Year1
- 材质：
- Q235B
- 规格：
- 219mm以上
- 质量等级：
- 正品（受质量异议）
Production process
The raw materials are steel strip coil, welding wire and flux. They must undergo strict physical and chemical inspections before being put into use.
For the head-to-tail butt jointing of steel strips, single-wire or double-wire submerged arc welding is used. After being rolled into steel pipes, automatic submerged arc welding is used for repair welding.
Before forming, the strip steel undergoes leveling, trimming, planing, surface cleaning, transportation and pre-bending.
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.
Adopt external control or internal control roller forming.
The weld gap control device is used to ensure that the weld gap meets the welding requirements. The pipe diameter, offset amount and weld gap are all strictly controlled.
Both internal and external welding use American Lincoln electric welding machines for single-wire or double-wire submerged arc welding to obtain stable welding quality.
The completed welds are inspected by an online continuous ultrasonic automatic flaw detector, ensuring 10% non-destructive testing coverage of spiral welds. If there is a defect, it will automatically alarm and spray mark, so that production workers can adjust the process parameters at any time to eliminate defects in time.
Use an air plasma cutting machine to cut the steel pipe into individual pieces.
() After being cut into individual steel pipes, each batch of steel pipes 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 they are manufactured. Only after the pipe process is qualified can it be officially put into production.
The areas with continuous sonic flaw detection marks on the welds will undergo manual ultrasonic and radiographic 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.
The pipes where the strip butt welds and the T-shaped joints intersecting the spiral welds are located have all been inspected by radiography or radiographs.
Each steel pipe has undergone hydrostatic pressure testing, 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.
The pipe end is machined to accurately control the end face verticality, bevel angle and blunt edge.
Weld seam treatment
The spiral steel pipe feeds the strip into the welded pipe unit. After being rolled by multiple rollers, the strip is gradually rolled up to form a circular tube blank with an opening gap. Adjust the pressure of the extrusion roller. Lower the amount to control the weld gap to ~ and make both ends of the weld flush.
If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the inter-crystal bonding of the weld will be poor, resulting in lack of fusion or cracking.
If the gap is too small, the proximity effect will increase and the welding heat will be too high, causing the weld to be burned or the weld to form a deep pit after being extruded and rolled, affecting the surface quality of the weld.
After the two edges of the tube blank are heated to the welding temperature, they are squeezed by the squeeze roller to form common metal grains that penetrate and crystallize with each other, eventually forming a strong weld. If the extrusion force of the spiral steel pipe is too small, the number of common crystals formed will be small, the strength of the weld metal will decrease, and cracking will occur after stress. If the extrusion force is too large, the molten metal will be extruded out of the weld, not only The strength of the weld is reduced, a large number of internal and external burrs are produced, and even defects such as welding overlaps are caused.
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