FIELD

The present disclosure relates to corner profiles and/or corner reinforcement for liners and linings that are suitable for use with tanks and other storage/containment vessels, such as process tanks, immersion tanks, indoor or outdoor containment pits, gravity feed conduits (e.g., concrete trench, canal, or drain, etc.) for transferring or conveying liquid, grain storage tanks or containers (e.g., dielectric or electrically non-conductive liners for grain storage, etc.), etc. The present disclosure also relates to tanks and other storage/containment vessels including liners and linings with corner profiles and/or corner reinforcement. Additionally, the present disclosure relates to methods, systems, and apparatus for providing corner profiles and/or corner reinforcement for liners and linings.

BACKGROUND

This section provides background information related to the present disclosure which is not necessarily prior art.

Process tanks are commonly used to store contents such as acids, coating or plating materials (e.g., chromium, black oxide, etc.) and other chemicals. These tanks relate to immobile types that may be installed above or below the ground, but also for the transportable types that are part of the over-the-road semi-trailers. The tanks may also be used on or in marine vessels as well as railroad cars. The size of the tank is not material, but the larger process tanks typically hold 1,000 gallons or more. Moreover, process tanks are particularly adaptable for tanks intended for highly corrosive liquids, but also may be used in conjunction with other pourable materials such as grain and pellets.

Many process tanks are steel, which, over a period of time, may become corroded as a result of the corrosive fluids stored therein or because of the rusting action of the exterior elements (e.g., ground water, rain, etc.). If the material stored in such tanks is corrosive, the corrosive material can contact the tank. In this situation, the life expectancy of the tank is relatively short and thus it becomes not only extremely expensive for replacement, but also highly dangerous for people and the environment. Furthermore, there is danger in the event that the tanks leak or are ruptured, or somehow fail to retain the contents and leak the contents into the ground (if the tanks are subterranean). Above-the-ground storage tanks or over-the-road type tanks may also present a danger along highways and to the passing public. Accordingly, many process tanks utilize a protective liner or protective lining.

One common type of liner is a pre-fabricated “drop-in” liner. While drop-in liners may be machine welded (radio frequency welding is commonly used for these liners), the drop-in liners have disadvantages with respect to a bonded lining. During the drop-in process, air is entrapped behind the liner, which can condense and cause the mild steel tank to rust. Furthermore, during the drop-in process, creases form in the liner sheet, which stresses the liner material and leads to premature cracking and failure. Additionally, a tank part may catch the crease or protruding wrinkle and cause tear damage to the drop-in liner. When the drop-in liner develops a leak, solution seeps behind the liner pushing it off the walls or bottom and causing the liner itself to move into the process tank area resulting in operational problems. After the solution is behind the drop-in liner, the liner is very difficult to repair as it may be almost impossible to find the source of the leak. Replacing the drop-in liner creates significant downtime, especially for electroplating tanks with auxiliary equipment affixed to the tank rim, e.g., ventilation hoods, piping, anode and cathode bars, heat exchangers and probes, level control devices, etc.

Also commonly used are bonded-to-metal linings. This type of lining uses manual “flat strip” welds on the butted side panels and “corner strip” welds on the vertical joining walls and side to bottom joints.

In current lining procedures, installation personnel prepare the interior of the surface of the tank10(FIG. 1) to receive the lining14. This preparation includes surface blasting the interior of the tank10and subsequent cleaning of the interior of the tank10.

With respect to the lining14, the installer cuts sheets of lining16(FIG. 2) from a roll of lining material. At the installation site, the installer applies an adhesive to the now cut sheets of lining16. Then, the installer manually applies the lining sheets16to the interior of the tank10. As known in the art, heat may be applied to the lining sheets16to assist in applying the lining sheets16to the tank wall. Tanks typically have protrusions such as tank welds that bond the tank walls to the tank bottom. These tank welds protrude into the interior of the tank10. Even careful placement of the sheets16will result in gaps between the sheets16that are placed over the protruding welds. In other words, the sheets16will lay over the protrusions further enhancing the gaps between the sheets16.

As shown inFIG. 2, current cutting procedures result in uneven and/or rough edges18for each lining sheet16. When the installer bonds the sheets16to the tank10and next to each other, the rough edges18of the sheets16do not evenly match thus resulting in gaps20forming between the sheets16. When the installer cuts relatively smooth edges18, installation gaps20still exist between the adjacent sheets16due to the difficult and labor intensive installation process (FIG. 3). For example, the sheets16are heavy and difficult to manage as the installer handles the sheets16while positioned within the tight constraints of the process tank10, which is a confined space with elevated temperatures. As such, the installer may apply adjacent sheets16in a non-uniform layout and/or with a distance between them, thereby further enhancing the gaps20between the edges18of the sheets16. Applying the sheets16at a corner of the tank10is particularly troublesome due to the space and angle considerations of the corner of the tank10.

After applying the lining sheets16, the installer welds a weld strip22(known as a “cap over flat strip weld” or a “cap over corner strip weld”) along the interface between a pair of adjacent sheets16(FIGS. 2 and 3). The installer manually welds the weld strip22to the adjacent lining sheets16. The welder used by the installer in this process heats the weld strip22to the sheets16. Similar to the application of the sheets16, hand welding the weld strips22is a labor-intensive process. Maintaining consistent pressure with the welder is difficult since the touch of the installer applies the pressure. Additionally, it is difficult with the hand welder to maintain a constant distance between the welding nozzle and the welding strip. Furthermore, the weld strip may melt faster than the sheet16such that the welding process must be done with special care. The sheets16must be heated to a glossy state, yet the weld strip or the sheets16cannot be charred as that would result in a failed weld.

The installer typically welds from the top of the lining sheet16to the bottom. As the process tank10may have a height such as twelve feet, this height causes starts and stops as opposed to continuous welds with tightly controlled temperatures and consistency in both pressure and timing. In addition, welding occurs within the tight constraints of the process tank10such that the installer is unable to provide a constant weld over any length of time. The tedious and laborious process for strip welding not only applies to welding strips to corner sheets, but it also applies to welding strips for sheets applied to the walls of the process tank10.

The human element of welding the strips22leads to weak welds (inconsistency of temperature, pressure and timing—the critical variables for welds) and leads to voids or “pinholes”24within the weld that bonds the weld strip22to the sheets16(FIG. 4). The pinholes24shown inFIG. 4are exaggerated for purposes of clarity. Although the welded strip22may pass a “spark test” commonly used in the art, these pinholes24lead to problems for the process tank10. Furthermore, the corner weld that bonds the sides and the bottom of the process tank10further exaggerates the effects of the gaps20and the pinholes24because the sheet16must position over the corner weld of the process tank10. This corner weld or other obstacle leaves a void between the sheet16and the tank weld.

When the tank10is filled with fluid12(FIG. 1) such as an acid, the pressure of the fluid forces the fluid through the pinholes24. Consequently, the fluid forces through the gaps20and disperses between the lining14and the tank10. This leaked fluid then corrosively attacks the tank wall. Additionally, this leaked fluid may also corrosively attack the bond or adhesive interface between the lining14and the tank wall resulting in the lining14pulling away from the tank wall. Accordingly, the gaps20and the pinholes24between the lining sheets16lead to adverse and dangerous conditions. When the installer repairs the welded strip, the heat from the repair welder draws the leaked fluid toward the interface of the adjacent sheets16, wherein this fluid further attacks the tank wall positioned behind the repaired weld strip.

