THERMOPLASTIC PRODUCTS

• 1. What are Benefits of Thermoplastic?

  THERMOPLASTIC BENEFITS

  Since the introduction of PVC in the U.S. during the 1940s, thermoplastic valves, pipes, and fittings have gained broad acceptance. Thermoplastic valves, pipes, and fittings are often the material of choice for systems that were traditionally designed in metal. Unlike metal, thermoplastic valves and piping components have a high resistance to corrosion, will not scale or rust, and will not contaminate sensitive fluids.

  Hayward manufactures products from compounds of PVC, CPVC, natural PP, glass fibre reinforced PP (GFPP), PVDF, Eastar, and Polyetherimide. These materials are non-conductors and, as such, are immune to electrolytic and galvanic corrosion. Equally important, they contain nothing to leach out and contaminate sensitive fluids. Benefits of Hayward thermoplastic valves and process control products include:

  NON TOXIC

  Hayward PVC and CPVC products are suitable for use with potable water and are consistent with National Sanitation Foundation (NSF) and Canadian Standards Association (CSA) requirements. Hayward products are made to ASTM and ANSI standards. See specific products in this catalogue for NSF / ANSI 61 compliance.

  CORROSION RESISTANCE

  Hayward thermoplastic flow control products are immune from corrosion. They are dielectric, meaning they will not support a charge, and will remain free from the ionization and corrosion that occurs with metal valves.

  EXTENDED SERVICE LIFE

  Hayward thermoplastic valves will outlast most metal valves and are not affected by normal weather conditions. They will provide years of maintenance-free service.

  LOW THERMAL CONDUCTIVITY

  Hayward thermoplastic valves have much less thermal conductivity than metal valves so that heat gain or loss is greatly reduced. Pipe insulation is rarely required for thermoplastic piping systems.

  IMPROVED FLOW RATES

  Hayward thermoplastic valves have a high flow coefficient and, as compared to metal, will absolutely not pit, rust or corrode. Their interior walls are moulded with an ultra-smooth finish that will remain smooth throughout the valve’s service life—resulting in a more consistent flow rate over time.

  HIGH TEMPERATURE SERVICE

  Hayward process control products are capable of handling corrosive chemicals at elevated temperatures—up to 250°F with glass fibre reinforced PP (GFPP).

  EASY INSTALLATION

  Hayward thermoplastic valves and process control products are generally 1/3 to 1/2 the weight of similar size and type metal valves. They are simple to install and result in reduced handling, labour, and installation costs.

  CONSERVATION

  Hayward thermoplastic valves and flow controls are energy efficient. The use of natural resources or fuels to produce a Hayward thermoplastic valve is half that of a comparative size metal one.

  ECONOMICS

  When evaluating the economics of Hayward thermoplastic valves and flow control products over metal equals, consider not only the initial cost savings, but the reduced freight, lower installation and maintenance costs, and the extended service life of the valves. Hayward thermoplastic valves and flow controls are a cost-effective alternative to metal piping products.

• 2. Can I substitute a plastic valve for a metal valve?

  Many times people with a metal piping system are attracted to a plastic valve or strainer because of its low cost compared to a stainless steel or bronze one. And also for all of the benefits plastic offers.

  The engineer that designed that system chose metal pipe for a specific application reason so you have to make sure a plastic component will work.

  Plastic components can, however, be used successfully in metal systems. But you have to be aware of several factors that will affect the success of the application. If these factors are not taken into consideration the chance of success is reduced. Applied and installed correctly, however, the valve or strainer will perform as expected.

  First, you have to be sure that the plastic valve or strainer will be used within its temperature and pressure rating. Metal piping is often used because of high operating temperatures. Make sure the temperature/pressure range of the application is within the acceptable range for the plastic product you are considering. Chemical resistance needs to be checked, as well, to ensure that there will not be a problem. Part of your application analysis should include the potential for shock pressure generation, i.e., water hammer in the system that could damage the plastic valve or strainer. Things to look for include a system flow rate of greater than 8 feet per second, quick starting pumps, positive displacement pumps, fast opening or closing actuated valves, and solenoid valves.

  Once it's determined that ALL of the application parameters are OK for the plastic component, it is important to look at how the plastic component is installed.

  Stress on the plastic valve or strainer is the single most important installation factor to consider. Stress can cause immediate damage, or it can build up over time and cause damage later on. There are several ways that this stress can be induced during installation and/or operation.

