transitions at corners where change of direction or elevation occurs as
required to provide continuous handrail. Clear columns or other vertical
or horizontal projections by at least 80 mm 3 inches. Furnish plates and
additional items as required for fastening to supporting members. Extend
kickplates 100 mm 4 inches above top of grating and install at the edge of
uncovered openings and at the edge of walkways and platforms. Kickplates
shall be constructed to allow water run-off. Shop fabrication shall be as
complete as possible and within standard industry practice. Large pieces
shall be left unassembled only to the extent necessary for shipment.
2.13.4.1
Grating
Fabricate grating main bars vertical within a tolerance of 2.5 mm per 25 mm
0.1 inch per inch of depth with the longitudinal bow before fastening to
supports shall be less than 1/200 of the length and the traverse bow before
fastening to supports shall be less than 10.41 mm in one meter 3/8 inch in
3 feet. Crossbars shall not deviate from a straight line perpendicular to
the main bars by more than 5.21 mm in one meter 3/16 inch in 3 feet.
Crossbars shall match crossbars of adjacent sections to form a continuous
pattern of straight lines. Grating panels shall be cut to size and piece
marked. Panel width and length tolerances shall be plus or minus 6 mm 1/4
inch. Provide openings in grating as required for installation of piping
and equipment furnished under this Contract. Band openings 100 mm 4 inches
and larger with a metal bar same size as main bearing bar. Weld to each
bearing bar with 4.76 mm 3/16 inch fillet weld 19 mm 3/4 inch long. Tack
weld to crossbars. Trim band open end of grating at head of ladder, manway
opening, hinged sections, and grating panels with four crossbars or less.
Grating shall be removable. Fasten raised pattern floor plate in place
with countersunk stainless-steel screw at each corner of each piece or plug
weld where permanent fastening is required. Screws shall be flathead, 6 mm
1/4 inch, national coarse thread stainless steel, and shall be countersunk.
2.13.4.2
Stairs
Construction of stringers of channel sections shall be adequate to carry
the specified design loads without excessive deflection. Construct cross
brace stringers to provide lateral stability where the horizontal run
exceeds 3.66 meters 12 feet. Provide struts and hangers where required to
suit specified live load with minimum size as specified. Bolt tread to
stringers with a minimum of two 9.53 mm 3/8 inch, national coarse thread,
stainless steel bolts.
2.13.5
Access
Provide access walkways across top of ductwork from boiler enclosures to
spray dryer absorbers as indicated. Extend walkways to fabric filter
baghouses as indicated. Stair access and platforms shall be supplied to
fabric filter baghouse hopper accessories. Provide stair access and
walkways for access to the tube sheet level of the fabric filter baghouses
with connecting walkways. Internal and external access walkways, lights,
and platforms shall be provided to access doors, inspection or maintenance
points, and other areas where access is required for operation, inspection,
testing, and maintenance. Walkways and platforms at each level shall be
interconnected by walkways at the same level. Walkways including roof,
shall be connected by stairs. Caged ladders shall be provided at each
level for secondary egress. Provide stair access and platforms to lime
system equipment levels. Access shall be provided for dust valves,
manholes, poke holes, hopper vibrators, conveyors, expansion joints,
dampers, portion of the ductwork subject to dust accumulation, gas sampling
SECTION 15864N
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