Chlorinated Polyvinyl Chloride
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Chlorinated polyvinyl chloride Production process CPVC is PVC (polyvinyl chloride) that has been chlorinated via a free radical chlorination reaction. This reaction is typically initiated by application of thermal or UV energy utilizing various approaches. In the process, chlorine gas is decomposed into free radical chlorine which is then reacted with PVC in a post-production step, essentially replacing a portion of the hydrogen in the PVC with chlorine. Depending on the method, a varying amount of chlorine is introduced into the polymer allowing for a measured way to fine tune the final properties. The chlorine content may vary from manufacturer to manufacturer; the base can be as low as PVC 56.7% to as high as 74% by mass, although most commercial resins have chlorine content from 63% to 69%. As the chlorine content in CPVC is increased, its glass transition temperature (Tg) increases significantly. Under normal operating conditions, CPVC becomes unstable at 70% mass of chlorine. Various additives are also introduced into the resin in order to make the material processable. These additives may consist of stabilizers, impact modifiers, pigments and lubricants.
Physical properties CPVC shares most of the features and properties of PVC. It is also readily workable, including machining, welding, and forming. Because of its excellent corrosion resistance at elevated temperatures, CPVC is ideally suited for self-supporting constructions where temperatures up to 200 °F (90 °C) are present. The ability to bend, shape, and weld CPVC enables its use in a wide variety of processes and applications. It exhibits fire-retardant properties.
Uses CPVC is a popular engineering material due to its relatively low cost, high glass transition temperature, high heat distortion temperature, chemical inertness, and flame and smoke properties. CPVC is used in a variety of industrial applications where a high functional temperature and resistance to corrosive chemicals are desirable. Besides pipe and fittings, it is used in pumps, valves, strainers, filters, tower packing, and duct, as well as sheet for fabrication into storage tanks, fume scrubbers, large diameter duct, and tank lining.
Pipe In use as plumbing materials, CPVC exhibits comparatively high impact and tensile strength and is non-toxic. In pressurized systems, it can be used with fluids up to 80°C and higher in lowpressure systems. It does require specialized solvent cement for assembly. Depending on local building codes, it can be used in hot and cold water systems as well as hot and cold chemical distribution systems in conditions where metal pipe is not indicated.
Tank and vessels for corrosion resistant applications Tanks and vessels and many corrosion resistant applications are made as per BS4994 using CPVC as an internal thermoplastic corrosion liner.
Comparison to polyvinyl chloride (PVC) Chemical resistance CPVC as well as PVC exhibits a good resistance to acids and bases (depending on the acid/base). There are several cases where it is useful to stay with PVC (e.g. ammonia hydrous solution, hydrofluoric acid). Additionally, it exhibits excellent resistance to salts and aliphatic hydrocarbons. Since the chemical properties of resins may vary according to the amount of chlorination and the types and quantity of additives, manufacturers' recommendations should be consulted before designing material handling systems using CPVC.
Heat resistance CPVC can withstand corrosive water at temperatures greater than PVC, typically 40°C to 50°C (72°F to 90°F) higher, contributing to its popularity as a material for water piping systems in residential as well as commercial construction.
Mechanical properties The principal mechanical difference between CPVC and PVC is that CPVC is significantly more ductile, allowing greater flexure and crush resistance. Additionally, the mechanical strength of CPVC makes it a viable candidate to replace many types of metal pipe in conditions where metal's susceptibility to corrosion limits its use.
