POLYETHYLENE PIPE

PE PIPE DIMENSION

2011-07-18T23:32:00.000-07:00

Polyethylene - PE - is popular and and commonly used material in water pipes. It is usual to use the PE 50, PEH or PE-HD (polyethylene high density) quality.

PE pipes are produced in different pressure grades - PN grades - indicating the pressure in bars the pipe can support with water at 20 oC.

The pressure grades available according to European standards are

PN 2.5 - max pressure 2.5 bar

PN 4 - max pressure 4 bar

PN 6 - max pressure 6 bar

PN 10 - max pressure 10 bar

PN 16 - max pressure 16 bar

1 bar = 105 Pa (N/m2) = 0.1 N/mm2 = 10.197 kp/m2 = 10.20 m H2O = 0.9869 atm = 14.50 psi (lbf/in2) = 106 dyn/cm2 = 750 mmHg

European standards and available PEH pipes:

Polyethylene Pipe Systems

2011-05-26T23:20:00.000-07:00

Polyethylene Pipe Systems

Polyethylene (PE) pipe manufacture commenced in Australia in the 1950's where small diameter pipes were used for rural, irrigation and industrial applications.

Since then PE use has grown enormously, due to the advantages it offers over iron, steel and cement systems. It is free from corrosion in all ground conditions and its flexibility allows it to withstand ground movements. No protective layers or finishes are required.

PE's resistance to ground instability means that PE gas and water systems were the only systems to survive the major earthquakes in Kobe, Japan in 1995. PE systems can be fusion welded so there is no risk of leaking from joint distortion. Costly anchorage is not required at junctions and bends. Root penetration is not a problem. PE's low friction bore is not subject to scale buildup

PE's flexibility allows cost savings during installation, and PE can be coiled to be supplied in long lengths, reducing the cost required for joints and fittings. Cost saving installation techniques take advantage of its flexibility and low weight, reducing disturbance to the public and environment. Trenchless technology can use PE by pulling long lengths through holes below ground bored by mechancial moles, avoiding the need for open trenches. PE is often used in renovation of old pipelines as it can be readily inserted as a lining into an old leading pipeline.

PE fittings complete the PE pipe system which has a high track record of reliability over a long period. A commitment to using only the highest standard of raw materials and the latest manufacturing technology has established Vinidex with a reputation as a quality supplier of Polyethylene Pipes in sizes ranging from 16mm to

Advantages Of Polyethylene Pipe

2011-03-11T22:04:00.000-08:00

In US polyethylene hdpe pipes are getting popular due to its high quality, easy maintenance and durability. Pipes fitted in homes and buildings often show signs of pipeline corrosion due to high humidity and soaring temperatures. However, in case of polyethylene pipe you can stay out of such troubles, since these pipes are made with special materials to avoid such corrosion.

In case of normal metal pipes such corrosion with force you to spend on repairing these pipes frequently. But then with polyethylene hdpe pipes this is not a problem. These pipes have higher resistant power. Thus, you can use HDPE pipes for years without facing the trouble of either replacing it or repairing it. If you have a factory of your won or are planning to build one, you can use polyethylene pipe to enjoy years of hassle-free service as these pipes help to avoid domestic or industrial pipeline problem.
HDPE pipes are durable and flexible in nature. Thus, by installing HDPE pipes you can get long-term service with spending anything extra on repair. So, what makes these pipes durable and resilient? It is the advanced technological engineering put into the development of these pipes. In order to manufacture HDPE pipes and polyethylene liner Process Intensification or PI technology is put to use.
So, why is the benefit of Process Intensification [PI]?
Through PI technology you can enjoy certain advantages:
1. Develop the reaction rate.
2. Reduces consumption of energy.
High Density Polyethylene pipe helps to lessen the wastage of energy. Moreover, you can reduce expenses as well. Again these pipes are weather resistant and this very quality is rendered due to the PI technology. In US and several countries all over the word face extreme weather condition ranging through the year. Hence, if pipes are unable to ensure such tough weather conditions, they will either form leakage or breakdown.
How to install HDPE pipes?
HDPE pipes are installed with the help of high quality polyethylene liner or pipeline liner.

