| 摘要 |
A method of welding using a preheating insert is disclosed. The method includes the steps of positioning and igniting a combustible solid fuel mixture within a pipe to preheat the pipe by convection to a proper temperature and welding the pipe. The preferred and illustrated embodiment incorporates an encircling bottom support having a centralized hollow tube. It is made of a frangible material to be easily broken should it fall into the pipe. It supports a hollow, cylindrical, combustible heating element. The heating element is made of thermite as an example. It includes a top located deflector plate to deflect hot gases flowing upwardly from combustion against the wall of a pipe to be heated. The apparatus is concentrically located within the pipe in the vicinity of the pipe section to be heated.
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