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Have you thought about PVC (polyvinyl chloride) pipe lately? Probably not, since it’s such a mainstream product, garnishing about 62 percent of the global pipe market. Since its introduction into the U.S. market in the early 1950s, PVC pipe has proven to be a durable, dependable and cost-effective choice for applications such as potable water, wastewater, agricultural and industrial applications. It out-performs traditional metallic pipe materials, due to its inherent resistance to corrosion, and functions well in numerous environments.
While not exactly a recent development in PVC pipe, the clear versions are finding more acceptance in a myriad of applications. These applications benefit from the pipe clarity, especially when that property is added to the traditional benefits of PVC.
These benefits are well recognized: excellent corrosion resistance, smooth interior walls for improved flow characteristics, light weight, ease of fabrication and assembly, good pressure ratings and competitive costs.
However, there are opportunities where clarity adds an important dimension to the application. For instance, the ability to visibly monitor chemical processes, mixing, filtration, potable and non-potable water lines provides an extra measure of safety for monitoring the process. It should be noted that potable water applications require that the material be listed with the National Sanitation Foundation (NSF International Standard 61). Certain clear PVC pipe materials also comply with FDA Title 21 requirements for food contact applications. (Check with your clear PVC pipe manufacturer for specific listing information.) This provides an advantage in certain food processing applications where visual monitoring is paramount.
It is also important that clear PVC pipe be produced in both Schedule 40 and Schedule 80 dimensions. This allows optimum performance/cost ratios and provides sufficient wall thickness for most pressure applications. When the clear process is done well, the clarity will not be compromised because of schedule differences. Several applications for clear PVC pipe include: chemical processing (i.e., mixing processes where visual monitoring of processes is critical), site glass, as well as visual leak detection (i.e., dual containment) to name a few.
This article was written by Russ Consentino, CPMR, Plastic Solutions, Inc.
|In This Issue:
The ins and outs of standard fluoroplastic convoluted tubing
Clear PVC offers even more benefits than regular PVC.
Innovative designers are selective with substrates
Sheet applications for chemical containment
The many agricultural applications of PVC panels
Test your knowledge
Plastics Education in Philadelphia
The International Association of Plastics Distribution, founded in 1956, is an international trade association comprised of companies engaged in the distribution and manufacture of plastics materials. Members include plastics distributors, processors, manufacturers, resin manufacturers, manufacturers’ representatives and associated products and services, all of whom are dedicated to the distribution channel. Harris Infosource is IAPD’s e-newsletter marketing partner and makes distribution to the engineering community possible. Harris Infosource offers special IAPD member pricing. Visit www.harrisinfo.com/iapd for more information.
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Designers and fabricators work with a variety of materials including plastics, woods, metals and others. As manufacturers introduce more specialized types of substrates, many designers and fabricators are sticking with a familiar material — a rigid board of moderately expanded polyvinyl chloride (PVC) — for many creative projects.
Material helps “wave the flags”
in school displays
For the display, 3 mm black rigid board of moderately expanded PVC was curved into “waves.” The depth of the curved waves was 8 inches. The flag images were printed onto self-adhesive vinyl and then mounted to the chosen material. Kirtis Kwik Signs of Lynchburg, VA, supplied the flag graphics and installed the display.
Waller chose a rigid display over one made of fabric for several reasons. “The rigid board of moderately expanded PVC provides a lightweight, smooth, hard surface that’s resistant to wear and is easy to clean — all at a very reasonable cost. It also lends an innovative look that was well integrated into the architecture of the lobby itself,” he said. “We worked closely with the principal and staff of the school to communicate their commitment to innovation and technology.”
Waller added, “We’ve done projects for schools across the country with exciting themes and an emphasis on technology. Our work is often part of an interior design renovation that converts old classroom space into new technology training areas for subjects ranging from science to the arts. Our projects have ranged from space shuttle simulators to animal labs and dance studios. With rigid board of moderately expanded plastic, we can offer our school clients the latest advances in technology and cost-effective solutions.”
