PHMSA advises operators of hazardous liquid and natural gas pipelines with dynamic risers, such as steel catenary risers on offshore floating production facilities, to perform regular inspection and maintenance of these risers, monitor nearby environmental conditions, and maintain records of these activities. Failure of a dynamic riser could significantly impact safety, the environment, and delivery of an important source of natural gas and petroleum products used in the United States. PHMSA strongly urges operators to perform the above-listed actions and any other actions needed to ensure the safe and reliable operation of these systems.

A recent natural gas leak from a steel catenary export riser in the Gulf of Mexico created significant and unexpected risk, as well as major supply disruption. Though a root cause analysis of this incident is not yet complete, visual inspection by divers has determined that the source of the leak was a flexible joint on the riser. In 2004, another offshore riser flexible joint failure resulted in a small oil spill. Subsequent preemptive visual inspections performed on other steel catenary riser flexible joints in the Gulf of Mexico discovered damage to the elastomeric seal area near the rotating ball and drove the replacement of four flexible joints. The flexible joint riser failures described above have created potential safety risks on floating production facilities, and have impacted delivery of energy supplies from the Gulf of Mexico.

The national consensus standard for dynamic risers, American Petroleum Institute Recommended Practice 2RD, is currently under revision. The revised version will directly address concerns raised in this Advisory Bulletin by including guidance for integrity management of dynamic risers. PHMSA will consider adopting the revised standard into its regulations for both natural gas and hazardous liquid pipelines.

FOR FURTHER INFORMATION CONTACT: Elizabeth Komiskey at 202-366-3169, or by e-mail to Elizabeth.Komiskey@dot.gov.

Note: the Department of Interior / Minerals Management Service also issued a similar notice in their recent Safety Alert No. 264.