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HIC & SSC test

HIC & SSC test

(OP)
I am working on one of its offshore project having field with wet sour H2S content . In data sheet of the slops tank ( UL-142 tanks D.P: 2.5 PSIG)& material showing HIC and SSC resistant. we are buying plate A516 GR 60 from Arcelor Mittal with HIC testing per NACE TM 0284 & Client specification and MTC states that material compliant to NACE MR 0175/ ISO 15156-2 & HIC test qualified
Also as per NACE MR 0175/ ISO 15156-2 section 7 Selection of pre qualified material resistant to SSC
" No additional laboratory testing of pre qualified material selected in this way require"

Now my question is

1) If the material is already Tested & passed for HIC test as per NACE TM 0284 & client specification also MTC stated for NACE MR 0175 / ISO 15156-2. DO we still required separate testing for SSC as per NACE TM-0177???.

As per my understanding for HIC qualification of plates it requires extra care during production phase of plate and SSC will automatically qualified once NACE MR 0175 section 7 calls for no separate testing as MTC already stated for HIC pass test result and compliance to NACE MR-0175/ ISO 15156-2. Also we have approached earlier a lot of mills but no one prepare to do both HIC & SSC testing on same plate with heat numbers saying only one test ( HIC OR SSC)can be performed. I have checked Client Specification which calls for HIC testing and Inspection for qualification but no separate specification for SSC specified. i dont want that at later stage client raise concern why plate is not SSC tested

Your valuable input will be much appreciate

RE: HIC & SSC test

Sulfide stress cracking(SSC) is a special case of hydrogen stress cracking, also known as hydrogen-induced cracking(HIC). This cracking mechanism depends on several factors:hydrogen fugacity, material strength, heat treatment/microstructure, applied stress, and temperature. For many steels, there is a threshold stress exists below which HIC doesn't occur. This threshold stress is a function of material strength and the specific hydrogen-bearing environments. It is not a fixed value and hence can't to be referred to as "material property".

NACE TM0284 provide two solutions for HIC/SSC test: Solution A - NaCl+CH3COOH saturated with H2S, Solution B - a synthetic seawater solution with H2S. However, this standard doesn't include acceptance or rejection criteria. The test results are only for reference. According to our supply experiences, for ASTM A516 Gr.60/65/70 HIC resistant steels, CLR≤10%, CSR≤3%, CTR≤1% in Solution A; CLR≤10%, CSR≤3%, CTR≤1.5% in Solution B. “HIC Resistant” can be achieved by carefully control the chemical composition such as Ni<1%, C<0.20%, O<0.0025%, S<0.002%, P<0.009%, CE<0.42%.

This technical article may be more helpful: http://www.metalspiping.com/whats-hydrogen-induced...

Hebei Metals Industrial Limited
www.metalspiping.com

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