interesting, pl. refer below. However it depends on your roll (my opinion expressed hereunder as mechanical designer)
-----Original Message-----
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Aarpee
Sent: Friday, February 05, 2010 12:22 PM
To: Materials & Welding
Subject: [MW:4220] Query 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 elaborate testing??
SSC /HIC testing not required for above steels unless it is requested by owner/licenser, only following additional restrictions will apply
Heat treat ment condition shall be met as per A2.1.2
Forgings produced in accordance with ASTM A 105 are acceptable if the hardness does not exceed 187 HBW.
Wrought pipe fittings to ASTM A 234 grades WPB is acceptable if the hardness does not exceed 197 HBW.
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??
Yes, unless it is requested by owner/licenser
you may refer figure B.1 for alternatives categorized as
1. suitable materials can be selected as given Annex A
2. Laboratory qualifications to equipment users requirements
3. Laboratory qualifications to obtain listing
in my opinion your case it falls under category 1 as above
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??
Yes, unless it is requested by owner/licenser
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??
Yes, unless it is requested by owner/licenser
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 Annexure B??
Yes, unless it is requested by owner/licenser
In the absence of suitable choices from Annex A, carbon and low alloy steels may be tested and qualified for use under specific sour service conditions or for use throughout a given SSC Region. Testing and qualification shall be in accordance with NACE MR0175/ISO 15156-1 and Annex B.
5) Can Casting body be straightaway considered as non-susceptible to HIC??
yes with restrictions provided under para A2.4
Regards
Aarpee
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