Welding seamless steel pipe
General Terms
Welding of seamless steel pipes is performed either when replacing a certain section of the pipeline, or when building into the pipeline of a new shut-off valve. In any case it is butt welding which procedure and sequence is regulated by norms and rules RD 39−01−0147014−537−87. This guiding document establishes the basic technological solutions of welding production at the enterprises and organizations of ministries and departments that perform installation and repair works when laying pipelines and critical steel structures.
Standards, SNiP
RD 39−01−0147014−537−87 is based on the requirements of standards, SNiP, as well as safety regulations that apply to the assembly, welding, heat treatment and quality control of welded joints of pipelines and critical steel structures, which use steel seamless pipes. The guideline document contains recommended technological processes for electric arc and resistance butt welding of the considered types of pipes.
Welding electrodes
The following grades of electrodes are used for manual welding of seamless steel pipes
If the steel seamless pipes are made of different grades of steel, the following types of welding electrodes are used:
When butt welding, welding wire or flux-cored wire can also be used.
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Welding technology
Before winter welding, pipes are heated (inductors or gas burners are used) and electrodes or fluxes are calcined. Seamless steel pipes are inspected for size and quality of ends, and the absence of rolling defects (dents, dents, voids, cracks). Similar control is carried out for welded pipeline fittings. Preparation of joints for welding consists in cutting of pipe ends. The method of cutting and geometric parameters of the end face are set depending on the selected welding procedure. Seamless steel pipes are welded in the following sequence:
- — Butt tacking of the joint surface (until at least half of its height is filled with consumable);
- — Overlaying the second layer (at intervals in the work it is recommended to insulate the joint with asbestos pads);
- — The applied roll shall be as flat as possible. After surfacing, be sure to remove the flux residue;
- — When the required parameters of the height and width of the weld reinforcement zone are reached, the welding is considered completed, and the executor’s branding is applied to the finished joint.
Purchase. Supplier, price.
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