GB1197408A - Methods of Forming Pre-Stressed Laminated Heads for Pressure Vessels - Google Patents

Abstract

1,197,408. Making pressure vessels, welding by fusion. HAHN & CLAY. 22 June, 1968, No. 29887/68. Heading B3A and B3R. A method of making a pre-stressed laminated pressure vessel head includes providing a solid inner layer L, forming a plurality of curved gores 10, 11, 12, applying an external force on each gore to engage the surface of the layer L, depositing weld metal around substantially the entire periphery of the gores, the quantity of weld metal being sufficient to cause the outer layer to place the inner layer under compression when the welds cool. The layer L is formed by forging or other shaping operation and is normally of quenched and tempered steel, stainless steel or carbon steel. The gores 10, 11, 12 are cut from sectors (S) of steel plate, Fig. 4 (not shown) and have a number of holes drilled at spaced locations. After drilling, a gore 10 is heated to about 500‹ F. and placed on the layer L, which is preferably heated to about 175‹-200‹ F. The gore is held in place by a hydraulically actuated ram 28, which is adjustably mounted on an arm 20. The arm is fitted with a hook 25 and is pivotally mounted on a pin 21 formed integrally with a base 22 which is temporarily welded to the layer L. The ram 28 is placed in positions adjacent the edges of the gore, where tack welds are made. The remaining gores 10, 11, 12 are similarly tack welded in place. The final welds between the gores are then made or they may be made when adjacent gores have been tack welded in position. The welds are ground and the holes are used to determine the gap between each gore and the surface of the layer L. If the gap is excessive, the gore is cut across in the area of the excessive gap and rewelded to reduce the gap. Further layers B, C, D, E are similarly added until the head is of the required thickness. The base 22 is removed after all the layers have been applied and circular sections (50), preferably also provided with measuring holes may be added, corresponding to each of the outer layers, Fig. 10 (not shown).