Walking the lines

Chris Patmore (left) and Steve Gilbert on pipeline duty with Bryce Wright (kneeling)

It’s a winter morning at Newport, Melbourne. Overnight rain has wet the ground between the tanks and bund walls of the Caltex terminal, and a chilly breeze off Port Phillip Bay brings the smell of the sea.

Clad in high-visibility work gear, Reliability and Maintenance (R&M) engineers, Steve Gilbert, Bryce Wright and Chris Patmore, walk slowly through the complex, checking pipelines.

They’re performing a low-tech but vital annual monitoring service keeping Caltex terminals and the community safe and preventing business interruptions.

While more specialised methods can help Caltex monitor the integrity of the many kilometres of lines in its 13 terminals, old-fashioned legwork, experience and a sharp pair of eyes are still indispensable. People can sometimes see what machines or technology can’t.

“We walk each line looking for corrosion, damage and leaks, checking pipe supports are adequate and checking that lines meet the current standards,” explains Reliability and Maintenance Manager (Terminals) Tim Moore. “We also inspect pressure safety valves, pumps, valves, vents and drains and investigate potential problem areas like deadheads [blinded lines].”

The lines are identified via frequent reference to Piping & Instrument Diagrams (P&IDs) in which each has a number. Inspections start with a review of the results of previous annual inspections and end with repairs. Problems are rated for priority: fix immediately (emergency) and fix within five years (low priority).

Rigorous program

The annual visual inspections are just one part of R&M’s rigorous program to maintain the piping network. Other methods include pressure tests (using diesel or water), long-range ultrasonic thickness gauging and magnetic flux leakage gauging. Pressure testing is the most common but the most intrusive, and can put pipelines out of service for up to seven days. It’s mainly used for high-risk links like dock and supply lines from refineries which cross public land. A potential leakage rate is calculated based on pressure and temperature measurements over a 24-hour period. If it’s over a certain limit, it may indicate a leak. Long-range ultrasonic thickness gauging is used to check hard-to-get-at lines, usually underground, often in conjunction with pressure tests. An ultrasonic signal is sent down the pipe to identify corrosion or other defects. Magnetic flux leakage is used to check wall thickness of lines. A sensor is mounted on a crawler that travels the outside of the pipe. At areas where there’s corrosion or thinning, magnetic “leakage” occurs from the metal and can be detected by the unit.

Obviously, says Tim, it’s all about safety and preventing disaster, like the recent incident in Victoria in which over 400,000 litres of petrol seeped from a pipeline, leaving a toxic plume under a Melbourne suburb.

“We don’t want this to happen to Caltex, ever,” says Tim who recently worked with Terminal Operations on replacing docklines (ship-to-shore piping) which had corroded at Gladstone and Hobart. “It’s our job to see that it doesn’t”. “Flying pigs” Another part of R&M’s responsibility for ensuring the integrity of Caltex lines is to support the New South Wales Operations group (under Colin Broom) who conduct seven yearly inspections of the 220-kilometre-long Sydney-to-Newcastle pipeline with “intelligent pigs”. These are sophisticated corrosion-detection devices o fficially known as Inline Inspection Tools. The computerised cylinders get their nickname from the squealing sound they make when they’re pushed through the pipeline by product, checking for faults and corrosion.¹

¹See Star 13, June-July 2003