Pre-insulated Pipe Systems for HTHW and Steam

Steel-cased pipe-in-pipe systems have been in use since 1930, and since the early sixties in Europe. Practical experience with these systems thus goes back more than forty years. Today they are considered to be a very safe and durable form of high temperature energy distribution.

Steel-Cased Pipe-in-Pipe Systems for Steam and High Temperature Fluids

The material for the inner pipe is selected according to the medium to be transported and its operating parameters. Plain steel pipes, welded or seamless, are used for hot water or steam, for aggressive media, stainless steel or copper may be used.

The heat insulation used consists of shells of resinoid-bonded mineral or glass wool, which are suitable for operating temperatures of up to 600ºC. The resinoid bonding volatilises at 250ºC but the shells still retain their shape. They are fastened with stainless steel bands.

The medium pipe and the insulation are encased in steel conduits, giving the system its name. The encasing pipe consists of longitudinally or spirally welded piping, with wall thicknesses designed to withstand traffic loads as per DIN 1072 SLW 60.

The conduit is protected externally against corrosion by a 6-8 mm coating of tropical quality bitumen or a 3-4 mm thick layer of polyethylene or equal.

Cathodic corrosion protection can be provided to supplement the conduit coating.

Steel-cased pipe-in-pipe systems are employed for temperatures of up to 400ºC and for all nominal pressures that occur. It should be noted, however, that there are no sufficiently reliable cathodic insulation pieces for temperatures exceeding 250ºC.

Please contact us for further information.