The hydraulic pipe connector is a component in the hydraulic system that connects the high pressure oil pipe and the high pressure oil pipe. Hydraulic couplings can also be divided into hydraulic hoses, high pressure ball valves, quick couplings, ferrule type couplings, welded couplings, high pressure hoses, transition couplings, three-way couplings, non-standard couplings, flared couplings, right angle couplings, rotary couplings, quick couplings, stainless steel couplings, copper couplings.

Chinese name Hydraulic pipe connector Definition of components connecting high-pressure oil pipe and high-pressure oil pipe Classification of hydraulic hose, high-pressure ball valve, etc. Welded pipe connector, ferrule type pipe connector, etc

catalogue

1 Differences

2 Connector principle

3-head standard

4 Pipeline cleaning

5 Formal installation of pipeline

The difference between the two is editing and broadcasting

Hydraulic pipe joint

Hydraulic pipe joint

The biggest and most significant difference is that the hydraulic pressure is amazing, and the impact force of the sudden oil burst of the hydraulic oil pipe is great.

It is not allowed to replace the special connector with an ordinary one, because the hydraulic one can withstand a lot of pressure, and the ordinary one is almost exhausted at 0.5 air pressure at most.

Connector principle editing and broadcasting

Quick change couplings are provided with and without check valves. For the application with one-way valve, the one-way valve end is connected with the air source. When it is disconnected, the one-way valve will automatically close, and when it is connected, the movable end thimble will open the one-way valve. The self-locking means that the steel ball is embedded into the groove and locked by the "cone cylinder" sleeve.

Type of pipe joint

type

Structural drawing

characteristic

Table and standard No

Welded pipe joint

Weld the pipe with the nozzle. The end face of the O-ring seal is used between the connector body and the connecting pipe. The structure is simple, easy to manufacture, and the sealing property is good. The requirements for the pipe size accuracy are not high. It is required to have high welding quality and inconvenient assembly and disassembly. The working pressure can reach 31.5MPa, and the working temperature is - 25~80 ℃. It is applicable to the pipeline system with oil as the medium

Table 6-14

JB966～1003-1977

Ferrule type pipe joint

It is widely used in hydraulic system because of its advanced structure, good performance, light weight, small volume and convenient use. The working pressure can reach 31.5MPa, and the pipe size accuracy is required to be high. Cold drawn steel pipes are required. The ferrule precision is also high. Applicable to pipeline system of oil, gas and general corrosive medium

Table 15-26

GB3733.1～3765-1983

Flared type pipe joint

The pipe end flaring is used for sealing without other seals. Simple structure, suitable for connection of thin-walled pipe fittings

It is applicable to low pressure pipeline system with oil and gas as medium. See Table 41 for allowable pressure

Table 27~41

GB5625.1～5653-1985

Inserting welded couplings

Insert the pipe with the required length into the pipe joint until the end face of the pipe contacts the inner end of the pipe joint, and weld the pipe and the pipe joint into a whole. The pipe joint can be omitted, but the pipe size is required to be strictly applicable to the pipeline system with oil and gas as the medium

Table 43~49

JB3878-1985

Conical seal welded pipe joint

One end of the connecting pipe is an outer cone surface with an O-ring to match the inner cone surface of the connector body, and it is screwed down. The working pressure can reach 16 ～ 31.5MPa, and the working temperature is － 25 ～ 80 ℃

Applicable to pipeline system with oil as medium

Table 50~62

JB/T6381～6385-1992

Buckle type rubber hose joint

The installation is convenient, but a tightening process is added. After the rubber hose is damaged, the joint jacket cannot be reused, and it is matched with the steel wire braided rubber hose to form an assembly. It can be connected with welded pipe joint with O-ring seal. It is applicable to the pipeline system with oil, water and gas as the medium. Medium temperature: oil: - 30~80 ℃; Air, - 30~50 ℃; Water, below 80 ℃

