Figure 9-21.—Outside ladder installed.

against the scaffold, as shown in figure 9-19. Locate each plate so it straddles a vertical seam of the side staves in the approximate installation position, counterclockwise. ADJUSTMENT OF CENTER SUPPORT LADDER— Check and adjust the ladder to the correct height before the installation of the deck plates. ‘he distance from the top of the tank bottom to the outer face of the top flange of the dome is 9 feet 6 9/64 inches. Raise or lower the ladder as required. Place a jack under one of the ladder steps. Adjust the ladder so that in the final position, one set of the holes in the bottom of the rails line up with the holes in the brace. Lock the jack Insert the bolts through the proper bolt holes in the brace to match the top holes in the rails. Apply the nuts to the bolts. Tighten the bolts. Unlock and remove the jack. When all of the deck plates have been installed on the tank, check the height to the outer face of the top flange of the manhole dome above the top of the tank bottom. If not the required height, adjust the ladder until it is the correct dimension. Insert the bolts in aligned bolt holes and tighten the nuts. INSTALLATION OF FIRST DECK PLATE.— The first plate installed should be a plate with a vent (fig. 9-19, #2). The remaining plate, fitted with a vent, must be installed directly across the tank from the first plate with a vent. Attach two rope deck hooks to the small end of the plate while it stands against the scaffold (fig. 9-13). Guide the large end of the plate and pull the plate in place by means of a haul line. Lower the large end of the plate over the proper bolts in the top chime of the staves, so it will straddle a vertical seam. The small end of the plate will drop over the proper bolts. Release the hooks. Apply four equally spaced catch nuts to the bolts through the large end of the plate. One catch nut will be sufficient to hold the small end in place. Do not tighten the bolts. INSTALLATION OF SECOND DECK PLATE.— Install a gasket over the bolts at the left lap seam of the plate (fig. 9-17, #3 and #4). Face the small end of the plate #4. Install this plate and all of the remaining plates to the left of the first plate or in a counterclockwise direction around the tank Raise the plate. Place the right lap seam of the plate over the bolts in the left lap seam of the first plate #4 and the large end over the proper bolts in the top chime of the staves. Install the nuts to six equally spaced bolts in the lap seam of the plates. Install the nuts on all of the bolts in the chime. Finger tighten all of the nuts. As the deck will have to be adjusted as the plates are installed, do not tighten any bolts until the deck is completely installed. Raise or lower the center support ladder as required to fit the plates in place. INSTALLATION OF INTERMEDIATE DECK PLATES.— There are 12 intermediate plates. The special plates remaining are installed to suit field conditions. LAST DECK PLATE.— Raise the last deck plate before the next-to-last plate is installed Raise the right lap seam of the first deck plate (fig. 9-20, #l). This is necessary to permit the installation of the last plate. Figure 9-20.—Installing last deck plate. Figure 9-21.—Outside ladder installed. 9-12