Wednesday 22nd September 2004
Two years after installation on Total E&P UK PLC's North Alwyn A&B oil platforms, Groveley detection's point infrared gas detectors have proved 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 being refitted to replace catalytic gas detectors on a one-for-one swap utilising existing field cables.
The GD10P Detectors enabled operators to reduce checking to yearly intervals because of their reliability.
By providing special fixing kits that included all the fasteners required, the change-out of gas detectors had been conducted very quickly on both platforms with a minimum of fieldwork. The brackets were designed to mirror the footprint of the existing gas detectors' mounting junction boxes.
The TOTAL contract for Norwegian-built Simrad GD-10P detectors was Groveley's largest-ever order at the time; the unit was chosen over major competition because of its low maintenance costs - basically it needs no calibrating during its lifetime.
Groveley's managing director Robert Bennet said: "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 had also designed special brackets that allowed GD10Ps 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.
Ewen Macdonald, senior systems engineer at TOTAL, reported: "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."
Robert Bennet said: "Infra red detectors offer many advantages over catalytic detectors; they cannot be poisoned, they work well in low oxygen environments and with constant exposure to background gases - even exposures to high gas concentrations will not affect service life."
The GD-10P performs self-diagnostic and calibration tests and gives clear warning if a malfunction is detected, without giving a false gas alarm. It has applications in offshore oil and gas platforms, chemical and petrochemical plants, waste disposal, gas turbines and general industry.
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