6.1.2 Appropriate gas detectors are to be provided, to give warning of gas
release in the following locations:
- Drill floor.
- Mudrooms.
- Shale shaker space.
- Wellhead and riser areas.
- Adjacent to process equipment.
- Machinery rooms with gas-fuelled equipment.
- Turret area.
- Areas for pipe-laying operations (as defined in Pt 3, Ch 17, 1.1 Application 1.1.1).
- Any other location where there is a significant risk of a
leakage of gas or of liquid liable to release flammable vapour.
6.1.3 Detectors are to be capable of initiating early warning of the presence
of gas and are also to be capable of initiating relevant shut-down actions via the
emergency shut-down system called for in Pt 7, Ch 1, 7 Emergency shutdown (ESD) systems when higher gas concentrations are
detected. To minimise nuisance shut-downs consideration should be given to trips
initiated by confirmed response by more than one detector within the space concerned
or the provision of similar voting arrangements.
6.1.4 Gas turbines and their enclosures are to be fitted with flammable gas
detectors at the following locations:
- Turbine air intakes.
- Ventilation system air intakes.
- Ventilation system exhausts.
The presence of gas in the turbine air intake and/or ventilation system
air intake is to initiate shut-down of the turbine and the ventilation system. If
gas is sensed only in the ventilation exhaust, the ventilation system is to continue
running and the turbine is to be shut down. Proposals involving shutting down and
inerting the turbine machinery enclosure for the conditions described will be given
special consideration.
6.1.5 If an enclosed hazardous area is supplied with a ventilation system, the
presence of gas in the enclosed hazardous area and/or the ventilation system air
extracts from this area is not to initiate the shut-down of the area’s ventilation
system as this will result in the build-up of hazardous gas in this area. However,
other suitable shutdown functionality (i.e. tripping of electrical equipment within
the area, process plant shut-down and emergency depressurisation, etc.) are to be
initiated dependent upon the degree of hazard.