Double Seal – 2 Type

The D-Series double seal from ATECO develops the concept of the compression plate secondary seal into a single unit combining the attributes of primary and secondary seals. Commencing from a new tank, the seal may be fitted without extensive welding of clips or attachments to the roof rim plate as is necessary with many other seals. The double seal is fitted solely to the rim plate projection. On retrofit applications, the double seal safely passes over the remaining clips and fasteners previously welded to the roof rim plates as left behind by most primary seals. This minimises the stripping out work when seals are being upgraded.


The D-Series double seal applies compression plate technology to both the primary and the secondary seal elements. Construction is as shown overleaf and it should be noted that an option using a flexible membrane sheet is available with the double seal.
Shell contact is by an extruded polymer tip attached to the upper edge of the secondary seal elements and to the lower edge of the primary seal elements. The polymer will be selected to meet the needs of the particular application and to withstand abrasion from the tank shell and attack from the weather. It is also suitable for use in MTBE service.
The lower, primary element seal tip is normally just above the stored liquid level. For highly volatile products such as gasoline or for dangerous substances such as benzene we recommend the addition of a skirt of light impervious sheeting which is attached to the lower seal tip and, being weighted, droops into the stored liquid. This has the effect of enhancing the sealing efficiency in areas where seal tip to shell contact is less than perfect due to protruding welds, severe corrosion of shell plates etc.

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.

Double Seal – 3 Type

Double Seal – 3 Type

Key Benefits

1. The double 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 double 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 double 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 double 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