GB936972A - Device for use in the heat-treatment of welded pipes - Google Patents

Abstract

936,972. Heat-treating pipe welds; exothermic compositions. KEMWELL A.G. July 10, 1962 [July 9, 1962], No. 26346/62. Classes 72 and 82. A heat-treatment for stress-relieving the welded area of butt-welded pipes comprises locating loosely around the pipes 4 in the region of the weld 5 two metal hoops 6 having tightening means, e.g. screws 7, locating in engagement with such hoops a plurality of adjacent exothermic composition blocks 1, each of which has embedded therein, or otherwise secured thereto, a metal strip 2, the ends 3 of which extend adjacent to the pipe beyond two opposite faces of the block and lie under the metal hoops, tightening the hoops to secure the blocks by the metal strip ends 3, firing the blocks and allowing them to cool in situ. The blocks may be multi-layer, at least one layer being of exothermic composition and at least one of heat-insulating composition, and may be moulded from mouldable compositions with the metal strip in the mould; or outer and end sleeves of heat-insulating material, similarly moulded, may enclose the exothermic sleeve. An example of an exothermic composition is: finely divided aluminium 30 parts, oxidizing agent, e.g. nitrates, chlorates, iron oxide and/or manganese dioxide 13 parts, and refractory filler, e.g. grog, sand, furnace aggregate or chamotte 42 parts, all by weight.