Routine maintenance and production process of thick-walled straight seam steel pipe

The advantage of thick-walled straight seam steel pipe is that the online heat treatment process of the weld eliminates the welding stress, refines the metallographic grains of the heat-affected zone, and improves the physical and mechanical properties. Western developed countries attach great importance to the application of HFW/ERW welded pipes. For example, Greece and Japan produce HFWф610mm×25.4mmX60 and X65 steel-grade welded pipes respectively to replace seamless steel pipes and thick-walled straight seam steel pipes. There is a misunderstanding in China that HFW/ERW welded pipes can be used below ф406mm, and thick-walled straight seam steel pipes should be used above ф406mm, which leads to the development of HFW/ERW units to produce thick-walled straight seam steel pipes.

The direction of structural adjustment of high-frequency straight seam welded pipes in the future is to enter the series of products with high steel grade and large wall thickness. Tube market demand. High-frequency longitudinal welded pipe heat treatment mode can also be developed for thick-walled longitudinal seam steel pipes for building structural pipes, boiler pipes, and marine pipelines. High-frequency longitudinal welded pipes should also pursue product diversification, and produce precision pipes for automobiles, light industry, chemicals, textiles, food, medical care, medium and low-pressure boilers, household appliances, construction, and container pipes.

The basic process of cantilever crane for daily maintenance of thick-walled straight seam steel pipe.
1. When the thick-walled straight seam steel pipe is hung and lifted, the wire rope is not allowed to be pulled obliquely to prevent the wire rope from falling out of the groove.
2. Pay attention during operation to ensure personal safety and equipment.
3. Frequently check the switches at the front and back of the trolley, and whether the switch with the maximum lifting limit of the hook is good and sensitive.
4. Lubricating points such as gears, sprockets, chains, ropes, etc. should be refueled regularly.
5. When operating the cantilever crane, it is necessary to cooperate closely with the hanger and obey the command of the hanger.
6. The hook should be fully hung with coils.
7. The wire rope should be replaced when 10% of its strands are broken.
8. Frequently check whether the hook lifting brake is good and sensitive.

The production process of large-diameter thick-walled straight seam steel pipe is automatic submerged arc welding, and the process procedures are 1 pre-bending, 2 pre-welding, 3 internal and external welding, 4 rounder straightening, and 5 port treatment. Large diameter thick wall straight seam steel pipe is becoming more and more important in the steel pipe application industry. The main application industries of large diameter thick wall straight seam steel pipe are hydraulic engineering, steel structure, electric power industry, chemical industry, urban planning construction, irrigation, oil and gas long-distance transmission Pipeline, bridge piling, and subsea oil pipeline.

1. Flaw detection of thick-walled straight seam steel pipe plate: before the steel plate for manufacturing large-diameter thick-walled straight seam welded steel pipe is put into production, the first step is to conduct wave preliminary inspection on the steel pipe plate;
2. Steel plate edge milling: The edge milling machine developed and researched by the thick-walled straight seam steel pipe mills the steel plate, and the steel plate becomes a V-shaped groove shape;
3. JCOE forming: JCO forming machine imported from Germany stamps the steel plate several times step by step to form a "J" shape, and then uses the same process to make the other end of the steel plate into a "C" shape, and finally forms an open "O" shape.
4. Opening pre-welding: The thick-walled straight-seam steel pipe blanks with openings are pre-welded and seamed. Here, cushion-type shallow welding is used.
5. Internal welding after pre-welding: Lincoln double-sided automatic submerged arc welding machine performs submerged arc automatic welding on the inner weld seam of thick-walled straight seam steel pipe; b. External welding: double-sided automatic submerged arc welder The outer seam is submerged arc automatic welding;
6. Cold expansion (reduction) diameter: the precision diameter expansion of thick-walled straight-seam steel pipe improves the precision size of thick-wall straight-seam steel pipe and reduces the internal stress of the steel pipe.
7. Non-destructive damage control of thick-wall straight seam steel pipe industrial TV assembly line operation Ⅰ: 100% strict inspection of inner and outer welds of straight seam welded steel pipes and adjacent base materials, working speed: 2.5 m/min.
8. Product hydraulic test: The steel pipes on the hydraulic testing machine are tested one by one to ensure the test pressure.
9. Port treatment: Qualified thick-walled straight seam steel pipes are processed to meet the required form of pipe ends.
10. Anti-corrosion of steel pipes: thick-walled straight seam steel pipes shall be coated with anti-corrosion and related work according to the contract process.