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CPVC Pipes - Benefits, Applications and Manufacturing

The boom in the building and construction industry, especially in the housing and commercial building sector has fueled high demand for cost effective, reliable, quality piping and plumbing systems. The choice of piping systems for water utilities is based on overall long term value. They must deliver on factors like long term costs, reliability, versatility, environmental effect, drinking water safety and public health. CPVC Piping systems are the ideal choice, because they are corrosion resistant, durable, smooth, friction free, resistant to bacterial growth and environment friendly, besides a host of other user friendly features.

CPVC Pipes - Manifold Benefits
CPVC Pipes provides several critical advantages like:
· Aesthetic, extremely easy, cost effective to handle and install
CPVC pipes are lightweight, which means low shipping costs along with faster, safer and easier handling, cutting and installation, reducing overall labour costs. Installation is easy by fast cold welding, which is cost effective as no electric/heat source is required. Simple cutter, chamfering tool and CPVC solvent are the only requirements for 100% leak proof jointing.
· Excellent resistance to chemicals, corrosion and abrasion
Does not breakdown ever under harshest water conditions and aggressive service conditions like low pH water, coastal salt air exposure and corrosive soils. It can even be buried directly under concrete slabs with no chemical interaction with concrete.
· Most suitable for carrying drinking water
Retards bacterial growth, which keeps the water quality healthy and very good. They are suitable even for aggressive water pH levels of less than 6.5. CPVC Pipes meant for carrying water should have NSF certification according to ANSI/NSF Standard 61/ program policy 45 (RVCM levels in these pipes are so low as to be undetectable).
· Smooth Internal Surface
Absence of scaling, pitting and leaching leads to smooth and full bore flow and low water noise. It maintains full water carrying capacity because of no scale buildup, avoiding water pressure loss.
· Energy efficient, lower thermal conductivity and insulation cost
It is self insulating with lower thermal conductivity, which greatly reduces heat and therefore requires low insulation levels and cost.
· Excellent performance in tough conditions
These piping systems are tough, rigid and strong with higher pressure bearing capacity. It requires less hangers and supports with minimum offsets/looping.
· High flexibility virtually eliminates water hammers
No water hammer arrestors required under normal conditions as intensity of water hammer is approximately one third that of copper or steel pipe.
· Extremely fire resistant
It has integral flame retarding property with very high Limiting Oxygen Index (LOI) of 60.Thus in air these pipes cannot be the ignition source of fire or support or sustain combustion. It does not increase fire load, has low smoke generation and low flame spread without flaming drips.
· Completely leak proof
The cold welding using CPVC solvent is fast and simple, ensuring leak free installation for the entire life span of the piping system.
· Cost - effective, durable with excellent long term reliability
CPVC pipes have high impact strength and durability. It has low initial cost and lower maintenance costs as against competitive materials.
· Ideal for home plumbing systems
The CPVC system is four times quieter than copper plumbing systems, reducing not only the sound of running water, but also the pounding noise of the water hammer. Its thermoplastic properties provide excellent insulation to virtually eliminate sweating and condensation. It keeps hot water hotter and cold water colder than copper plumbing. There is minimal energy loss through pipe walls, saving money on heating and cooling.
· Less subject to job site thefts as compared to copper or metal pipes.
· Relative price stability over a long time.
· Eco friendly as its production is very energy efficient.

Wide Range of Applications
The excellent qualities of CPVC Pipes make them ideal for
· Hot and cold water distribution in residential, industrial and public projects.
· Carrying drinking water and food liquids
· Water and waste water treatment systems
· Transportation of chemical and hot corrosive fluids, which includes a wide variety of inorganic acids, bases used in chemical processing
· Use in industries like metal finishing, plating and treatment, pulp and paper, air pollution control, mining, aerospace, textile, food and beverage processing, fine sprinkler piping and municipal projects.
· Use as high tension cable protection pipe for electric net improvement (Large dia. CPVC Pipes).
· Solar heating, central heating and radiant floor heating application
Installation and Maintenance of CPVC Pipes

