(Canadian OH&S News) — Pipeline valves are expensive pieces of equipment, and leaks in them can cause major damage that can potentially result in months of lost production, not to mention wasted fuel and hundreds of thousands of dollars spent on valve replacement. “It can really be a disheartening situation,” said Ernie Coates, services and training manager with Calgary-based valve sealant producer Sealweld Corporation, during his seminar “Common Causes and Prevention of Leakage in New Valves” at the Global Petroleum Show in Calgary on June 10.
Coates’ talk focused on causes of valve leaks and methods of preventative maintenance. He alluded to a major pipeline project in which he’d been involved in 2001, involving valves that had become damaged during the commissioning process.
“The first time the valves were turned with natural gas in them, the seats were damaged severely to the point that the valve wouldn’t seal,” he recalled. “I tried everything to seal the valves. I couldn’t even slow them down. So right away, pipeline integrity was lost.”
As a result, the project lost three months of production and the valve replacement ended up costing nearly half a million dollars, Coates added.
Among the typical causes of leaks in new valves, according to Coates, is construction debris, such as sandblast, grinding compounds or metal end cuttings from the pipe.
Companies should also consider how the valve was transported, since valves can sustain damage from road bumps, as well as how long it has been in storage and whether the covers were installed properly on the pup ends.
“If nobody takes care of the equipment, they end up in the system and then they don’t seal. If they don’t seal, they’re a liability,” said Coates. “This happens a lot.”
A worker can determine in advance if a valve leaks by performing an inside-out low-pressure test, which consists of the following:
* Test the assembly components;
* Connect the assembly to the body drain port;
* Inject 120 pounds per square inch of air into the valve body and isolate it;
* Monitor the gauge for any loss of pressure;
* Drain the air to purge any test fluid remaining; and
* Repeat this process after any welding or cutting occurs near the valve.
During the commissioning phase, Coates suggested, it would be a good idea to apply a thin layer of grease inside each valve’s seat rings, to help prevent debris from getting into sensitive areas. A worker should also check the injection fittings and body vents to see if they need upgrading. “The body vent on the valve is a critical tool,” he said. “So many times I see on ball valves, there are plugs where the vents should be.”
In addition, pipeline companies should develop a comprehensive preventative maintenance schedule for ball valves, which are very maintenance-intensive. During the first year of a project’s operation, when there tends to be a lot of debris left over from construction, a company should inspect and test valves every month and lubricate the seats every time that it cycles the valves, Coates said. The second year should have a semi-annual top-up service, which would become an annual top-up in succeeding years.
Coates concluded by noting that a small investment in maintenance could pay off countless times over in worry-free operation, extended life for both valves and pipelines and higher credibility for pipeline transportation. “Pipelines are scrutinized these days. It’s all our intention to make sure that this equipment is sound,” Coates said. “It’s all our responsibility to make sure that it’s strong.
“We need these lines. We need this stuff to be solid. We need it to work.”