A truncated cone bladder features a long service life and maximizes the trapped vapor volume inside the tank. The bladder is constructed as two fiat fabric pieces: one a circle and the other a truncated cone. The ring is either assembled and welded in the tank on pipe stands during tank construction or later during bladder installation.
The top circular fabric piece is brought into the tank; the center plate is attached and the fabric is stretched out and clamped to the ring (See Figure 3). Attachment is made by placing sections of 3/8" aluminum rod on a marked line and folding over the fabric. This rod and fabric fold is held in place by pipe sections, which are held in place by periodic clamps. By working around the tank, butted rod and joined pipe sections are used to form a continuous seal. The fabric can be adjusted prior to final sealing to eliminate any laps and minimize wrinkles. The bladder is sealed to the ring using a rubber sealant. The seal is caulked and clamps replaced. Sealant is used under clamp washers to seal the cap screws which penetrate from outside to inside the bladder volume.
