CA2431599C - Oil tank protective coating - Google Patents

Abstract

A process is used for applying, a corrosion-resistant, polymer based polyurethane or epoxy coating as an interior or exterior liner for a receptacle, The coating iseffective for leak mitigation or prevention. A particular application of the process is a polyurethane coating for the exterior underside of residential and industrial steel oil tanks which tend to corrode and eventually fail.

Description

OIL TANK HAVING PROTECTIVE COATING
The present invention relates generally to the field of coatings and particularly to the field of coatings for residential and industrial oil tanks and mitigation or prevention of leaks therein.
Steel oil tanks can deteriorate over time from internal corrosion thus eventually weakening and perforating the steel and allowing oil to leak out of the tank. A coating may be applied to the interior or exterior of such a tank or other containment vessel so as to reduce the risks of the tank leaking.
The following patents are considered to be of general relevance to the subject matter of the present invention and are not believed to anticipate or render the present invention obvious, whether taken alone or in any combination.
United States Patent No. 6,387,538 (Lee et al.) entitled "Surface-Treated Steel Sheet for Fuel Tanks and Method of Fabricating Same" describes a multi-layered surface treatment of steel used for fuel tanks. In one embodiment the layer includes a cald rolled steel sheet, zinc plating layer, chromate film, and resin coating layer. The resin coating layer may be urethane and is purposed to inhibit corrosion. The patent teaches the use of a resin to prevent corrosion on both the tank's outer and inner surfaces.
United States Patent No. 3,505,769 (Miron et al.) entitled "Corrosion-Resistant Storage Tank and Method of Forming" discloses a corrosion resistant tank for corrosive fluids with a bottom consisting essentially of polymerized thermosetting resin reinforced with fibrous glass. An example of such corrosive fluid is fuel ail. The resin is applied to the interior of the tank. The design serves to prevent escape of vapour from the tank, withstand internal pressure owing to both vapour pressure and the weight of the liquid above a particular point within the tank, and to minimize the effect of corrosive reactions both interior and exterior of the tank.
United States Patent No. 4,826,644 (Lindquist et al.) entitled "Method of Entombment of Tanks in Concrete" describes a containment method for fuel in a storage tank.
Polyurethane is disposed between the steel tank and an outermost concrete layer to provide a fluid tight seal. A spaced layer is also present between the steel and the polyurethane which is -1_ preferably polystyrene which is purposed to control temperature and vapour pressure within the tank. The particular type of storage tank contemplated is an underground storage tank.
Canadian Patent Application No. 2,212,160 (Ketch et al.) entitled "Protective Polymeric Film for Lamination to Metal" describes a protective polymeric film which can be laminated to metal substrates including metal containers such as aerosol cans and which provides protection against scratches, solvents and corrosion. The film comprises three layers, a scratch resistant layer, a compressible layer which may be a polyurethane, and an adhesive layer which also may be polyurethane. The entire film is from 0.01 to 0.51 mm.
Residential oil tank leaks presently result in cost to the insurance industry and to homeowners in the form of cleanup costs. A standard steel residential oil tank is a strong durable tank with one major problem, namely that it tends to leak oil to the environment when it fails from internal corrosion. The present invention may allow tanks to perform leak free for an extended period at least until the tank's expiration date.
According to an aspect of the present invention there is provided a receptacle for storage of liquid, the receptacle having a corrosion-resistant, polymer based polyurethane or epoxy coating as an interior or exterior liner, the coating being effective for leak mitigation or prevention.
The receptacle may be a metal tank, and may be a cold roll steel residential or industrial oil tank. The coating may be a spray grade polyurethane including SP-1868 TUFF
TANK. The coating may be applied to the underside of the receptacle and partially up the sides thereof and/or to corrosion prone areas of the receptacle. The coating may be a minimum thickness of 40 mils preferably between approximately 40 to 60 mils. The coating may directly contact the surface of the receptacle. A top coat of a vinyl/acrylic polymer coating, including SP-5891 AcrylicT"~, may be applied at least over the coating and possibly over the entire receptacle.
According to another aspect of the present invention there is provided the use of a corrosion-resistant, polymer based polyurethane or epoxy coating as an interior or exterior liner for a liquid storage container, the coating being effective for leak mitigation or prevention. The coating may be applied as an exterior coating on a cold roll steel residential or industrial oil

