seen framstella spenningsfria row, device for utovande of set, and according to the set framstellda row

摘要

Circumferential stresses in tubes are relieved by exerting an axial pull on a tube sufficient to elongate the tube at least 0.2%, and maintaining the pull on the tube for a predetermined period of time. The extent of elongation can be as much as 1% and the axial pull can be maintained for several minutes. The technique is particularly useful for substantially reducing or eliminating circumferential stresses in thin wall tubes which are created by straightening the tube with hyperbolic profile rollers.