Glass Fiber Reinforced Resin Tank With Particular Joint Structure

This invention relates generally to glass fiber reinforced resin storage tanks, and more particularly, to the joint between two tank halves.

Glass fiber reinforced resin tanks are typically made of isophthalic resin, chopped glass strands, and a filler such as sand. External ribs of woven glass roving, glass filament windings, and resin are usually provided. Generally, a resin-rich liner is also provided consisting of about a 20 mil thickness of resin with a surface mat and an 80 mil thickness of resin and chopped glass strands. When a tank is to be used to store corrosive liquids which attack isophthalic resin, polyester or vinylester resin is used as the liner resin. The tanks are made of two halves generally disclosed in U.S. Pat. No. 3,700,512, joined by an external lay-up of resin and a plurality of interleaved layers of woven glass roving and chopped strand mat. Prior to my invention, tanks for corrosive liquid service were also provided at the joint with an internal lay-up of interleaved layers of woven glass roving and chopped strand mat impregnated with polyester or vinylester resin. For application of this internal lay-up, one of the tank halves had to be provided with a manway, which added considerably to the cost of the tank.

In accordance with the invention, a joint structure is provided in a tank for corrosive liquid service, wherein no internal lay-up is required, and therefore no manway is required, but the isophthalic resin portion of the tank at the joint is nevertheless shielded from corrosive liquids, by a corrosion resistant flexible gasket or sealing member made of a suitable resin such as polyethylene or polyvinyl.

The invention is more fully explained hereinafter with reference to the accompanying drawings wherein:

FIG. 1 is a view of two generally cylindrical tank halves and a central gasket, prior to assembly in accordance with the invention;

FIG. 2 is an enlarged fragmentary sectional view taken generally along the line 2--2 of FIG. 1.

FIG. 3 is a view similar to FIG. 2, but showing the items partially assembled;

FIG. 4 is a view similar to FIG. 2, but showing the tank halves fully assembled with the gasket and also showing an external lay-up; and

FIG. 5 is a view similar to FIG. 4, but showing an alternative embodiment of the invention.

With reference to the drawings, FIG. 1 shows two tank halves 10 and a gasket 11 just prior to being assembled in accordance with the invention. The normal external ribs on the tank halves 10 are omitted. The tank halves 10 are shown with tapered sidewalls, as though made on a tapered mandrel such as shown in U.S. Pat. No. 3,700,512, but they could just as well be truly cylindrical and made on a collapsible mandrel such as shown in U.S. Pat. No. 4,233,020.

FIG. 2 shows that the gasket 11 is generally H-shaped in cross section. The gasket material may be polyethylene, polyvinyl, polytetrafluoroethylene, or other suitable material resistant to chemicals that might be stored in the tank. The tank halves 10 include polyester or vinylester resin in a liner 10a and isophthalic resin in a structural wall 10b. Glass fiber reinforcement and sand filler (see "Background Art") are not shown. The open ends of the tank halves 10 are coated with an adhesive 12 and the gasket 11 is pressed on the coated open ends, as progressively shown in FIGS. 3 and 4. An external lay-up 14 of isophthalic resin is then applied to hold the tanks together, the glass fiber mat reinforcement in the lay-up (see "Background Art") being only partially shown.

The gasket 11 shields the isophthalic resin, in the structural wall 10b at the open ends of the tank halves 10, from corrosive fluid in the tank.

FIG. 5 shows an alternative embodiment of the invention wherein two tank halves 20 include polyester or vinylester resin liners 20a and isophthalic resin structural walls 20b, glass fiber reinforcement and sand filler not being shown. A chemically resistant gasket 21 is provided at the inside of the joint. The gasket 21 is formed around an inner metallic band 22 having spaced threaded studs 23 projecting outwardly therefrom at regular intervals all around the peripheries of the tank halves 20. An outer metallic band 24 slotted to receive the studs 23 is initially held in place by washers 25 and nuts 26. Initially the nuts 26 are loose enough for assembly of the gasket 21, band 22, studs 23, band 24, washers 25 and nuts 26 with the tank halves 20 from the outside of the tank formed thereby. Thereafter, the nuts 26 are tightened on the studs 23 to firmly clamp the gasket 21 in place at the inside of the joint and protect the isophthalic resin in the structural walls 20b at the open ends of the tank halves 20 from later attack by corrosive liquids stored in the tank. An external lay-up 27 of isophthalic resin and interleaved layers of woven glass roving and chopped strand mat is then applied over the joint to secure the tank halves 10 together, the glass fiber reinforcement in the lay-up 27 being only partially shown.

In both embodiments, the gasket protects the isophthalic resin at the open ends of the tank halves and in the external lay-up from attack by corrosive liquids stored in the tank, and no manway is required in the tank to permit work inside the tank.