-2-tank for mitigating or preventing leaks due to corrosion of the steel. The coating may be applied directly to the receptacle surface. The coating may be applied in a single pass.
According to another aspect of the present invention there is provided a receptacle for storage of a liquid having a coating thereon, the coating comprising a fibreglass layer as an interior or exterior liner and being effective for leak mitigation or prevention. The receptacle may be a metal tank including a cold roll steel residential or industrial oil tank.
According to another aspect of the present invention there is provided the use of a corrosion-resistant fibreglass coating as an interior or exterior liner for a liquid storage receptacle, the coating being effective for leak mitigation or prevention. The coating may be applied as an exterior coating on a cold roll steel residential or industrial oil tank for mitigating or preventing leaks due to corrosion of the steel.
According to another aspect of the present invention there is provided a process for leak-proofing a liquid storage receptacle comprising the steps of a) spray applying a corrosion-resistant, polymer based polyurethane or epoxy coating to a portion of a clean dry surface of the receptacle at an ambient substrate temperature of at least 5 degrees (F) above the dew point to a maximum of 212 degrees (F) to a minimum thickness of 40 mils; and b) airless spray applying, at least over the coating of step a), a vinyl/acrylic polymer coating to a thickness of approximately 7 or 8 mils wet to achieve approximately 4 to 5 mils DFT (dry film thickness).
Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawing, in which:
Figure 1 is a perspective view of a residential oil tank showing an exterior coating thereon, representing an embodiment of the present invention.
Figure 2 is a cross-section of a residential oil tank showing an exterior coating thereon, representing an embodiment of the present invention.
Figure 3 is a cross-section of a residential oil tank showing an interior coating thereon, representing an embodiment of the present invention.

-3-With reference to Figure 1, a residential oil tank 1 is shown, having a coating 2 on an underside thereof. Feet 3 are shown for receiving legs to provide support for the tank above a ground or floor surface. In Figure 2, the tank is shown in cross-section and the top coat 3 is also illustrated as will be described below.
Figure 3 is an example of a tank with a coating 2a on the inside surface.
Again, a top coat 3 is illustrated.
Generally, a polymer based, polyurethane, or epoxy coating is disclosed for any number of containment vessels as an inner or outer lining. The present invention in a preferred form includes a thick, polymer based, polyurethane or epoxy coating applied to the exterior bottom area of a steel oil tank to mitigate or prevent leaks caused by corrosion of the steel.
Prevention of leaks serves to protect against the potential harmful and costly effects of oil leaks.
Although the preferred form of the present invention is that of exterior coatings, interior coating is also contemplated. Such primary containment is possible where the coating is applied to protect the bottom area of the inside of the tank where water created by condensation and acid properties of corrosion microbes can attack the steel. As a primary protection system the water is prevented from contacting the steel surface and prevents corrosive conditions from causing pinholes in the steel due to corrosion. If the steel is attacked from the exterior and creates a hole, the cohesive properties of the coating respond as a durable liner to prevent the tank from leaking. In experiments, coatings were applied to the internal surfaces of an oil tank that are affected by the corrosion cell. This area, in the tank of this experiment, was 8 inches wide for the entire length of 60 inches on the bottom of the tank and two inches up the sides for the side outlet tank. Several applications were performed to develop a system to prepare the surface and apply the urethane coating to the interior surface but it was proven that an application of such, would have quality issues and would prove to be to an expensive process. The research and development process exposed the coating to 120 days of a brine solution consisting of salt, water and hydrochloric acid. This brine solution is many times stronger than the sludge that forms in an oil tank and proved to have no effect on the coating.
The results from the testing proved that using this polymer based coating on the bottom of the oil tanks would prevent any possibility of corrosion damage to the internal bottom of the tank.

