Two years after installation on Total E&P UK Plc’s North Alwyn A&B oil platforms, Groveley’s point infrared gas detectors have proven the company’s claim to reduce maintenance costs through zero calibration.
The North Sea installation involved 495 of Groveley’s GD-10P point infrared gas detectors refitted to replace catalytic gas detectors on a one-for-one swap using existing field cables. The units’ reliability enabled operators to reduce checking to yearly intervals.
Special fixing kits that include all the required fasteners allowed quick change-out of gas detectors on both contracts with a minimum of fieldwork, the company says. Groveley designed the brackets to mirror the footprint of the existing gas detectors’ mounting junction boxes.
Total’s contract for Norwegian-built Simrad GD-10P detectors was Groveley’s largest-ever order at the time. The unit was chosen because of its low maintenance costs - basically it needs no calibrating during its lifetime, Groveley says.
“Simrad’s two infrared sources are so stable that once a point detector is factory-calibrated, it needs no adjustment on site throughout its working life, with obvious savings on maintenance and service costs,” Groveley’s managing director, Robert Bennet, says.
Groveley had also designed special brackets that allowed GD-10Ps to be mounted in the North Alwyn ducts without altering the existing cut-outs used for the old catalytic detector duct-mounting brackets.
The GD-10P unit detects flammable gas or carbon dioxide with two solid-state infrared sensors and a silicon-based infrared source that lasts up to 60 years - unlike normal infrared lamps that survive only 3-4 years.
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Ewen Macdonald, senior systems engineer at Total, reports: “We have had a good experience with the units with very few faults; and they have quickly detected on the rare occasions when we have experienced a leak.”
The GD-10P performs self-diagnostic and calibration tests and gives clear warning if a malfunction is detected, without giving a false gas alarm.
