The advantage of thick-walled straight seam steel pipes is that the online heat treatment process of the weld eliminates the welding stress, refines the metallographic structure grains in 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 below ф406mm can be used, and thick-walled straight-seam steel pipes must be used above ф406mm, which has led to the development of HFW/ERW units in the direction of producing thick-walled straight-seam steel pipe products.

The direction of structural adjustment of high-frequency straight seam welded pipes in the future is to move towards high-grade steel and large-wall thickness product series. The typical process is the "F.F.X forming + thermal tension reduction + full-pipe heat treatment" mode to adapt to oil and gas pipelines, subsea pipelines, and oil wells. tube market demand. The high-frequency straight seam welded pipe heat treatment mode can also be used to develop building structural pipes, boiler pipes, and marine pipelines for thick-walled straight seam steel pipes. High-frequency straight seam welded pipes should also pursue product diversification, producing precision pipes such as automobiles, light industry, chemical industry, textiles, food, medical, medium and low-pressure boilers, household appliances, construction, container pipes, etc.

Basic procedures for daily maintenance of thick-walled straight-seam steel pipe cantilever cranes.
1. When lifting thick-walled straight-seam steel pipes, the wire rope is not allowed to be pulled diagonally to prevent the wire rope from coming out of the groove.
2. Pay attention to personal safety and equipment during operation.
3. Always check the switches on the front and rear of the trolley and whether the switch for the maximum hook lifting limit is sensitive.
4. Lubricating points such as gears, sprockets, chains, and ropes of thick-walled straight-seam steel pipes must be lubricated regularly.
5. When operating the cantilever crane, you must cooperate closely with the hanging personnel and obey the hanging instructions.
6. The hook should be fully hung with the coil.
7. The wire rope should be replaced when 10% of its strands are broken.
8. Always check whether the hook lifting brake is easy to operate and sensitive.

The production process of large-diameter thick-walled straight seam steel pipes is automatic submerged arc welding. The process procedures are 1 pre-bending, 2 pre-welding, 3 internal and external welding, 4 round straightening, and 5 port processing. Large-diameter thick-walled straight-seam steel pipes are becoming more and more important in the steel pipe application industry. The main application industries of large-diameter thick-walled straight-seam steel pipes include water conservancy projects, steel structures, the electric power industry, the chemical industry, urban planning and construction, irrigation, and long-distance oil and gas transportation. Pipelines, bridge piling, submarine oil pipelines.

1. Flaw detection of thick-walled straight-seam steel pipes and steel plates: Before the steel plates for manufacturing large-diameter thick-walled straight-seam welded steel pipes are put into production, the first step is to conduct a preliminary inspection of the steel pipe plates;
2. Steel plate edge milling: The thick-walled straight-seam steel pipe's self-developed edge milling machine mills the steel plate into a V-shaped groove shape;
3. JCOE forming: The JCO forming machine imported from Germany stamps the steel plate multiple 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. shape
4. Opening pre-welding: The thick-walled straight-seam steel pipe blanks with formed openings are pre-welded, and shallow welding is used here.
5. Internal welding after pre-welding: a double-sided automatic submerged arc welding machine performs automatic submerged arc welding on the inside of the thick-walled straight seam steel pipe; b. External welding: a double-sided automatic submerged arc welding machine performs automatic submerged arc welding on the outside of the thick-walled straight seam steel pipe The weld seams are automatically welded by submerged arc;
6. Cold expansion (reduction) of diameter: Precision diameter expansion of thick-walled straight-seam steel pipes improves the precision size of thick-walled straight-seam steel pipes and reduces the internal stress of the steel pipes.
7. Non-damage control of thick-walled straight-seam steel pipe industrial TV assembly line operations Ⅰ: 100% strict inspection of the internal and external welds of the straight-seam welded steel pipe and the adjacent base metal, working speed: 2.5 meters/minute.
8. Product hydraulic pressure test: The steel pipes on the hydraulic pressure testing machine are tested one by one to ensure the test pressure.
9. Port processing: Qualified thick-walled straight seam steel pipes are processed to meet the required form of pipe ends.
10. Steel pipe anti-corrosion: Thick-walled straight-seam steel pipes are provided with anti-corrosion coating and related work according to the contract process.

Judging from the existing technology, the hot-feeding and furnace-charging technology for continuous-cast round billets can be promoted in continuous-rolled pipe production lines and some AR and ASSEL rolling mill production lines to achieve 100% continuous-cast round billets. The online quenching heat treatment process for large-diameter seamless steel pipes has been successful in Valin Hengyang Steel Pipe, which simplifies the alloy steel pipe production process and reduces energy consumption and heat treatment costs per ton of steel. The products of the "piercing + cold drawing (rolling)" unit can adapt to market demand and user recognition, and still have vitality at this stage; hot-rolled seamless steel pipe units below ф76mm are designated as backward production capacity, and there is still controversy in the industry about this.