What is ISO 15156-2 - Cracking-resistant carbon and low-alloy steels about?
ISO 15156-2 describes general principles and gives requirements and recommendations for the selection and qualification of carbon and low-alloy steels for service in equipment used in oil and gas production and in natural gas treatment plants in H2S-containing environments, whose failure can pose a risk to the health and safety of the public and personnel or to the environment. ISO 15156-2 can be applied to help to avoid costly corrosion damage to the equipment itself. ISO 15156-2 supplements, but does not replace, the materials requirements given in the appropriate design codes, standards, or regulations.
ISO 15156-2 addresses the resistance of these steels to damage that can be caused by sulfide stress cracking (SSC) and the related phenomena of stress-oriented hydrogen-induced cracking (SOHIC) and soft-zone cracking (SZC). ISO 15156-2 also addresses the resistance of these steels to hydrogen-induced cracking (HIC) and its possible development into stepwise cracking (SWC). ISO 15156-2 applies to the qualification and selection of materials for equipment designed and constructed using load-controlled design methods.
NOTE: ISO 15156-2 is not necessarily suitable for application to equipment used in refining or downstream processes and equipment.
Who is ISO 15156-2 - Cracking-resistant carbon and low-alloy steels for?
ISO 15156-2 on cracking-resistant carbon and low-alloy steels, and the use of cast irons is beneficial for:
- Corrosion engineers
- Maintenance Agency
- Technical Management Board
- Metallurgical engineers
- Welders
- Oil and chemical industries
- Testing authorities
- Manufacturers and suppliers of materials for use in H2S-containing environments
- Manufacturers and suppliers of alloy steel
Why should you use ISO 15156-2- Cracking-resistant carbon and low-alloy steels?
Sulphide stress cracking (SSC) is a form of hydrogen embrittlement which is a cathodic cracking mechanism.
ISO 15156-2 describes and lists SSC-resistant carbon and low alloy steels. The hardness of parent materials and of welds and their heat-affected zones play important roles in determining the SSC resistance of carbon and low alloy steels. Hardness control can be an acceptable means of obtaining SSC resistance. Materials conforming with ISO 15156-2 shall be made traceable, preferably by marking, before delivery. Suitable labelling or documentation is also acceptable.
Overall, ISO 15156-2 is helpful as it provides guidance on the qualification of a material for use in application-specific service conditions.
What’s changed since the last update?
BS EN ISO 15156-2:2020 supersedes BS EN ISO 15156-2:2015, which is withdrawn.
BS EN ISO 15156-2:2020 cancels and replaces the third edition (ISO 15156-2:2015), which has been technically revised. The main changes compared to the previous edition are as follows:
- Title changes from Shear rams to Rams in A.2.3.2.2
- Addition of C110 and changes the designation of C95 to R95 in Table A.3
- Reference change to NACE TM0316 in Table B.1
- Addition of reference to BS 8701 in B.4.3
- Changes and additions to Table B.3