The materials of butt welding elbow include cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, nonferrous metal and plastic, etc.Pipe connection: butt welding elbow direct welding (the most common way) flange connection, hot melt connection, electric melt connection, thread connection and socket connection.According to the production process can be divided into: stamping elbow, push elbow, welding elbow, casting elbow.Other names: 90 degree bend, right Angle bend, love and bend, etc.
Butt welding elbow use: connect two of the same or different nominal diameter tube, and have made line 90 °, 45 °, 180 °, and various degrees of corner.Bending radius less than or equal to 1.5 times the pipe diameter belongs to the elbow, greater than 1.5 times the pipe diameter belongs to the elbow
Technical requirements for welded elbows.
1. Since most pipe fittings are used for welding, in order to improve the welding quality, the end part is turned into groove with a certain Angle and a certain edge. This requirement is also strict.The surface quality and mechanical properties are basically the same as those of pipes.For welding convenience, the pipe fitting is the same type of steel as the pipe being connected.
2. is the packaging requirements for small pipe, such as exports, it is necessary to do a wooden box, about 1 cubic meter, the number of elbow in the box is not allowed to exceed about a ton, the standard allows suits, that is, a small set, but the total weight generally not more than 1 ton.For large items, a single package is required; for items like "24", a single package is required.It is to pack mark additionally, mark is to want to make clear dimension, steel number, batch number, manufacturer mark to wait.
3. It means that all pipe fittings shall be treated with surface treatment, and the scale of internal and external surface shall be sprayed out through shot peening, and then coated with anticorrosive paint.This is for export needs, in addition, in order to facilitate transportation and prevent corrosion and oxidation, to do this work.
The following factors should be paid attention to during welding and installation of butt welding elbow to avoid engineering problems:
1. Before the installation of butt welding elbow, pipe joints shall be measured one by one and numbered. It is advisable to use the joint group with the smallest diameter difference for butt joint.When joining pipes in the ground face, 14CM*14CM sleepers should be used to level the pipes. Iron steel pipes should not be used, and the rolling of pipes should be minimized to avoid damaging the external corrosion of pipes.
2. Check the internal and external anticorrosive coating of the pipe joint before laying the pipe, and only after passing the inspection can the pipe be laid down.The length and hoisting distance of the pipe section shall be determined according to the pipe diameter, wall thickness, material type of the outer anticorrosive coating and the method of pipe laying.The hoisting rope should be made of soft materials such as steel wire rope with rubber tube sleeve or strong rope, so as not to damage the outer anti-corrosion layer of the steel pipe.The distance from the starting point of the elbow to the interface shall not be less than the pipe diameter, and shall not be less than 100MM.The welding rod used for pipe joint welding shall comply with the design and specification.
3. Clean the dirt in the pipe, and polish the edge of the pipe mouth and both sides of the welding mouth to expose the metallic luster and make groove.Locate the two pipe ends in the center of the pipe, and spot weld 3 places along the circumference of the pipe (the electric welding seam is about 4MM long and 5MM high), and position the two pipes.Use 2-3MM layer welding full pipe seam.The welding surface of elbow welds is smooth without cracks, pores, sand holes and other defects.
4.when the environment temperature is lower than 0 ℃, after completion of welding must be covered with asbestos.Remove the welding slag after the completion of electric welding.The flatness of the pipe shall be checked after the alignment, and the measurement shall be made 200MM away from the interface center, with the allowable deviation of 1MM/M, but the allowable deviation of the whole length shall not exceed 10MM.The pipe should be firmly padded to avoid deformation during welding.