2 clause 7 gives requirements in order to be resistant to all three (SSC, SOHIC, and SZC). SZC/SOHIC involves looking at unfailed SSC specimens after testing looking for indications of SZC/SOHIC.

2) For HIC/SWC, take a look at Section 2 clause 8. It explains the various product forms and factors involved.

3) HIC and SWC is highly product form and cleanliness dependent. Section 2 clause 8 explains.

I would advise carefully reading the definitions of each mechanism in the standard, as these terms are used incorrectly or differently in other industries as well as the oil/gas industry.

 

[SJones]

2) Part 2, Clause 8 is a bit of a waste of time in what is supposed to be a standard. I proposed the following text in an official ballot which got duly rejected for being in the too hard box:

8 Assessment of carbon and low alloy steels for their HIC/SWC performance

HIC/SWC can develop in any product form of carbon and low alloy steel exposed to environments containing even trace amounts of H2S. This cracking threat can result in loss of containment giving rise to a hazardous event.

NOTE Even trace amounts of H2S fall within the definition sour service, see ISO 15156-1, 3.19

The equipment user shall perform a risk assessment for a hazardous event caused by HIC/SWC. This risk assessment should be performed in accordance with an approach described in ISO 17776, API RP 14J, or local risk assessment regulations where these are obligatory. Regardless of the approach used, the risk assessment process shall address the probability and consequences of HIC/SWC failure.

NOTE: Although ISO 17776 and API RP 14J are aimed at offshore activities, the risk assessment principles contained therein can be applied to any petroleum and natural gas facility whether offshore or onshore. For example, the International Oil & Gas Producers Association (OGP) have drawn heavily on ISO 17776 for their Risk Management microsite at

http://info.ogp.org.uk/RiskManagement/

that addresses exploration and production installations generally

Where the applicable product standard, design code, or regulations do not require HIC/SWC testing, the results of this risk assessment shall be used to determine the need for additional testing.
Annex B provides guidance on test methods and acceptance criteria to evaluate resistance to HIC/SWC.

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]

I agree that this clause leaves much to be desired on the subject. A majority of the standard reads like a group of metallurgists and lawyers were locked in a room and required to come up with something before they were allowed to leave. Also as I'm sure you're aware, if you don't know the history and reasoning behind many parts in the document it can be applied incorrectly.

The more I'm in this industry the more things I see get placed in that "too hard" box. It's frustrating to say the least. Between that and the "that's how we've always done it" rationale, I'm surprised there aren't more failures than already occur.

Maybe if you reworded your proposed text to be more confusing, unclear, and subjective it would make it through. At least it would fit right in with the rest of the standard.

 

[SJones]

I've had my shot, so I will leave it to someone else to take up the mantle. The Star Chamber for the standard do pronounce their august and learned interpretations at

http://isotc.iso.org/livelink/livel...tober_2014.pdf?func=doc.Fetch&nodeid=16840849

but who am I to point out that, in their answer to Inquiry #2014-02 proclaiming that, quote "only flat-rolled carbon steel products are susceptible to HIC/SWC," they seem to be neglecting that NACE TM0284 also gives requirements for fittings and flanges.

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.