-4-A more cost-effective environmentally friendly solution for these leaky tanks uses a standard steel tank with a polymer-based coating on the exterior of the tank to achieve secondary containment. In this process the coating protects the exterior surface from corrosion but does not prevent the internal to be attacked by corrosion. If the corrosion creates a pinhole through the steel to the protective coating, the adhesive and cohesive properties of the coating respond as a durable liner that is bonded to the tank and prevents the likelihood of an oil spill. Such tanks also have excellent structural strength. Adhesion of the polymer to the steel is important and improves the production time for surface preparation, coating application, and inspection thus leading to a more cost effective product.
According to a preferred embodiment of the present invention there is provided a polyurethane exterior liner bonded to the bottom of the tank. This exterior liner is a chemical and corrosion resistant product that retains the oil in the tank. It is a secondary containment bonded to a primary container.
The polymer-based coating may be applied during the manufacturing process to newly manufactured oil tanks which prevents the rusting that results in costly, destructive oil leaks.
The coating may alternatively be applied to used tanks. The coating is chemical and corrosion resistant which serves to protect a standard steel tank from leaks caused by corrosion- induced failure. 100% solid urethane coating used in today's heavy industrial protective coating market is one preferred material. A good coating should have acceptable corrosion resistance, chemical resistance, flexibility, impact resistance and high build capability.
A preferred material for use as the coating is that of SP-1868 TUFF TANKT"~
produced by Specialty Polymer Coatings Inc. of Langley B.C. Canada. Table 1 is a product data sheet produced by Specialty Polymer Coatings Inc. of SP-1868 TUFF TANKT"~. As seen in Table 1 this material has excellent adhesion to steel surfaces and provides excellent protection against salt water and other corrosive environments and is recommended for use as internal and external coating of domestic or industrial oil storage tanks.

-5-TABLE 2. PRODUCT DATA SHEET - SP-1868 TUFF-TANK
DESCRIPTION SP-1868 Tuff -Tank is 100% solids (No VOCs) two-component spray grade polyurethane. Although similar to SP-1864~, this formulation has enhanced reverse impact properties and the pot life has been increased to facilitate usage in a continuous in-plant application. SP-1868 Tuff- Tank coating has excellent adhesion to steel surfaces and provides excellent protection against salt water and other corrosive environments.

RECOMMENDED Internal and External Coating of Domestic or Industrial Oil USES Storage Tanks.

APPLICATION Plural Component Airless Spray Equipment:

EQUIPMENT - Graco Hydra-Cat;

- Tip Size: .019 to .027 CLEANING SP-10~ Equipment Wash MATERIALS SP-11~ Tool Cleaner SP-12~ Internal Storage Lubricant SURFACE Steel Substrate : - Self Priming PREPARATION Cleanliness Standards:

- Near White - Sa 2 h (Swedish Scale, ISO 850-1 ) Profile: - 2.5 to 3.5 mils (62 to 87 microns) APPLICATION Minimum: 0C (32F) TEMPERATURE Maximum: 100C (212F) Application at temperatures below 1 C (33F) must be monitored carefully since ice crystals could be present in the surface pores of the steel resulting in poor adhesion and reduced corrosion protection.

_6_ RELATIVE HUMIDITY Normal application requires relative PARAMETERS humidity below 80%. To avoid risk of condensation, application should be performed with MIXING RATIO the temperature of the steel substrate at least 3C (5F) above the dew point. If application must be done at temperatures at or below the dew point, the steel substrate must be preheated.
By Voiume: - 3 Parts Base to 'I Part Activator THINNING None - 100% Solids Coating HANDLING

PROPERTIES:

POT LIFE Base and Activator @ 25C (77F) 100 gm mass 20 minutes Base @ 55C (149F) and Activator @

25C (77F) 100 gm mass 5 minutes TACK FREE TIME 20 mils (0.50 mm) coating thickness @

25C (77F) 2 hours 20 mils (0.50 mm) coating thickness @

DRY HARD TIME

25C (77F) 4 hours Store iri a dry area at temperatures STORAGE /SHELF be~een 5C (41 F) and 40C (104F).

LIFE Keep lids sealed. The Shelf Life of Base is 24 months. The Activator must be checked for crystallization before use.

