Coal Tar and its Distillation
Lone Star coal tar coatings are products of carefully chosen coal tars having low carbon values, carefully blended with mineral fillers, carbon plasticizers and selected grades of heavy oils and solvents distilled from coal tar.

The coal tars used are products of the destructive distillation of chosen grades of coal having low ash and good coking quality which produces a selective low carbon tar.

Coal tar is the primary condensation product resulting from the carbonization of coal for making coke or gas; the tar is produced as a by-product.

By placing coal into a chamber and heating it out of contact with air, the coal is decomposed into volatile products and into a non - volatile residue, coke. The volatile products are made up of condensable materials and non - condensable gases.

As the temperature rises in the oven, the coal starts to melt and tiny bubbles from in this tar - like substance. Gases and vapors begin to evolve and escape from the oven through the ascension pipe into the collecting main. The gas is drawn from the coke ovens through the suction main. To help the tar flow on its course as well as to cool the gases, ammonia liquor is sprayed into the gas; this starts the condensation of the water and tar from the gas. The ammonia liquor flows into the liquor collecting tank and is re-circulated through the flushing system.

The raw tar as obtained from the coke ovens is processed or distilled to produce a variety of products. Usually the first step in processing coal tar is to subject it to a primary distillation to produce several fractions of cuts. In general, at least two cuts are made. These are often referred to as chemical oil and creosote oil. The material remaining after the removal of the oil distillates is either pitch or a refined coal tar base.

How far the tar is distilled depends upon the products to be manufactured. If the plant is primarily interested in the distillate oils, the tar is distilled to a hard fuel pitch. On the other hand, if the plant is to make specific residual products, such as road tar, briquetting pitch, or roofing pitch, the distillation is controlled to give an appropriate end point.

The coal tar distillate oils are mixtures of chemical compounds. Most of these compounds fall into one of three groups; hydrocarbons, acids, and bases. The hydrocarbons present in coal-tar distillates belong to the aromatic series; typical coal-tar hydrocarbons are benzene, naphthalene and anthracene. The acidic compounds occurring in coal-tar oils are chiefly phenolic compounds, such as phenol, cresol, xylenols, and naphtols.

What Makes a Good Pipeline Coating?
Following are some desirable characteristics of pipe coating materials.

1. Good electrical insulation.
2. Low moisture absorption.
3. Insolubility in hydrocarbon.
4. Inertness to soil chemicals.
5. Retention of form under soil pressures.
6. Ease of application.
7. Resistance to bacteria.

Selecting the Right Coating Material
Coal tar based enamels, as manufactured by Lone Star Specialties Inc., have the above desirable properties for pipe coating materials. All Lone Star enamels are subjected to laboratory tests to insure the high quality of our protective coatings.

In order to prevent costly coating failures, care should be taken in selecting the proper enamel for your coating system. Some critical points which should be considered in selecting the right Lone Star enamel for any pipeline, are:

1. The highest continuous operating temperature anticipated for the life of the pipeline.
2. Extremes of ambient temperatures anticipated during coating and installation of the pipeline.
3. Soil stress expected.
4. Condition of the backfill, whether smooth and fine of full of rocks, hard clods, etc.
5. Coating system selected (see coating specifications).
6. Cost overall.

Types of Corrosion Encountered on Buried Structures
1. Electrolytic corrosion or electrolysis caused by external sources of direct current generation.
2. Galvanic corrosion, caused by combination of metal with dissolved chemicals in the soil.
3. Biochemical corrosion resulting from microorganisms. The predominant type encountered in water and soil are sulfate reducing bacteria.

Product Stewardship - An Ongoing Commitment
Lone Star Specialties Inc. is dedicated to continuous improvement in our health, safety, and environmental performance in our operations in the U.S. and around the world. As an active participant in the American Chemistry Council's Responsible Care^® initiative, Lone Star Specialties Inc. and its employees are committed to the safe and environmentally sound development, manufacture, distribution, use, and disposal of our products.

Meaningful discussions of the environmental impact of any substance necessarily include three areas of potential concern - air quality, groundwater and surface water protection, and degradation products. The following discussions present evidence that addresses these concerns as they relate to Coal Tar Enamel.

Volatile Organic Compounds (VOCs)
Unlike paints or thermosetting coatings, which require complete release of the solvent (VOC) to cure or to produce a dry film, the thermoplastic nature of Coal Tar Enamel results in the emission of VOCs only when the material is at or near the material's application temperature (475° F). When the enamel cools to below its softening point (220° F), VOC emissions diminish immediately, limiting the duration of VOC emissions during the coating process to about 15 seconds. Fume hoods placed above the heating kettles, the hot Coal Tar Enamel reservoir, and the application equipment capture VOCs, preventing their release into the atmosphere.

Highly Resistant to Leaching
Potential contamination of groundwater through the process of leaching is a legitimate concern that must be taken seriously. However, because of Coal Tar Enamel's chemical inertness and resistance to moisture penetration and microbial attack there is only minimal leaching to groundwater and / or surface water.

In-Ground Performance Shows Excellent Stability Over Time
A sample of a Coal Tar Enamel removed from a pipeline after 27 years of underground service shows no chemical change when compared with a current enamel.

Virtually Impervious to Degradation by Soil Bacteria
Visual inspection of pipelines exposed to a wide range of soil and moisture conditions indicates that properly applied Coal Tar Enamel does not change in any significant way over time.

Laboratory research also confirms that Coal Tar Enamel is not degraded by microbial activity. In a study conducted by the Department of Bacteriology of Kansas State College, researchers discovered that of eight pipeline coating materials tested, only Coal Tar Enamel coatings resisted attack by microbial organisms.

Disposal of Coated Pipe
Coal Tar Enamel and pipes coated with Coal Tar Enamel are not classified as hazardous waste under the Federal Resource Conservation and Recovery Act (RCRA). They are not "listed" wastes, nor are they characteristically hazardous. They are not ignitable, corrosive, reactive nor toxic pursuant to the RCRA criteria. Coal Tar Enamel should be disposed of in accordance with applicable federal, state, and local regulations governing potentially hazardous material.

Please direct your questions and comments to:

Lone Star Specialties, LLC