NATIONAL ALUMINIUM COMPANY LIMITED - Rites

(i) Wherever possible, access shall be provided by means of stairs.
(ii) All walkways and stairs leading to working platforms shall have minimum 800 mm width
of walkways/flight of stair.
(iii) All other walkways and stairs leading to areas for maintenance purpose, or due to
restriction iction of space, shall have a minimum width of 800 mm of walkway/flight of stair,
unless required otherwise.
(iv) Staircases shall be generally designed with slope of approximate 37.5 37.5° with the
horizontal. (In no case the slope shall exceed 40 ° with the horizo horizontal). Intermediate
landings shall be provided wherever required such that vertical rise of each flight does
not exceed 3000mm. Risers in one flight shall be equally spaced.
(v) Walkway floors and stair treads shall be designed with chequered plate (or non non-slip
type plates). Ribbed floor/treads may be provided wherever the possibility of
accumulation of dust exists, taking care that such provisions do not crate a nuisance to
the operating personnel on the shop floor.
(vi) Rise of treads in staircases shall not excee exceed 200 mm.
(vii) A minimum headroom of 2200 mm shall be provided over operating platforms, visitor's
galleries, or other areas with possibility of public gathering. In all other platforms,
walkways and stairs, minimum headroom of 2000 mm shall be provided. Only i iin
special
cases, local headroom of 1800 mm may be allowed (i.e. at intersection with structural
members etc.).
(viii) Cat ladders shall be provided for access, wherever provision of staircase is impractical
due to limitations of space, or the access is required vvery
ery infrequently.
(ix) Wherever the height of cat ladder exceeds 4.0 m, safety cage shall be provided.
Intermediate landing shall be provided to cat ladders such that vertical height of single
rise does not exceed 8.0 m.
(x) Cat ladders shall be designed with follo following provisions:
i. Width of rung = 500 mm
ii. Minimum rise of rung = 250 mm; Maximum rise of rung = 300 mm
iii. Minimum clearance from rung of ladder to back of cage (in case of caged
ladders) = 700 mm
iv. Minimum clearance from the centre of cage all round = 350 mm
v. Slope of cat--ladders:
I. For normal cat cat-ladders, ladders, slope shall be within the range of 75 75°-90° with the
horizontal.
II. For ship-type type ladders (i.e cat cat-ladders ladders with short side handrails) the slope shall be
within the range of 65 65°-75° with the horizontal.
(xi) All walkways, platforms and stairs shall be provided with safety handrails. All handrails
shall be constructed with steel tubes / angles for posts, top and middle rail and
plates/sheets for toe plates. In case of stairs, the toe guards need not be provided.
(xii) The he vertical height of hand hand-railings railings on walkways and stairs shall be minimum 1000 mm
above floor level.
(xiii) Hand-railing railing along edge of roof and gutters shall have a minimum height of 600 mm
over top edge of gutters/sheets. In such hand railings toe guards need not be provided.
(Only top handrail and midrail shall be provided).
Technical Specification:Sec-4,System System Parameters, Operation & Control Philosophy
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