The correct arrangement of hydraulic seamless steel pipe

The correct arrangement of hydraulic seamless steel pipe

Hydraulic pipe installation is a major project of hydraulic equipment installation. The quality of pipeline installation is one of the key factors related to the normal performance of hydraulic system.


1. When designing and piping, we should first consider the components, hydraulic components, pipe joints and flanges required to be connected according to the hydraulic schematic diagram.

2. The arrangement and direction of pipeline laying should be neat and consistent, with clear layers. Try to use horizontal or vertical pipe, horizontal pipe non-parallelism should be less than or equal to 2/1000; The non-verticality of vertical pipes should be less than or equal to 2/400. 

3. There should be a gap of more than 10mm between parallel or cross pipe systems.

4, the pipeline configuration must make the pipeline, hydraulic valve and other components loading and unloading, maintenance convenient. Any section of pipe or element in the system should be as free as possible to disassemble and assemble without affecting other elements.

5, with hydraulic steel pipe must make the pipeline has a certain rigidity and vibration resistance. Pipe supports and clamps shall be provided appropriately. The bent pipe shall have a bracket or clamp near the starting point of the bend. Pipes shall not be welded directly to supports or pipe clamps.

6, the weight of the pipeline should not be borne by the valve, pump and other hydraulic components and accessories; Heavy component weights should also not be supported by the pipe.

7. For longer pipes, effective measures must be considered to prevent stress caused by temperature change and pipe expansion.

8. The pipe material used must have a clear original basis material. The pipe with unknown material is not allowed to be used.

9, hydraulic system pipe diameter below 50mm can be cut by grinding wheel cutting machine. Pipes with a diameter of more than 50mm should be cut by mechanical machining. If gas cutting is used, mechanical processing must be used to remove the tissue changes formed by gas cutting, and welding groove can be produced at the same time. Except for the return pipe, the pressure is not allowed to be cut by the roller type extrusion cutter. Pipe cutting surface must be smooth, remove burr, oxide skin, slag, etc. The incision surface shall be perpendicular to the pipe axis.

10. When a pipe is composed of multiple pipe sections and fittings, it shall be successively taken over to complete one section, and then the subsequent section shall be configured after assembly, so as to avoid cumulative errors caused by one welding.

11. In order to reduce the local pressure loss, the section of the pipeline should avoid the local sharp expansion or contraction of the section and sharp bending.

12. The pipe connected with the pipe joint or flange must be a straight pipe, that is, the axis line of this section of pipe should be parallel and coincide with the axis of the pipe joint and flange. The length of this straight section shall be greater than or equal to 2 times the pipe diameter.

13, the pipe diameter is less than 30mm can be cold bending method. When the outer diameter of the pipe is 30~50mm, the cold bending or hot bending method can be adopted. When the outer diameter of the pipe is greater than 50mm, the hot bending method is generally adopted.

14. Welders who weld hydraulic pipes shall hold valid welding certificates for high pressure pipes.

15, the choice of welding process: acetylene gas welding is mainly used for general carbon steel pipe wall thickness is less than or equal to 2mm pipe. Arc welding is mainly used for carbon steel pipe with wall thickness greater than 2mm. The pipes are best welded with argon arc welding. For pipes with wall thickness greater than 5mm, argon arc welding shall be used for backing and arc welding filling. If necessary, the pipe hole should be filled with protective gas welding method.

16, the electrode, flux should match the welded pipe, its brand must have a clear basis for information, a product certificate, and within the effective use period. The electrode and flux should be dried according to the product instructions before use, and kept dry during use, and used on the same day. The electrode coating should be free of shedding and significant cracks.

17, hydraulic steel pipe welding should be used butt welding. Before welding, the surface dirt, oil stains, moisture and rust spots of the groove and its vicinity 10~20mm wide should be removed.

18. Butt welding flanges should be used for the welding of pipes and flanges, and insertion flanges should not be used.

19. The welding of pipe and pipe joint shall adopt butt welding, not insertion type.

20. Butt welding shall be adopted for pipe to pipe welding, and insertion welding is not allowed.

21. When the hydraulic pipe adopts butt welding, the inner wall of the weld must be 0.3~0.5mm higher than the pipe. Do not allow the phenomenon of concave into the inner wall. After welding, use file or hand-held grinding wheel to smooth the high weld in the inner wall. Remove welding slag and burr to achieve smoothness.

22. The cross section of the butt welding seam shall be perpendicular to the center line of the pipe.

23. The weld section is not allowed in the corner, and should also be avoided between the two elbows of the pipe.

24. When welding pipes, it is necessary to spot weld the pipe according to the installation position, remove and weld it, and then assemble and shape it after welding.

25. In the whole process of welding, the invasion of wind, rain and snow should be prevented. After pipe welding, weld seams with wall thickness less than or equal to 5mm should be cooled naturally at room temperature, and should not be forced to cool by strong wind or dousing water.

26. The weld should be thoroughly welded and the appearance should be even and smooth. The welds of pressure pipelines shall be inspected by sampling inspection.

27. After piping welding, all pipes shall be pre-installed according to their location. Connect the hydraulic components, valve block, valve rack and pump station. Interfaces should be naturally aligned and aligned, and cannot be forcibly connected. When loosening the pipe joint or flange screw, the center line of the relative joint surface should not be misaligned, off the seam or cross Angle. In this case can be eliminated by fire baking plastic. (Guangzhou Changben)

28. The pipe clamp can be welded firmly to the frame after all piping is finished, or it can be crossed as required.

29. After piping, welding and pre-installation, the pipeline is disassembled again for pickling and phosphating treatment. Hot air is passed into the pipe for rapid drying after pickling and phosphating. After drying, if in a few days to reassemble into the system, pipe into the long hydraulic steel pipe oil, generally can not be used for rust treatment, but should be properly kept. If you need to use for a long time, you need to apply antirust coating, you must be in phosphating treatment 48 hours before painting. It should be noted that the antirust coating must be compatible with the cleaning fluid or hydraulic oil used in future pipe cleaning.

30. Before the pipe is installed again after pickling, phosphating and drying, it is necessary to conduct a pre-cleaning on the inner wall of each pipe. After pre-cleaning, the system shall be reinstalled as soon as possible to carry out the overall cycle purification treatment of the system until the cleanliness level required by the system design is reached.

31, hose application is limited to the following occasions:

-- Between movable elements of equipment

-- where replacement parts can be easily replaced

-- to suppress the transmission of mechanical vibration or noise

32. The installation of the hose must pay attention not to cause additional force, distortion, sharp bending, friction and other bad conditions in the hose and joint.

33. Before loading the hose into the system, the inner cavity and joint should also be cleaned.