PE Pipe Technical Catalogue (PDF) - Pipelife Norge AS

Pipelife Norge ASPE CATALOGUE-SUBMARINE APPLICATIONS, PIPELIFE NORGE AS, December 2002.Solution :First we find the weight of the concrete weights and the pipe in water by use of A.4.3) :2400 −1025w cw = 6.5 ⋅kN=3.2 kN(a piece)24003.2w cw = kN / m=0.64 kN/m(pr. m pipe)5wpipe w950 −1025= 0.35 ⋅ kN / m950= −0,28 kN/mThe internal diameter of the pipe is :2 ⋅ 500d = (500 − )mm = 454.6 mm22We apply formula A.4.2) to calculate the degree of air filling :(0.64 − 0.028) ⋅100a a =% = 37.5%20.45463.14 ⋅ ⋅1025⋅9.814The corresponding degree of displacement can be found from fig. A.4.1 by interpolating betweenSDR 17.6 and SDR 26 for sea water.This gives : a d ≈ 32 %For all practical situations will a a > a dA.4.2Types of concrete weightsThere are 3 types of concrete weights by reference to the shape :− Rectangular− Circular− StarredThese are schematic shown in fig. A.4.2.1.Rectangular Circular StarredRectangular Circular StarredFig. A.4.2.1 Different types of concrete weightsAll weights are to be bolted on the pipe. The fix force should be sufficiently to avoid sliding duringsinking and rotation on seabed.As a rule of thumb, the bolt force shall be in the range 2-3 times the weight of the concrete weight inair.Between the concrete weight and the pipe wall there shall be a rubber band, type EPDM orequivalent. In most cases we also recommend rubber compensators in the bolts to reduce localstresses in the pipe wall caused by internal pressure.Side 50 av 84