NACE MR0175/ISO 15156

[balven]

I have two questions regarding NACE MR0175/ ISO 15156:
1. NACE MR0175-2001 edition had a clause 1.3.2.2 for Low perssure Oil and Gas Multiphase systems: "When the total pressure is less than 1.8 MPa abs (265 psia), the maximum gasil ratio (SCF:BBL) is 5000 or less, and the H2S content is less than 15 mol% and the H2S partial pressure is less than 0.07MPa abs (10 psia)."

I would like to know why was this clause removed from the subsequent revisions of NACE MR0175 and now ISO 15156. I am using ECE IV and it still considers the above mentioned clause 1.3.2.2.

2. ISO 15156 now states that Crude Handling and Storage facilities operating under a maximum pressure 65 psia are exempt from NACE requirements. I would like to have a view on this thread about how realistic this 65 psia limit is and could it be applied to, say, a two or three phase separator?

 

[SJones]

1. Not being a user of MR0175 it's not easy to trace the history back. I would hazard a guess that it got removed because the MR0175 of that vintage dealt only with SSC. When it merged with ISO 15156, HIC and SOHIC came into the picture and that exclusion could no longer be supported. You will have to take up the issue with the suppliers of the ECE software, perhaps they can provide you a patch to rectify; or, try to sell you ECE 5!!

2. It's not quite true to say that they are 'exempt;' they are a "permitted exclusion," i.e. the end user has to make the decision whether to apply the pertinent requirements or not particularly after having read clause 8 in Part 2.

Steve Jones
Materials & Corrosion Engineer

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