Customized 301 304 304L 321 316 316L Stainless Steel Welded Pipe

Main production process: round steel → re-inspection → peeling → blanking → centering → heating → perforation → pickling → flat head → inspection and grinding → cold rolling (cold drawing) → degreasing → heat treatment → straightening → pipe cutting (fixed-to-length) )→pickling/passivation→finished product inspection (eddy current, ultrasonic, water pressure)→packaging and storage.

1. Round steel cutting: After receiving the round steel from the raw material warehouse, calculate the cutting length of the round steel according to the requirements of the process, and draw a line on the round steel. Steels are stacked according to steel grades, heat numbers, production batch numbers and specifications, and the ends are distinguished by paints of different colors.

2. Centering: When centering the cross arm drilling machine, first find the center point in a section of the round steel, punch out the sample hole, and then fix it vertically on the drilling machine table for centering. The round bars after centering are stacked according to steel grade, heat number, specification and production batch number.

3. Peeling: peeling is carried out after passing the inspection of the incoming materials. The peeling includes lathe peeling and whirlwind cutting. The lathe peeling is carried out on the lathe by the processing method of one clamp and one top, and the whirlwind cutting is to hang the round steel on the machine tool. Perform whirling.

4. Surface inspection: The quality inspection of the peeled round steel is carried out, and the existing surface defects are marked, and the grinding personnel will grind them until they are qualified. The round bars that have passed the inspection are piled up separately according to the steel grade, heat number, specification and production batch number.

5. Round steel heating: Round steel heating equipment includes gas-fired inclined hearth furnace and gas-fired box-type furnace. Gas-fired inclined-heart furnace is used for heating in large batches, and gas-fired box-type furnace is used for heating in small batches. When entering the furnace, the round bars of different steel grades, heat numbers and specifications are separated by the old outer film. When the round bars are heated, the turners use special tools to turn the bars to ensure that the round bars are heated evenly.

6. Hot rolling piercing: use piercing unit and air compressor. According to the specifications of the perforated round steel, the corresponding guide plates and molybdenum plugs are selected, and the heated round steel is perforated with a perforator, and the pierced waste pipes are randomly fed into the pool for full cooling.

7. Inspection and grinding: Check that the inner and outer surfaces of the waste pipe are smooth and smooth, and there must be no flower skin, cracks, interlayers, deep pits, serious thread marks, tower iron, fritters, Baotou and sickle heads. The surface defects of the waste pipe can be eliminated by the local grinding method. The waste pipes that have passed the inspection or those that have passed the inspection after repairing and grinding with minor defects shall be bundled by the workshop bundlers according to the requirements, and stacked according to the steel grade, furnace number, specification and production batch number of the waste pipe.

8. Straightening: The incoming waste pipes in the perforation workshop are packed in bundles. The shape of the incoming waste pipe is bent and needs to be straightened. The straightening equipment is vertical straightening machine, horizontal straightening machine and vertical hydraulic press (used for pre-straightening when the steel pipe has a large curvature). In order to prevent the steel pipe from jumping during straightening, a nylon sleeve is used to limit the steel pipe.

9. Pipe cutting: According to the production plan, the straightened waste pipe needs to be cut head and tail, and the equipment used is a grinding wheel cutting machine.

10. Pickling: The straightened steel pipe needs to be pickled to remove the oxide scale and impurities on the surface of the waste pipe. The steel pipe is pickled in the pickling workshop, and the steel pipe is slowly hoisted into the pickling tank for pickling by driving.

11. Grinding, endoscopy inspection and internal polishing: the steel pipes that are qualified for pickling enter the outer surface grinding process, the polished steel pipes are subjected to endoscopic inspection, and the unqualified products or processes with special requirements need to be internally polished deal with.

12. Cold rolling process/cold drawing process

Cold rolling: The steel pipe is rolled by the rolls of the cold rolling mill, and the size and length of the steel pipe are changed by continuous cold deformation.

Cold drawing: The steel pipe is flared and wall-reduced with a cold drawing machine without heating to change the size and length of the steel pipe. The cold-drawn steel pipe has high dimensional accuracy and good surface finish. The disadvantage is that the residual stress is large, and Large-diameter cold-drawn pipes are frequently used, and the finished product forming speed is slow. The specific process of cold drawing includes:

① Heading welding head: Before cold drawing, one end of the steel pipe needs to be headed (small diameter steel pipe) or welding head (large diameter steel pipe) to prepare for the drawing process, and a small amount of special specification steel pipe needs to be heated and then headed.

② Lubrication and baking: Before the cold drawing of the steel pipe after the head (welding head), the inner hole and outer surface of the steel pipe shall be lubricated, and the steel pipe coated with lubricant shall be dried before cold drawing.

③ Cold drawing: The steel pipe after the lubricant is dried enters the cold drawing process, and the equipment used for cold drawing is a chain cold drawing machine and a hydraulic cold drawing machine.

13. Degreasing: The purpose of degreasing is to remove the rolling oil attached to the inner wall and outer surface of the steel pipe after rolling by rinsing, so as to avoid contaminating the surface of the steel during annealing and preventing carbon increase.

14. Heat treatment: Heat treatment restores the shape of the material through recrystallization and reduces the deformation resistance of the metal. The heat treatment equipment is a natural gas solution heat treatment furnace.

15. Pickling of finished products: The steel pipes after cutting are subjected to finished pickling for the purpose of surface passivation, so that an oxide protective film can be formed on the surface of the steel pipes and enhance the excellent performance of the steel pipes.

16. Finished product inspection: The main process of finished product inspection and test is meter inspection → eddy probe → super probe → water pressure → air pressure. The surface inspection is mainly to manually check whether there are defects on the surface of the steel pipe, whether the length of the steel pipe and the size of the outer wall are qualified; the eddy detection mainly uses the eddy current flaw detector to check whether there are loopholes in the steel pipe; the super-detection mainly uses the ultrasonic flaw detector to check whether the steel pipe is cracked inside or outside; the water pressure , Air pressure is to use hydraulic machine and air pressure machine to detect whether the steel pipe leaks water or air, so as to ensure that the steel pipe is in good condition.

17. Packing and warehousing: The steel pipes that have passed the inspection enter the finished product packaging area for packaging. The materials used for packaging include hole caps, plastic bags, snakeskin cloth, wooden boards, stainless steel belts, etc. The outer surface of both ends of the wrapped steel pipe is lined with small wooden boards, and the outer surface is fastened with stainless steel belts to prevent the contact between the steel pipes during transportation and cause collision. Packaged steel pipes enter the finished product stacking area.