Safety advisory focuses on welds on high strength steel pipe
The Canada Energy Regulator (CER) has issued Safety Advisory SA 2020-01 to all its regulated companies regarding high strength steel pipes and the connecting welds (known in the industry as girth welds).
There is no indication of immediate risk to the public. Large diameter pipelines in Canada are primarily welded using mechanized welding techniques, which appear to be less susceptible to the observed failures. There may be several factors contributing to the risk of failure - for example, the force applied to the pipeline or strength of the weld relative to the strength of the pipe.
As a result of this Safety Advisory, CER-regulated companies that are currently constructing projects will need to demonstrate that all potential hazards have been considered in the design, construction, and operation of pipelines where strain could potentially accumulate in under-matched girth weld areas. The appropriate preventative measures must be outlined in companies' Integrity Management Plans.
"Safety Advisories are issued proactively as a way to inform companies of an identified safety or environmental concern. It is our duty as Canada's national energy regulator to ensure companies have all available information related to safety, and are addressing the issues appropriately," advised Dr. Iain Colquhoun, P.Eng, Chief Engineer, Canada Energy Regulator.
Pipeline projects currently in service or that have recently completed their construction activities will not be expected to replace existing girth welds. Rather, companies will be expected to monitor the issues outlined in the Safety Advisory and update their Integrity Management Plans accordingly.
As part of its lifecycle oversight, CER Inspection Officers and other staff will undertake compliance verification activities to ensure that any necessary follow-up is undertaken.
The CER will continue to study this issue to gain a better understanding of the issue, its specific causes, and potential remedial measures that could be taken.
Contributing factors linked to these weld failures include:
- High strength pipe in which the actual strength exceeds the minimum strength specified.
- Weld strength under-matched with the actual pipe steel strength.
- Pipe steel adjacent to the weld joining the pipes that has a lower strength than the base pipe steel as a result of the welding process.
- Significant forces applied to the pipeline that result in longitudinal (lengthwise) strain, such as those in areas of slope movement or ground settlement.
- Manual or semi-automatic girth welds.