Spiral welded pipe is also a type of welded pipe equipment. Its strength is generally higher than that of straight seam welded pipe. It can use narrower billets to produce welded pipes with larger diameters. It can also use billets of the same width to produce welded pipes with different diameters. However, compared with straight seam pipes of the same length, the weld length is increased by 30~100%, and the production speed is lower. Therefore, smaller-diameter welded pipes mostly use straight seam welding, while large diameter welded pipes mostly use spiral welding.
Spiral steel pipe production process: It is a spiral seam steel pipe welded by automatic double-wire double-sided submerged arc welding process using strip steel coil plate as raw material, constant temperature extrusion molding.
1. The raw materials are strip steel coil, welding wire, and flux. Before putting into use, they must go through strict physical and chemical tests.
2. The head and tail of the steel strip are butt-jointed using single-wire or double-wire submerged arc welding. After being rolled into a steel pipe, automatic submerged arc welding is used for repair welding.
3. Before forming, the strip steel is leveled, trimmed, planed, surface cleaned, transported, and pre-bent.
4. Electric contact pressure gauges are used to control the pressure of the cylinders on both sides of the conveyor, ensuring smooth conveying of the strip.
5. Adopt external control or internal control roll forming.
6. The weld gap control device is used to ensure that the weld gap meets the welding requirements and that the pipe diameter, misalignment, and weld gap are strictly controlled.
7. Both internal and external welding adopt American Lincoln electric welding machines for single-wire or double-wire submerged arc welding, to obtain stable welding specifications.
8. All the welded seams are inspected by the online continuous ultrasonic automatic flaw detector, which ensures 100% non-destructive testing coverage of the spiral welds. If there is a defect, it will automatically alarm and spray the mark, and the production workers can adjust the process parameters at any time according to this to eliminate the defect in time.
9. Use an air plasma cutting machine to cut the steel pipe into single pieces.
10. After being cut into individual steel pipes, the first three steel pipes in each batch must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion status of the welds, the surface quality of the steel pipes, and non-destructive testing to ensure that the pipe making process is qualified. After that, it can be officially put into production. 11. The areas with continuous sonic flaw detection marks on the welds will undergo manual ultrasonic and X-ray re-examination. If there are indeed defects, they will be repaired and then undergo non-destructive inspection again until it is confirmed that the defects have been eliminated.
12. The pipes where the strip steel butt welds and the D-shaped joints intersected with the spiral welds are all inspected by X-ray TV or film.
13. Each steel pipe has passed the hydrostatic pressure test, and the pressure is radially sealed. The test pressure and time are strictly controlled by the steel pipe water pressure microcomputer detection device. Test parameters are automatically printed and recorded.
14. The pipe end is mechanically processed to accurately control the verticality of the end face, the bevel angle, and the blunt edge.
Anti-corrosion spiral welded pipe technology
Since the individual mass of spiral welded pipes is relatively large, they must be stacked outdoors. However, they will inevitably be exposed to the sun and rain, so the problem of rust has always plagued the storage time and conditions of spiral welded pipes. Therefore, we must provide a comprehensive answer to the antirust knowledge of spiral welded pipes. Mainly use tools such as wire brushes to polish the steel surface. Cleaning and preheating the spiral welded pipe can remove loose or lifted scales, rust, welding slag, etc. The rust removal of hand tools can reach the Sa2 level, and the rust removal of power tools can reach the Sa3 level. If the iron oxide scale is firmly attached to the surface of the steel, the rust removal effect of the tool will not be ideal and the anchor pattern depth required for anti-corrosion construction will not be achieved.
Pickling uses solvents and emulsions to clean the surface of welded steel pipes (welded pipes) for low-pressure fluid transportation to remove oil, grease, dust, lubricants, and similar organic matter, but it cannot remove rust, oxide scale, flux, etc. on the steel surface. Therefore, it is only used as an auxiliary means in anti-corrosion production.
Generally, chemical and electrolytic methods are used for pickling treatment. Only chemical pickling is used for pipeline anti-corrosion, which can remove scale, rust, and old coatings. Sometimes it can be used as a reprocessing after sandblasting and rust removal. Although chemical cleaning can make the surface reach a certain degree of cleanliness and roughness, its anchor lines are shallow, and it is easy to cause pollution to the stacking environment of spiral welded pipes.
Reasonable use of means to clean up rusted pipe fittings ensures that the pipe fittings will serve production for a long time and create more production benefits.
Post time: Sep-06-2023