BS EN ISO 15156-1:2020

What is ISO 15156-1 - Selection of cracking-resistant materials about? 

ISO 15156-1 describes general principles and gives 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 can pose a risk to the health and safety of the public and personnel or to the environment.   

ISO 15156-1 can be applied to help to avoid costly corrosion damage to the equipment itself. ISO 15156-1 supplement, but does not replace, the materials requirements given in the appropriate design codes, standards, or regulations. 

ISO 15156-1 addresses all mechanisms of cracking that can be caused by H2S, including sulphide stress cracking, stress corrosion cracking, hydrogen-induced cracking and stepwise cracking, stress-oriented hydrogen-induced cracking, soft zone cracking, and galvanically induced hydrogen stress cracking. ISO 15156-1 applies to the qualification and selection of materials for equipment designed and constructed using load-controlled design methods. 

NOTE: ISO 15156-1 is not necessarily applicable to equipment used in refining or downstream processes and equipment. 

Who is ISO 15156-1 - Selection of cracking-resistant materials for?  

ISO 15156-1 on selection of cracking-resistant materials 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 

Why should you use ISO 15156-1 - Selection of cracking-resistant materials? 

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

ISO 15156-1 applies to the qualification and selection of materials for equipment designed and constructed using load-controlled design methods. It is the equipment user's responsibility to ensure that any material specified for use in their equipment is satisfactory in the service environment and it is the equipment or materials supplier's responsibility to meet the metallurgical and manufacturing requirements. 

Laboratory testing in accordance with the ISO 15156-1 may be used for the following: 

• To qualify metallic materials for their resistance to SSC and/or SCC under service conditions up to the limits that apply to materials  
• To qualify metallic materials for their resistance to SSC and/or SCC under service conditions with other limits 
• To qualify carbon and low-alloy steels with respect to their resistance to HIC, SOHIC, or SZC 
• To qualify corrosion-resistant or other alloys with respect to their resistance to galvanically induced HSC 

Overall, ISO 15156-1 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 15156-1:2020 supersedes BS EN ISO 15156-1:2015, which is withdrawn. 

BS EN ISO 15156-1:2020 cancels and replaces the third edition (ISO 15156-1:2015), which has been technically revised. The main changes compared to the previous edition are as follows: 

• New definition on "galvanically induced hydrogen stress cracking", "chemical activity" and "fugacity" 
• Inclusion of an expanded description of factors affecting the susceptibility of materials to cracking caused by H2S. The expanded description includes specific guidance provided in ISO 15156-2:2020, Annex C for gas-phase containing systems using H2S fugacity (as an alternative to H2S partial pressure) and application of non-ideal thermodynamic rules for gas-free liquid systems