AWWA steel pipe coating and lining standards are based on the maximum service temperature of potable water. Consult the epoxy manufacturer for conditions. (Revision of ANSI/AWWA C). AWWA Standard. West Quincy Avenue . Denver, CO T compwalsoihassre.cf c 91 awwa standard for fusion bonded epoxy coating for - c 91 awwa standard pdfsdocuments2 com - awwa c standard pdf free download here awwa to awwa c standard and be either the conforming to awwa c or c
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American Water Works Association ANSI/AWWA C (Revision of ANSI/ AWWA C) R AWWA STANDARD FOR LIQUID-EPOXY COATING SYSTEMS. Awwa c steel pipe - 15 ebooks - free download Awwa c steel pipe download on Liquid-Epoxy Coating: AWWA C While the. Awwa C Liquid-epoxy Coatings and Linings for Steel Water Pipe and Fittings [Not Available] on compwalsoihassre.cf *FREE* shipping on qualifying offers.
Differences between an interior coating and a lining The McGraw-Hill Dictionary of Scientific and Technical Terms generally defines a coating as any material that will form a continuous film over a surface. A lining is described as a material used to protect inner surfaces as of tunnels, pipe, or process equipment. However, an interior coating may suggest a thinner applied material compared to a lining which is often a thicker applied material. Therefore, an interior coating can be applied as a lining, and a lining is a type of coating.
Forty-eight U. The specification establishes the minimum testing, marking, and in-plant Quality Control QC requirements for epoxy coatings to be used on the internal surfaces of potable water pipe.
Specifications written to protect owner assets often include requirements of material conformance to American Water Works Association AWWA standards for coating systems to be used on the interior of water transmission pipe. Of these standards, 14 deal with coatings and linings that are available for the protection of metallic pipe, and five are applicable to linings of water transmission pipe.
All AWWA steel pipe coating standards are based on the maximum service temperature of potable water. The purpose of the standards is to provide the minimum requirements for coating systems for the interior of steel water pipelines, including material, application, inspection, testing, handling, and packaging requirements.
This differs from U. The toxicological evaluation criteria are based on lifetime exposure to the concentration of contaminants in drinking water. NSF toxicologists perform a formulation review of each water contact material to determine any possible ingredients, contaminants or reaction by-products that may potentially leach from the material into drinking water. This formulation review then determines the battery of chemical analyses that will be performed on a particular material.
The testing of the finished product is performed by exposing the product to pH 5 and pH 10 waters and analyzing for regulated metals such as antimony, arsenic, barium, cadmium, chromium including chromium VI , copper, lead, mercury, selenium, thallium and nickel. The product is also exposed to pH 8 water which is tested for organic chemical contaminants that could leach out into the water.
Common interior coating types There are five common types of interior coating or lining material for steel potable water transmission pipe. The list includes coal tar enamel, cement mortar, liquid-applied epoxy, fusion bonded epoxy FBE , and polyurethane PU.
Each of these lining technologies have inherent advantages and limitations.
Additionally, each interior coating type has installation requirements for surface preparation and application. The fillers and coal add flexibility and strength to the product.
The strong molecular arrangement provides CTE with the characteristics necessary to produce pipeline corrosion protection.
These can be summarized as follows: Water resistant — negligible water absorption and vapor transmission. Stable chemical structure — resistant to acid and alkali Resistant to cathodic disbonding — most pipelines are protected using impressed current or sacrificial metal anodes; CTE is resistant to the alkaline environment formed at exposed metal surfaces.
Adhesion — forms a strong permanent bond to the steel surface. Resistant to attack by bacteria, marine organisms and root penetration. Shortages in the availability of qualified applicators, increasing costs, challenges of worker exposure during application, concerns of leachability of trace contaminants into the potable water, and effects on human health have contributed to the decline in usage of coal tar enamel, specifically in the United States.
Application considerations: Surface preparation is critical to CTE performance, and application of the CTE requires an understanding of its limitations during cold-weather and high humidity. Coal tar enamels generally require heating and continuous agitation of the material during application, and the enamel is required to be maintained moisture and dirt free during application. Cement Mortar — Cement mortar linings provide long-term protection at a low cost, and remain one of the standard linings for potable water pipes.
A major benefit with cement mortar is the ease of application. The mixing and application of mortar is straight forward, leading to low risks in application. Cement mortar linings provide active protection of the steel pipe by creating a stable hydroxide film at the steel-mortar interface.
The corrosion protection is referred to as active, because it provides protection even where there are discontinuities in the lining.
Cement mortar linings have a track record of conveying water for extended periods to required water quality standards, and currently meets all applicable standards throughout the world. Cement mortar does not support microbiological growth. The actual cement application of cement-mortar linings is performed by pumping or pouring a high slump cement mixture onto a slowly rotating length of pipe.
The rotating speed is then increased, creating centrifugal forces that level out the wet mortar to a uniform thickness. Continued spinning removes the excess water and compacts the mixture to a dense and solid surface.
