align the three bolt holes at the top of the rails with similar holes in the side of the dome. Insert 1/2-by 1 Ml-inch bolts through the rails and the dome, in that order. Apply gaskets and washers to the bolts (fig. 9-16, #6). Make sure that the cup side of the washers is facing down over the gaskets. Apply the nuts to the bolts. Make sure that the rounded face of the nut is bearing against the washer. Tighten the bolts. Install a 28 bolt hole gasket (fig. 9-17, #1) on the inside face of the bottom flange of the dome. Insert 1/2- by 1 1/4-inch bolts through the flange and the gasket. The gasket will hold the bolts in place.

Install the ladder anchors (fig. 9-16, #8) at the bottom of the rails. Place the long leg of the anchor over the three bolt holes in the vertical leg of the rails. The short leg of the anchor faces outward. Adjust the outside bolting face of the short leg so it measures 9 feet 5 15/16 inches from the top flange of the dome. Insert two bolts through each anchor and rail. Apply the nuts to the bolts and tighten securely.

Figure 9-18. - Center support ladder installed.

Figure 9-19. - Deck plates ready for installation.

Line up two diametrically opposite lap seams (fig 9-18) in the tank bottom. Remove a nut from each bolt in the lap seams and the first bolt to the right and left of each lap seam. Raise the ladder assembly and se the anchors over the bolts. Apply the nuts and tighten

Top Deck Assembly

The assembled deck consists of 14 tapered, flat steel plates (fig. 9-19) with an integral formed flange along the right lap seam. The seams are identified rig and left, facing the large end All of the plates are interchangeable.

Of the 14 plates, three are special. Two plates a fitted with a tank thief and vent, and one plate is fitted with a liquid level indicator. Each deck plate has deck plate channel and a rafter bolt retainer angle assembled on it. The small end of the plates is bolted to the bottom flange of the dome. The large end bolted to the top chime of the staves.

LAYOUT AND ASSEMBLY OF PLATES. - Lay out the plates around the outer perimeter of the tank foundation. Place the blocking on the ground, spaced to fit inside the confines of the plate. Lay the inside of the flange with the short leg facing outward. Insert four equally spaced bolts through the angle and flange. Apply the nuts to the bolts. Tighten the bolts. Turn the plate over with the flange down. Install a gasket along the full length of the right lap seam. Allow a two bolt hole overlap at each end.

LAYOUT OF ASSEMBLED PLATES. - As the plates are assembled, raise them up and stand them