Galvanized straight seam steel pipes mainly include hot-dip galvanizing and cold-galvanizing. The surface is welded with hot dip or galvanized steel. Zinc plating can increase the corrosion resistance of steel pipes and prolong their service life. Production process of thick-walled straight seam steel pipe for arch bridge: slab–milling–pre-bending–forming–pre-welding–internal welding–outer welding–ultrasonic inspection. Hot-dip galvanizing is to first carry out steel pipe pickling.
in order to remove iron oxide on the surface of the steel pipe, after pickling, it is washed by ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to a hot dip plating tank. Galvanized straight seam steel pipe is widely used, in addition to pipelines for general low-pressure fluids such as water, gas, oil, etc. It is also used as oil well pipes, oil pipelines, oil heaters for chemical coking equipment in the petroleum industry, especially in marine oil fields. Condensation cooler, tube for coal distillate oil exchanger, and bridge tube pile, support tube for mine tunnel, etc.
Urban drainage water spiral steel pipe is mainly used as a water pipeline. The material is Q235B, and the implementation standard is sy/t5037, also known as the standard spiral steel pipe. Compared with lsaw steel pipe, spiral steel pipe has many demand highlights in the pipeline field. Housing construction and municipal engineering still provide stable domestic demand, but short-term regulation pressure. The water conservancy construction policy is strongly supported.
The thick-walled straight seam steel pipe for arch bridges greatly enhances the demand for pipelines. As a basic industry for water conservancy construction, it will surely become a beneficiary. Under the construction of rural drinking water safety system and building materials, the demand for spiral steel pipe is continuously upgraded. Considering that China’s rural market has great potential and has not yet been excavated, the development space of the spiral steel pipe industry is undoubtedly broader.
The gas supply system and heating consumption trend will also bring about an increase in demand. China has established a pipeline application industry mainly consisting of large-diameter spiral steel pipe, thick-walled spiral steel pipe and anti-corrosion spiral steel pipe. These three types of material products occupy spiral steel pipe. The main supply ratio of the industry. The supporting industrial chain of anti-corrosion spiral steel pipe is perfected and supported by domestic raw materials, making anti-corrosion spiral steel pipe occupy half of the market in recent years. With the upgrading of consumption and the promotion of chemical materials, the future of China’s large-diameter spiral steel pipe, thick-walled spiral steel pipe and anti-corrosion spiral steel pipe will increase demand.
Spiral steel pipe with thick-walled lsaw steel pipe for arch bridge is a spiral-stitched steel pipe which is made of steel coiled coil as raw material, which is often heated and extruded by automatic double-wire submerged arc welding process. The main production process is as follows: Both the outer welding and the US Lincoln welding machine are used for monofilament or double wire submerged arc welding to obtain stable welding specifications.
The welded welds are inspected by online continuous ultrasonic automatic injury inspection, which guarantees the non-destructive testing coverage of 100% spiral welds. If there is a defect, the mark is automatically and sprayed, and the production worker adjusts the process parameters and defects in time. The thick-walled straight seam steel pipe for the arch bridge is cut into individual pieces by an air plasma cutting machine.
The first three inspections of each batch of steel pipe shall be strictly inspected, and the mechanical properties, chemical composition, bonding condition, surface quality of the steel pipe and non-destructive testing shall be checked to ensure that the pipe making process is qualified before being formally put into production. The part of the weld with continuous acoustic flaw detection marks, after manual ultrasonic and X-ray review, if it is defective, after repair, it will pass the non-destructive test again until the defect is confirmed. The tube of the butt weld of the strip and the tube of the butt joint intersecting the weld are all inspected by X-ray television or film.