Marine Breakaway Couplings FAQ

1. What is a Marine Breakaway Coupling?

The Marine Breakaway Coupling (MBC) is a device installed into hose transfer systems at offshore tanker discharging or loading terminals. The MBC is designed to prevent oil spills and protect the transfer system from damage in the event of tanker breakout or excessive pressure surge.

Tanker breakout in this context is a vessel moving off station while connected to a hose transfer system. There are numerous reasons for breakout or why an oil tanker would break from its mooring hawser.

Excessive pressure surge is caused by the inadvertent closure of the export tanker manifold valve during full flow conditions. The typical cause of a pressure surge is the inadvertent closure of the export tanker manifold valve or the failure and slamming shut of the hose end butterfly valve (if fitted) during pumping operations. Not only does the Gall Thomson MBC protect against the detrimental consequences of excessive pressure surges, but it is also totally unaffected by the usual pressure fluctuations experienced during normal transfer operations.

Both tanker breakout and excessive pressure surge could cause rupture in the hose transfer system with the likely consequence of substantive oil spill and damage to assets.

For a deeper insight into potential risk scenarios based on decades of in-field experience, contact Gall Thomson. For an introduction to oil spill risk see Offshore oil spills Frequently Asked Questions

2. What are the benefits of installing an MBC?

Environmental pollution due to substantial oil spill and the cost of oil spill clean-up and other potential consequences can be considerable. The installation of a Gall Thomson MBC will minimize the risk of substantial oil spill and help safeguard transfer equipment from the consequences of tanker breakout or pressure surge.

The danger to capital equipment such as the hose string, mooring buoy structure or storage vessel off-take manifold, sub-sea PLEM (in the case of CBM systems), shuttle tanker or barge manifold can be substantially reduced with the fitting of a Gall Thomson MBC. The risk of costly vessel and transfer system downtime caused by spill and damage is also minimised.

Note that some operations are configured to not require MBCs to protect against pressure surge. Gall Thomson also offer MBCs that protect only against scenarios such as tanker breakout.

3. How does the Gall Thomson MBC work?

The MBC is designed to provide an identified safe parting point in a hose transfer system.

When its pre-set parting load is exceeded, the MBC activates; the valves close and shut off the line. The coupling separates and relieves the tension in the hose system before it can rupture.

Closure may be controlled or instantaneous depending on the specification of the MBC as determined for the system.

4. What type of MBC is most suitable for my application?

Gall Thomson offers two types of MBC:

The Petal Valve MBC is suitable for controlled closure and often used in handling heavy media such as crude oil and heavy fuel oil.

The Flip-Flap MBC offers instantaneous closure and is often used for low viscosity products such as gasoline, kerosene, diesel, LPG, Ammonia and CO2.

Gall Thomson works closely with operators to determine the exact specification required to ensure reliability. Dependable cost-efficient performance is enabled during this process by Gall Thomson drawing from its nearly 50 years of field experience.

Application, bore size, transfer media and flow rates are some of the basics, but the processing of this and much more information enables Gall Thomson to interrogate the variables to ensure a dependable and cost-efficient specification.

For further details contact Gall Thomson:

Tel: +44 1493 857 936

Email: support@gall-thomson.co.uk

5. What are the most important features to look for when buying an MBC?

MBCs are only about minimising risk of oil spill and damage to assets whilst also avoiding the consequences of negative media attention. There is no other reason to spend money on this device other than to demonstrate due diligence in first deciding to install an MBC and then choosing the correct MBC based on the available information. Choosing the right MBC is actually more important in that to choose incorrectly means you have simply spent money on a false sense of security.

The primary purpose of MBCs is to deliver dependable performance at two levels.

MBCs must float in a hose line for years (for a permanently floating hose string), usually enduring constant movement from waves and currents and the frequent abrasive flow of media during transfer.

When an emergency occurs then the MBC is expected to activate in an instant and within the parameters it was designed. The MBC must then fulfil the activation sequence to an accurately predicted conclusion.

The ability to predict a dependable response to an emergency scenario is a point of value that the operator must seek and confirm when commissioning an MBC within the context of preserving effective risk management.

