Pitch coatings

Because of it s cancerogenic potential, pitch coatings are to longer used in Middle-and Northeurope. 

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Pech, n. pitch asphalt, -art,/, kind or variety of pitch or asphalt, pechartig, a. pitchy, bituminous. Pech-bleude,/. pitchblende, -draht, m. pitched thread, shoemaker s thread, -eisenerz, n. pitchy iron ore (applied to pitticite, triplite, and a compact variety of limonite). pecheln, v.i. smell pitchy extract pitch. — v.t. extract pitch from pitch, coatjwith pitch, pechen, v.t. pitch, coat with pitch. 

Figure 2. Manufacturing steps and coproducts in producing coal tar pitch coating base.

Epoxy cresol novolac epoxy-pitch coatings, marine paints Cresylic acid Epsom salt mfg. 

Coal tar pitch coatings n. Most plastics plated today are finished with a copper/nickel/ chrome electroplate, but many other finishes are possible, such as bright brass, antique brass, satin nickel, silver, black chrome, and gold. The actual composition of the electroplate is designed for a particular application of the electroplate. 

Nickel- 40% nickel- Antifriction 40% Pitch Coated Coated Molybdenum... 

Paint is one of the most common and widely used materials in home and building constmction and decoration (see Building materials). Its broad use comes from its abiHty to provide not only improved appearance and decoration but also protection of a substrate to which it is appHed. Evidence of the historical uses of paint goes back over 25,000 years to cave paintings found in Europe. The Bible describes pitch being used to coat and protect Noah s Ark. Over 10,000 years ago in the Middle East, various minerals and metals such as lime, siHca, copper and iron oxides, and chalk were mixed and reacted to produce many colors. Resins from plant sap and casein were also used. Over 2000 years ago in Asia, resins refined from insect secretions and sap from trees were used to make clear lacquers and varnishes (2). 

Paper. Paper is the principal apphcation for talc throughout the world. It is used as a filler, a coating pigment, and a process aid in pulping and de-inking for pitch and stickies control. As a paper filler, talc is used because of its platiness, softness, whiteness, abiUty to space Ti02, and ink receptivity. 

Coal-tar pitch for other uses is similarly subject to a few national specifications but mainly sold to users specifications. Pitch intended for roofing, dampproofing, and waterproofing is the subject of ASTM specification D450 and Federal specification R-P-381 hot-appHed tar-based coatings (pipeline enamels) are the subject of BSS 4164/1987, amended in 1988, and, in the United States, of American Water Works Association (AWWA) specification C203. 

Goal Tar. In roofing, coal tar is used as mopping bitumen in between 15 and 20% of the BUR roofs installed. Coal-tar pitch and asphalt are considered incompatible and should not be mixed. If mixed, an oily exudate is formed that plasticizes the bitumen, and the mixture remains soft and does not weather well. For this reason, if coal tar is used in BUR systems the felts must be coal-tar saturated. There has been some success using asphalt-coated fiber-glass mat felts with coal-tar pitch. However, this has only been done for a limited number of years so the actual compatibiHty is not fully known. 

Enzymes in Pulp and Paper Production. Enzyme-modified starch has been used for adhesives to strengthen paper base and for surface coating. Developments since the late 1980s of further uses of enzymes in papermaking include pitch control and bleach boosting, (see Paper Pulp). 

A tank with a fixed cover of plain carbon steel for storing 60°C warm, softened boiler feed water that had a tar-pitch epoxy resin coating showed pits up to 2.5 mm deep after 10 years of service without cathodic protection. Two separate protection systems were built into the tank because the water level varied as a result of service conditions. A ring anode attached to plastic supports was installed near the bottom of the tank and was connected to a potential-controlled protection rectifier. The side walls were protected by three vertical anodes with fixed adjustable protection current equipment. 

Figure 20-14 shows the protection of a gravel filter in the treatment of raw water. The 200-m internal surface was coated with 300 jlm of tar-pitch epoxy resin. Long-term experiments indicated that at = -0.83 V, no cathodic blisters were formed, but were formed at more negative potentials (see Section 5.2.1.4). TiPt anodes 400 and 1100 mm in length, 12 mm in diameter, and with an active surface of 0.11 m were installed [29]. 

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