This article was written by Robert Hendricks, Alcan Composites USA Inc.
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In most industrial facilities that are handling or processing chemicals, there are several concerns for the corrosion engineer within the facility. They must deal with receiving the chemicals, mixing them for their specific use, containing the mixtures, exhausting corrosive fumes, scrubbing the fumes and do it all within the local state and federal guidelines. Needless to say, the corrosive potential is very great. The material choices to handle these applications can vary from the simple commodity products to the high-tech engineering products. The focus of this article will be on the more commodity oriented sheet products involved in bulk containment and handling as well as the equipment that can be made for these products.
A common choice of thermoplastic material is high density polyethylene (HDPE). These large HDPE tanks are usually rotational molded, but they can also be fabricated from sheet. HDPE offers a wide range of chemical resistance, temperatures and mechanical strength for this application. Fiberglass or steel tanks are used in areas that need additional mechanical strength; however, they would be used with an appropriate thermoplastic liner material to handle corrosive chemistry. Liners can be constructed from PVC, CPVC and PP.
Other more expensive polymers such as PVDF, TFE and ECTFE can be used for more extreme conditions. The choice of materials is dependent on the chemicals and temperature for a given tank. PVC is a common choice because it has a broad chemical resistance to acids and bases up to 140°F (60°C) and it is receptive to the adhesives that bond it to the fiberglass or steel tank. CPVC also has good chemical resistance and it can be used up to 180°F (82.2°C). Both PVC and CPVC are not good choices for solvents and some surfactants. PP used as a tank liner needs to have an adhesion promoter in the form of a scrim or mesh that is embedded in the sheet that acts as a tie layer. PP has excellent chemical resistance to acid bases and some organic solvents. PP can be used up to 200°F (93.3°C) but it should not be used with strong oxidizing agents.
Mixing and processing
Some cooler processing vessels, like rinse tanks or anodizing tanks, may use steel tanks with liners as noted above in bulk storage. Many chemical mixtures in a plating facility also have additives, like wetting agents, metal salts and surfactants, which will crystallize on cooler surfaces or find small weld seam leaks.
Proper welding techniques, flanges, secondary containment and leak testing are of the utmost importance. Upon inspection, the weld seams and liquid level line will be the areas susceptible to attack. The pumps that handle these corrosive chemicals often utilize a wide variety of specialized ($$) polymers for the pump bodies, impellers, seals and gaskets.
Exhaust and scrubbing
As we discussed earlier, PVC type I and II, and CPVC all have good chemical resistance, but type II offers the fabricator an additional advantage. Type II PVC can be cold formed, and it is less likely to break during an installation because of the higher impact strength. Type II PVC has slightly lower chemical resistance as a trade-off to the increase in strength. Specially formulated CPVC is also a good choice for higher temperature applications. It also offers the fabricator the ability to match the fabricated parts with the off-the-shelf pipe and fittings for a completely compatible system.
This article was provided by Scranton Products/VyCOM Div./ABP, Inc.
The use of plastic is an important and evolving element in many agricultural applications today.
PVC liner panels can be used to resurface feed bunks, making cleaning easier and decreasing the amount of waste at the same time. The sheets are rust-proof and are resistant to abrasions and scratching. The PVC liners can also be utilized in hog barns, dairy farms, meat packing, sheds, poultry farms, factories, kennels, food processing or workshops. PVC liner panels are lightweight, non-flammable and have an attractive bright white coloring that gives exceptional light reflectance. They are resistant to chemicals and are easy to clean with standard spray equipment, which makes them an excellent application for sanitary purposes, for example, when dealing with the ammonia effects of manure in poultry and hog farms.
In addition to the ease of application of PVC panels, the product is now being recycled after it can no longer be used in farming and agricultural applications. More and more of the agricultural products are being recycled into “plastic wood” and numerous other secondary products.
The popularity of “plastic wood” is proving to be the best way to keep used PVC panels out of the landfills. Because of this single product, recycling plants are springing up all over the country. This helps decrease the negative environmental impact and enhances the sustainability of farmers in the future.
