Steel pipe making: the following technological process is used to make the steel pipe
1. Sample making: for the convenience of inspection and ensuring the manufacture and installation accuracy of steel pipe and all kinds of pipe parts, δ = 0.5mm galvanized steel plate is used to make sample plate. According to the design requirements, the internal diameter of steel tube radians inspection, support ring, stiffening ring and so on must make a template, the arc length of the template must conform to the specification requirements (according to the diameter of the pipe, the arc length of the template is 1.5 m). The template must be inspected and marked by a professional constructor to prevent mixing during use. To set out directly on a spliced steel plate by means of a ground gauge, steel ruler, etc., under the responsibility of a professional constructor, quality worker, or technical worker. The responsible person checks correctly before discharging.
2. Steel plate splicing and cutting: according to the design requirements, combined with the actual situation on the spot, the steel plate made of steel pipe all adopt a fixed steel plate, long, wide edge are left a little margin; In order to ensure that the circumference error of steel pipe is controlled in the minimum range, the method of splicing the two fixed plates and then cutting the material is adopted. The welding process of carbon dioxide protection welding is adopted in splicing. Before splicing, check whether the side length is straight, wide edge and long edge are perpendicular, at the same time, the steel plate is repaired with oxygen acetylene flame cutter to ensure that the width of the plate is in accordance with the design. Slag, burrs, and notches for cutting and planing surfaces, grinding with grinding wheels, all plates shall not have edges after processing Defects such as cracks, sandwich layers and slag inclusions. Remove the rust, slag, oil dirt, water stains and so on from the two sides of the welding joint 1020 cm before welding. After welding on one side, the steel plate is slowly turned over with gantry crane, the root is cleared by arc, and the welding is carried on after grinding.
3. According to the thickness of the plate, the spliced steel plate determines the size of the expansion, and draws the development diagram on the plate, carefully checks the parallel line and diagonal line, checks the accuracy before cutting; the cutting material is cut with oxygen acetylene flame cutter. Bend pipe, gradual tube and other pipe fittings and steel pipe cutting method is the same.
4. Firstly, the plane expansion diagram of the tube and shell is drawn by computer, and the chord length of each reference point is obtained after the coordinate of each point on the X axis and Y axis is found. In the actual layout, the two plates are docked, the length is larger than the maximum chord length, the width is the small opening chord height and the actual height of the steel pipe. At the same time, the coordinate points are drawn on the steel plate, and the coordinate points are tactically connected to each coordinate point. Check that the arc length of the branch and supervisor connection is the same, check before loading.
5. After cutting, the groove of weld seam is cut by oxygen-acetylene flame, then molded with angle to the grinder.
Bend pipe, gradual tube and other pipe fittings and steel pipe cutting method is the same. Cutting allowance and welding shrinkage allowance should be taken into account when the sheet is lofting and cutting. In general, 3-4 mm is reserved.