JB/ZQ4427～4428-1986

Three petal rubber hose connector

It is not necessary to strip the outer rubber layer of the rubber hose during assembly. For rubber hoses with slightly different outer diameters, the precompression of the joint sleeve on the rubber hose shall be used to compensate. The prepressing shrinkage of the rubber hose is within the range of 31%~50%, which can ensure that there is no leakage under the working pressure, no rubber pulling, and no breakage of the outer rubber layer. It can be connected with welded pipe joints, quick change joints and ferrule type pipe joints. It is applicable to the pipeline system with oil, water and gas as the medium. Its working pressure and medium temperature are limited according to the connected rubber hose

JB/ZQ4429～4431-1986

Quick coupler (open and closed at both ends)

After the pipe is disassembled, it can be self sealed, and the liquid in the pipe will not be lost, so it is suitable for frequent disassembly. The structure is relatively complex, and the local resistance loss is large. It is applicable to the pipeline system with oil and gas as the medium. The working pressure is lower than 31.5MPa and the medium temperature is - 20~80 ℃

JB/ZQ4434-1986

Quick coupler (open at both ends)

It is applicable to the pipeline system with oil and gas as the medium, and its working pressure and medium temperature are limited according to the connected rubber hose

JB/ZQ4435-1986

Head standard editing broadcast

Assembly of ferrule type pipe joint

（1） Pre assembly ① The most important part of the pre assembly of the ferrule type pipe joint directly affects the reliability of the seal. Generally, special pre heater is required. The joints with small pipe diameters can be preassembled on the bench tongs. The specific method is to use a joint as the parent body and press the nut and ferrule onto the pipe. It mainly includes ferrule type straight pipe joint, ferrule type end straight connector, ferrule type three-way pipe joint, etc. The author found that the depth of the tapered hole on these joint bodies is often different, even if it is a batch of goods from the same manufacturer, resulting in leakage, which is often ignored. The correct way is to use what kind of connector body to connect one end of the pipe, and the corresponding connection end is pre assembled with the same type of connector, so as to avoid leakage to the greatest extent. ② The end face of the pipe shall be flush. After the pipe is sawed off, it shall be polished and leveled on the grinding wheel and other tools, and the burrs shall be removed, cleaned and blown with high-pressure air before use. ③ During pre assembly, try to keep the coaxiality between the pipe and the connector body. If the pipe deflects too much, it will also cause sealing failure. ④ The preassembly force should not be too large, so that the inner edge of the ferrule is just embedded in the outer wall of the pipe, and the ferrule should not have obvious deformation. When connecting pipelines, assemble according to the specified tightening force. ф 6-1 The tightening force of the ferrule is 64-1 15n, 16 ф mmr 259n、 ф 450n for 18mm. If the ferrule is severely deformed during pre installation, it will lose its sealing effect.

（2） It is prohibited to add sealant and other fillers. Someone applied sealant on the ferrule in order to obtain better sealing effect. As a result, the sealant was flushed into the hydraulic system, resulting in the blockage of the anion hole of the hydraulic element.

（3） When connecting pipes, make sure that the pipes have enough deformation allowance to avoid tensile force on the pipes.

（4） When connecting the pipeline, it should avoid being subjected to lateral force. Excessive lateral force will lead to poor sealing.

（5） . When connecting the pipeline, it should be done at one time to avoid multiple disassembly, otherwise the sealing performance will become worse.

Installation of ferrule type pipe joint

(1) According to the requirements of Chapter 9, the pipes to be pickled shall be pickled first;

(2) Cut off the pipe with sawing machine or special pipe cutter according to the required length. It is absolutely not allowed to cut the pipe with melting (such as flame cutting) or grinding wheel; Remove the internal and external burrs, metal chips and dirt at the pipe end; Remove the rust inhibitor and dirt from the pipe joint; At the same time, ensure the pipe roundness;

(3) Insert the nut and ferrule into the pipe successively, and the front edge (small diameter end) of the ferrule shall be at least 3mm away from the pipe mouth, and then insert the pipe into the tapered hole in the connector body until it reaches the top;

(4) Slowly tighten the nut, and at the same time, turn the tube until it stops, and then tighten the nut for 2/3~4/3 turns;

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

(6) Retighten the nut after inspection.