_7_ RE-COAT INTERVAL 25°C (77°F) ~ Maximum 12 hours If the maximum re-coat window is exceeded, the surface must be brush off blast as per SSPC SP 7 to ensure inter-coat adhesion. Small areas (250 sq.cm. or less) may be sanded using a circular motion with medium grit (80-100) ', carborundum cloth. All dust from sanding or brush off blast must be removed prior to application of coating.
LIQUID PROPERTIES: I BASE ~ ACTIVATOR
~ APPEARANCE I 1f\Ihite I Amber Liquid ~ SOLIDS CONTENT (%) ~ 100 I 100 SPECIFIC GRAVITY
(ASTM D-792) Base and Activator Mixed 1.~5 COVERAGE
(THEORETICAL) Base and Activator Mixed 1629 ft2/U.S.
Gallonlmil 1.0 m2lLitre/mm I FLASH POINT
>150°C (302°F) _g_ PHYSICAL - Shore Durometer "D" (25C177F) (ASTM 60 PROPERTI ES D-2240) - Tensile Adhesion to Steel (PSl) 3000 (25C/77F) (ASTM 4541 Type lV) - Elongation, Percent (25CI77F) (ASTM

25%

D-638) - impact Strength (in-Ib.ljoules) (25CI77F) (ASTM D-256) Reverse 48/5.36 Direct 105/11.73 - Flexibility Mandrel Bend Test (ASTM D-522) Pass '~2 "

- lNater Vapour Transmission (perm-in) (ASTM 1653-93) 0.0029 - Vofume Resistivity (ohm-cm) (AS~'M D-257) 1.0 X 10'a - Dielectric Strength (voItI10~ in) (ASTM D-149) - Cathodic Disbonding (mm) (25C/77F) (CSA 2245.20-98 Clause 12.8) <18 CHEMICAL Nitric Acid, ~ 0% solution No change RESISTANCE (One observed Week Immersion At Ambient Temperature) Sulfuric Acid, ~% solution No change observed No change Acetic Acid, 5% solution observed No change Sodium Hydroxide, 10% solution observed No change Sodium Chloride, ~ 0% solution observed No change Phosphoric Acid, 10% solution observed No change observed Ethylene Glycol No change observed Ammonium Salts No change observed Fuel Oil No change observed Certain advantages afforded by the present invention and/or preferred embodiments thereof include the following. SP1868 Tuff tankTM is a 100% solid urethane that can be applied directly to metal and has no solvent base. The topcoat SP-5891 ACRYLICT"" is a direct-to-metal acrylic that can be applied over SP1868 while it is still wet. The coating is a high build product that can be applied to its maximum thickness in a single application or pass. The additional qualities of the coating such as resistance to abrasion, impact, chemical and corrosion enhance the quality of the product. This process can be used with all sorts of tanks as a leak prevention system.
A variety of coatings could be used in place of SP 1868 TUFF TANKT"". The present invention relates to the concept of applying the coating on the bottom of the tank to stop leaks caused by corrosion. The size, metal thickness or specified areas of application on the tank may be varied and the present invention can be used with a variety of articles of various shapes and sizes and structural material. One possible alternative material to be used as a coating is fibreglass.
This type of coating could be used for all sorts of applications such as containment for steel tanks to concrete tanks, to boats or as exterior or interior liners for a variety of containers or other units. The leak prevention system is not restricted to any one specific coating or tank style.
The coating adhesion must be capable of retaining the pressure exerted by a full tank of oil.
A test was performed with a tank having four holes drilled in the bottom starting from 1/8 to %z inch in diameter. The holes were plugged and then the tank was coated with SP-1868T"~
to a dry film thickness of 1.2 millimeters thick. The tank was then sent back to the tank manufacturer lab for pressure testing where they pressurized the test tank with air up to 44 psi without any coating failure to any one of the holes. During the tank manufacturing process ULC standards require that 5 psi pressure is forced into the tanks for inspections.
The average pressure exerted on a '/2 inch hole on the bottom of a full oil tank would be about 3/4 of a pound. This means that the strength of the coating and the adhesion is about 58 times over the maximum pressure exerted on a %2 inch hole.

