John Crane has launched its new Type 8628VL, a mechanical seal engineered to withstand volatile pressure and temperature conditions by using spiral groove non-contacting technology. It has been designed to maintain sealing integrity in multiphase ethane and ethylene pipelines
The multiphase challenge
Ethane pipelines present several challenges that compromise seal performance, due to fluid phases shifting from liquid to vapour to supercritical.
Designed with these challenges in mind, the Type 8628VL employs dual non-contacting seal faces in a tandem configuration.
This design was validated by peer-reviewed Lubricants (MDPI) research, which confirmed that spiral groove non-contacting seal faces offer improved hydrodynamic lift, phase-change resiliency, and zero-wear operation in volatile fluid applications.
Field installations
An ethane transmission company operating along the U.S. Gulf Coast were faced with the challenge of managing phase change during pumping with pressure variations.
Ethane exists as a liquid at around 18 °C and 40 bar, 580 psi, and transitions to a vapour at 32 °C. This phase change resulted in sealing and reliability issues, impacting uptime and seal life.
The operator installed four Type 8628VL seals on the ethane pump equipment, and after three months of continuous operation and intermittent shutdowns, the results revealed: non-contacting performance across all phases, low leakage and no failures.
Features of the Type 8628VL include:
- A mean time between repair (MTBR) of up to 48 months or more
- Requires only 2-3GPM of flush fluid
- The dual unpressurised arrangement removes the need for API Plan 54 or 53B systems
Mike Eason, chief technology officer at John Crane, said, "Unlike hybrid or contacting seals, the Type 8628VL delivers pure non-contacting operation, even during rapid phase transitions."
"We will continue to expand our portfolio with products that meet customer reliability and energy transition goals. The Type 8628VL is a testament to our commitment to innovate for greater efficiency, zero greenhouse gas emissions".
