Cryogenic Breakaway Coupling Features
A cryogenic breakaway coupling is designed to safely transfer liquefied industrial gases at cryogenic operating temperatures.
The cryogenic liquids include liquefied natural gas (LNG), liquid nitrogen, liquid oxygen, liquid argon, ethylene, ethane and liquid carbon dioxide.
These breakaway couplings are used during fluid transfers to avoid cryogenic media spills in the event of extreme pressure flow or pre-emptive drive-off.
Cryogenic Breakaway Couplings: How They Work
Cryogenic breakaway coupling technology functions as follows:
Over Pressurisation or Excess Tension
Excess pressure or tension in the transfer system is passed onto the cryogenic breakaway coupling. The coupling acts as the weakest link in the hose system.
The Coupling Halves
The pressure or tension exceeds the coupling’s pre determined break bolts, and the coupling halves. This resolves the pressure or tension in a controlled manner, minimising the risk of equipment damage or injury to personnel.
Instantaneous Shut-Off
Both precision valves close instantaneously to halt the upstream and downstream flow, preventing major product spillage. Any risk of injury such as freezing burns, asphyxiation or fire is mitigated.
Cryogenic Breakaway Coupling Applications
- Ship Bunkering
- Ship-to-Shore Unloading
- Road Tanker Loading
- Rail Tanker Loading
- Bulk Storage Loading and Unloading
- Loading Arm Installations
Cryogenic Breakaway Coupling Specifications
- Multiple end connections avoid the need for separate end connectors
- Wrench spanner flats included in design for easy threaded end attachment
- All couplings pressure tested with nitrogen gas prior to sale to ensure durability
- Adhere to Pressure Equipment Directive (PED)
One half of the cryogenic breakaway couplings will be fixed to the flexible loading hose or loading arm, while the other end will be fixed to the ship, storage unit, or road/rail tanker.
Breakaway couplings can also be flanged in the middle of a hose line, which is especially useful in marine applications.
Cryogenic Breakaway Coupling Variations:
There are a few variations on the cryogenic breakaway coupling release mechanism. Here are some of the most commonly used variants:
Marine Breakaway Coupling
Marine variants of the breakaway coupling are limited to straight-pull release, due to the commonness of lateral forces at sea. The marine breakaway couplings come in all four of the following variants.
Breaking Pin Version
Breaking pin breakaway couplings are used for higher break-loads and are common in marine applications. Some tensile loads are to be expected at sea, where strong winds and swell cause movement in the hose line.
Cable Release Version
Alternatively, to avoid any tension on the hose whatsoever, a cable release coupling might be used. A cable which is shorter than the length of hose will be attached at one end to the breakaway coupling and the other to the receiving vehicle. Once the cable is pulled taut, it triggers the coupling to halve.
Cable release couplings are especially common when using cryogenic breakaway couplings. Due to the hazards of the cryogenic media being transferred, any tension on the hose is undesirable.
Emergency Release Coupling
An emergency release coupling (ERC) comes in two forms: either as a coupling fitted in the hose line, or a collar fitted onto a breakaway coupling. Emergency release coupling technology allows the coupling to respond to triggers other than excess pressure or tension. The coupling can act as a standard breakaway coupling, or be triggered in two other ways: Emergency Separation Device (ESD) or manual override.
ESDs are cable-activated devices connected to a ship at port; much like a cable release coupling, they trigger with excess tension. This usually triggers alarms in the facility and can also automatically trigger ERCs. Manual override sends a remote signal to disconnect ERCs from a control room in case of an emergency in the facility.
Proximity Switch
Cryogenic breakaway couplings can be fitted with an optional proximity switch. This is raised indicate when the breakaway coupling is secured and ready for media transfer. Some switches send electrical signals which can be used to monitor the breakaway coupling’s status remotely.