The process flow for the production of steel pipes is as follows:
1. Sample preparation: In order to facilitate the inspection, the production and installation accuracy of the steel pipe and various pipe parts are ensured, and the sample is made of galvanized steel plate
with δ=0.5mm. According to the design requirements, the inner diameter arc inspection, support ring and stiffening ring of the steel pipe must be made into samples. The arc length of the sample must meet the requirements of the specification (the arc length of the sample is 1.5~2m according to the pipe diameter). After the sample is finished, it must be inspected by a professional constructor and marked at the same time to prevent mixing during use. Elbows and elbows are directly placed on the spliced steel plate by using the ground gauge and steel ruler. After the inspection is completed by a professional constructor, quality technician or technical person in charge, the material can be cut.
2. Steel plate splicing and blanking: According to the design requirements, combined with the actual situation of the site, the steel plates for the production of steel pipes are all made of fixed-length steel plates, leaving a small margin for both the long and wide sides; to ensure that the error of the circumference of the steel pipe is kept within the minimum range. The method of splicing two fixed-length boards after cutting is adopted; the splicing is welded by carbon dioxide protective welding process, and whether the side length is a straight line, whether the wide side and the long side are vertical are checked before splicing.
At the same time, the steel plate is trimmed with an oxygen-acetylene flame cutter to ensure that the width of the steel plate conforms to the design, and the slag, burrs and notches of the cutting and planing surface are ground by the grinding wheel. The edges of all the plates after processing shall not have cracks or interlayers. Defects such as slag inclusion; rust, slag, grease, water stains, etc. in the range of 10 to 20 cm on both sides of the welded joint shall be cleaned before welding. After inspection, the welding shall be carried out; Slowly turn the surface, use an electric arc to clear the roots, polish it and then continue welding.
3. The spliced steel plate is determined according to the thickness of the plate, and the unfolding size is determined. At the same time, the unfolded drawing is drawn on the steel plate, and the parallel lines and diagonal lines are carefully checked. The inspection can be performed after the inspection is correct; the oxygen-acetylene flame cutting knife is used for the blanking. Cutting. Pipe fittings
such as elbows and grading pipes are the same as those for steel pipes.
First, use the computer to draw the plane development of the elbow shell. After finding the coordinates of each point on the X and Y axes, the chord length of each reference point will be obtained. In the actual lofting, the two steel plates will be docked, and the length is greater than The chord length of the largest mouth, the width is the actual height of the small mouth and the string height plus the steel pipe. At the same time, draw the coordinate points on the steel plate, smoothly connect the coordinate points, and carefully check whether the arc length of the branch pipe and the main pipe connection are the same, and the check is correct. Can be cut at the rear.
4. After cutting, the groove at the weld is cut with an oxygen-acetylene flame and then ground with an angle grinder. Pipe fittings such as elbows and grading pipes are the same as those for steel pipes. When cutting and unloading the sheet, the cutting allowance and the shrinkage allowance of the sheet should be considered. Under normal circumstances, leave 3-4mm.