GB744435A - Improvements in or relating to corrugated metal pipes - Google Patents

Abstract

744,435. Electrically heated pipes. PIRELLIGENERAL CABLE WORKS, Ltd., and ARMAN, A. N. Aug. 12, 1954 [Oct. 22, 1953], No. 29213/53. Class 39(3). [Also in Group XXVIII] Corrugated pipes made of metal such as aluminium, copper, zinc or their alloys or of steel or stainless steel, are heated electrically by resistance wires 3 accommodated in the external troughs formed by the corrugations and are insulated from the pipes. In Fig. 1, twin wires 3 enclosed in an insulator 4 are laid in a helical trough 2 formed in a pipe 1, which is then enclosed in lagging 5 and a waterproof covering 6. The wires are joined at one end, the other ends being connected to a power supply, or are connected in parallel to the supply terminals. In Fig. 2 (not shown), a bare wire rests on an insulating tape laid in the trough and is covered by a second tape ; the pipe acts as return conductor. In Fig. 3 an insulated feeder strip 9 is laid in the trough 2 outside a wire 3, and in Fig. 4 (not shown) the wires 3, 9 are bare and laid between insulating tapes. The corrugations may comprise separate troughs each in a plane at right angles to the pipe axis, separate wires being provided or a single wire passing from groove to groove. In Fig. 5 (not shown) the corrugations are formed by a two-start helix, a heater wire being laid in one and a circular feeder, to fit the trough, in the other, and in Fig. 6 (not shown), bare wires laid between insulating strips are used ; both a heater and a feeder wire may be located in either or both troughs. Where a feeder wire is used, the heater wire may be divided into lengths connected in series,parallel or series-parallel between the feeder and a return conductor consisting of a second feeder or the pipe 1. When lengths of pipe are joined together, the connections for heater and feeder wires and the pipe are made in a box formed as a separate unit or as part of the pipe coupling, and where parallel pipes are used one is used as the outgoing feeder and the other as return.