The hydraulic quick coupling is a joint that can quickly connect or disconnect the pipeline without tools. It has four main structural forms: straight-through, single-enclosed, double-enclosed, and safe and leak-free. The materials are mainly carbon steel, stainless steel and brass.
There are a large number of quick couplings in coiled tubing equipment, mainly at the tubing drum, hose drum, blowout preventer and injection head. Today, two common quick coupling structures are briefly introduced.
The first structure is a flat quick coupling, which is currently the most widely used. The flat quick coupling has the following technical characteristics and options:
• Interchangeability standards: ISO16028 (from 6.3 to 25) and HTMA (10)
• Valve system: flat seal
• Connection method: steel ball lock
• Docking system: push-in connection
• Dismantling the system: pull off the female connector sheath
• Butt joint with residual pressure: not allowed
• Dismantling with residual pressure: not allowed
• Optional thread: BSP, NPT, SAE
• Customized thread: metric external thread or other
• Structural material: high-strength carbon steel
• Surface treatment: carbon steel galvanized
• External spring: 302 stainless steel
• Internal spring: C72 steel
• Steel balls: high-strength carbon steel
• Seal: NBR (nitrile rubber)
• Other sealing materials: VITON (fluorine rubber) or other
• Anti-extrusion retaining ring: PTFE (polytetrafluoroethylene)
The main advantages of flat quick connectors are as follows:
• The flat type is easier to clean, helping to reduce pollution to the entire hydraulic system.
• Ensure minimum leakage during disassembly and docking, and reduce oil loss
• Disassembly and docking have the least amount of air clamping, which enhances the performance of the entire hydraulic system
• The internal valve design minimizes pressure drop and improves the efficiency of the entire system
• Modular design allows more flexible interface configuration
• Withstand pulse pressure
• Compact structure
• Simple and safe to use
The main points of attention for the use of flat quick connectors are as follows:
• Clean the docking plane before docking to prevent contaminants from entering the hydraulic circuit
• When docking, push one end of the male connector into the female connector and vice versa
• After docking, please rotate the outer lock sleeve to the locked position to prevent accidents when disconnected
• When disconnecting, turn the outer lock sleeve to the safety lock position corresponding to the lock slot, and pull back the lock sleeve.
• Do not use the female connector alone under high-frequency pulse pressure
• Do not connect-disconnect when there is hydraulic oil flowing and/or dynamic pressure in the circuit;
• Do not connect-disconnect when the hydraulic oil temperature in the circuit is higher than 80°C (176°F);
• When the quick connector is not connected, it is recommended to use a dust cap
Cone-type quick couplings were more common in early imported equipment, but later as the equipment grew over time, they were basically replaced by flat-type couplings. Cone type quick couplings have the following technical characteristics and options:
• Interchangeability standard: ISO 7541-1A
• Valve system: poppet valve
• Locking method: steel ball locking
• Push-in-pull-out connection system: female connectors with partitions are optional
• Docking system: Push in the male connector (push)
• Disconnect the system: pull out the male connector (pull)
• Connection with residual pressure: not allowed
• Dismantling with residual pressure: not allowed
•Thread type: BSP (DIN 3852), metric thread (DIN 3852 and DIN
2353/ISO 8434-1)
•Thread type: NPT (ANSI B.A.20.A), JIC (SAE J514-ISO 8434-
And other threads
• Structural material: carbon steel
• Surface treatment: carbon steel galvanized
• Spring material: C72 steel
• Steel ball material: high-strength steel 100 C6
• The inner spool guide has a copper limit component
• Seal: NBR (nitrile rubber)
• Sealing method type: VITON (Fluorine rubber)
• Anti-extrusion retaining ring: PTFE (polytetrafluoroethylene)
The main advantages of taper quick couplings are as follows:
• The snap-off function can effectively prevent the hydraulic pipeline from being damaged under strong axial forces
• When non-butting, the elastic seal on the poppet valve provides the strictest sealing effect
• The exterior design of internal parts reduces turbulence and pressure drop
• Modular design makes the thread connection method rich
• Compact structure
• Simple and safe to use
The main precautions for the use of cone type quick joints are as follows:
• For the snap-off function, the female connector must be installed on the partition, and the shaft is locked with a circlip.
• The female connector should be connected to a hose to allow the internal valve body to move when the quick connector is docked and disconnected.
• Clean the docking part before docking to prevent contaminants from entering the hydraulic circuit.
• Push the male connector into the female connector when docking.
• Pull out the male connector when disconnecting.
There are advantages and disadvantages of flat and tapered quick couplings. Here is a brief summary:
• The flat quick-connect has small leakage and is easy to clean. It can greatly reduce the chance of air and impurities entering the system when plugging or unplugging. This is why this structure is widely used.
• The biggest feature of the tapered quick coupling is that it will automatically disengage when the axial force is too large. This is a design concept of foreigners. It is better to let the quick coupling disengage by itself than to allow excessive axial force to tear the hose.
• When plugging and unplugging the quick connector, be sure to use a clean cloth to wipe the impurities on the connector. This habit can increase the life of the quick connector several times.
• How to replace quick couplings needs to master a principle. The first is to replace the same brand and the same standard, followed by the same standard replacement of different brands, and the quick couplings of different standards must not be mixed. In principle, the quick couplings are replaced in pairs, but in fact the female connector is damaged. The odds are greater.
• Whether the quick connector can be plugged and unplugged under pressure, the answer is yes, but when selecting the type, it must be clearly seen whether it is under pressure on one side or on both sides.
