Intelligent Pigging of an Unpiggable Gas Pipeline in Australia
Quest Integrity Group was approached by a client to inspect two sections of an unpiggable 14” high pressure gas pipeline in Australia. The line is over 40 years old and the client wished to evaluate its integrity so as to ensure safe operation for the remaining life of the affected facility. Quest Integrity utilized its InVista™ intelligent pigging technology to perform the inspection.
Challenges associated with inspecting this pipeline included:
- No launcher or receiver facilities
- No valves at the locations suitable for attaching temporary pig traps
- Insufficient water storage capacity at site to completely flood the pipeline during the intelligent pigging process
- One section of the line had an unbarred 45Ëš Y piece and back-to-back bends
- Space constraints in a pit used as the receiving location meant that a temporary 1D elbow needed to be installed in the pit to allow a temporary pig receiver to be installed
- One section of the line had a rise and drop in height of 12 meters over the first 150 meters.
Quest Integrity’s InVista tool successfully overcame these challenges with its unique free floating and near zero buoyancy properties, along with its ability to negotiate 1.0D bends.
To complete the inspection, Quest Integrity and subcontractor Red Rock Oilfield Services developed and executed a project procedure that included the pre-cleaning, inspection and drying of this unpiggable gas pipeline. Red Rock was responsible for designing and supplying the temporary pig traps and spool pieces used, as well as performing the necessary pre-cleaning and drying of the pipeline after the inspection. Inspection results enabled targeted repairs to be performed.
After completing data analysis and a Level 2 fitness-for-service assessment of the line in accordance with the API 579 standard, Quest Integrity identified three sections in the pipeline that did not satisfy the API 579 criteria due to critical wall loss anomalies consistent with heavy external corrosion. The remainder of the pipeline was found to be fit-for-service in accordance with the API 579 standard.
The client used the results provided to prove up and verify the presence of heavy external corrosion defects at the locations specified by Quest Integrity. The client repaired the affected sections and returned the pipeline to service with confidence that it can now be operated safely for the remaining life of the affected facility.