Brand new steel tanks have been known to fail in as little as eight months and homeowners have lost the value of their property and are labored with higher insurance premiums and suffer with the problems of oil spill remediation. This standard steel tank enhanced with a protective coating of the present invention compares with expensive high-end tanks that can be found on the market today.
The tank material is usually cold roll steel. This steel is excellent for achieving the surface profile that is recommended for applying the coating. The adhesion or bonding between the two surfaces is very important to the success of containing leaks. The present invention is purposed to achieve improved impact resistance and abrasion resistance without losing good adhesion properties. The tank having a coating according to the present invention may last well beyond the tank's requirements in the field.
The coating selected for the application should be suitable for thin metal application of 12 gauge or 14 gauge and possess good abrasion resistance, chemical resistance, corrosion resistance, impact resistance and high cohesion.
The coating may be applied only where the protection is needed. The coating may be applied to the entire tank but the costs are then higher. A preferred coverage area is anywhere from 12 inches to 18 inches wide across the bottom plus 2 inches up on each side along the entire length of the tank. The coating acts as a plastic retainer that is bonded to the steel by means of achieving a 75 micron profile with a steel shot blaster.
A preferred thickness of the urethane coating (SP 1868 TUFF TANKT"") is a minimum of 1 millimetre or 40 mils. Any thickness between 40 and 60mils is preferred. If the coating is applied thicker than 60 mils there is a chance that the coating will sag and cause thin areas on the topside of the sag.
Comprehensive studies by the oil tank manufacturers have shown that the corrosion affected area in a residential oil tank runs about eight inches wide along the entire bottom of the tank. The application of the SP 1868 urethane is applied 16 inches across the base and along the entire length of the tank including two inches up each end.
Extensive testing has proven that the chemical resistance, corrosion resistance, improved impact resistance, and adhesion is a superior system for this type for application. This coating can withstand environments a thousand time worse than what a tank will experience in it normal day to day operations.
A preferred process of applying a coating to the exterior of a residential oil tank will now be described.
SURFACE PREPARATION
1.0 All surfaces to be coated shall be shot blasted to SSPC-SP10 Near White cleanliness. The resulting roughness profile shall be 75 microns across the bottom and 25 microns over the remaining surface.
1.1 All narrow edges, weld beads, pits and handles shall be blasted the same as specified in 1Ø All surfaces must be clean with no trapped particles when blasting is complete.
1.2 All surfaces to be coated must be completely dry, free of moisture, soil, dust and steel shot. All weld splatter and rough welds must be ground smooth prior to coating.
1.3 All surfaces blasted shall not be exposed long enough to develop flash rusting. In the event that substrate should flashover the surface shall be reblasted to its original condition.
Surface preparation may also be done by acid etch surface preparation.
SURFACE PREPARATION INSPECTION
2.0 All shot blasted surfaces shall be visually inspected to determine that the standard of blast is to specification.
2.1 Testex measurements shall be taken once per blasting shift to ensure that the blast profile achieved is to specification. The testex shall be placed on the daily work sheet for a permanent record of the daily activities.
TAPE AND WRAPPING PROCESS
3.0 The tape and wrapping process will incorporate using duct tape to outline the perimeter of the designated area to be coated. Duct tape shall be firmly pressed to the surface of the tank to prevent the under creep of the coating. This is to produce the solid straight line of coating that is visible after the tank is painted.
3.1 The remaining surface shall be covered with shrink wrap to prevent the over spray created during the urethane application from contacting the blasted substrate.

4.0 SP 1868 Spray grade must be applied to a clean dry surface only. The ambient substrate temperature must be a minimum of 5 degrees (F) above the dew point to a maximum of 212 degrees (F) 4.1 SP 1868 Spray grade shall be applied with a Graco Hydra-Cat plural component spray system that will pressurize, heat, mix and spray the ooating onto the substrate.
4.2 SP 1868 shall be spray applied to a minimum thickness of 40 mils in one single application. Wet film thickness checks shall be continuously performed to ensure close adherence to the thickness specification. If an additional application is required it shall be applied while the proceeding coat is still tacky and not exceeding four hours of the previous coat.
4.3 A minimum of four hours curing above 68 degrees (F) is required prior to handling.
The finished coat shall be generally smooth and free of protuberances or holidays.
There shall be no drips, sags running or discontinuities in the coating appearance.
TAPE AND WRAP REMO~iAL
5.0 The tape and wrap shall be removed only afterthe coating has cured for 30 minutes.
During this removal the coating cannot be allowed to over ours and must be removed before the two hour time limit.
5.1 The duct tape and shrink wrap shall be removed in a controlled method as to ensure that the coating ridge does not get distorted. The tape shall be pulled at a vertical angle to the surface of the tank in a smooth and steady motion. The remover shall be conscious that the tacky over spray does not contact the cleanly blasted surface.
COATING INSPECTION

