Page 174 - Offshore Electrical Engineering Manual

Helidecks 161

illuminating access ladders, landings and equipment on the derrick itself, the der-
rick may be used for positioning drill floor and monkey board floodlights. Designers
should remember the discomfort and danger involved in maintaining derrick lighting
when selecting the type and number required, as once installed, the luminaires must
be regularly cleaned and re-lamped. Permanent safety-hooped access ladders with
caged landings at appropriate intervals must be provided.
If there is a suitably high structure nearby which overlooks the derrick, on
which floodlights may be mounted, the above problem may be alleviated to some
extent. Drilling and wellhead areas present a flammable gas hazard, and luminaires
within this area must be certified for use in the hazardous zone in which they are
located.

LAYDOWN AREAS
Because of the continual movement of containers and equipment around these areas,
and the crane operations involved, laydown areas should be floodlit rather than
locally lit. While illuminance calculations are in progress, it is important to study
crane operating loci in order to establish suitable locations for floodlights, to ensure
that as well as providing good lighting of the area, they are unlikely to come into
contact with parts of any crane or their moving loads.

HELIDECKS
As a result of the G-REDU accident in February 2009, a new CAP437 lighting
scheme has been developed, which includes the following elements:

• Green helideck perimeter lights:
• The white painted ‘H’ should be outlined with steady green lighting, forming a
lit ‘H’.
• The Touchdown/Positioning (TD/PM) circle should be fully outlined with
steady yellow lighting
• Omni-directional low intensity steady red obstacle lights should be fitted to the
highest points of the installation, crane booms, lattice towers, etc.
• Omni-directional low intensity steady red obstacle lights should be fitted to
objects which are higher than the landing area and close to it or the LOS bound-
ary (150 degrees Limited Obstacle Surface cone above helideck level).
• Status lights (for night and day operations, indicating the status of the helicopter
landing area) consisting of flashing red lights indicating ‘landing area unsafe:
do not land’.
• Installation/vessel emergency power supply design should include the entire
landing area lighting system (see CAP437 Appendix C) fed from a suitable
battery-backed secure power (UPS) supply system.