  One is improper alignment of the plastic component in the metal piping system. If either one has to be forced into position, it is sure to cause problems. A second problem to look out for is oversize face-to-face dimensions of the mating pipe flanges, as well as misalignment of the flanges.

  Thermal expansion can be a problem is some applications. Expansion joints can help compensate for this. Another solution is to install plastic pipe on the inlet and outlet of the valve or strainer to isolate it from the metal pipe.

  Plastic valves and pipeline strainers can be used successfully in many metal piping systems. You just have to be aware of all of the application parameters and how they relate to the plastic component. Not all applications are the same and the recommendations that have been made here may not apply in all cases.

• 3. Plastic vs Metal - Why use thermoplastics?

  In many applications plastic pipe, valves and fittings can be a viable replacement for metal. Recent estimates show that about 25% of the expenditures for metal pipe, valves and fittings could be spent on plastic ones. And, in a lot of those systems, plastic would not just do the job, it would be better.

  We can summarize some of the things that support the fact that in many applications where metal valves are specified, plastic ones would do a better, more cost effective job.

  First and foremost is the corrosion resistance advantage of plastics over metal. This results in some obvious, and not so obvious, benefits. More than just being a low maintenance valve, a plastic one will never jam, stick, or fail because of rust or corrosion.

  Another often overlooked benefit of corrosion resistance is that plastic valves never have to be painted to withstand corrosive environments or harsh climatic conditions. They can be installed and used right out of the box in places where a metal valve would have to be epoxy coated just to survive.

  Another benefit is cost. Not only the cost of the individual valve but the total cost of the installed system. When all costs are considered, including freight, installation and service life, a metal system will in most cases be more expensive.

  The differences can be significant. Exotic metal alloy systems can cost up to 13 times that of a plastic system . Even carbon steel can be almost twice the cost of PVC - depending on the size and complexity of the piping system involved.

  Flow rates are another area where plastic pipe has an advantage. The interior of plastic pipe is smooth and clean and it will stay that way year after year. Metal pipe can rust , corrode and scale - resulting in reduced flow rates and higher pressure drops over time.

  Often, users are not aware of the engineering advances that have been made with regard to plastic piping materials over the last several years. Users of metal pipe, valves, and fittings are often concerned with what they believe to be the mechanical strength limitations of plastics. While it is true that there is no commonly available plastic system that can match the temperature/pressure service levels of metals, significant advances have been made. And plastic piping systems are now commonly available that provide adequate tensile strength or operation up to 200F. Plastic pipe is also available that maintains its pressure bearing capabilities for over 50 years.

• 4. List of materials used in Hayward products

  Hayward Material Description

  PVC (Polyvinyl Chloride)

  Type 1, Grade 1 PVC is the most frequently specified of all plastic valve materials. It has been successfully used for over 40 years in such areas as chemical processing, industrial plating, chilled water, deionized water lines, chemical drainage, DWV piping and irrigation systems. PVC is generally inert to most mineral acids, bases, salts and paraffinic hydrocarbon solutions. PVC is not recommended for use with chlorinated or aromatic hydrocarbons, esters or ketones. PVC possesses excellent fire performance properties. In particular, it will not burn once the source of heat or flame is removed. PVC has excellent weatherability. The PVC used in Hayward products conforms to ASTM D1784. The maximum recommended working temperature of PVC is 140°F. PVC products can be installed using solvent cement, threaded or flanged end connections.

  CPVC (Chlorinated Polyvinyl Chloride)

  CPVC is generally inert to most mineral acids, bases, salts and paraffinic hydrocarbon solutions. CPVC is not recommended for use with chlorinated or aromatic hydrocarbons, esters or ketones. The CPVC used in Hayward products conforms to ASTM D1784-23447B. The maximum working temperature for Hayward products made of CPVC is 190°F at 60 PSI. It has been proven an excellent material for hot corrosive liquids and hot and cold water distribution. CPVC products can be installed using solvent cement, threaded or flanged end connections.

  GFPP (Glass Filled Polypropylene)

  GFPP is a lightweight material with generally high resistance to chemical attack. It has the highest long-term temperature resistance of any material furnished by Hayward. It has been used successfully for years in such areas as chemical processing, industrial plating, chilled water, deionized water lines, chemical drainage, DWV piping and irrigation systems. GFPP is generally inert to most mineral acids, bases, salts and hydrocarbon solutions. The GFPP material used in Hayward products conforms to ASTM D4101. The maximum recommended working temperature of PP is 250°F. GFPP products can be installed using threaded or flanged end connections.

