1. Tanker breakouts
Tanker breakouts can be caused by storms, sudden squalls, strong currents, variable tides, tankers mismanoeuvring or failure of deck equipment. The consequences of such incidents can be horrendous, with the possibility of massive pollution and damaged hose systems. Tanker and terminal downtime also add to potential problems. Following a tanker breakout and without the protection of an MBC, the close proximity of CBM systems to the shore means the clean-up operation can be a complex and lengthy process.
2. Pressure surge
Excessive and damaging pressure surge can be generated by 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.
Generally a typical CBM hose string has a reinforced submarine hose at one end connected to the PLEM, several mainline submarine hoses, possibly a tapered submarine hose and then one or more submarine tail hoses and a rail hose.
In the vast majority of CBM systems, the MBC is installed without floatation collars between the first and the second hoses off the PLEM.
As the hose string is composed of 8, 10 or 12 hoses then should a tanker breakout occur, the load will be transmitted very early onto the MBC. This prevents damage to the hoses and PLEM and avoids a major pollution incident. In this position, the MBC is not subject to unnecessary bending moments during the lifting of the tail and rail hoses.
If the CBM is composed of several hose strings then each hose string should be protected with an MBC suitable for the media transferred.
Key considerations for CBM terminals: