Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60P—VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS
  • B60P3/00—Vehicles adapted to transport, to carry or to comprise special loads or objects
  • B60P3/22—Tank vehicles
  • B60P3/2205—Constructional features
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60P—VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS
  • B60P3/00—Vehicles adapted to transport, to carry or to comprise special loads or objects
  • B60P3/22—Tank vehicles
  • B60P3/24—Tank vehicles compartmented
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D88/00—Large containers
  • B65D88/02—Large containers rigid
  • B65D88/06—Large containers rigid cylindrical
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D90/00—Component parts, details or accessories for large containers
  • B65D90/02—Wall construction
  • B65D90/022—Laminated structures

Definitions

• the present invention relates to containers for transporting highly corrosive fluids, and more particularly, the present invention relates to fluorocarbon polymer-lined transport containers and methods of fabricating the same.
• the present invention relates to container units comprising a plurality of relatively small diameter structurally strong tanks, each having a seamless liner of a chemically resistant thermoplastic polymer, ganged together in parallel relation on a support such as a truck chassis or pallet.
• container units are designed to transport chemicals of all types, including highly cor ⁇ rosive fluids, and products such as food, where the purity of the products must be retained in transit, and the like.
• the tanks are easily cleaned, and are much lighter in weight than commonly used stainless steel tanks.
• tanks have been lined with fluorocarbon polymer sheet material, the marginal edges of the sheets being overlapped and welded together to form a continuous liner.
• One of the problems of such liners, which are relatively expensive to install, is that such welding weakens the liner in the zone of the overlap, where the liners tend to crack and tear.
• the tanks are generally not completely filled with liquid in order to provide headspace for expansion, the liquid sloshes back and forth in the tank in response to starting and stopping of the vehicle on which it is mounted. This fluid motion causes a vacuum to be applied to the liner, and the vaccuia tends to tear the liner from the inside of the shell, as a result of which the shell is subject to attack by the acid.
• a primary object of the present invention is to provide improved containers for transporting various types of chemicals, including corrosive liquids, bulk food stuffs of all types, and other cargoes where maintenance of purity of the product in transport is essential.
• Another object of the present invention is to provide a novel transport tank unit composed of a plurality of tanks, each having a chemically resistant seamless thermoplastic liner which is firmly secured within an outer shell formed of fiberglass-reinforced thermosetting resin which provides each tank with the necessary structural rigidity and strength.
• Still another object of this invention is to provide transport tank units comprising a plurality of tanks which are not subject to attack by chemical vapors, even if such vapors are capable to permeating the liner material.
• the present invention provides a transport tank unit particularly suited for hauling chemicals of all types, including highly corrosive liquids.
• the tank unit comprises a support and a plurality of tanks mounted in parallel relation on the support.
• Each tank includes a rigid outer shell of fiberglass-reinforced thermosetting resin, and a seamless tubular liner of chemically resistant thermoplastic material, such as a copolymer of polytetrafluoroethylene and hexafluoropropylene, securely fastened to the inner surface of the shell.
• the liner and shell are joined by means of an intermediate' layer in the form of a glass fiber fabric, which may be woven, knit, braided, etc.
• the exterior surface of the seamless thermoplastic liner is rendered in a molten state and caused to expand into the interstices of the glass fabric which surrounds the liner as a tight-fitting sleeve.
• a permanent mechanical bond is achieved between the liner and fabric.
• a layer of con ⁇ tinuous fibers, preferably of glass, impregnated with a thermosetting resin, such as polyester resin, is applied to the outer surface of the glass fabric-reinforced liner and the resin is cured, whereby the outer layer is bonded to the glass fabric.
• This outer layer provides each tank with the desired structural rigidity and strength.
• Each tank may be provided with a pressure equalizer tube con ⁇ necting upper portions of the opposite ends of the tank to control vacuum induced by fluid sloshing back and forth in the tank.
• FIG. 1 is a side elevational view of one embodiment of a tank transport unit embodying the present invention
• FIG. 2 is an enlarged rear end view taken on line 2-2 of FIG. 1;