Prevention of leakage at pipe joints

In the hydraulic system, both metal pipe joints and hose joints are prone to leakage. For ferrule type pipe joints, leakage is caused by looseness of ferrule or deformation of pipe end surface due to large external force or impact force on the pipe. At this time, check whether the ferrule is out of round, whether the cutting edge is damaged, whether the pipe end is intact, and the compression degree of ferrule nut. At the same time, eliminate the external force on the pipe. For flared pipe joints, most of the flares are deformed or cracked due to excessive flaring, substandard quality or repeated disassembly. At this time, the front end can be cut off and flared again. If the male and female cones are used for sealing, the leakage is mostly due to the damage of the two cones. The cone can be ground with abrasive sand. Used in some“ о” There are several reasons for leakage when the O-ring is sealed against the end face or outer diameter:“ о” Leakage caused by aging or deformation of ring; “ о” The O-ring is not assembled in place, which makes the connection between two planes uneven or“ о” The O-ring is cut to cause leakage; “ о” The ring is not compacted and the elastic deformation is insufficient, causing leakage; “ о” The O-ring groove is too deep, causing leakage. For this, it is necessary to re select the ones with the same outer diameter and thicker section“ о” The sealing surface with the groove can also be cut or ground to reduce the depth of the groove“ о” The T-ring shall have enough elastic deformation (the compression shall generally be 0.35-0.65mm). For leakage at pipe joints using oil resistant rubber sheet, wool felt, mild steel paperboard, combined sealing gasket or sealant, no matter what the material, first check whether the sealing elements are damaged, deformed, aged and too rough, and then take corresponding measures.

Precautions for installation of high-pressure rubber hose joint

(1) The rubber hose shall not be excessively bent or bent at the root when moving or stationary, and shall be bent at least 1.5 times of its diameter;

(2) When the rubber hose moves to the extreme position, it shall not be pulled too tightly, and it shall be relatively loose;

(3) Try to avoid torsional deformation of rubber hose;

(4) The rubber hose shall be as far away from the thermal radiation components as possible, and the heat insulation board shall be installed when necessary;

(5) External damage of rubber hose shall be avoided, such as long-term friction with component surface during use;

(6) If the rubber hose is excessively deformed due to its own weight, supporting parts shall be provided.

Pipeline pre installation

1. Pipeline introduction

(1) Double line main pipe and branch pipe: from the lubricating pump to the oil inlet of all distributors, the bearing pressure is relatively high. Cold drawn seamless steel pipe is usually used, and the material is 10 or 15 # steel. Never use seriously rusted pipes;

(2) Oil supply pipe: from the distributor to the oil inlet of all lubrication points (oil hole of bearing seat), the bearing pressure is relatively low. The drawn copper pipe is usually used, which is convenient for piping when bending. Cold drawn seamless steel pipe or stainless steel pipe is also used;

(3) Rubber hose joint shall be used when connecting with moving parts.

2. Pipeline layout requirements

(1) The pipeline shall avoid high temperature radiation, cooling water spray and other places where the temperature is too high or too low, especially the rubber pipe joint;

(2) The pipe laying shall not affect the operation of the host and other equipment, and shall be safe, reliable, convenient for work, observation and maintenance;

(3) The pipe laying shall be horizontal and vertical, neat and beautiful. Try to avoid bending or small angle bending, and adopt large arc to reduce oil flow resistance;

(4) In case of conflict in installation, small pipes shall give way to large pipes, and low pressure pipes shall give way to high pressure pipes;

(5) The pipes shall be separated from each other at a certain distance when they cross each other;

(6) The joints of parallel pipes shall be staggered to avoid affecting the installation and disassembly;

(7) In order to facilitate disassembly and cleaning of pipes, movable joints shall be properly installed, but shall be used less to reduce the possibility of leakage.

3. Determine the pipe length

(1) Determine the length of the pipe on site according to the fixed piping path determined in Article 8.2, and pay attention to the influence of the radius of the bend;

(2) The influence of various pipe joints connected to the pipeline shall be taken into account;

(3) The pipe length shall be determined, cut off and preassembled section by section to facilitate on-site adjustment according to the actual situation. If all pipes are cut off at one time, it will be difficult to arrange pipes in case of accumulated errors;

(4) The cut short pipe shall be used as far as possible at each place where the short pipe is needed. If necessary, the straight pipe joint can be used for extension, but the number of joints on the pipe section should not be more.

