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Australia-first process leak detection system turns heads

At the Australasian Oil & Gas Expo in Perth last month, hazardous area specialists Pacific Ex revealed an Australian-first leak detection system for process lines which can detect pipeline leaks to within one metre of the exact location, essentially minimising plant downtime and production loss.

The product has been developed over the past 10 years by UK-based Sensornet and uses a fibre optic cable to measure temperature instead of the traditional method of measuring only gas substances in the air, allowing it to continuously detect leaked gas, according to the company’s general manager, Stephen Armstrong, who was on-site at the show. Armstrong says it has been effectively implemented in emergency shut-down systems in LNG process lines in Europe and the USA

“Based on distributed fibre optic sensing technology, Sensornet’s Digital Leak Detection provides a revolutionary cryogenic monitoring solution that can instantly locate a leak anywhere in the LNG terminal,” a brochure from Sensornet claims.

The device can be used for monitoring leaks in loading and unloading pipelines; storage tanks (monitoring the annulus); tank base monitoring; and spill channels — each area that has traditionally been difficult to access.

According to Sensornet, conventional leak monitoring technology meant that there was a gap between what the plant operator believes is occurring throughout his installation and what was actually happening. Sensornet’s technology is designed to overcome the limitations of measurement technologies available today to close the monitoring gap.

Armstrong says the Sensornet Digital Leak Detection technology is an intrinsically-safe, extremely sensitive system with the capability to detect the smallest of leaks. Leaks can be rapidly detected (within 10 seconds for LNG) and pinpointed within a very small window of one metre, anywhere within the terminal.

Benefits of using Digital Leak Detection over existing technology also include the improvement of safety for the infrastructure and for plant personnel.

A system using Sensornet will also be more reliable, with reduced inspection time and therefore less downtime. Lower nuisance alarms will also result in improved productivity, the company claims.

The system is also fully-automated — reducing the risk of human error — and can interface with the SCADA industrial control system using standard protocols including OPC, Modbus and electrical relays.

It is based on temperature measurements using distributed fibre optic sensing technology. Distributed Temperature Sensors (DTS) place the fibre optic as the sensor, eliminating the need for active components or moving parts within the sensing cable.

Using Sensornet’s DTS system in conjunction with fibre optic sensing cable allows a full temperature profile to be obtained along the entire length of the cable, with measurement points every one metre. In the event of a cryogenic leak within the LNG terminal, there will be a significant drop in temperature (typically greater than 100°C). When the cryogenic fluid comes into contact with the sensing cable this will be detected instantly and pinpointed, meaning rapid action can be taken to mitigate any risk and control the situation.

Multiple cables can be operated by one DTS acquisition system, meaning complete plant coverage of an entire terminal can be achieved, including pipelines, tanks, channels and basins. The cables are run from the acquisition unit based in the control room.

The Sensornet system is particularly useful when used to monitor the LNG export or import pipeline to the storage tanks — a critical area that represents one of the largest sections of infrastructure in the plant (sometimes up to several kilometres long), often with limited access. The sensors can be used to monitor the pipes through everyday running including cooldown to ensure that the process proceeds smoothly and that undue stress is not exerted on the pipeline.

Sensornet can be installed on different pipe configurations, including Vacuum Insulated Piping (VIP). The system also has approval from the US Federal Energy Regulation Commission (FERC) for use on VIP systems.

Pacific Ex’s Sensornet team will manage a customer’s entire project through to its handover. Since the system is based on safety and system integrity, the technology is ISO 9001 accredited and meets all Health & Safety Executive requirements, it says. The Sensornet systems can achieve a SIL 2 or 3 rating (safety integrity level) which is now a common requirement for process operations.

The new technology can also be used to measure reservoir levels and has already been installed in approximately 50 dams in Sweden, said Sensornet vice president — downstream process, Jerry Worsley, who was also present at the exhibition.

“Sensornet has been used worldwide for ten years, but we are only launching in Australia now,” he said. “We needed to find the right distributor before we could launch here — and Pacific Automation has the right kind of experience for the job.”

Pacific Ex is a division of process control and automation solutions distributor, Pacific Automation, based in Western Australia, which specialises in safety solutions for the oil and gas, mining, industrial and utilities operations.

Pacific Ex also displayed the new range of Weidmuller intrinsically-safe isolators at the show.

With such a strong portfolio of brands, Pacific Ex’s Armstrong said he expects to get “good business” from the Australasian Oil and Gas Expo this year.

“We are a privately-owned company so we can really gear up for the hard times ahead,” Armstrong said. “We have noticed our end-users backing-off on stock due to the economic crisis, and contractors are being put on hold. However, we expect only a 10 to 15 per cent downturn in business this year — which is a small sum compared to some of the other manufacturing industries out there. There has been better traffic at this year’s show than the last exhibition in 2007, which makes us optimistic.”

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