• FIG. 3 is a side elevational view of another embodiment of a tank transport unit
• FIG. 4 is a rear end view of the -unit illustrated in FIG. 3;
• FIG. 5 is a greatly enlarged fragmentary sectional view illustrating one preferred tank structure;
• FIG. 6 is a modified version of one of the tanks of the tank transport unit illustrated in FIG. 1, which tank is provided with an equalizer tube for equalizing pressures at the ends of the tank.
• FIG. 1 illustrates a tank transport unit 10 fabricated in accordance with the present invention.
• the transport unit 10 comprises a trailer chassis 11 which supports a series of tanks 12 to 15 extending in spaced parallel relation lengthwise of the chassis 11.
• the tanks 12 to 15 are fastened together and to the chassis 11 by any one of various means, such as yoke assemblies 16, 17, and 18.
• a pair of upper tanks 12 and 15 are superimposed vertically above a lower pair of tanks 13 and 14. It should be understood, however, that although four tanks are illustrated, six or more tanks can be similarly mounted, depending upon the overall capacity desired for the transport unit.
• odd or even numbers of tanks may be arranged in the manner illustrated in FIGS.
• tanks 21, 22, and 23 are mounted in staggered relation on a support pallet 24.
• This embodiment provides a transport tank or container unit 25 which is particularly suited for shipment in oceangoing vessels as containerized cargo.
• Each of the tanks, such as the tank 12, is designed to carry corrosive liquids, such as acid or caustic solutions, or food products, the non-contamination of which must be maintained in transit, and the like.
• one of the problems encountered in transporting corrosive liquids in relatively large diameter transport tanks resides in the proclivity- for the lining of the tank to crack due to flexure (if fabricated of glass) or to separate from the inside surface of the tank (if fabricated from chemically resistant plastic) due to vacuum applied to the inside of the liner by sudden stopping or acceleration of the vehicle on which the tank is mounted.
• Another problem is the permeation of the liner by corrosive vapors, which attack the adhesive bond between the liner and metal shell, as well as the shell itself.
• the tank 12 comprises a rigid tubular shell 12a having a pair of radially outwardly extending annular flanges 12b at opposite ends, only a portion of one such flange being shown in FIG. 5.
• the flange members and tubular shell are fabricated separately according to the methods hereinafter described, and the ⁇ flanges have a circular opening just slightly larger than the outside diameter of the tank shell so as to be able to receive the end of the shell and be ad ⁇ hesively bonded thereto.
• a circular cover plate 12c is mounted across opposite ends of the tank 12 and is secured to the flanges 12b by bolts 12d.
• the cover plate 12c has an outlet fitting 12e and a vent 12f (see FIG. 2), both of which preferably have a liner or are made of corrosion- resistant material, e.g. a fluoropolymer.
• the inner periphery of the shell 12a is covered by a liner 19 of chemically-resistant thermoplastic material which, in the present instance, is preferably a copolymer of polytetra- fluoroethylene and hexafluoropropylene.
• a layer 21 of the same material is also provided on the inside surface of the cover plate 12c.
• the liner 19 is preferably an extruded seamless tube of cylindrical cross-section.
• the tank shell preferably has an inside diameter of about two feet or somewhat less, and the length of the tank may vary, depending upon the intended use. In the embodiment of FIG. 1, the length is about thirty feet, providing a length to diameter ratio of about 15:1.
• the liner 19 is extruded so as to have a wall thickness of 100 mils or somewhat greater.
• each tank may be provided with means for equalizing the pressure in the headspace above the liquid.
• an equalizer tube 30 (FIG. 6) is provided to connect fit ⁇ tings 31 and 32 located at the top positions of the ends of tank 12.
• the equalizer tube 30 communicates with the headspace above the liquid in the tank at opposite ends of the tank 12 when the tank is level, but functions, when the tank is carrying fluid and is subjected to sudden • axial movement, to afford the flow of fluid into the tube 30, such as illustrated in FIG. 6, when the tank 12 is subjected to lefward acceleration.
• a vent 33 is provided in the equalizer tube 30; and the tube 30, fittings 31 and 32, and vent preferably have the same construction as the tanks themselves so as to be resistant to corrosive chemicals.
• the tanks for the transport tank units of this invention preferably are made according to the process described in copending application Serial No. 06/200,263 filed October 24, 1980 for "Process for Forming Laminated Pipe.”
• a sleeve of fabric which may be seamless, is applied about a seamless tube of chemically-resistant thermoplastic polymer.
• a plug is inserted into each end of the liner to seal the interior of the liner from the surrounding atmosphere.