This article was written by Brittany Sullivan and Jim Ralles, AmeriLux International, LLC.
Polyvinyl chloride (PVC) is one of the most versatile thermoplastics in use today. It is used extensively in all walks of life, from food packaging, to home construction. Its excellent strength-to-weight ratio and superior flame resistance, coupled with its low cost, make it the material of choice for the most demanding applications. Polyvinyl chloride (PVC) or “vinyl” is usually an amorphous thermoplastic material with excellent chemical resistance and dielectric properties, good tensile, flexural and mechanical strength, low moisture absorption, exceptional dimensional stability and good flammability characteristics.
The maximum service temperature for PVC is 140°F (60°C). The physical properties of PVC can be readily altered by the addition of plasticizers, impact modifiers and other ingredients to develop and enhance specific properties.
Generally, there are many types of PVC with specific physical and mechanical properties. They are available in rigid and/or flexible and in formulations in between. Additional subcategories of rigid and flexible PVC, with desirable physical properties for specific applications, can be developed by mixing additives with the base resin (e.g., the addition of UV stabilizers to enhance weatherability of rigid vinyl siding used in outdoor applications). PVC is available in a wide spectrum of colors as well as transparent variations.
PVC is manufactured into products by the injection molding process (e.g., pipe fittings), extrusion (e.g., pipe, shapes, siding, etc.), blow molding (e.g., bottles, etc.) and calendering (e.g., sheet).
Joining and fabrication of PVC can be easily accomplished by using standard metal and woodworking equipment with tools specifically prepared for PVC. Fabrication includes joining by solvent cementing process, hot gas welding, machining, vacuum forming, thermoforming, milling and drilling. The wide range of formulations, processing characteristics, fabrication capabilities, durability and relatively stable cost provide an economical material for a broad range of applications.
Technology has created the ability to foam both flexible and rigid PVC. The most significant growth has been in the lines of foamed rigid PVC. The process of foaming reduces the density of the PVC by 50 percent or more, which significantly impacts weight and cost, while still maintaining good physical properties. This class of products has seen significant growth in a relatively short period of time. It has replaced materials such as wood, metal, acrylic and styrene. It is used in many of the same applications as traditional PVC, but because of its lower cost, it is now the material of choice for point-of-purchase applications, signage and building construction. (See the property table for PVC on the IAPD web site at www.iapd.org/new/bookstore/free_resources.html.)
For more information on PVC and other plastic materials, IAPD’s Introduction to Plastics is an invaluable training manual. Details about it and other IAPD educational resources are available online at www.iapd.org.
What do you know about PVC? Answers are at www.iapd.org/popquiz.html.
1. PVC pipe is available in many grades, schedules and standard colors. Which of these is not one of them?
2. What is the impact strength Izod (ft-lb/in of notch) of rigid PVC?
Your IAPD Distributor is your choice in finding the right material for your application. Go to www.iapd.org to find a distributor in your area. You can search by company name, location or product category.
The IAPD Magazine web site at www.theiapdmagazine.com allows you to search by material, trade name and fabrication process. You can also search for fabrication capabilities.
Join IAPD in Philadelphia September 20 for a special one-day educational package specifically for engineers and specifiers to learn about innovations in both plastic materials and applications.
IAPD experts will first present the popular IAPD Plastics Applications Seminar, which offers a look at a wide variety of plastics applications. The seminar introduces and reintroduces materials in a variety of eye-opening applications. After the seminar, be sure to attend the IAPD Plastics Exhibition, a great opportunity to experience first-hand the best of the plastics stock shapes and pipe, valves and fittings distribution industry. Last year’s exhibition featured 70 exhibitors, and the show is the only one of its kind in North America.
Information is available online at www.iapd.org/new/pdf/events/ac/one_day.pdf.
Designing with Plastics is published by the International Association of Plastics Distribution. While every effort has been made to ensure accuracy, IAPD encourages you to verify information with a plastics distributor to ensure you select the correct plastic products to meet your needs.