Pronal Lifting Bags used to position pipelines
Australia presents many challenges when lifting, shifting and engineering pipelines to ensure safety and security of supply.
A huge variety of terrain has to be crossed as they run over hundreds of kilometres, often between States, carrying substances as widely varied as water, petroleum and gas.
Between the source of production and the eventual destination (be it processing point, export point or final market) they encounter situations that can potentially impose huge strains on the structure, including hills, gullies, bridges, subsidence and trenches in muddy or sandy locations – often with restricted space in which to engineer the lift.
One company with huge experience in this highly specialised field is the international Nacap group, which over the past 40 years has laid more than 40,000 km of underground pipelines ranging in diameter from 250 to 1,500 mm (10” to 60”) and reaching lengths of 2,000 km, for the transmission of oil, gas, water and chemicals.
Its projects range from a crossing of the Po river as part of the Snam Rete Gas DN750 (30”) pipeline Mortara – Alessandria in North Western Italy, to the contract for Epic Energy to construct the Queensland to South Australia/New South Wales Link to deliver coal seam gas to southern markets. Australian projects also include the Dampier-Bunbury natural gas pipeline, the Magnet slurry and return water pipeline, the Tallawarra gas pipeline project, the Wimmera-Mallee Water Supply system, and numerous other oil, gas and water projects.
Nacap is helping to ensure safety and security in Australia by using an innovative method of de-stressing piplines as they are shifted and lifted to overcome and circumvent obstacles, obviating risks that could rupture the pipelines and create safety and supply problems.
It is using advanced elastomer lifting cushion technology developed by the French company Pronal, the company that provided the enormously strong lifting bags to raise artifacts from the ocean liner Titanic 4km down on the Atlantic ocean floor.
Pronal lifting bags, distributed in Australia by Air Springs Supply Pty Ltd, are now being used in groups of up to a dozen to gently raise and position sideways pipelines from 8-32in in diameter.
Guided by strain gauges located along the sections of pipeline, they are precision inflated to provide shifts down to a millimetre or two when this is all that’s required –or much bigger steps when these are needed.
One NSW project, the Mallaty Creek gas pipeline, involved horizontal movements up to 1.4m using Pronal lifting bags braced with geofabric sandbags. Nacap’s Construction Managers Hugh Boyd and Roger Vouges worked with Alinta engineering consultant GHD on that project.
While the CLP 67 cushions can each provide up to 67 tons of lifting capacity (enough to hoist a decent size locomotive or truck) they spread this force evenly over a broad area of the pipeline and give minute control.
This fine lifting capability was employed on another gasline project, Simpson’s Creek, which involved vertical movements only, says Jack Walsh, Nacap Construction Superintendent on this major project, for which Frontier Engineering Solutions was Alinta’s engineering consultant for Phase Two and GHD for Phase Four.
“The reason we use them is they give absolute control of the lift and therefore great safety and security of supply. Hydraulics might provide a 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 180cfm 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, step by step. 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.
“With them the lifts become a relatively straightforward two-man job, one each side of the pipe. The bags are easy to position and extremely robust,” said Mr Walsh.
Air Springs Supply National Sales Manager Mr Simon Agar says the compact lifting ability of the Pronal bags can be a major asset in mining, petroleum, gas and 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.
“These tough, seamless and versatile lifting cushions can delicately raise loads ranging from pipelines of all types to trucks, tracked vehicles, beams, bridge components, building components, machinery and resource development structures,” he says.
Pronal’s newest cushions range from ultra-thin bags (just 20mm thick deflated) that can lift weights of up to 67 tons 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 700mm (or 1400mm where a pair are employed).
“These are superbly engineered lifting cushions developed for industrial, military and civil tasks by the French elastomer specialists Pronal, “says Mr Agar.
“The materials used are so tough and durable that they are used to recover immobilized aircraft, for example, or to lift tanks or split rocks in quarries.
“In addition to the standard models – such as the workhorse 920X920mm square cushion – a major advantage of Pronal cushions is that they 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.
Features of the product include:
- As well as straight lifting, they can be used for pressing, clamping, tilting and guiding
- Strokes from 10-585smm (CLP), with longer strokes provided by combinations of cushions
- In addition to standard sizes, specific sizes and shapes can be made to order to suit particular applications.
- Ease of use, with inflation either by compressor or simple air cylinders
- Inflation pressures up to eight bar, regardless of stroke (CLP models – CPB pressures vary from under one bar, depending on model)
- Seamless construction from threaded layers coated with chemical resistant elastomer, hot vulcanised under pressure in one operation.
- Non-slip surface providing maximum friction when stacking two cushions
- Control systems tailored to particular uses