Advantages of polyethylene hdpe pipes:

There are several advantages of HDEP pipes. They are weather resistant, durable, flexible, and cost-effective in the same time. Most of these pipes are custom built. Thus, these pipes can be easily created based on your request. You can even select the size of these pipes according to the measurement of your building. Once that is done, proper fusion of pipeline liner is completed to shield the fusion process.

After the fusion is done, this follows with the condensing of polyethylene liner. The size is comparatively small when compared with host pipe diameter. Hence, HDPF Pipes enjoy he flexibility and they can remain rust free during monsoon, expand in summer and compress during the winters.
Apart from the above there are other features of HDPE pipes. With these pipes you can remain in peace without getting troubled of water clogging and floods.
If you wish to have a trouble free and hygienic life, make sure you install polyethylene pipes. Once you replace your metal pipes with HDPE pipes you can watch the difference.

Using HDPE pipe for drainage problems.(high-density polyethylene pipe)

2011-02-23T21:46:00.000-08:00

he Corrugated Polyethylene Pipe Association (CPPA) recently held a "Send Us Your HDPE Pipe Stories" contest. The following winning entries described unique and/or innovative applications, as well as stormwater drainage installations in which high density corrugated polyethylene pipe (HDPE) solved a specific problem.

FLAT LAND LEADS TO FLOODING

Several homes along Forrest Drive, a residential street in North Pekin, Illinois, near Peoria, suffered serious flooding during periodic heavy rains. The land along the drive was flat, and the village's old ditch-and-culvert drainage system was incapable of handling even 1.5 in. of rain, creating frequent floods for area residents.

INDUSTRIAL AND CHEMICAL

2010-12-28T22:24:00.000-08:00

INDUSTRIAL AND CHEMICAL

Corrosion resistance and resistance to attack by many industrial chemicals make plastics pipes the obvious choice for chemical plant installations. Like with all materials used in the construction of chemical plants care must be taken in selecting the correct plastics pipes and fittings that will withstand the operating conditions.

The wide range of polymers used in manufacture of plastics pipes and fittings provide a good range of products from which to select the appropriate material. PVC piping systems are widely used in water, wastewater and chemical transfer. Polyethylene piping systems are well suited to installation in difficult industrial situations. Their high strength and ease of installation also makes them ideal for compressed air reticulation

AGRICULTURE, IRRIGATION & DRAINAGE

2010-12-26T22:25:00.000-08:00

AGRICULTURE, IRRIGATION & DRAINAGE

A variety of alternatives to PVC are used both for water delivery and for drainage. Irrigation sprinkler, drip and drainage systems have long been available in HDPE and have significant advantages in resilience against compression, shovel attack and ground movement. Corrugated steel, concrete and HDPE are all competitive alternatives for drainage. HDPE drainage pipe is now available in formulations with high-recycled content. Plastic pipe has carved a hunk of the huge market previously dominated by concrete and steel. Highway drainage is a fast growing market for HDPE. Recently, the Corrugated Polyethylene Pipe Association initiated a third party certification system, which allows for increased acceptance of their product by the American Association of State Highway and Transportation Officials. Footing and under slab drains are all available in HDPE.

AGRICULTURAL AND RURAL

Water is a lifeline for all farming operations and the security of water is essential. Plastics pipes are available for the wide range of farming applications. Pressure pipes for irrigation, plant watering and potable water reticulation. Non-pressure pipes for irrigation, stock watering, micro-irrigation and general water reticulation systems.

Low cost, wide range of pipe sizes, flexible and easy to handle and transport are all advantages important to the farmers.

PLUMBING

2010-12-05T22:14:00.000-08:00

PLUMBING

PVC pipes and fittings for plumbing and drainage applications is the choice of plumber’s word wide. Low cost, lightweight, long life expectancy usually for the life of the installation is the overwhelming advantages. PVC does not corrode internally or externally eliminating the possibility of pipe failures or blockages. Cross-linked polyethylene, polypropylene and Polyethylene pipes are used in hot and cold-water reticulation in domestic, commercial and industrial installations. Ease of installation using compression fittings is providing a cost advantage.

