Your understandings are correct.
First of all if the H2S partial pressure is less than 0.05 psia, it does not
fall under sour service category (unless other factors specified in Sec 6.0
of NACE MR0175/ISO15156-2 is adverse). It is normally designated as NON Sour
service. NACE MR0175/ISO15156 does not discuss in detail about this service
requirement.
1. A 106 Gr B, A 234 product forms are seamless in construction & due to the
manufacturing route, these materials are least susceptible to HIC & SSC.
Normally these materials not require any SSC /HIC resistance test unless
stipulated by a project/ material specification. They can be used without
any testing for sour service conditions (subject to meeting A 2.1.2 /A 2.1.3
& sulfur as mentioned in sec 8.0 i.e 0.01% for S/Less & 0.025 % for castings
& forging).
2. If all other factors specified in Sec 6.0 of NACE MR0175/ISO15156-2 does
meet, & Project material specification does not call specifically tests (the
design criteria like need not call for additional testing during the
material selection process).
3. NO. Subject to meeting A 2.1.2 /A 2.1.3 conditions and Project material
specification does not call specifically for stringent testing (the design
criteria like this need not call for additional testing during the material
selection process).
4. Normally No. Seamless & forging products with current modern technology
manufacturing route are less likely HIC/SSC sensitive.
5. Yes. Casting are less susceptible to HIC. (Subject to Sulfur content &
heat treatment restriction). Normally Flat rolled products & products formed
from Flat rolled products are more susceptible to HIC.
Regards,
Sanjeevan
----- Original Message -----
From: "Aarpee" <ramprasad.chari@gmail.com>
To: "Materials & Welding" <materials-welding@googlegroups.com>
Sent: Friday, February 05, 2010 10:52 AM
Subject: [MW:4220] Querry on NACE std
> Dear all,
> I have few questions,as under,on NACE requirement and I seek
> clarification of same on my understanding.Please share your experience
> on interpretation of NACE standard.
>
> 1)Steel used by us(SA106GRB,SA105,SA234GRWPB), for Natural Gas,Crude
> Oil and Condensate service application(with partial pressure of wetH2S
> in the system much less than 0.05 psia),is not of very high UTS and
> hardness is less than 22HRC.Is such steel susceptible to SSC and HIC
> and needs compliance to MR0175/ISO15156 with eloberate testing??
>
> 2)If my above referred steel meets the requirement of A.2(Nace MR0175/
> ISO15156-2)(with partial pressure of wetH2S in the system much less
> than 0.05 psia),does it comply to NACE MR0175/ISO15156 SSC resistant
> without any testing as per Annexure B??
>
> 3)If my above referred steel complies to requirement of % Sulphur as
> per CL8.0 of Nace MR0175/ISO15156-2(with partial pressure of wetH2S in
> the system much less than 0.05 psia),can it be considered complying to
> NACE MR0175/ISO15156 HIC resistant without any testing as per Annexure
> B??
>
> 4)If my system falls in SSC Zone 0(Fig 1,Cl 7.2.1.2 Page 9 of the
> standard) with respect to H2S partial pressure vs Ph,does it still
> call for NACE HIC compliance to the standard??
>
>
> If my system falls in SSC Zone 1(Fig 1,Cl 7.2.1.2 Page 9 of the
> standard) with respect to H2S partial pressure vs Ph,can we
> straightaway go for material listed in A.2 without any testing as per
> Annexre B??
>
> 5) Can Casting body be straightaway considered as non-susceptible to
> HIC??
> Regards
> Aarpee
>
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