1 The minimum clear opening of not less than 600
mm x 800 mm may also include an opening with corner radii of 300 mm.
An opening of 600 mm in height x 800 mm in width may be accepted as
access openings in vertical structures where it is not desirable to
make large openings in the structural strength aspects, i.e. girders
and floors in double-bottom tanks.
2 Subject to verification of easy evacuation of
an injured person on a stretcher the vertical opening 850 mm x 620
mm with wider upper half than 600 mm, while the lower half may be
less than 600 mm with the overall height not less than 850 mm is considered
an acceptable alternative to the traditional opening of 600 mm x 800
mm with corner radii of 300 mm.
3 If a vertical opening is at a height of more
than 600 mm steps then handgrips should be provided. In such arrangements
it should be demonstrated that an injured person can be easily evacuated.