Sealing system around tank floating plate
According to the requirements of API650 and GB50341, the annular space between the tank wall and the floating plate must be equipped with a sealing system around the floating plate. According to the structure of the floating disc and the nature of the stored materials, it is particularly important to select a suitable peripheral sealing method to shield the oil and gas volatilization, reduce the loss of the stored materials and air pollution, and ensure the safety and environmental protection of the storage tank.
The peripheral sealing system of the tank floating plate is divided into the inner floating plate peripheral sealing system and the outer floating plate peripheral sealing system.
Inner floating disc peripheral sealing system
1 Bladder seal
The bladder seal is an economical and practical sealing device. It uses polyurethane foam elastic element as the filler, and is wrapped with sealing material in contact with the medium. It is fixed on the outer ring plate of the inner floating plate with adhesive strips and fasteners, and filled in the annular space between the tank wall and the inner floating plate. The bladder seal has a large contact area and good sealing effect, and is applicable to all kinds of tanks, but it has a high requirement for the tank wall finish.
2 Tongue seal
Tongue seal is one of the earliest forms of sealing applied to the periphery of the inner floating disc. The section of the tongue tape is trapezoidal. It uses its own rigidity and elasticity to push the outer edge to the tank wall and make sliding contact with the tank wall to achieve good sealing effect. Tongue tape is usually installed above the liquid level to avoid direct contact with the liquid. It is usually used for tanks with diameter greater than 10m.
3 Double seal
The double seal is composed of the combination of single capsule seal and single tongue seal, which combines the advantages of various single seal forms and improves the overall sealing performance.
Outer floating disc peripheral sealing system
Toothed bladder type primary seal
The tooth-shaped bladder type primary seal uses polyurethane foam elastic element as the filler, and is wrapped with tooth-shaped sealing material in contact with the medium. It is fixed on the edge plate of the outer floating plate by pressing plate, locating plate and fastener, and filled in the annular space between the tank wall and the outer floating plate. The tooth-shaped bladder type primary seal has large contact area and good sealing effect, and is widely used in various steel outer floating plate tanks.
Tubular liquid-filled primary seal
Tube-type liquid-filled primary sealing toothed wear-resistant sling wraps the liquid-filled hose, which is fixed on the outer floating plate and installed along the tank wall with pressing plates and fasteners. The liquid-filled hose is filled with an appropriate amount of liquid to fill the annular space of the tank, forming a seal with good compensation performance and large sealing contact surface. It is a new type of primary seal.
Secondary seal of outer floating plate
The secondary seal of the outer floating disc is a set of sealing device added on the basis of the primary seal. It is composed of polymer materials and metal materials. The polymer materials include rubber sliding plates and gas barrier films processed from special rubber, and the metal materials include pressure plates made of galvanized sheet (or stainless steel sheet) and various pressure plates. Effectively prevent rainwater from entering into the tank, and form a double seal with the primary seal to strengthen the effect of inhibiting oil and gas volatilization and protect the primary seal.
