Cushioning Australia’s gas infrastructure

Between the source of production and the eventual destination, be it processing point, export point or final market, pipelines encounter situations that can potentially impose huge strains on their structure, including hills, gullies, bridges, subsidence and trenches in muddy or sandy locations – often with restricted space in which to engineer the lift.

The elastomer lifting cushion technology developed by Pronal and supplied by Air Springs Supply can help to mitigate the risks associated with manoeuvring pipelines in a variety of conditions. Pronal is famous for providing the enormously strong lifting bags that raised artefacts from the ocean liner Titanic, 4 kilometres beneath the Atlantic Ocean’s surface.

Pipeline construction company Nacap uses the lifting bags on a variety of its projects. The company has worked on projects such as the QSN Link, the Dampier to Bunbury natural gas pipeline and the Tallawarra gas pipeline project.

The company is helping to ensure safety and security in Australia by using the Pronal lifting bags method of de-stressing pipelines as they are shifted and lifted to overcome and circumvent obstacles, obviating risks that could rupture the pipelines and create safety and supply problems.

The bags are now being used in groups of up to a dozen to gently raise and position sideways pipelines ranging from 8-32 inches in diameter. Guided by strain gauges located along sections of the pipeline, the bags are precision inflated to provide shifts down to a millimetre or much bigger when required.

In New South Wales, the Mallaty Creek gas pipeline involved horizontal movements of up to 1.4 metres using the lifting bags braced with geofabric sandbags.

While the CLP 67 cushions can each provide up to 67 tonnes of lifting capacity, they spread this force evenly over a broad area of the pipeline and give minute control. This lifting capability was employed on the Simpson’s Creek gas pipeline, which involved vertical movements only, says Jack Walsh, Nacap Construction Superintendent for the project.

“We use them because they give absolute control of the lift and therefore great safety and security of supply. Hydraulics might provide half an inch of concentrated movement, when we only need one millimetre.”?

One of Mr Walsh’s larger lifts, using five bags, involved 238 metres of pipeline passing through a gully, so there was quite a lot of weight involved, he says. Using a diesel 180 cubic feet per minute compressor, load sensors and the gauges and valving provided with the bags, the pipeline was repositioned to obviate the effects of slope and ground subsidence.

“In that job, and indeed in all jobs, safety is number one priority, absolutely. That’s what we are all focussed on – the whole team, the load control system people, the stress gauge people, the engineers, the client – we are all focussed on security of the workforce, the infrastructure and the supply of the contents of the pipeline.

“Nothing happens; nothing moves until everyone is happy with the process step by step and until it is signed off. Risk management, risk elimination, is paramount. That’s one of the reasons why the Pronal lifting bags are so good – they treat the lift with kid gloves. They are very central to the task.”

Air Springs Supply National Sales Manager Simon Agar says that the compact lifting ability of the Pronal bags can be a major asset in gas infrastructure applications.

“Especially in remote, rugged and sometimes muddy or sandy locations – including trenches – it can be difficult to provide crane access overhead or to obtain sufficient clearance and a firm foundation for a lift from underneath. “?

Pronal’s newest cushions range from ultra-thin bags – just 20 mm thick
deflated – that can lift weights of up to 67 tonnes each, to powerful spreading cushions that can exert hundreds of tonnes of force to part plant and machinery components for servicing, or to extract quarried material. Complementary low-pressure CPB Maxi-Lift cushions can be used on land and under water, offering greater strokes of up to 700 mm – or 1,400 mm where a pair is employed.

Mr Agar says “The materials used [in the lifting cushions] are so tough and durable that they are used to recover immobilised aircraft, for example, or to lift tanks or split rocks in quarries.

He says that in addition to the standard models, the cushions can be custom-engineered to particular shapes and sizes to perform particular tasks as they are inflated by compressors or portable air cylinders or pumps.

“Sometimes it is not necessary or desirable to use cranes, slings or cylinders for lifts that present particular technical challenges in terms of lifting surfaces or surfaces to which lifting force is to be applied. Where considerable investments may be contemplated in custom-engineering a conventional lifting platform, it may be well worth considering the simple principle of pneumatic actuation,”? said Mr Agar.

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