How to measure and confirm a dependable MBC

Field Verified was designed to confirm MBC predictability. This means proven ability of the MBC type and its manufacturer to perform exactly as forecast based on in-field perfor mances exposed to all relevant scenarios.

Gall Thomson invented the MBC and has been supplying and servicing MBCs around the world for nearly 50 years. It is this consequential amount of immense experience and data that has enabled the Field Verified profile to mean something of real and crucial value to operators.

Manufacturer specification and MBC management assistance also requires experience of complex variables that can only come from fulfilling the expectations of Field Verified. Being aware of all these variables and understanding how they interact both with each other and the environment and application can be cunningly deceptive to the newcomer. Confirming Field Verified is therefore a substantive point of validation for the operator choosing an MBC.

Gall Thomson MBCs are the only Field Verified MBCs available on the market. See MBC Field Verified.

6. Can an MBC be reset following activation?

Depending on the circumstances of activation, the MBC can be reset.

MBC4 is a Gall Thomson package of MBC specific services that enables operators to choose the best option for servicing or resetting activated MBCs. It is designed to comple ment each operator’s circumstance and logistics.

Options include Gall Thomson MBC service centres strategically placed around the world that enable local support. Some operators opt for MBCs to be returned to the Gall Thomson UK technology centre and others prefer on-site resetting where possible. For details see MBC4 Service Options

Servicing and resetting should always be undertaken or supervised by GTAC trained personnel (Gall Thomson GTAC Approved Certification). Gall Thomson MBC service centres are GTAC approved. GTAC training is also available. For more on GTAC see GTAC Approved Certification

7. Can Gall Thomson supply a GTAC service engineer to service/re-assemble an MBC?

It is usually possible to provide a Gall Thomson GTAC engineer to site to perform servicing and refurbishment work. An MBC that requires servicing also means refurbishment and this requires the MBC being sent to a Gall Thomson local service centre or the UK Technology Centre.

8. What are the international recommendations regarding the use of MBCs?

OCIMF guidelines recommend employment of MBCs but there are no governing body rules relating to the device. No such equipment existed prior to the invention of the original MBC by Gall Thomson, which has since become the “Industry Standard”. The Gall Thomson MBC is in fact deployed by every major oil company and a vast number of smaller operators around the world.

The Field Verified profile offered by Gall Thomson is therefore an important validation based on proven field performance within the known range of applications and emergency scenarios. This includes wider aspects such as service, product life cycles, MBC specification and management.

Gall Thomson MBCs have a track record of well over 2500 units supplied world-wide.

The Gall Thomson MBC is manufactured and tested to accepted oil field procedures and quality requirements. Gall Thomson MBCs are also independently tested and witnessed by Third Party Classification Societies such as BV, Lloyds, ABS and DNV with the attendance of Clients.

9. Are there any ancillaries recommended for MBCs?

Flushing Adaptor Spools may be considered to facilitate the evacuation of product from the line in the event of MBC activation. This device converts the parted MBC ends into standard ASME flanged connections which can be bolted directly onto the tanker manifold or the support vessel flange for line flushing.

Floatation Collars reduce the residual weight of the MBC when full of product in the hose line. Double Closure Petal Valve MBCs for floating hose strings are supplied with floatation collars fitted to the downstream and upstream halves of the MBC. For more information see Floatation Collars

Resetting/Refurbishment Spares Kits are available and should be held in stock in case of an activation.

Blind flanges are available should it be necessary to blank off the hose end following MBC activation and connection of the Flushing Adaptor Spool.

For more on available ancillaries and how they are used and managed, contact Gall Thomson.

10. What additional after-sales support is available from Gall Thomson?

Refurbishment/servicing of units within manufacturer recommendations.
Pre-service inspections.
Commissioning inspection.
Post-activation resetting information and recommendation.
Advice on MBC management including maintenance.
Extended warranties.
Pro-active technical support.
Post MBC activation spill simulation.
Guidance on Protected Transfer System (PTX) installation in conjunction with the MBC. See Protected Transfer System

For additional information contact Gall Thomson: