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• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />• <br />(overlap) on each anchor bar. Both sides of each anchor bar will be welded to the frame. Rods bogs shall <br />protrude through holes drilled in the grate frame. Torch-cut holes will not be accepted. Rods bolts will be <br />tightened securely and the nuts tack welded. The grate material will then be positioned onto the secured <br />frame and welded at every other bearing bar, one side, around the entire perimeter of the grate. Painting is <br />not required. <br />If a hinging and locking mechanism is required, the hatch and hatch frame will be welded into the center area <br />of the grate. The locking door shall be constructed as shown on Standard Drawing Number 6. The grating <br />material shall be the same as the surrounding grating. <br />Ali voids along the edges of the grating larger than one inch (1") must be filled with bolt protection plates where <br />anchor bars or bolts are exposed from above, or pieces of welded grating or angle to fig the void. <br />Following installation of the grating, the CONTRACTOR shall weld a 3' inside diameter 4' long steel pipe to <br />the grating, the brass cap, provided by the owner, shall be grouted flush to'/,' below the top of the pipe using <br />non-shrink grout such as Pour Rock, Kwik-Crete, Epoxy Bond, or Moly Parabond. <br />8.3.3. Beams <br />Steel beams will be used to reduce all grating spans to a maximum as shown below. For shaft spans of <br />twelve feet (12'), or less, W4 x 13 steel beams will be used. For shaft spans between twelve feet (17) and <br />twenty feet (20'), W6X20 steel beams shall be used. <br />Table 10.1 <br />Bearing Bar Size Bearing Bar Spacing Cross Bar Spacing Maximum Grating <br />Sim" feet <br />1-1/4'x 1/8' 1-3/16" 4" 3.5 <br />1-1/4"x 1/8" 15116" 2' 4.0 <br />1-1/4" x 3116' 1-3/16" 4' 4.0 <br />1-1/4"x3/16* 15116' 2' 4.5 <br />1-112" x 1/8' 1-3/16' 4" 4.5 <br />1-1w x 1/8' 15116' 2" 5.0 <br />1-1 x 3/16' 1-/16" 4" 5.0 <br />1-12/` x 3/16" 15116" 2" 5.5 <br />1-314" x 3116' 1-3116' 4' 5.5 <br />1-3/4' x 3/16" 15116" 2' 6.0 <br />2" x 3/16' 1-/16" 4- 6.0 <br />Y x 3/16" 15/16' 2' 6.5 <br />2114" x 3116* 1-3/16" 4" 6.5 <br />21/4" x 3/16' 15/16" 2' 6.5 <br />2 1u2" x 3116" 1-3/16' 4' 6.5 <br />2 /2" x 3116" 15116" 2" 7.0 <br />Steel beams will be embedded and covered in concrete for the entire length of the beam that rests on the <br />tooting surface, except for the top portion where grating will be placed. The steel beams must extend to the <br />edges of the grating. Grating may be set on steel beams immediately following the embedment of beam ends <br />in concrete. Where grating crosses a support beam, every other bearing bar shall be welded for a length of <br />one inch to the support beam. Paint, if any, will be wire brushed or ground off beams prior to welding. <br />8.3.4. Installation Within Historical Structures <br />Gratings constructed within wooden headframe structures will require modifications to conform to the existing <br />support columns. Custom fitting and welding operations while the grate is in the structure will be allowed If the <br />adjacent wood is adequately protected from sparks or flames, and only when an approved fire extinguisher is <br />at the site. Additional connector plates, stiffeners or otlaer steel reinforcing elements may be required to <br />Colorado Division of Minerals and Geology GENERAL BID SPECIFICATIONS <br />2004 Page 41