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Summary following an audit of the integrity and handling of slip joints on mobile drilling facilities

In 2008/2009, the Norwegian Safety Authority Norway (PSA) conducted an audit of drilling contractors using mobile drilling facilities (semi-submersible drilling facilities) on the Norwegian shelf.

The audit concerned challenges in connection with leaks on the slip joint gasket, and problems relating to the manual handling and use of manrider during the connection of the choke and kill lines to the slip joint.

Background for the audit
The PSA has seen an increase in the number of reported incidents involving a leak in the gasket element on slip joint gaskets (telescopic gaskets).

We refer to our main priority concerning prevention of damage to the external environment and the regulatory requirements stipulated in Section 76 of the Activities Regulations  relating to well barriers.

We experience that during new constructions and upgrades, companies still plan for the use of manriders and manual operations to connect the choke and kill lines with a gooseneck to the slip joint.

We also refer to our main priority relating to follow-up of risk-exposed groups and regulatory requirements, cf. Section 4 of the Facilities Regulations relating to the design of facilities and Section 31 of the Activities Regulations relating to arrangement of work.

Purpose of the audit
The purpose of the audit was to identify how the players comply with the barrier requirement in connection with discharges from the slip joint, and how the players follow up and intend to improve this operation. Moreover, the objective was to identify how often manual operations are used when connecting the choke and kill lines with a gooseneck to the slip joint.

Result of the audit
It is still common to use a manrider and manual operations to connect the choke and kill lines with a gooseneck to the slip joint, even though much remote-operated equipment has been installed on the newest facilities. Furthermore, we have observed that manual operations are much more time-consuming than remote operations, and that the manual solution often exposes personnel for extended periods during manrider operations.

With regard to the slip joint gasket elements, there are relatively few differences in equipment on the various facilities. The major differences are in the operation control systems and pressurisation of the gaskets. 

It emerged that there have been few design changes to this type of equipment during the last 30 years. It is our impression that the original equipment suppliers have not actively developed remote-operated solutions and control systems for gaskets elements.

During the audit, it emerged that there has not been much transfer of experience from or knowledge of incidents that have occurred using the same equipment or equipment make, nor has there been much transfer of experience between the various companies. 

Journal 2008/227 (document in Norwegian)