Secondary Seal – 3 Type

Even well designed and properly maintained, primary seals operating in geometrically accurate tank shells permit significant vapour losses from storage tanks. The basic mechanism of loss is due to the swirling, scouring action of the wind. For vapour loss read cash loss. To counter the cash loss, the independently mounted secondary seal of the compression plate type is unequalled. Besides cutting vapour losses, the secondary seal confers other benefits.


The S-Series range of compression plate type secondary seals from ATECO TANK exploits the spring action obtained when custom designed steel plates are compressed to bridge the annular rim gap from tank roof to shell. The plates may be mounted on horizontal or vertical roof rims and made to accept specific bolt pitching. Adjacent compression plates are overlapped, lightly attached and soft gasketed to permit relative movement while presenting an impervious barrier to the passage of vapour. Plates are clamped to the roof rim by channels. As a variant on the above we can provide an option where a flexible vapour barrier is fitted behind the compression plates and the adjacent plates overlap but are not bolted and gasketed. This option is available on request; however, the former details are in our opinion superior for long life and fire safety. Contact with the tank shell is by an extruded S-Series seal polymer tip attached to the upper edge of the compression plates. The form of the extruded tip will be selected from the two styles described below: 1. Single contact: Suitable for butt welded tank shells. High wear resistance. Positive tank shell contact permits removal of waxy deposits. 2. Double contact: Suitable for butt welded tank shells. Lighter contact with shell. Use where shell distorted or very rough, protruding welds, etc. Can be supplied for benzene service. The above are formulated for long life in exposed, arduous conditions.

Available On Request

Fire Protection: note, we can provide access ports in the compression platesfor halon or BCF injection.

Regulatory Compliance

ATECO Tank Engineering seals meet or exceed the allowable gap requirements set forth by the governmental and regulatory agencies throughout the universe. This design will show superior sealing ability throughout the roof travel; accounting for roof shifting, out of roundness, buckling, and the expansion and contraction requirement of each tank.


ATECO TANK warrants its seals to be free from defects in the material and workmanship for a period of two year. Our liability under any express or implied warranty is limited to the purchaser price of any part found defective. Any seal systems installed by ATECO TANK TECHNOLOGY ENGINEERING SERVICE will have an additional two-year warranty.

Secondary Table Floating Roof Seal Ateco Tank

Key Benefits

1. The secondary seal can be installed while the tank remains in service. since no hot work is required.
2. Independent overlapping support plates, bolted together, produces greater flexing in the seal to accommodate shell deformities.
3. The extruded seal tip is highly abrasion resistant and can be used in most services, resulting in a long life for a long-term maintenance free operation. Alternative seal tips are available for lap welded and riveted tanks.
4. The secondary seal design diverts most rainwater from entering the primary seal area. The standard vapor seal tip fits vertical with the shell. Seals designed with horizontal tips will not flip in unison causing compliance problems and more internal moisture.
5. The secondary seal is designed for a tight fit to prevent vapor loss. Reduced vapour loss resulting in fewer odour problems and offering a cost-effective way of complying with air quality standards.
6. A continuous fabric is installed as a vapor barrier to eliminate possible vapor leakage that occurs in bolted support plate construction. Fabric can be replaced on underside or on the top side of the support plates, depending on inspection requirements and/or exposure issues.
7. Can be used in almost all service conditions up to 100% aromatics.
8. Easy access for visual inspection.
9. Can be paired with all primary seal types.
10. Enhanced safety by reduced free hydrocarbons above the seal.
11. Irregularly shaped tank shells can be accommodated.
12. Includes seal stand-off wheels to protect against malformed tank shells.

Design Features

ATECO Flex Vapor Seal—Follows an established industry design that has a proven record of service life and seal integrity.
Design criteria:
1. Forms a vapor tight seal between the floating roof and tank shell wall meeting the radial variations of ± 5 inches.
2. These can be installed while the tank remains in service. No need hot work is required.
3. Operates independently and without interfering with the primary seal.
4. Designed to accommodate roof movement, shell defects, contraction, and expansion.

Ateco Tank Leaflet
Ateco Tank Sample Project
Ateco Tank Metarial Specification
Ateco Tank Summary Specification
Ateco Tank Typical Drawings
Ateco Tank General Specification