The production process of Pipe fittings tee
1, Acceptance of raw materials
1. Raw materials should comply with the requirements of relevant standards and technical specifications.
2. The surface of raw materials should be free of oil stains, excessive rust and corrosion, obvious dents and defects, low melting point metal contamination, etc.
3. Check the quality certificate, furnace number, batch number, specifications, manufacturer, and implementation standards of the raw materials.
4. Raw materials are mechanically derusted with wire brushes to meet the requirements of non-destructive testing.
5. Raw materials undergo dimensional testing (length, width, thickness, and unevenness of steel plates).
6. After entering the factory, steel plates and pipes should undergo ultrasonic re inspection, and Level I is qualified.
7. Physical and chemical testing, chemical element analysis, mechanical properties, and hardness testing shall be conducted on the steel plates entering the factory according to the furnace batch number and specifications. The test results shall meet the requirements of the raw material standards.
8. After re inspection, it shall be numbered and registered according to the factory regulations
2, Manufacturing process
(1) Hot pressing forming
1. Material selection and cutting, according to the specifications of the tee, select appropriate steel plates (rolled into tube blanks, mechanically beveled and corrected) or steel pipes, and use semi-automatic oxyacetylene flame or plasma cutting. And clearly label the furnace, batch number, pipe specifications, project name, and serial number of the raw materials.
2. Pipe fittings tee molding
① Operators should learn relevant process documents and be familiar with the operation methods and process of the equipment, and be prepared with various tools required during the work process.
② Furnace heating: Load the three-way billet into the natural gas heat treatment furnace, and use a shim at the bottom to isolate the billet from the furnace car, ensuring that the three-way spacing is ≥ 200mm and the heating rate above 400 ℃ is ≤ 200 ℃/h.
③ Heat and insulate the three-way billet to ensure that it is fully burned out before being flattened out of the furnace (ensuring that the weld seam is in the center of the three-way), so that the short axis length after pressing is not greater than the outer diameter of the three-way (inner diameter of the mold).
④ Continue heating and insulation in the furnace, and then quench the three-way pipe blank (with the weld at the bottom) after it is removed from the furnace. Quickly place the pipe blank into the mold and bulge it. Under pressure, the uncooled part flows along the inner cavity of the mold to form a branch pipe.
⑤ Repeat process ④ until the branch pipe meets the requirements.
⑥ Hole opening: Measure a certain distance towards the branch pipe based on the three-way bottom, and measure a certain distance towards the branch pipe based on the shoulder of the main pipe. Draw a line and use a cutting gun to open the hole.
⑦ After continuing to heat and insulate the Pipe fittings tee billet, quench the main pipe with water and quickly place the three-way into the mold. Place the die into the branch pipe and press it down with a press (the die should be pressed vertically during compression to ensure that the branch pipe is not biased) until the branch pipe meets the requirements.
⑧ End measurement: Measure a certain distance from the center of the branch pipe to the end of the main pipe; Measure a certain distance towards the branch pipe based on the three-way bottom, and remove the excess part with a cutting gun.
⑨ Plastic surgery: Heat the tee again and use a press to round the main and branch pipes of the tee.
6. Heat treatment: According to the heat treatment process, the three-way valve is put into the furnace for heat treatment.
7. Surface treatment: After heat treatment, use a sandblasting machine or polishing machine to remove the surface oxide scale of the pipe fittings.
8. After surface treatment, 100% radiographic testing shall be carried out on the three-way weld seam, and it shall be qualified as Grade II. 100% magnetic particle or penetrant testing shall be carried out on the pipe body, and the results shall meet the requirements of Grade I of NB/T47013.4-2015 or NB/T47013.5-2015.
9. Mechanical performance testing: According to relevant standards, conduct mechanical performance tests on tees to ensure that their mechanical performance meets the standards. The testing items and sampling directions should comply with the requirements of relevant standards or technical specifications.
10. End processing: Perform mechanical end face groove processing according to the design confirmation drawing. Within a range of 50mm from the pipe end, the excess height of the inner and outer welds shall be ground using an angle grinder.
11. Appearance inspection
① There should be no cracks, overburning, overheating or other phenomena on the three-way joint, and there should be no hard spots on the surface.
② There should be no obvious wrinkles at the root of the three-way branch pipe.
③ Any defects on the three-way pipe body are not allowed to be repaired by welding.
12. Dimensional inspection
The relevant inspection personnel of the company shall conduct dimensional inspection according to the requirements of the drawings and relevant standards of the pipe fittings, and meet their tolerance requirements.
13. Surface treatment: The inner and outer surfaces of the three-way joint should be smooth, without any damage to strength or appearance defects, such as scars, scratches, heavy skin, etc. If defects are found, they should be ground and the thinning amount at the ground should not be less than 93.5% of the original wall thickness. The ground should be smooth and confirmed with coloring agents or magnetic particle inspection until the defects are removed.
14. Acid pickling and passivation treatment
Stainless steel fittings should also undergo acid pickling and passivation treatment.
15. Identification
Mark with template spray or low stress impression, and clearly indicate the content required by the standard in order on the outer wall.
16. Stacking and transportation of tees
Three links should not come into contact with any part of the carriage during transportation to avoid collision.