4. Pipe cutting

(1) Cut off the pipe with sawing machine or special pipe cutter, and it is absolutely not allowed to cut with melting (such as flame cutting) or grinding wheel;

(2) The cut shall be flat, the flatness of the section shall not be greater than 1mm, and the perpendicularity to the pipe axis shall not be greater than 1 degree;

(3) Remove chips and burrs with files, scrapers, etc;

(4) Use clean compressed air or other methods to remove the debris and floating rust attached to the pipe;

5. Pipe bending

(1) The pipe bender shall be used for cold bending instead of hot bending (the elbow can be replaced by a right angle joint for large diameter pipes), and the bending radius shall be more than 4 times of the pipe diameter;

(2) The ovality (change of long and short diameters) of the bend shall be less than 10% of the pipe diameter, and no wrinkles shall occur;

(3) If there is a joint at the pipe end at the bend, the pipe end shall be connected with a straight pipe to avoid affecting the installation;

6. Welding of pipes and joints

(1) The argon tungsten arc welding or argon arc welding shall be used for back sealing and arc welding and filling welding. When the pressure exceeds 21 mpa, 5l/min argon shall be injected into the pipe at the same time;

(2) When the pipe wall thickness is greater than 2mm, the outer circle shall be cut with a 35 ° groove, and a 3mm gap shall be left at the butt joint; When the pipe wall thickness is ≤ 2mm, the groove shall not be cut, and a 2mm gap shall be left at the butt joint;

(3) When aligning, the pipe axis must be coincident, the unfitness is less than 15% of the wall thickness, and the deflection is less than 1:200;

7. Installation of pipe clamp

(1) The base plate of pipe clamp is generally welded to the structural member directly or through brackets such as angle steel, and the bracket is fixed with expansion bolts on the concrete floor or wall side;

(2) Pay attention to leveling when installing the pipe clamp, that is, the installation surface is at the same height;

(3) Spacing between pipe clamps: pipe diameter ≤ φ At 10:00, about 0.5~1m; pipe diameter φ About 1-1.5m at 10~25; pipe diameter φ At 25~50, it is about 1.5~2 meters, but at the right angle turn, a pipe clamp shall be used on both sides.

8. Pre installation

(1) Connect the pipe joint with the equipment and pipe joint section by section until all the pre installation is completed;

(2) See Chapter 4 for the installation method of pipe joints;

(3) At the same time, the pipe clamp base plate shall be welded on the structural member or support, and the pipe shall not be welded on the pipe clamp or support;

(4) After the pre installation is completed and checked to be qualified, the matching marks shall be printed on the pipelines, one for each, and the matching marks shall be numbered as a table for future use. After the pipeline is removed and cleaned, it shall be restored according to the number.

9. Precautions

(1) Before installation, all steel pipes can be pickled according to the requirements of Chapter 9, especially the steel pipes connected with ferrule type pipe joints shall be pickled first, and then the ferrule shall be fastened on the pipe end in advance;

(2) All pipe joints shall be cleaned with kerosene for installation, and the o-ring inside shall be temporarily taken out for storage and put on again after formal installation;

(3) During construction, the oil ports, pipe joints, pipe ends and other openings of pumps, distributors and other equipment shall be kept clean, and foreign matters such as water and dust shall not enter;

(4) The pipeline shall be laid in a free state, and the welded pipeline shall not be forcibly fixed and connected with excessive radial force;

(5) The oil hole of the bearing seat shall be checked in advance to see whether the internal oil path is unblocked and whether the oil port thread is matched with the joint.

Pipeline cleaning editing broadcast

In order to ensure the cleanness of the lubricating system and supply clean lubricating grease to the bearings of mechanical equipment, the pre installed pipelines must be removed for cleaning. There are two kinds of cleaning: kerosene cleaning and acid cleaning.

1. Kerosene cleaning object and method

(1) Copper pipe, stainless steel pipe;

(2) Steel pipes that have been pickled before pre installation and have no rust and oxide scale on the inner wall;

(3) Pipe joints soiled during preassembly;

(4) Dismantle the pipes and joints to be cleaned. Wipe the inside of the pipes with a cloth (without shedding the wool yarn) dipped in kerosene.