Fire properties CPVC is similar to PVC in resistance to fire. It is typically very difficult to ignite and tends to selfextinguish when not in a directly applied flame. Due to its chlorine content, the incineration of CPVC, either in a fire or in an industrial disposal process, can result in the creation of dioxins
Organotin in PVC and CPVC Water Piping Organotin Environmental Programme 29may01 Note: The Organotin Environmental Programme (ORTEP) Association is an industry association dealing with the scientific and technical information on the environmental effects of organotin compounds. 29 May 2001 Ms. Kelly O'Grady, R.N. Lead Environmental Awareness and Detection (L.E.A.D.) 219 Welland St. Pembroke, Ontario Canada K8A 5X5 Dear Ms. O'Grady: The questions you posted recently on the CEHN listserver concerning trace levels of organotins in drinking water and the use of triethyltin in PVC were forwarded to the Organotin Environmental Programme (ORTEP) Association for response. In response to your first question, I believe the study you are referring to is the Draft Environmental Impact Report (EIR) for Chlorinated Polyvinyl Chloride (CPVC) Pipe Use for Potable Water Piping in Residential Buildings. The State of California, Department of Housing and Community Development (HCD) published the report in June 1988. The intent of the EIR was to examine the use of CPVC for interior potable water plumbing in residential buildings in California. As part of the EIR, leachates from CPVC pipe into water were reviewed, including organotins. Organotin compounds are added to CPVC as stabilizers, and there are established standards for organotin leachates from CPVC. The National Sanitation Foundations (NSF's) testing of CPVC pipe and fittings includes tests for organotins. Only CPVC pipe and fittings which meet the ANSI/NSF standards may be certified and sold in California. The Lead Agency, HCD, concluded that pipe leachates would not cause adverse health effects or significant environmental contamination. Consequently, CPVC pipe was approved for use in residential structures in California. Several studies by Health Canada have been published documenting measured concentrations of butyltins in drinking water. In both PVC and CPVC pipe, levels of monobutyltin (MBT) and dibutyltin (DBT) in potable water have been noted in the parts per trillion (ppt) range (Forsyth and Jay, 1997). However, the occurrence of organotin compounds at low concentrations does not suggest any potential risk from drinking water. Sadiki and Williams (1996) studied 45 municipalities and found butyltins in six. The values at most municipalities were below detectable levels (i.e., c0.5 ppt), Sadiki et al. (1996) further studied the organotins measured in tap water of five municipalities and found butyltins in only 1 of 22 homes sampled. In a comprehensive study, Sadiki and Williams (1999) monitored Canadian drinking water distributed through recently installed PVC pipe and found a few positive detections of butyltins (DBT maximum of 53 ppt, MBT maximum of 28.5 ppt), though in most cases the concentrations were not detectable (r0.5 ppt). If one considers drinking water consumption to be two liters per day for an adult and a standard adult body weight to be 60 kg
(WHO 1993; USEPA 1989), a "safe" long-term intake for DBT in water is at least 300 µg/day (as tin) for an individual. On a concentration basis, this translates to 150 µg/L (as tin) as a "safe" long-term concentration in water. Considering the recent monitoring data reported for butyltins in drinking water (Sadiki and Williams 1999), this predicted safe drinking water level is more than 2,800 times higher than the highest concentration of DBT (53 ppt as Sn) recently measured from drinking water in PVC piping. Concerning your second question about whether triethyltin (TET) is used in PVC pipes. The mono- and di-methyltins and octyltins are used mainly in rigid PVC water pipes and fittings in countries where lead stabilizers are not permitted by regulation. Tri-substituted organotin compounds are not used as stabilizers, but some are used primarily as biocide in antifouling paints for ocean going vessels as fungicides for industrial wood protection or as miticides in the agricultural area. There are no industrial uses of triethyltin, and there never have been. Without information concerning the analytical method and quality control measures undertaken, there is no way to determine whether triethyltin was actually present in the sample analyzed or was a laboratory contaminant, or misidentified compound. Because organotin compounds vary considerably with the nature and number of organic groups bonded to the tin atom, the most appropriate methods of organotin analysis are those that are species-specific. The Organotin Environmental Programme (ORTEP) Association is an industry association dealing with the scientific and technical information on the environmental effects of organotin compounds. One of the ways we accomplish this effort is by providing information on our website (www.ortepa.org). We, too, are concerned over allegations of human health issues which is why we are constantly studying our products and support third party certification by organizations like NSF to assure that the use of organotins does not present a threat to human health. You are encouraged to periodically check the ORTEPA website for new updates. Sincerely, Terry Phipps ORTEPA Website Administrator
Summary. The bill will prevent human and environmental exposure to toxins, as well as encourage the recycling of consumer packaging, by phasing out the use of toxic, nonrecyclable PVC packaging. Position and Status. CAW Supports. AB 2505 was held by Senate Appropriations committee. Previously the bill passed out of Sen. E.Q. committee June 23 with a 5-2 vote, passed off the Assembly floor May 28 with a 42-33 vote, passed out of Assembly Appropriations committee May 22 with a 12-5 vote, and passed out of the Asm. Environmental Safety & Toxic Materials committee on April 15 with a 5-2 vote. Description. PVC packaging is a human health and an environmental threat. PVC packaging is toxic in all stages of its lifecycle. PVC production involves large amounts of dangerous chlorine gas, as well as vinyl chloride, a dangerous carcinogen. PVC production is responsible for at least one superfund site in
California and studies have linked it with high cancer rates. In the home, PVC packaging can leach its many toxins through contact with the mouth, and may also shed these particles into the air to be inhaled. These include phthalates, which mimic human hormones and cause abnormal growth and heavy metals such as Lead and Cadmium, which cause brain damage in very small amounts. Once disposed, PVC packaging is not recycled. In fact, PVC packaging is a potent and expensive contaminant in the recycling streams of other, nontoxic plastic packaging, preventing municipalities from recycling more. When landfilled or littered PVC packaging leaches its toxins into the surrounding toxins. Recognizing the dangers these leached toxins pose to wildlife, the California Ocean Protection Council, an organization created by Governor Schwarzenegger, called for the banning of vinyl chloride packaging. AB 2505 would phase out the use of PVC consumer packaging beginning 2013 and concluding 2015.