Secondary seal (KQS-102)

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Secondary seal (KQS-102)

The secondary sealing system of floating roof oil tank is a set of equipment added on the basis of primary sealing. It is composed of two parts: polymer material and metal material. The polymer material includes rubber sliding sheet and gas barrier film made of special rubber. Metal materials are pressure-bearing plates and various pressure plates made of stainless steel plates (or galvanized plates).

•The secondary seal replaces the traditional rain shield, which is more effective than the rain shield to prevent rainwater from entering the tank. It forms a double seal with the primary seal and protects the primary seal.

• The secondary seal and the primary seal share the bolt holes on the edge of the floating plate, which are installed and fixed with common bolts, and there is no need for fire or welding other devices, which is especially convenient for the transformation of old tanks.

•The pressure-bearing plate is installed along the circumference of the tank to press the rubber sliding sheet and form a seal against the tank wall.

•Compared with the traditional sealing form, the use of secondary sealing has good economic benefits, and the increased investment can be recovered in a shorter period of time.

•The safety is improved. Due to the enhanced sealing, the volatilization of oil and gas is reduced, which can effectively avoid unsafe phenomena such as fire, explosion, etc. struck by lightning.

Relevant technical requirements and acceptance criteria:

•Secondary sealing rubber sliding sheet should have abrasion resistance, oil resistance, aromatic hydrocarbon resistance, aging resistance, weather resistance, high strength, tear resistance and other properties.

• Each rubber sliding piece is about 25 meters, and the connection between each piece is covered by a stainless steel plate.

• The rubber sliding sheet and the tank wall should maintain a good sealing effect, and the contact height with the tank wall should not be less than 60MM.

•The elastic bearing plate presses the tank wall through the rubber sliding sheet to form a seal. When the annular distance is 25MM, the deviation is ±125MM; when the annular distance is 200MM, the deviation is ±100MM, and it can still maintain a good seal. And under normal circumstances, the pressure of the secondary seal on the tank wall is not less than 25KG/extended meter.

•The secondary seal adapts to the temperature range -35℃ to 80℃.

The physical and mechanical properties of the rubber sliding sheet meet the following requirements

Indicator name


Indicator name


Tearing strength MPA ≥


Brittleness temperature ℃≥


Elongation at break% ≥


Abrasion reduction CM3/1.61KM


Permanent deformation at break% ≤


Oil resistance weight change rate ≤


Hardness (Shore A type)


Aging coefficient%≥


Impact elasticity


Ozone resistance (ASTMDII49 50℃, 100PPM ozone environment)

No cracks in any form

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