6.0 After the SP 1868 100% urethane has cured to a tack free condition, dry film thickness readings shall be conducted to ensure that the applicator has applied the _t~._ coating to the specified thickness. The measurements taken shall be recorded on the daily report sheet.
6.1 Holiday detection (spark testing) shall be performed to ensure adequate corrosion protection. Maximum voltage shall be 100 volts for every 25 microns of coating. The average thickness shall be 1000 microns thus the specified voltage shall be 5 ISV.
Notification of any defects shall be reported and repaired within a reasonable time frame.
6.2 Holiday repairs shall be conducted by abrading around the surface of the pin hole.
Solvent swipe the area abraded and apply 40 mils of SP1868 to the prepared area.
The repair shall be allowed to cure until tack free then inspected again with the holiday detector.
LEG INSTALLATION

7.0 Steel legs will be installed by threading 1 '/$ inch pipe into the shoes of the tank for the next process. The installer shall be careful not to disturb the newly applied coating.
APPLICATION OF TOPCOAT

8.0 The top coat will be a two pack corrosion resistant aliphatic polyurethane enamel to ensure a long life of corrosion resistance and good appearance. Plugs will be inserted into the threaded hole prior to the application to ensure that the threads do not become clogged with paint. The Top Coat may be SP-5891 DTM produced by Specialty Polymer Coatings Inc. of Langley B.C. Canada. Table 2, below, is a product data sheet produced by Specialty Polymer Coatings Inc. of SP-5891 DTM.
As seen in Table 1 this material has excellent resistance to wear, impact and aliphatic hydrocarbons.
8.1 The urethane shall be applied with an airless spray system as described in the application procedures forthe coating to be used. The specified application thickness will be 7 to 8 mils wet to achieve 4 to 5 mils DFT.
8.2 The application of the two pack polyurethane will be applied over the SP-1868 after the coating has become touch dry and within a period not more than 12 hours after the SP 1868 has been applied. The two pack urethane shall be applied directly to the prepared metal for the remainder of the tank. The applicator shall pay close attention to ensure that the coating covers hard to reach areas around the handles.

TABLE 2. PRODUCT DATA SHEET - SP-5891 DTM ACRYLIC
DESCRIPTION Specialty Polymer Coatings, Inc.'s SP5891 DTM
Acrylic is a one-component Direct-to-Metal coating based on vinullacrylic polymers. The product contains anti-corrosive pigments to provide excellent corrosion protection. SP-5891 DTM Acr)~lic has excellent resistance to wear, impact and aliphatic hydrocarbons.
RECOMMENDED USES - SP-5891 DTM Acrylic is used as a protective coat on the exterior of above ground domestic or industrial storage tanks, piping and structural steel.
SP5891 DTM Acrylic can be used as a topcoat for SP1868 Tuff-Tank and may be applied wet to wet.
- SP5891 DTM Acrylic is suitable for use in areas where other coatings that contain isocyanates may be prohibited.
ADVANTAGES SP-5891 DTM Acrylic is a high build one-coat system (up to 4-6 mils} that can be applied Direct-to-Metal.
APPLICATION METHOD - Airless Spray, Air -Assisted Airless Spray or Conventional Air Spray - Brush or Roller - Thinning - 5% (if necessary} by volume with SP-15 Solvent.
Guide Only - Amount of thinning affected by temperature.
-t 6-APPLICATION Minimum: 5C (41 F) TEMPERATURE Maximum: 50C (122F) **

** At high temperatures, extra thinning with SP-15 Solvent may be necessary to prevent dry spray.

RECOMMENDED DRY 4 - 6 mils (100 - 150 microns) FILM THICKNESS

APPEARANCE OF Gloss - Egg Shell FINISHED PRODUCT

Colour - Enviro-Green (Other shades available on special orders) SURFACE PREPARATION Steel must be completely dry and free of moisture, oil, grease, salt, dirt and any contaminants.
Surface to be abrasive blast to SSPC SP-6-Commercial Blast or better with a surface profile of 1 -1.5 mils (25 - 37 microns).

TOP COATING OF SP- SP-1868 Tuff-TankT"~ coating may be top coated with 1868 TUFF-TANK SP-5891 DTM AcrylicT"~ while still wet.
The maximum over-coat timing for SP-1868 Tuff-TankT""
is 8 hours at 25C (77F). If the over-coating time is exceeded, roughing of the surface is necessary to ensure inter-coat adhesion.

