Pipe fitting butt welding protecting method and apparatus

Abstract

The invention relates to a protection device for pipe fitting butt welding, comprising two balloons communicated with an expandable tube; by charging gas to the balloons through the expandable tube, the balloons are expanded and closely adhere to the wall of the tube; a gas filling tube passes through the balloons, which can fill in welding protective gas to the cavity formed between the pipe wall and the two balloons after the balloons are expanded; an exhaust pipe also passes through the balloons, and the gas in the cavity can be exhausted to the outside by the exhaust pipe. When butt welding of pipe fittings is performed, the two balloons are respectively arranged at both sides of a joint, and the two balloons are charged with gas through the expandable tube; the expanded balloons and the inner wall of the pipe fitting press closely, and an independent cavity can be formed between the expanded balloons and the pipe wall; welding protective gas is charged into the cavity by the gas filling tube, meanwhile the air in the cavity is exhausted by the exhaust pipe; when the cavity is completely filled with the welding protective gas, welding can be performed. The protection device of the invention greatly reduces the amount of the welding protective gas, simultaneously shortens air emptying time before welding and gas filling time of the welding protective gas greatly, therefore welding efficiency is improved.

Description

technical field [0001] The invention relates to a method for protecting the pipe fittings to prevent the seams from being oxidized during butt welding of pipe fittings; and a device for protecting the butt welding of pipe fittings using the method. technical background [0002] When pipe fittings are butt welded, the joints are easily oxidized at high welding temperatures, which affects their mechanical properties and corrosion resistance. In order to prevent the joints of the two pipes from being oxidized during the welding process, so that the joints also have excellent performance, usually the butt-joined pipes are closed from both ends during welding, and nitrogen gas is filled into the entire closed pipe cavity. The welding shielding gas evacuates the original air in the pipe, so that the cavity after the exhausted air is filled with welding shielding gas such as nitrogen, so as to prevent the oxidation of the seam. However, this method requires the use of a large amou...

AI Technical Summary

Problems solved by technology

However, this method requires the use of a large amount of welding shielding gas, especially when the pipe fittings to be joined are long, to exhaust the air in the inner cavity of the pipe fittings with both ends closed and fill them with welding shielding gas, a large amount of welding shielding gas is required, while requiring a long inflation time

For infusion pipelines on ships, the pipe fittings are often tens of meters or even tens of meters long. To meet the welding requirements, sometimes it is necessary to continuously fill the inner cavity of the pipe fittings with welding shielding gas for several hours before welding, which is wasteful. A large amount of welding shielding gas greatly affects the efficiency of welding

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