GB1443940A - Piping - Google Patents

Abstract

1443940 Weight coated steel pipe BRITISH PETROLEUM CO Ltd 12 Dec 1973 [4 Dec 1972] 55842/72 Heading F2P A weighted submarine steel pipe comprises a steel pipe 1 which has an outer cover consisting of a plurality of tubular collars of plastics material, each of the collars having a larger internal diameter than the external diameter of the pipe and having at the ends thereof closing means whereby a discrete annular cavity is defined between the pipe and the cover which cavity is filled with a weighting material. The collars may be made from a foamed plastics material or from a material, e.g. high density polyethylene having an Izod impact strength which preferably lies between 3 and 5. The collars are preferably designed with spacing rings at either end which define the cavity between the collar and the pipe and which separate the weighting material in adjacent collars. Internal ribs 4 position the collars on the pipe and also serve to strengthen the collars. They preferably have undercuts 5 to allow a flowable, settable weighting material to easily fill the cavity and to lock the collars on to the pipe when the weighting material sets. In order that the collars can be more easily placed around the pipe they may be made in sections 2 and 3 the longitudinal joint between them being in the form of a tongue and groove, the sections being held together by glueing the joint or by banding. For ease of filling the uppermost section may have a hatch 9 through which the weighting material is poured, a cover being provided to close the hatch to prevent loss of weighting material during the setting period. The flowable, settable weighting material may be concrete or an unsaturated polyester resin/aggregate mix having an aggregate to resin ratio in the range 1 : 7 to 1 : 15. The pipe 1 may be wrapped with an anticorrosion material consisting of bitumen or polyester resin containing glass fibres prior to the application of the weight covering.