People around the world use pipe supports and restraints; in fact they spend somewhere in the region of £150million on ‘engineered supports’ each year.

The majority of pipes that we support and restrain are actually long thin pressure vessels operating at high pressures and temperatures, and occasionally at very low temperatures. In general they connect one large piece of equipment to another and facilitate the flow of fluid between the various processes. In some cases we supply supports for pipes that operate at temperatures as high as 850°C and diameters large enough to walk through.

During the operating cycle of the plant there is inevitably a change in temperature; when the plant is not working it is at ambient temperature and when it works it operates at a different temperature. Even changes in temperature between day and night can have significant effects.
Almost all materials expand or contract as their temperature is increased or decreased. A pipe that carries steam from a boiler to a turbine heats up from room temperature to 570°C between not working and working. This change in temperature will cause the pipe to expand by approximately 7.5mm/m, though the change is most prominent in the length of the pipe rather than in its diameter.

Imagine if the pipe could not expand or contract freely, the force generated in preventing the expansion to take place will cause substantial damage to either the pipe or the equipment at each end of it!

Consider the pipe work in a power station and liken it to your own central heating system; fluid is pumped around a closed system. In the boiler water is heated under pressure allowing its temperature to be increased to over five times the normal boiling temperature of water. An escape of steam under these conditions would simply cut a man in half.

This steam passes through the pipe work into the turbine where the pressure drives the turbine and generates the electricity. Inside the turbine the pressure is reduced and the temperature of the steam decreases. It is then sent back to the boiler where it is heated up again and so the cycle continues. The greater the demand on the power station, the higher the operating pressure and temperature will be.

The analogy with the central heating system; when your heating comes on or goes off you hear all sorts of creeks and bumps as the system heats-up or cools-down. That is simply because the piping is expanding and contracting between fixed points; the noises are due to the pipe moving against the joists and floor-boards of your house.

On a large, coal fired power station such as Drax in Yorkshire the boiler may be as tall as a ten storey building and the turbine will be perhaps 500m away from the boiler. The length of pipe could quite easily be 1km between the two. When you consider the amount of the expansion mentioned above, the whole pipe will grow in length by 7.5m.

Peel away the insulation around the pipe when it is hot and you will actually see the pipe glowing a dull cherry red – at this temperature the metal from which the pipe is made becomes like plasticine. If it is not supported correctly it will sag and deform; this will cause problems to the subsequent operation of the plant. Drainage slopes will become disturbed, excessive forces will be transferred to the boiler and turbine connections and eventually the power station will not be able to operate.

An example of what can go wrong under such situations occurred at Money Point power station in Ireland some years ago. Steam was released into pipe work where a pool of water had gathered; the pressure of the steam forced the water through the pipe causing severe damage to the pipe, the supports and even the building structure. A very costly repair followed!