• One such plug has a pressure relief valve to prevent pressure within the liner from exceeding a given value upon heating the liner and sleeve to elevated temperatures.
• the liner with surrounding sleeve is then placed on a pair of spaced parallel rolls, which extend the length of the liner, and are designed to support and rotate the liner and sleeve about the axis of the liner.
• Heat is applied to an arcuate portion of the outer surface of the liner through the sleeve while the liner and sleeve are rotated.
• the heat causes the polymer on the external surface of the liner to melt, and also causes volatilization of a portion of the liquid within the liner so that the pressure within the liner exceeds the pressure of the atmosphere external of the liner.
• the liner expands radially, whereby the molten surface thereof enters the interstices of the surrounding fabric.
• the liner into the fabric also results to a large degree at the nip between the liner and sleeve and the supporting rolls due to the weight of the liner and sleeve and liquid it contains.
• the liner is then cooled to solidify the molten polymer, whereby a permanent mechanical bond is formed between the liner and sleeve.
• the supporting shell is then applied to the exterior of the sleeve.
• This shell may be formed by passing bundles of continuous filaments, e.g. glass filaments, through a bath of a liquid thermosetting resin, such as a polyester resin, and then wrapping the resin- impregnated fibers about the sleeve. This can be accom ⁇ plished by placing the liner and sleeve on a mandrel and rotating same.
• the outer shell is thus built up by applying layer after layer of resin-impregnated fibers until the shell has a thickness sufficient to provide the ultimate tank with the desired rigidity and strength, e.g. from about 1.5 to about 12.7 millimeters. Thereafter, the resulting composition is allowed to stand at room temperature to cure the thermosetting resin.
• the liner 19 may be formed of any thermoplastic material which has those properties, particularly resistance to chemical attack by the material, required to maintain the purity of the material to be transported.
• thermoplastic polymers are poloylefins, such as polyethylene and polypropylene, and fluorinated polymers, the latter being particularly preferred for liners for tank units designed to transport hightly corrosive chemicals.
• fluoropolymers are polyvinylidene fluoride and melt-fabricatable perhalofluoroethylene copolymers , which include chlorotrifluoroethylene and tetrafluoro- ethylene copolymerized with fluoroolefins such as hexa- fluoropropylene (FEP), or with perfluoroalkyl vinyl ether, or with nonfluorinated monomers such as alkylenes, e.g. ethylene, including the tetrafluoroethylene/ethylen binary polymers and terpolymers, copolymers of tetrafluoroethylene and hexafluoropropylene (FEP) being especially useful.
• fluoroolefins such as hexa- fluoropropylene (FEP)
• FEP hexa- fluoropropylene
• nonfluorinated monomers such as alkylenes, e.g. ethylene, including the tetra
• FEP copolymers such as those containing 5-20% by weight of hexafluoropropylene and 80-95% by weight of tetrafluoro- ethylene are particularly preferred as the liner material for the tanks of the transport tank units of this invention.
• the wall thickness of the liner may vary, but generally will be on the order of about 100 mils or some ⁇ what greater.
• the fabric sleeve which surrounds the liner it can be woven, knit, or braided from any fiber which does not undergo degradation at the elevated temperatures used in laminating the liner to the sleeve.
• Suitable fibers include natural or synthetic fibers, such as glass fibers, metal fibers, graphite fibers, ceramic fibers, asbestos fibers, ara id fibers, and the like. Because of the desirable physical properties, such as chemical inertness, strength, etc., glass fibers are preferred.
• the sleeve may be applied to the liner in the form of a woven fabric which is helically wrapped about the liner.
• the sleeve may be a seamless braid or tubular knit which Is applied over the liner.
• the end covers or caps for the tanks can be fabricated by taking a section of the tubular liner to which a fabric sleeve has been mechanically bonded by the process described in the above-identified copending application, and slitting it lengthwise to obtain a flat sheet.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Health & Medical Sciences (AREA)
• Public Health (AREA)
• Transportation (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=22948784

Family Applications (1)

Country Status (5)

Families Citing this family (5)

Family Cites Families (10)

• 1982
  • 1982-03-24 DE DE19823239738 patent/DE3239738T1/de not_active Withdrawn
  • 1982-03-24 GB GB08232940A patent/GB2108438A/en not_active Withdrawn
  • 1982-03-24 EP EP19820901334 patent/EP0075008A4/de not_active Withdrawn
  • 1982-03-24 WO PCT/US1982/000362 patent/WO1982003374A1/en not_active Ceased
  • 1982-03-24 JP JP57501390A patent/JPS58500476A/ja active Pending

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