PAINT STRIPPER, HOT TANK
can be stripped of paint using aqueous chemicals at elevated temperatures.
These chemicals are biodegradable and can be discharged into the sewer system,
thereby virtually eliminating hazardous waste disposal costs. However, certain
hazardous constituents in the paint may contaminate the solution. Check
your local discharge regulations prior to disposing the contaminated solvent.
By using these chemicals in a hot tank, the elevated temperatures increase the stripping action by stripping paint as well as removing grease, oil, rust, and dirt. The parts requiring stripping are immersed into the solution and then agitated to speed up the stripping process. In conjunction with optional equipment such as filtration systems and skimmers, the chemical solution may be recycled and used again.
Most of the aqueous strippers are alkaline in nature. These strippers are different from acid strippers in that acid strippers may attack the metal parts, causing structural weakening (hydrogen embrittlement). In addition, acid strippers normally require a neutralization process after stripping.
Hot tanks can come in a variety of sizes, from 100-gallon to 2,500-gallon capacities. Most hot tanks have an agitating operation to accelerate the stripping. With agitation, the mechanical force of the moving solution keeps washing newly formed emulsions and soaps away from surfaces while applying fresh chemical stripping agents to the newly exposed layers of paint, thereby speeding the entire action. Most hot tanks have a temperature range from 180-210oF.
Unlike the current practice of using a cold tank in conjunction with solvents, no solvent waste streams are generated with the hot tank using biodegradable cleaners. Effluent waste streams associated with the use of hot tank aqueous strippers would be the aqueous solution and sludge products composed of paint, grease, oil, and dirt. The aqueous solution may be recycled, or if it meets local sewer discharge limits, it may be discharged directly into the local sewer system. Any sludge products generated would require proper disposal. However, the use of hot tank/aqueous strippers eliminates exposure to toxic solvent vapors.
The Army, Navy, Marine Corps, and Air Force currently use hot tank/aqueous strippers. They are used to strip paint from a variety of parts, including aircraft components.
The use of a hot tank paint stripper which uses aqueous chemicals in place of solvents will decrease the generation of waste solvent from stripping operations. The decrease in hazardous waste helps facilities meet the requirements of waste reduction under RCRA, 40 CFR 262, Appendix. It may also help facilities reduce their generator status and lessen the number of regulatory requirements (e.g., recordkeeping, reporting, inspections, transportation, accumulation time, emergency prevention and preparedness, emergency response) with which they must comply under RCRA, 40 CFR 262. In addition, since less solvent is used, the possibility that a facility meets any of the reporting thresholds of SARA Title III for solvents (40 CFR 355, 370, and 372; and EO 12856) is decreased. Use of an hot tank paint stripper may decrease the amount of ODSs used at a facility. This will help the facility meet the requirements under 40 CFR 82, Subpart D and Executive Order 12843 requiring federal agencies to maximize the use of safe alternatives to Class I and Class II ozone depleting substances, to the maximum extent practicable. Replacing toluene, 1,1,1-trichloroethane, and methyl ethyl ketone used in cleaning prior to sealing may decrease the likelihood of the facility requiring an air permit under 40 CFR 70 and 71. Switching from a halogenated solvent (e.g., methyl chloroform, methylene chloride, perchloroethylene, carbon tetrachloride, or chloroform) may also decrease the need for a facility to meet the NESHAPs for halogenated solvent cleaning (40 CFR 63). A wastewater discharge permit may be required from the local POTW.
The compliance benefits listed here are only meant to be used as a general guideline and are not meant to be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g. the amount of workload involved.
used in hot tank paint stripping are compatible with most metals; e.g.
iron, steel, magnesium, titanium, and stainless steel. However, the aqueous
solution may darken the metallic surface. Also, some aqueous strippers
cannot be used on metals such as aluminum, zinc, and tin. The product
container label should be consulted for metals compatibility.
|Safety and Health:||
Though biodegradable and environmentally friendly, the majority of the cleaners are corrosive and may cause burns to the skin or other parts of the body with which they come into contact. Proper personal protective equipment (PPE) should be worn. In addition, since the tank will be heated, caution should be exercised to prevent burns. Insulation should be provided for both energy conservation as well as protection from skin burns.
Consult your local industrial health specialist, your local health and safety personnel, and the appropriate MSDS prior to implementing this technology.
following cost elements are reported for Hot Tank Paint Stripping and Cold
Tank Paint Stripping using Trichloroethane.
Annual Operating Cost Comparison for Hot Tank Stripping and Solvent Stripping
Economic Analysis Summary
for Hot Tank Stripping: $7,292
Click Here to view an Active Spreadsheet for this Economic Analysis and Enter Your Own Values.
Approval is controlled locally and should be implemented only after engineering approval has been granted. Major claimant approval is not required.
|Points of Contact:||
Mr. Rudy M. Pontemayor
Ramco Equipment Corporation
Mr. Rudy Pontemayor, Deputy Force Environmental Advisor,
N451, April 1999.