After the spinning process, the lining is cured either by moist air at ambient temperature or by an accelerated process using steam. Like concrete, cement-mortar linings can develop drying cracks, but these cracks will self-heal when the lining is wet.
Wetting the cement lining also causes the lining to swell, which increases strength and adherence. Cement-mortar linings can add significant stiffness for resistance to deflection forces. The strength of the mortar lining may be added to the strength of the steel when calculating stiffness.
It is applied in a cost-efficient manner to combat corrosion and other factors that reduce the life of a piping system, as well as to reduce the leaching of harmful metals such as lead or excessive copper into the drinking water supply.
Regulatory Process and Approvals The process of approving the epoxy lining material and its application falls under three primary categories: health, physical properties and code compliance. Originally adopted as IGC , several updates have brought the Interim Guide Criteria to its current version, IGC , which covers applications of epoxy lining to both metallic and non-metallic piping systems.
This standard covers minimum standards for the manufacture and performance of epoxy barrier coatings mechanically applied to the interior surfaces of piping systems.
This criteria was intended to establish the minimum criteria necessary for the use of a proprietary, mechanically mixed, blended, epoxy barrier coating that is mechanically applied to the interior of pressurized water pipes. Figure 2a. The inside of a copper pipe that has pinholes.
Basics of Pipe Restoration Various approaches to pipe restoration are used in the business. A more detailed step-by-step description follows. Also see Figure 1.
Evaluate local and on-site water quality. Determine the extent of present damage to the wall thickness of the piping and overall integrity of the piping system; identify leaks. Develop corrosion control proposal, including options for pipe and fitting replacement. Deliver all equipment and supplies. Complete mechanical isolation of the piping system.
Setup all hosing and equipment. Adapt isolated areas of piping system so they can be connected to the restoration equipment. Drain the isolated section of water.
Using moisture- and oil-free hot compressed air, flush the section to assure water is removed. Dry the section using heated air. Length of drying sequence is determined by pipe type, diameter, length complexity, location and degree of corrosion contained within the piping system, if any.
Complete inspections to assure a dry system. Figure 2b. A rehabilitated copper pipe with an epoxy lining. Step Four - Sanding Profile the dried pipes using an abrasive agent, which is introduced into the piping system by use of the pre-dried compressed air.
The abraded pipe, when viewed without magnification, must be free of all visible oil, grease, dirt, mill scale, and rust; and be prepared to a minimum NACE 3 Standard. Visually inspect the pipe to assure proper cleaning and profiling standards are achieved. Air flushing sequence the piping section to remove any residuals left in the piping system. Check the piping system for leaks. Inject epoxy into the piping system using heated compressed air.
Examine pipe segments to assure appropriate coating coverage. Reconnect water system and water supply. Complete system checks, test and evaluate the integrity of the piping system, and pressure test. Evaluate water flow and quality, and complete pipe labeling.
Figures 2a, 2b and 2c show the before-and-after effects of this epoxy-lining treatment on pipe. Figure 2a shows the inside of a copper pipe that has pinholes, while Figure 2b shows a rehabilitated copper pipe with an epoxy lining.
Figure 2c shows a heavily-corroded pipe made of galvanized steel. Figure 2c. A heavily-corroded pipe made of galvanized steel. Epoxy Lining Performance Long-term durability of an applied epoxy lining depends on various factors related to resin formulation and contractor performance, including: physical and chemical properties of the epoxy material sensitivity of the epoxy material, in terms of these properties, to mix ratios thoroughness of surface preparation of pipe interiors prior to lining quality of site application, including the stability of the mix ratio and curing condition sensitivity of the epoxy material to application conditions In view of these factors and their various potential combinations, it is apparent that the behavior of lining systems could differ greatly even within an individual rehabilitation, making it difficult to assess an open-ended statement of long-term durability.
However, long-term durability of epoxy lining can be approached from a number of fronts, including: examination of known testing data, examination of coated samples of previous applications and the documented history of epoxy coating performance. Figure 3. Examination of Known Testing Data — Adhesion Correlation to Longevity Corrosion control by the use of protective barrier coatings has progressed to a scientific level. This allows engineers and utilities to make reliable predictions and selections regarding specific corrosive conditions and coatings, and to use a selected coating to prevent corrosion and reduce the leaching of harmful metals into the water supply from metallic piping systems.An affidavit from the valve manufacturer showing the following: 1.
Cement-mortar linings can add significant stiffness for resistance to deflection forces.
Affidavit of compliance if required Sec. Case study. Burton, Baker Coupling Company Inc. The pipe is 35 years old. The mixing and application of mortar is straight forward, leading to low risks in application. The exposed threads shall be coated as provided in Sec. The coatings products typically are coal tar enamel, cement mortar, liquid-applied epoxy, fusion bonded epoxy FBE , or polyurethane PU and all are initially required to have a toxicological evaluation of chemical concentrations.
Also see Figure 1.
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