Pneumatics key to off-shore spraying system

Edited by the Engineeringtalk editorial team Oct 10, 2000

Covercat Spray Systems has worked with Norgren to develop the pneumatics for its unique Covercat Pipe Snake, which coats sub-sea spools made out of super duplex with a corrosion-resistant substance

In the harsh conditions of a Norwegian oil-field safety is of paramount importance.

That is why Middlesborough-based Covercat Spray Systems, global specialist in the design and manufacture of plural component spray equipment, has worked with Norgren to develop a pneumatics system for its unique Covercat Pipe Snake.

Risk of explosion in hazardous environments means that no electrical parts can be used in the system, which coats sub-sea spools made out of super duplex used to connect sub-sea well heads in the North Sea oil fields and carry the oil to a central location.

The pipes must be coated with a corrosion-resistant substance as they remain in place for long periods of time.

Coating takes place after the pipes are in place on the seabed as pressure testing needs to take place before they are coated.

Pneumatic components are used instead of an electric system to remove the risk of a spark igniting hazardous or inflammable substances.

The system has been developed for use in situations where pipes are not straight and cover uneven ground with steep inclines and declines.

The Snake gets its momentum from three air-powered gear motors and is driven into the pipe by three independent drive units coupled together.

Having three separate drive sections, with multiple drive wheels, positioned in a series enables the Snake to negotiate bends as tight as 0.7 metres and climb vertical inclines.

Independent suspension enables the drive units to automatically adjust to the size of the pipe using a mechanism which guarantees that the drive unit is always on the centre line of the pipe.

All the control functions of the machine are supplied by Norgren and because the machine relies on compressed air to operate, filter, regulator and lubrication equipment is key to its success.

The Snake is fitted with Norgren's 1 1/2" BSP ported filter, 1/8" emergency stop buttons, 1/4" reset button, 1/2" 3/2 pilot spring valves, 1" remote regulators, 1" ported regulator and 1/4" 5/3 lever/spring valves as well as many pushfit fittings from the pneufit range, small gauges and regulators, silencers and a large quantity of 8mm nylon tubing.

Covercat Spray Systems' general manager Garry Stonehouse said: "We are always asking Norgren for new products and use non-standard products in many of our other products in addition to the Pipe Snake." Spraying takes place as the Snake is on its way out of the pipe so the hose itself is clearly marked at every metre to enable the operator to know when it has reached the desired penetration distance.

The speed of the snake determines the thickness of the coating and the speed and stroke rate of the pump are controlled by the operator who has access to the centrally mounted control unit.

The system can be used to spray any type of coating from wax to epoxy paint and attachments such as a video camera can be mounted on the front of the Snake in order to carry out internal investigations of pipes.

It is available in a range of pipe sizes from 145mm to over 300m and requires compressed air at 10 bar (600 cfm) to operate.

Covercat Spray Systems specialises in heavy-duty products designed to help the off shore oil and shipping industries beat the problem of corrosion.

The Pipe Snake was developed specifically for the Norwegian Construction Company, Halliburton, which designs and builds products for the oil industry.

Many of the company's customers are based in America and the Scandinavian countries.

"We have been providing Covercat with pneumatic components for the past 16 years and were delighted to have been granted preferred supplier status four years ago on the basis of both price and quality," said Richard Pell Norgren's UK marketing manager.