CLEANING MATERIALS SP-10~ Equipment Wash SP-11~ Tool Cleaner HANDLING PROPERTIES:

DRY TIME (ASTM 1640) @ 25C (77F) - Touch: 1.5 Hours - Hard: 4 Hours LIQUID PROPERTIES
APPEARANCE I Enviro-Green ' VOLUME SOLIDS (%) ~ 39%
COVERAGE 635 (ft.2/U.S. Gallonlmil) (THEORETICAL) SAFETY O Read Materials Safety Data Sheet before use.
NOTES The maximum Dry Senoice Temperature of SP-5891 DTM Acrylic is 50°C (122°F). SP-5891 DTM Acrylic is not resistant to aromatic hydrocarbons or sfrong solvents.
EFFECTIVE DATE I November 10, 2002.
TOPCOAT INSPECTIONS

9.0 The two pack aliphatic polyurethane shall be allowed 24 hours dry time and checked for hardness. The appearance shall be smooth and continuous without runs, sags, pin holes, orange peel and low mils thickness.
9.1 Dry film thickness readings shall be performed and recorded to ensure that the top coat application has been applied to specification.
INSTALLING ULC TAGS

10.0 The ULC tags are stamped with a serial number and year of manufacturing.
The tags shall be inserted into the tag bracket where the sides of the brackets are hammered down over the edge of the tag to hold it into place.
PAC6<AGING AND SHIPPING

11.0 The tanks shall be packed three high onto a pallet and laid on their side with a layer of foam packing between the first tank and the pallet And form packing between each tank to protect the coated surface.
_lg_ 11.1 The stacked tanks shall be strapped together with three wraps of plastic straps to ensure the tanks will not fall over during shipping. The straps shall be pulled tightly against the tanks as to compress the foam layers tightly to prevent the tank from shifting during transport.
Another application method which may be employed is that of acid etching to provide a profile in the steel and the application of a tie coat between the substrate and the coating to achieve a good adhesion to a relatively smooth profile created by the etching.
An adhesion test of SP 1868 on OakiteT~" treated panels was conducted using four treated panels from Granby Tank ( 4 x 4 size.) Two panels were coated with SP 5819 Tie-Coat and allowed to dry to slight surface tack ( approx 30 minutes at 25 °C) before top coating with SP 1868 Tuff Tank.
Two Oakite panels were treated with SP 1868 Tuff Tank. Two pull-off adhesion dollies were glued on to each panel after 4 hours cure at 25 °C and then all panels were allowed to cure for 48 hours at 25 °C before testing. The results of the test are shown in Table 3.
Table 3. Adhesion test.
Panel # #1 #2 #3 #4 Tie-Coat 1.25-1.75 2.0-2.9 milsNo Tie-Coat No Tie-Coat mils SP 1868 35.0 mils 32 mils Av 30.0 mils 34.0 mils Av Av Av Doll #1 3630 si 3017 si 3425 si 3793 si FailureMode*80%C 80 % C 95%G5%C 100%C
20 %A/F 20%A/F

Doll # 2 3017 si 2854 si 3425 si 3262 si Failure Mode80 % C 100 % C 85 %C 15 % 90 % G 10 20 % A/F G % C

*Failure Mode: C = cohesive break of SP 1868 Tuff Tank G = Glue.
A/F = adhesion between Tuff Tank and SP 5819 Tie Coat.
Test Summary : From the above results the overall adhesion with and without Tie -Coat are very good. However the Tie-Coat had a consistent mode of failure which makes it the preferred system. The A/F failure mode reported was not a clean break between the two coatings, there was always a semi-transparent off white color left on the surface indicating some Tuff Tank was still adhering to the tie-coat.

Claims (34)

THE EMBODIMENTS OF THE PRESENT INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A receptacle for storage of liquid, the receptacle having a corrosion-resistant, polymer based polyurethane or epoxy coating as an interior or exterior liner, the coating being effective for leak mitigation or prevention.

2. A receptacle in accordance with claim 1, wherein the receptacle is a metal tank.

3. A receptacle in accordance with claim 1 or 2, wherein the receptacle is a cold roll steel residential or industrial oil tank.

4. A receptacle in accordance with any one of claims 1 to 3, wherein the coating is a spray grade polyurethane or epoxy coating.