  PP (Polypropylene)

  PP is a member of the polyolefin family of pure hydrocarbon plastics. Even though PP has half the strength of PVC and CPVC, with a design stress of 1,000 PSI at 73°F, it has the most versatile chemical resistance of the thermoplastic materials. PP is superior for concentrated acetic acid or hydroxides. It is also very suitable for milder solutions of most acids, alkalis, salts and many organic chemicals, including solvents. However, PP is not compatible with strong oxidizers, such as the hypochlorites and higher concentrations of sulfuric, nitric and hydrofluoric acids. The PP used in Hayward products conforms to ASTM D4101. The maximum recommended working temperature of PP is 200°F. PP products can be installed using fusion weld, threaded or flanged joinery.

  EASTAR

  Eastar is a clear polyester thermoplastic compound having excellent impact strength, chemical resistance and high clarity. It is used in a variety of applications such as chemical processing and ultra-pure industries.

  PVDF (Polyvinylidene Fluoride)

  PVDF is a thermoplastic polymer with excellent corrosion, chemical and abrasion resistance. It has a good mechanical and thermal stability with a maximum operating temperature of 300°F. The material has a high impact resistance and excellent UV resistance. It is used in applications of high purity and chemical processing.

  EPDM (Ethylene Propylene Diene Monomer)

  EPDM rubber is an elastomer prepared from ethylene and propylene compounds. It has been used continuously to a temperature of 300°F. The material is recommended for water, steam, dilute acids, dilute alkalis and alcohols. EPDM is not recommended for petroleum oils or diester lubricants.

  FPM, FKM or Viton (Fluorocarbon Rubber)

  The fluorocarbon elastomers have a maximum service temperature of 400°F. Fluorocarbon materials are recommended for petroleum oils, diester base lubricants, silicate fluids and greases, halogenated hydrocarbons, acids and vacuum environments. Fluorocarbon materials are not recommended for ketones, amines, anhydrous ammonia, hot hydrofluoric or chlorosulfonic acids.

  Nitrile or Buna-N

  Nitrile, chemically, is a copolymer of butadiene and acrylonitrile. Nitrile maximum service temperature is 275°F. The material is recommended for petroleum oils and fluids, cold water, silicone greases and oils, diester base lubricants and ethylene glycol base fluids. Nitrile is not recommended for halogenated hydrocarbons, nitro hydrocarbons, phosphate ester hydraulic fluids, ketones, strong acids, ozone and automotive brake fluid.

  PTFE (Polytetrafluoroethylene)

  PTFE is chemically stable and virtually unaffected by chemicals, acids, bases and solvents. It has a maximum service temperature of 500°F. PTFE is used as a seat material in several lines of Hayward valves due to its low coefficient of friction and chemical stability.

  ETFE (Ethylene Tetrafluoroethylene)

  ETFE is a fluorocarbon based polymer. It has a very good resistance to solvents and chemicals as well as outdoor weathering. The material has a maximum service temperature of 300°F. It is widely used in the electronics, chemical processing and laboratory testing equipment industries.

• 5. Flow Velocity in Plastic Piping System

  Flow Velocity

  Flow velocity refers to the rate at which the process media flows through a pipe, typically measured in feet per second. While high flow velocities themselves may not pose immediate risks, they can generate shock pressure, also known as water hammer.

  Shock Pressure

  This shock pressure, sometimes reaching hundreds of pounds per square inch, has the potential to inflict severe damage on plastic piping systems, typically rated for pressures around 150 psi. It occurs during sudden actions such as the rapid opening or closing of valves, starting or stopping of pumps, or initiating a pump in an empty system or section.

  Safe Flow Velocity

  Hayward establishes a generally accepted safe flow velocity for plastic piping systems. For systems without fast opening or closing valves, a maximum velocity of 8 feet per second is recommended. However, for systems equipped with such valves (like solenoid or pneumatically actuated valves lacking speed controls), the maximum velocity is typically limited to 5 feet per second. In contrast, metal piping systems are often designed to accommodate flow rates of up to 15 feet per second, significantly higher than those acceptable for plastic systems. This distinction is crucial when considering the installation of plastic components such as valves, strainers, or filters within a metal system.

  Please refer to Velocity in Schedule 80 Plastic Pipe for Water Chart for more information.