Considerations with High-Pressure
Sealing at ultra-high pressures
CEJN recommends the use of metal-to-metal cone seats for ultra-high pressure hydraulic couplings. For pressures of 70 MPa and above, we have developed a unique seal that incorporates a 120° cone. The 120° cone allows for the seal to take place on a relatively small diameter, which minimizes strain on the threads. Additionally, the threads are straight, not tapered, thereby eliminating the risk of cracked threads under overtorque conditions. Because the CEJN connection has very good sealing properties at low tightening torque, the joint can be reassembled many times without damaging the sealing surfaces.
When using tapered threads, such as NPT or R, we recommend the use of a liquid or paste sealant - not thread tape (i.e. PTFE based tape), which may serve more as a lubricant and lead to cracked components. Thread tape may also become dislodged and find its way into hydraulic components, thereby causing damage or system malfunction. Rubber-metal seals can be used when sealing parallel threads against boss or components with the appropriate sealing face. Rubber-metal seals should be avoided at pressures above 100 MPa.
Connecting the two halves
When connecting the two halves, always make sure that the locking sleeve moves forward to ensure a positive lock. Ultrahigh pressure series couplings are not designed to be connected under pressure, as seal damage may occur.
Dust caps
Extend product life by using dust caps. Dust or dirt on the coupling/nipple can easily enter the hydraulic system and in doing so impair the oil quality and system performance and in the worse possible scenario result in production downtime.
CEJN’s dust caps can, as an extra safety precaution, be connected together to prevent dust from becoming attached to them when the nipple and coupling are connected.
Despite these precautions, you should still wipe off the coupling and nipple before connection.