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Graver Primary Tank Seal (GVR)

Graver Primary Tank Seal (GVR)

The Graver Primary Tank Seal (GVR) can be used on either external floating roofs or internal pan decks. This seal design has been used on tanks of long range of diameters, containing the full range of Crude and Refined products, though it is not generally used with Waxy Crudes. This Tank Seal is designed to enable installation and removal to be carried out from the top of the roof.  The sealing effect between the roof and the tank shell is achieved by the use of special octagonal foam sections. The foam sections are held in position by an internal hold-down plate.

The position of the seal in service i.e. whether it is in contact with the stored product or, held above the stored product is determined by the top bolting position. The hold-down plates and foam sections are encapsulated within a synthetic rubber seal-envelope. The seal envelope is produced from a highly abrasion-resistant coated fabric material to obtain an efficient soft sealing effect.

Weather shields can be installed as illustrated to help reduce the amount of rainwater entering the product, although in recent years it has proved more practically and economical to fit Secondary Seals. When the Graver Foam Seal is product-mounted, i.e. installed with the stored liquid, the sealing efficiency is very high.

For other designs, please head to our Floating Roof Storage Tank Seals page where you can find a range of internal and external tank seals.

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Material Specification:

Two alternative standard envelope materials are generally used:

– Polyurethane Coated Nylon fabric 1.0 mm. thick

– PVC Nitrile elastomer coated Nylon fabric 1.5 or 2mm mm. thick

Service life:

8 – 20 years

Typical weight of complete seal:

20 kg per linear meter

Technical data:

Rim space:

200 mm ± 100 mm (standard)

Aromatic resistance:


Alternative designs and specifications for the Graver Primary Tank Seal (GVR) are available on request

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