Pipeline Connector Leak

An offshore 6,800 psi working pressure bulk oil pipeline sustained a leak 300 feet from the platform near the Load Limiting Connector (LLC). Observations by divers and video cameras indicated leakage past the seals between the inner and outer barrels of the LLC. The conventional alternative was a risky and expensive clamp procedure in 300 feet of water, so Seal-Tite® was employed to prepare a sealant and repair procedure.

After the pipeline was flushed and filled with saltwater, a train consisting of Seal-Tite® sealant between two foam pigs was launched from the platform and down the pipeline until the front edge of the sealant had reached the leak site. The pipeline was shut-in and pressure cycled between 200 and 1000 psi to push the sealant through the leak site and polymerize the sealant. Pressure testing of the pipeline indicated that the leak rate had been decreased, but not eliminated. A second sealant operation was performed using the same procedure with an adjusted

Seal-Tite® sealant formula. With this second operation, the leak was fully sealed and tested to MMS specifications at a pressure of 1000 psi.