1. Pipe fittings. Parts used in the pipeline system for direct connection, turning, branching, reducing, and end use, including elbows, tees, tees, reducer pipe joints, pipe hoops, internal and external threaded joints, unions, fast Joints, thread nipples, reinforced pipe joints, pipe plugs, pipe caps, blind plates, etc. (excluding valves, flanges, fasteners).

2. Pipeline accessories. The general term for pipe fittings, compensators, valves and their assembly, etc.

3. Special pipe parts. Refers to non-ordinary standard components, which are pipeline components specially manufactured according to engineering design conditions, including expansion joints, compensators, special valves, rupture discs, flame arresters, filters, flexible joints and hoses.

4. Welded steel pipe parts. Welded steel pipe fittings are seamless steel pipes or welded steel pipes (small and large heads can also be made of steel plates) that are processed by cutting and welding. Common welded steel pipe fittings include welded elbows, welded elbow pipe sections, welded tees, and welded heads.

5. Forged pipe fittings. Use the forging machine's hammer head, anvil, punch or die to apply pressure to the pipe blank to make it plastically deformed to obtain a pipe of the desired shape and size.

6. Elbow. Pipe fittings where the pipe turns.

7. Reducing elbow. Elbows with different diameters at both ends.

8. Long radius elbow. The elbow with a bending radius equal to 1.5 times the nominal diameter of the pipe.

9. Short radius elbow. An elbow with a bending radius equal to the nominal diameter of the pipe.

10. 45° elbow. Turn the pipe to the 45° elbow.

11. 90° elbow. Turn the pipe to a 90° elbow.

12. 180° elbow (return elbow). Turn the pipe 180° elbow.