Plastic Pipe

It is hard to compete with plastic as an industrial piping material. Plastic pipe will last longer, it can handle heavy loads, extremely corrosive conditions and best of all, its flexible and light, making it easy to install in hard to reach places. Plastic pipe has a lot to offer the designer, contractor and engineer. It could be used for above and below ground applications and for pressure and non-pressure applications. Typical uses include piping for transporting clean and waste water, chemicals, steam, gases, heating and cooling fluids, food solids and slurries.

By joining small molecules into macromolecules, the first modern thermosetting synthetic resin was created in 1909 and called Bakelite. It was another 20 years before plastic was used as a piping material and another 20 years before it was widely accepted as such. By 1955 plastic pipe was an industry standard and was used primarily in the agriculture and oil industries.

History of Plastic Pipe as a Piping Material
Since the late 50s and the early 60s, the use of plastic pipe has increased at a breathtaking rate. Just a few of its applications include water mains, hot and cold water distribution, drain, waste, and vent (DWV), sewer, gas distribution, irrigation, conduit, fire sprinkler and industrial processes. From this point on, plastic pipe has not only expanded its applications, different kinds of plastic have been constantly refined to meet every possible need. The most popular plastic pipe materials include polyvinyl chloride (PVC), polyethylene (HDPE), acrylonitrile butadiene styrene, or ABS, each with its own set of advanatages and disadvantages.

It is no secret that plastic is relatively a new kid on the block as a piping material. Concrete has, in some form or another, been around since the Assyrians, Babylonians and Egyptians, while steel was first patented in 1855. Plastic, on the other hand, beginning with polyvinyl chloride or PVC in 1926, dates back to the 1930s, when it was used for sanitary drainage. With the introduction of butadiene as a third monomer to the styrene acrylonitrile copolymer in the 1940s, ABS plastic pipe became the most popular way to transport hot liquids. Low density polyethylene was discovered in 1935 and it wasn't until sixteen years later in 1951 that high density polyethylene appeared on the scene in response to a need for a superior insulating material that could be used for such applications as radar cable. Since the late 1950s and early 1960s, polyethylene has made its way into every corner of our lives.

As a relatively newcomer in the piping industry, polyethylene is constantly making its way into applications normally reserved for the older piping technologies. This is partly due to the fact that there are certain characteristics (or combinations of characteristics) of high density polyethylene that make it a viable alternative. Whether it is an issue of installing a new piping system or rehabiliting an existing one, there are certain requirements placed on the piping material: that it simple to install, that it doesn't leak or cost a lot to maintain, and will last forever. As long as polyethylene can satisfy these demands better than any other material, it will continue its meteoritic rise in popularity.

Why use Plastic as a Piping Material?
Within the industry, plastic pipe is used as a part of piping system to transport fluids, or basically anything that can flow, from one location to another. Piping engineers and contractors are responsible for finding the best and most efficient manner of transporting fluid to where it is most needed. When selecting a piping material for the transportation of water or the protection of sensitive electrical and communication systems, their selection was based on a number of factors.

Mostly known as a material for piping systems found in sewer, drainage and and irrigation systems, plastic is not thought of as a suitable replacement for the more traditional piping materials such as concrete and metal. This is due, in part, to the medium being transported, i.e., corrosive wastewater, and on the specific support conditions, i.e., load, pressure, etc. Some attributes of plastics may be favourable or unfavourable, depending on the particular service conditions and the type of plastic. The effect of some unfavourable attributes can be reduced or eliminated through proper design and installation of the pipes. Choosing the right material therefore, requires a thorough knowledge of the physical features of various plastics and other piping materials like concrete and metal.

Choosing the Right Plastic
The plastic pipe used today, with their various physical properties, meet most of the requirements of pipeline construction. Apart from the special properties that separate them from one another, all forms of plastic pipe share some common characteristics.

Light Weight	easy to handle and move
Non-Corrosive	will not rust or corrode
Smooth Inner Surface	prevents clogging or blockages
Flexibility	can bend without fittings
Chemical Resistance	resistance to acids and alkalis in soils
Simple Joining Procedure	heat fusion for leak free joints

Plastic Pipe vs Concrete Pipe
Concrete pipe continues to be the pipe of choice when durability, structural strength, long service life, and low maintenance are required. As a rigid pipe solution, the strength of concrete pipe reduces the bedding and backfill requirements compared to plastic pipe. Since concrete itself serves as a structure, it is not as dependent as plastic pipe on its surrounding conditions.