CPVC Pipes and Fittings for potable water applications are available in CTS (Copper Tube Size) ½ through 2 inches and in IPS (Iron Pipe Size) ¼ through 12 inches. CPVC Pipes and Fittings are joined by solvent cementing and CPVC Pipe and other piping materials are connected by use of adapter fittings. These CPVC Pipes are available in wall thickness of either SDR 11(Copper Tube Size), SDR - PR, Schedule 40 or Schedule 80. These pipes and fittings are pressure rated as per ASTM D 2846 for continuous use at 100 psi at 180 degrees F and 400 psi at 73.4 degrees F.
These pipes should be designed with a water flow rate between 5 and 12 feet/sec and while laying them it must be remembered that CPVC Pipes expand and contract more than metallic pipes. Compensation must be provided for expansion and contraction, where they are installed in long, straight lengths, by using offset piping arrangements like loops or bends. Adequate horizontal supports and vertical hangers at appropriate distances must be provided.
For cutting CPVC Pipes fine tooth saws/simple hack-saws/rachet saws or a circular tubing cutter modified with a plastic cutting blade can be used. Care should be taken to avoid cracking of the pipe wall while cutting. For larger diameter pipes power tools are also used at major sites for cutting.
Only CPVC solvent cements which meet the specifications of ASTM F 493 should be used while installing CPVC Pipes. Orange CPVC solvent cement or Purple primers are used when required to facilitate identification and plumbing inspection. Unpigmented CPVC solvent cement/primer, clear cement/primer, one step cements are the other alternatives available for joining purposes.
Teflon Tape can be used with CPVC threaded adapters very effectively. However before using paste or pipe dope, it is better to check with the manufacturer as some of these pastes or dopes may contain solvents incompatible with CPVC.
While connecting CPVC Pipes to gas water heaters, the pipe should not be located within 6" of the heater's flue, to avoid the possibility of damage to the plastic pipes from the flue heat. A flexible appliance connector or metal nipple is used for the connecting. However the hot water from the heater does not affect the CPVC.
CPVC is affected by prolonged exposure to sunlight/ultraviolet radiation. Pigments are added to CPVC to make pipe and fitting resistant to degradation. CPVC pipes can be protected from sunlight /UV radiation by painting them by exterior grade latex paint.
If a section of the piping systems freezes in the cold, it can be thawed by wrapping it with a cloth saturated with hot water and keeping the cloth hot by re-dipping in hot water till required. Alternatively a low wattage heater/blower can used to blow heated air on the frozen area to thaw the pipe.

Important CPVC related Standards

Standard Topic
ANSI/NSF Standard 61 CPVC Pipes-Potable Water Supply This is a critical certification without which CPVC Pipes cannot be used for carrying potable water
ASTM D2840 CPVC Hot Cold Water Distribution Systems
ASTM F439 CPVC Schedule 80 CPVC Fittings
ASTM F441 CPVC Schedule 40 & 80 Pipes
DIN-8079 CPVC Pipes Dimension
DIN-8080 CPVC Pipes General Quality Requirements and Testing
BS 7291/4 CPVC Pipes and Fittings for Hot and Cold Water Distribution
NFT 54-014-1/2 CPVC Pipes and Fittings for Hot and Cold Water Distribution
EN-ISO 15877:2003 Plastics Piping Systems for Hot and Cold Water Installations -Chlorinated Poly Vinyl Chloride (PVC - C)

CPVC Pipe Extrusion
CPVC Pipe processing is done on Twin Screw Pipe Extrusion Plants, where the specially designed screws are triple chrome plated for longer life. Each screw requires special screw geometry to process for optimum shear, as the material is much more heat sensitive as compared to normal PVC. The screws are designed to give good melt homogeneity. The Die Head manufactured from stainless steel offers least resistance and stagnancy to flow path. The flow optimized Spider Die offers uniform melt distribution and very good flow properties throughout the entire flow channel. It also allows optimum dwell time spectrum with targeted temperature guidance of sensitive material to give outstanding pipe quality. It also ensures benefits like low pressure built-up, low melt temperature, even with high throughput. CPVC being highly viscous requires high torque gear box and drive.

Next Generation CPVC Pipe Extrusion Plants
Next Generation CPVC Twin Screw Extrusion Plants are being manufactured for the first time in India, incorporating all critical aspects mentioned above. This plant with Extruder having L/D ratio of 22, has successfully produced CPVC Pipes of excellent quality. Earlier all CPVC Pipe Plants were imported. Downstream Equipments like stainless steel Vacuum Calibrator, Spray Baths for intensive cooling, Haul-off Unit, Cut-off Unit etc., are part of the Line. These plants are capable of manufacturing CPVC pipes which conform to NSF - USA and other stringent International quality standards likes DVGW (Germany), WRAS (U.K.), CSTV (France), KIWA (Netherlands), TSE (Turkey), CSA (Canada) etc.

CPVC Pipes - Increasing Demand
These pipes have been successfully used worldwide for over forty years. It has a proven track record of being used in water distribution applications in houses, apartments, hotels, condominiums and commercial establishments with increasingly developing demand.

Author : Mr. T. K. Chattopadhyay, VP (Works), Kabra Extrusiontechnik Ltd.

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