Abstract
In the design of pipelines for high-temperature service, allowance has to be made for the thermal expansion of the heated pipe. One particular aspect of this problem is the use of bellows expansion joints which, particularly on board ship, can transmit the pipe movements through bulkheads whilst providing a watertight flexible anchorage.
An approximate theory has been developed for the compression of a bellows, the convolutions of which have a cross-section formed by circular arcs subtending any semi-angle α. Numerical results have been calculated for the two cases α = π/2 and α = 3π/4.
Experiments have been carried out on six bellows, four corrugated-pipe type α = π/2, one S-type α = 3π/4, and one flat-plate type which was not analysed theoretically. Deflexion and resistance strain-gauge readings were taken on each bellows, and reasonable agreement was found between the theoretical and experimental results for the five bellows in which these could be compared.
It has been found that for certain design conditions optimum relationships exist between bore, wall thickness, and radius of convolution for the maximum flexibility. Stress intensification and flexibility factors have been calculated to cover a range of bellows proportions.
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