Assembly notes of Compression fitting

The application of compression fitting is very common in the hydraulic industry. The precautions for installation are also a matter of great concern. This article will introduce some precautions when installing the compression fitting.

1. Assembly of Compression fitting

(1) The most important part of the pre-installation of the cutting ring fitting directly affects the reliability of the seal. Generally, a dedicated device is required. Small diameter fittings can be pre-assembled on the vise. The specific method is to use a fitting as the mother body to press the nut and ring onto the pipe. There are mainly straight type compression fitting, compression fitting straight-through connectors, tee type compression fitting, etc. What kind of fitting body is used to connect one end of the pipe, the corresponding fitting end is preinstalled with the same type of fitting, so as to avoid leakage problems to the greatest extent.

(2) When pre-installing, try to keep the coaxiality between the pipe and the fitting body. If the pipe deflection is too large, it will cause the seal to fail.

(3) The preloading force should not be too large so that the inner blade of the ring just fits into the outer wall of the pipe, and the ring should not be significantly deformed. When connecting the pipeline, assemble it according to the specified tightening force. If the ring is severely deformed during pre-assembly, the sealing effect will be lost.

2.It is forbidden to add sealant and other fillers

In order to obtain a better sealing effect, some people apply sealant on the ring. As a result, the sealant is flushed into the hydraulic system, causing malfunctions such as clogging of the internal holes of the hydraulic components.

3. Connect the pipeline

The pipe should have enough margin of deformation to avoid the pipe subjected to tensile force.

4. When connecting the pipeline, avoid subjecting it to lateral force. Excessive lateral force may cause a loose seal.

5.When connecting the pipeline, it should be done at one time and avoid multiple disassembly, otherwise the sealing performance will be deteriorated.

6. Compression fitting installation

(1) The pipes that need pickling should be pickled first;

(2) Use special pipe cutting machine to cut the pipe according to the required length. It is absolutely not allowed to use melting (such as flame cutting) or grinding wheel cutting; remove the internal and external round burrs, metal chips and dirt of the pipe end; remove the anti-rust of the pipe fitting Agent and dirt; at the same time, the roundness of the tube must be ensured;

(3) Put the nut and the ring into the pipe one after the other, with the front edge of the ring (small diameter end) at least 3mm away from the pipe mouth, and then insert the pipe into the taper hole in the fitting body until it reaches;

(4) Slowly tighten the nut, while turning the pipe until it stops, then tighten the nut 2/3～4/3 turns;

(5) Disassemble and check whether the ring has been cut into the pipe and whether the position is correct. The ring is not allowed to move axially, but can rotate slightly;

(6) Retighten the nut after passing the inspection.

7. Precaution of leakage at pipe fittings

In the hydraulic system, whether it is a metal pipe fitting or a hose fitting, there is a problem of easy leakage.

(1) For compression fitting, most of the pipes are subjected to greater external force or impact, which causes the pipe to loosen or the end of the pipe is deformed to cause leakage. At this time, check whether the pipe is out of round, whether the cutting edge is defective, and the pipe Whether the end is intact and the compression degree of the ferrule nut, etc., while eliminating the external force of the pipe.

(2) For flared pipe fittings, mostly due to excessive flaring, substandard quality or repeated disassembly, resulting in flaring deformation or cracks, etc., causing leakage. At this time, the front end can be cut off and flared again. If the male and female cone top pressure is used for sealing, the leakage is mostly due to the damage of the two cone surfaces, and the cone surface can be ground with abrasive sand.

(3) In some occasions where the "о" ring is sealed by the end face or outer diameter, the leakage causes are as follows: the "о" ring is aging or deformed to cause leakage; the "о" ring is not assembled in place, causing the two When the plane is connected, the pressure is not flat or the "о" ring is cut to cause leakage; the "о" ring is not compacted, and the amount of elastic deformation is insufficient to cause leakage; the "о" ring is too deep to cause leakage. In this regard, it is necessary to re-select the "о" ring with the same outer diameter and thicker section, or cut or grind the sealing surface with the spigot groove to reduce the depth of the spigot groove to make the "о" The ring has enough elastic deformation (compression should generally be between 0.35-0.65mm).

(4) For leaks at pipe fittings using oil-resistant rubber sheets, wool felt, soft steel cardboard, combined sealing gaskets or sealants. Regardless of the material, first check the seals for damage, deformation, aging, and excessive roughness, and then take corresponding measures.

Are the precautions for assembly of the compression fitting helpful to you? Welcome your message.

Topa can not only provide a wide range of compression fittings, but also hose fittings, hydraulic hoses and other products.

If you need more information, please contact us: sales02@cntopa.com

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