Most cities in North America use concrete pipe in their water systems. While durability is cited as the main reason for choosing concrete, it also considered one of the safest piping material available. It doesn't burn or rust and will significantly reduce the risk and any potential liability associated with a fire related catastrophe. While concrete is superior in certain ways, plastic pipe is often more abrasion and chemically resistant, and has a better flow capacity than concrete pipe, As to which is better, the final selection will usually be based on a choice between the cost of installing the much heavier and rigid concrete pipe and the much lighter and flexible plastic pipe. Plastic's light weight also permits the use of longer sections, and cutting the pipe at the job site, resulting in easier and shorter installations.

Plastic Pipe vs Metal Pipe
In most cases, plastic pipe is a viable replacement for metal pipe. There is no doubt that it is cheaper to install plastic pipe than metal pipe. In a lot of cases, plastic would not only do the job, it would do it better.

In the first place, plastic is more resistant to corrosion than metal. A plastic piping system will never jam, stick or fail because of rust or corrosion. 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. A second advantage involves flow rates. The inside of plastic pipe is smooth and clean and it will stay that way for years. Metal pipe can rust , corrode and scale - resulting in reduced flow rates and higher pressure drops over time. Users of metal pipe, valves and fittings are often concerned with they believe are the mechanical strength limitations of plastics.While it is true that there is isn't a plastic system that can match the temperature and pressure service levels of a metal piping system, few realize that plastic piping systems can provide adequate tensile strength or operation up to 200° F.

Hdpe vs PVC
PVC, a rigid plastic pipe, is often thought to be quite similar to hdpe pipe. While both have good flow capacity rates, and are available in longer lengths and greater diameters, both also can be buried underground and transfer their loads the surrounding soil, hdpe is a flexible piping material. Equally resistant to chemical corrosion compared to metal or concrete, hdpe is highly abrasion resistant, while PVC is only moderately abrasion resistant, and hdpe is less susceptible to surge shocks than PVC. In general, while PVC is stiffer than hdpe pipe, it is more brittle than hdpe making it vulnerable to shipping and handling damage.

The biggest difference is that PVC has environmental issues that hdpe doesn't (PVC is made using chlorine which is a carcinogenic material) and are joined together by gaskets while hdpe is welded. Because it is chlorine free, hdpe pipe requires fewer additives to make. Unlike PVC pipe, hdpe pipe is also dioxin free the most potent carcinogen around. When it comes to the environment, hdpe pipe is a much more benign plastic. As such hdpe pipe is considered a viable alternative for some pipe and conduit applications typically reserved for PVC. It's flexibility results in fewer ruptures from freezing and construction around the pipes making it a popular piping material for stormwater and irrigation applications.

	PVC	ABS	HDPE

Durability	Decades	Decades	Decades
Joining	Solvent	Solvent	Fusion
Joint Integrity	Leak Free	Leak Free	Leak Free
Weight	Light	Light	Lighter than PVC
Flexibility	flexible	flexible	flexible
Internal Wall Smoothness	Good	Good	Good
Tensile Strength	Fair	Fair	Fair
Abrasion Resistance	Fair	Fair	High
Chemical Resistance	Fair	Fair	High
Impact Resistance	Fair	Fair	High
Fire Resistance	Fair	Fair	Fair
Operating Temperature	-40�C to +65�C	-40�C to +80�C	0�C to +60�C

Applications of Plastic Pipe

Plastic pipe found its first use in the construction and building industires. The building industry continues to be a large user of plastics, accounting for 400,000,000 lb. in 1955. Most engineers now realize that plastics are not merely substitutes for other conventional engineering materials. Their unique properties and production methods make possible the fabrication of building components by entirely new procedures and in designs departing markedly from those formerly used. Plastic, as a piping material, is chosen primarily for its lightweigh, chemical resistance, and non-corrosive properties. The primary applications in which plastic piping is used include the following:

Non Pressure Applications
Drainage
Building Drain, Waste and Vent (DWV)
Building Sewers and Drains

Pressure Applications
Industrial Processes
Water Service
Hot and Cold Water Distribution

Other
Fire Sprinkler Piping
Swimming Pool Piping
Chilled Water Systems
Irrigation
Ice Melting
Radiant Floor Heating

Copyright ® 2003 - 2008 \| Oxford Plastics Inc. \| All Rights Reserved
Oxford Plastics Inc. ~ PO Box 119, Oxford Road 6, Embro, Ontario, CANADA, N0J 1J0
Office: 519.423.6232 ~ Fax: 519.423.6057 ~ Toll Free: 1.800.263.0502