5. A receptacle in accordance with any one of claims 1 to 4, wherein the coating is SP-1868 TUFF TANK.TM.,

6. A receptacle in accordance with any one of claims 1 to 5, wherein the coating is applied to an underside of the receptacle and partially up sides thereof.

7. A receptacle in accordance with any one of claims 1 to 6, wherein the coating is applied to corrosion prone areas of the receptacle.

8. A receptacle in accordance with any one of claims 1 to 6, wherein the coating is applied to all metallic surfaces of the receptacle.

9. A receptacle in accordance with any one of claims 1 to 8, wherein the coating has a minimum thickness of 40 mils.

10. A receptacle in accordance with any one of claims 1 to 8, wherein the coating has a thickness of between approximately 40 to 60 mils.

11. A receptacle in accordance with any one of claims 1 to 10, wherein the coating is directly adhered to a surface of the receptacle.

12. A receptacle in accordance with any one of claims 1 to 11, having a top coat of a vinyl/
acrylic polymer coating.

13. A receptacle in accordance with claim 12, wherein the top coat is SP-5891 Acrylic.TM..

14. Use of a corrosion-resistant, polymer based polyurethane or epoxy coating as an interior or exterior liner for a liquid storage receptacle, said coating being effective for leak mitigation or prevention.

15. The use in accordance with claim 14, wherein the coating is applied as an exterior coating on a cold roll steel residential or industrial oil tank for mitigating or preventing leaks due to corrosion of the steel.

16. The use in accordance with claim 14 or 15, wherein the coating is a spray grade polyurethane or epoxy coating.

17. The use in accordance with any one of claims 14 to 16, wherein the coating is SP-1868 TUFF TANK.TM..

18. The use in accordance with any one of claims 14 to 17, wherein the coating is applied to an underside of the receptacle and partially up sides thereof.

19. The use in accordance with any one of claims 14 to 17, wherein the coating is applied to all metallic surfaces of the receptacle.

20. The use in accordance with any one of claims 14 to 18, wherein the coating is applied to corrosion prone areas of the receptacle.

21. The use in accordance with any one of claims 14 to 20, wherein the coating is applied directly to a receptacle surface.

22. The use in accordance with any one of claims 14 to 21, wherein a top coat of a vinyl/acrylic polymer coating is applied over the coating, or over the coating and some or all of the remaining receptacle surface.

23. The use in accordance with claim 22, wherein the top coat is SP-5891 Acrylic.TM.

24. The use in accordance with any one of claims 14 to 23, wherein the coating is applied in a single pass.

25. A receptacle for storage of a liquid having a coating thereon, the coating comprising a fibreglass layer as an interior or exterior liner and being effective for leak mitigation or prevention.

26. A receptacle in accordance with claim 25, wherein the receptacle is a metal tank.

27. A receptacle in accordance with claim 24 or 25, wherein the receptacle is a cold roll steel residential or industrial oil tank.

28. Use of a corrosion-resistant fibreglass coating as an interior or exterior liner for a liquid storage receptacle, the coating being effective for leak mitigation or prevention.

29. The use in accordance with claim 28, wherein the coating is applied as an exterior coating on a cold roll steel residential or industrial oil tank for mitigating or preventing leaks due to corrosion of the steel.

30. A process for leak-proofing a liquid storage receptacle comprising the steps of:
a) spray applying a corrosion-resistant, polymer based polyurethane or epoxy coating to a portion susceptible to corrosion of a clean dry surface of the receptacle at an ambient substrate temperature of at least 5 degrees (F) above the dew point to a maximum of 212 degrees (F) to a minimum thickness of 40 mils; and b) airless spray applying, over the coating of step a) and some or all of the remaining clean dry surface, a vinyl/acrylic polymer coating to a thickness of approximately 7 or 8 mils wet to achieve approximately 4 to 5 mils dry film thickness.

31. A process in accordance with claim 30, wherein the coating of a) is SP-TANK.TM..

32. A process in accordance with claim 31, wherein the vinyl/acrylic polymer coating is SP-5891 DTM Acrylic.TM..

33. A process in accordance with any one of claims 30 to 32, wherein the coating of step (a) is applied over pre-existing coatings on the receptacle surface.

34. A process in accordance with any one of claims 30 to 32, wherein the receptacle surface is stripped of pre-existing coatings and the coating of step (a) is applied to the stripped receptacle surface.