ISO 15156 (=NACE MR0175) and NACE MR0103
1. A part of job specification All materials for components exposed to wet hydrogen sulphide in concentrations exceeding 100 mg/kg (100 ppm) or exceeding the limits prescribed by ISO 15156 or NACE MR0103 (as applicable) shall conform to the reduced hardness requirements of ISO 15156 or NACE MR0103 as follows: a. ISO 15156 is applicable to oil and gas production facilities and natural gas sweetening plants. (NACE MR0175 is equivalent to ISO 15156). b. NACE MR0103 is applicable to other applications (e.g., oil refineries, LNG plants and chemical plants). c. The previous requirements (a) and (b) equally apply to all external bolting on the casing and seal glands even if ISO 15156 or NACE MR0103 (as applicable) restricts the requirement to enclosed bolting. 2. Interpretation by NACE MR0103 and ISO 15156 (=NACE MR0175) The hardness limitations specified in NACE MR0103 and ISO 15156 vary depending on the specific materials and conditions. Here are the general hardness limitations provided by...