NACE MR0175/ISO 15156 as international Standard which in harmonizing between NACE (National Association for Corrosion Engineer) and ISO (the international organization for Standardization). These standard was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures for petroleum and natural gas industries.

NACE MR0175/ISO 15156 as first edition was issued on 2001 has general title Petroleum and natural gas industries-Materials for use in H2S-containing environments in oil and gas production. Consist of the following part:

-          Part 1: General  principles for selection of cracking-resistant materials

-          Part 2: Cracking-resistant carbon and allow steels

-          Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys

This part of standard describe general principles and give requirements and recommendations for the selection and qualification of metallic materials for service in Equipment used in oil and Gas Production and in Natural Gas sweetening plants in h2S-containing environments, where the failure of such equipment could pose a risk to the health and safety of the public and personnel or to the environment. This standard also can be applied to avoid cost due to corrosion damage to the equipment itself such as line pipe, valve etc.

As part of materials selection to determine the service is in sour or sweet condition can be obtained by use the actual data from the field especially H2S content to get h2S partial pressure which limited in 0.05 psi more than this pressure categorized as sour service condition. Designing of material selection shall consider the material such carbon steel or corrosion alloy which can withstand to sour gas condition. To know that materials which will be used as part of the equipment based on this standard also give recommendation such kind of testing which shall be conducted to determine the resistant of steel during exposed on H2S gas without crack which exceeding from acceptance criteria. The kinds of testing which normally applied are Hydrogen Induced Cracking (HIC) and Sulfide Stress Corrosion Cracking (SSCC) with the test method refers to NACE TM 0284 and NACE TM 0177 respectively.