BS EN ISO 15156-3:2020

What is ISO 15156-3- Cracking-resistant CRAs about? 

ISO 15156-3 gives requirements and recommendations for the selection and qualification of CRAs (corrosion-resistant alloys) and other alloys for service in equipment used in oil and natural 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 15156-3 can be applied to help avoid costly corrosion damage to the equipment itself. ISO 15156-3 supplements, but does not replace, the materials requirements given in the appropriate design codes, standards, or regulations. 

ISO 15156-3 addresses the resistance of these steels to damage that can be caused by sulfide stress cracking (SSC) stress corrosion cracking (SCC), and galvanically induced hydrogen stress cracking (GHSC). ISO 15156-3 applies to the qualification and selection of materials for equipment designed and constructed using load-controlled design methods. 

NOTE 1: ISO 15156-3 is not necessarily suitable for application to equipment used in refining or downstream processes and equipment. 

NOTE 2: ISO 15156-3 is concerned only with cracking. Loss of material by general (mass loss) or localized corrosion is not addressed. 

Who is ISO 15156-3 - Cracking-resistant CRAs for?  

ISO 15156-3 on cracking-resistant CRAs (corrosion-resistant alloys) and other alloys 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 alloys 

Why should you use ISO 15156-3 - Cracking-resistant CRAs? 

Sulfide stress cracking (SSC) is a form of hydrogen embrittlement which is a cathodic cracking mechanism.  

CRAs and other alloys shall be selected for their resistance to SSC, SCC, and/or GHSC as required by the intended service. Conformance of a CRA or other alloy with ISO 15156-3 implies cracking resistance within defined environmental service limits. These limits are dependent on the material type or the individual alloy. In defining the severity of H2S-containing environments, exposures that can occur during system upsets or shutdowns, etc. shall also be considered. 

Overall, ISO 15156-3 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 15156-3:2020 supersedes BS EN ISO 15156-3:2015, which is withdrawn. 

BS EN ISO 15156-3:2020 cancels and replaces the third edition (ISO 15156-3:2015), which has been technically revised. The main changes compared to the previous edition are as follows: 

• Table A.27 UNS S17400 (17-4PH SS) has new limits. The use of the alloy at the annotated environmental conditions is now limited to applications where sustained stress is no more than 50 % of SMYS 
• Table A.32 new limits and annotations for UNS N09946 separate from UNS N09945 
• Table A.41 inclusion of UNS R55400 (new a-b Ti alloy) 
• Table A.3 UNS S20910 (Nitronic 50) note modifications 
• Tables A.22, A.23, A.26 through A.30, and A.33 temperature conversion corrections