Mechanics Property and Chemical Component Solubility of Spiral Submerged Arc Welded Steel Pipe Inspection Weld

Mechanics Property and Chemical Component Solubility of Spiral Submerged Arc Welded Steel Pipe Inspection Weld

Spiral submerged arc welding steel-plastic pipe is a kind of spiral welded steel pipe, which is made of strip coil as raw material, often extruded at high temperature and welded by automatic double-wire double-sided submerged arc welding process. The raw materials are strip coil, welding wire and flux. Strict physical and chemical tests are required before investment. The head and tail of strip are butted by submerged arc welding with single or double wires, and repaired by automatic submerged arc welding after coiling into steel pipe. Before forming, the strip is leveled, trimmed and planed, and the surface is cleaned, conveyed and bent. The electric contact pressure gauge is used to control the pressure of the cylinder on both sides of the conveyor, which ensures the smooth conveying of strip steel. Externally or internally controlled roll forming is adopted. Weld clearance control device is used to ensure that weld clearance meets welding requirements, pipe diameter, offset and weld clearance are strictly controlled. Both internal and external welding are performed by single or double wire submerged arc welding with Lincoln Welding Machine, USA, so as to obtain stable welding specifications. All the welds were inspected by on-line continuous ultrasonic automatic damage instrument, which ensured 100% non-destructive detection coverage of spiral welds. If there are defects, alarm automatically and spray marking, production workers can adjust the process parameters at any time to eliminate defects in time. The steel pipe is cut into single pieces by air plasma cutting machine. After cutting into a single steel pipe, each batch of steel pipes must carry out strict first inspection system to check the mechanical properties of welds, chemical composition, dissolution status, surface quality of steel pipes and non-destructive testing to ensure that the pipe-making process is qualified before being put into production. After manual ultrasonic and X-ray examination, if there is any defect in the weld, after repair, the weld is subjected to non-destructive inspection again until the defect has been confirmed to have been eliminated. The tube where the butt weld of strip steel and the T-joint intersected with the spiral weld are all inspected by X-ray television or photography. After hydrostatic test, the pressure of each steel pipe is sealed radially. The test pressure and time are strictly controlled by the micro-computer detection device of steel pipe hydraulic pressure. The test parameters are printed and recorded automatically. The end of the pipe is machined so that the verticality, groove angle and blunt edge of the end face can be accurately controlled.