Gall Thomson PetalC Breakaway Coupling
Application
Hose offshore transfer of media between Floating Production Storage and Offloading platforms (FPSOs) and tankers or between tankers or vessels – specifically relevant to reel applications.
Purpose
The offshore marine breakaway coupling is designed to protect a transfer operation in an emergency.
This coupling will automatically activate due to either one of two ends of the line moving beyond a pre-defined distance or because of an unacceptable pressure surge.
Unacceptable movement in an offshore environment can be due to vessel displacement where the vessel moves beyond the available distance offered by the transfer line. This scenario is often due to the breaking of moorings in adverse weather conditions, error or equipment malfunction.
Pressure surge is typically due to a malfunction of another component within the transfer line.
When the coupling is activated, the up and downstream flow is shut down by the closure of two Petal Valves. The coupling then separates into two pieces. This enables the hose string to separate into two halves.
Without this coupling, stress on the hose caused either by unacceptable movement or pressure surge can result in damage to hoses and other assets, potential injury, extended downtime and spill of media into the environment.
Product profile
The PetalC activation is provoked by the use of breakstuds which are designed to split at pre-defined breakloads. These breakloads are determined at the specification stage.
PetalC is specifically beneficial to hose reel applications. Compared to a standard Petal Valve marine breakaway coupling, the PetalC is compact with an installed length reduced by 60 per cent. This is achieved by elements of its cartridge profile positioned inside the hose nipples.
This optimisation of overall geometry enables a reduction of axial load on the most exposed breakstuds of up to 30 per cent. This removes the need for MBC transit bolts when reeling the hose, although they can still be fitted if requested by the operator.
The reduced body size is smaller than the diameter of adjacent hose flanges. This minimises the risk of external structural impact and abrasion damage.
Typical operational applications
Floating hose strings at FPSO, SPM CALM/SALM Buoy terminals.
Typical media
Viscous media such as crude oil.
Performance
PetalC is self-contained and self-energised in that the valves are powered by the energy of flowing product acting on the Petal assembly. This means the unit does not rely on any external power source or multiple levels of MBC management complexity – both of which introduce additional risk that may unnecessarily compromise operational reliability.
Parting load and closure speed are defined during specification.
The design is compact, lightweight and radially in balance.
PetalC is full bore and headloss is minimal.
Limitations
PetalC is not suitable for nippleless hoses.
Cost assessment
Additional costs – servicing
To ensure reliability of breakaway couplings, it is important to adhere to the recommended service schedule. If you currently don’t have a marine breakaway coupling in your transfer line but plan to fit one then expect to integrate its servicing into your maintenance schedule.
Based on normal operating conditions, PetalC should be serviced every five years. Expected life is 20 years over three service life cycles.
Potential cost savings compared to alternatives
Because less stress is placed on the hose while on the reel, PetalC provides potential extended life to hoses.
Gall Thomson MBCs are the optimum solutions in protecting hose transfer systems. No complicated or high maintenance monitoring systems are required.
Conclusion
Minimising risk for an operation and undertaking due diligence in protecting the environment is an important objective for modern operations. The Gall Thomson PetalC offers a cost-efficient protective and proven solution for operations involved with the transfer of media in an offshore environment.
Further information from supplier: gallthomson.com/petalc
Shown: PetalC being commissioned.
Shown: PetalC in hose string