Polyethylene, like other plastics, has a thermal coefficient of expansion higher than metals. When subjected to a temperature change, unrestrained (not buried) polyethylene pipe will experience expansion and contraction.

The coefficient of thermal expansion/contraction for Polyethylene is 1.0 x 10-4 in/in/°F. As a general allowance, 1" per 100' of pipe per 10°F change in temperature.

Forces due to thermal expansion and contraction can be significant. Proper system design should be used to account for the compressive and tension stresses that can be generated.

When pipe is used in pressure applications, the longitudinal stress created by the sum of the bending radius, internal pressure and other stress loads on the pipe should not exceed the material’s design stress rating. Severe but acceptable bends in polyethylene pipelines should be buried or properly restrained.

SEWERAGE AND DRAINAGE

2010-11-11T21:23:00.000-08:00

SEWERAGE AND DRAINAGE

The use of plastics pipes for both pressure and a gravity sewer is extensive. In addition, there is rapid growth in the use of plastics liners for repair of old and leaking sewer installations.

Availability of large diameter plastics pipes at competitive prices gives design engineers an opportunity to select products on cost and performance basis. Long life expectancy, low maintenance requirements are major advantages in the use of plastics pipes for sewage and drainage applications.

As in water main pipe, HDPE is a comparable alternative to PVC pipe in sewer systems. HDPE sewer pipes are also available in diameters ranging from 4 inches to 36 inches, although for storm sewer, much of the demand is for 10 to 15 inch, while for sanitary 8 to 12 inch are popular diameters. At larger diameters, the major market share is held by concrete, primarily due to cost.

Prior to the 1960s most sewer systems were combined sewers, that is, carried both sanitary and storm water. The system had to be designed to carry large volumes of water during rain events, but otherwise the capacity was little used. In addition, when it did rain the flood of relatively fresh water often negatively impacted water treatment. Design changed so that by the mid 1960s sanitary and storm systems were designed and constructed separately. Storm sewers collect water from roof drains, parking lots and streets. Unlike sanitary sewers, storm wastewater is not typically treated and the flow is directly discharged into a receiving body of water.

Similar to water distribution use, PVC is dominant in the smaller size sewer pipe market with HDPE just beginning to seriously compete. These smaller lines are commonly used in the collection network of subdivisions. In this segment, the competing concrete pipe is non-reinforced concrete pipe in 8" and 10" sections. The smallest diameter reinforced concrete pipe is usually 12" pipe.

The flow formula for smooth pipe should be used to compute the gas flow rate through Polyethylene. It has been found that the Mueller formula for smooth wall pipe describes the flow characteristics of Polyethylene

WATER SUPPLIES

2010-10-28T22:19:00.000-07:00

WATER SUPPLIES

The use of plastics pipes in potable water supply applications has been growing rapidly. Both PVC and Polyethylene pipe have major advantages over competitive materials and as polymer technology, keeps improving the choice of plastics pipes for water supply infrastructure projects keeps increasing.

Plastics pipes have design life in excess of 100 years during which they provide excellent performance and trouble free service life. They are corrosion resistant and because of their relatively lightweight are easy to handle, transport and install. Plastics pipes are flexible and fatigue resistant and can withstand repetitive pressure surges. Plastics pipes provide a smooth biological growth free bore through the life of the product eliminating flow restrictions common to other materials.

Water mains typically operate at pressures from 100 to 150 lbs per sq. in. (psi), while distribution lines operate between 40 and 100 psi. Service connection lines are usually a diameter of 1" or less and can be made of various materials: polyethylene, PVC, iron or copper pipe. Currently, PVC has a dominant share of the market for small diameter pipe in the water main (4” - 12”), sanitary sewer and storm sewer (4”-15”) markets, while traditional materials (ductile iron and concrete) continue to have majority market share in the larger diameter pipe. According to the Plastics News (July 16, 2001) the demand for large diameter pipe plastic pipe has increased 8.3% between 1990 and 2000.

The smaller tube sizes used for in building distribution are primarily split between PVC, copper, and iron. There is limited data on the breakdown of market share. Polyethylene is just beginning to penetrate the market for all sizes. The use of galvanized steel and Polyethylene has declined due to corrosion problems with galvanized and catastrophic failures with Polyethylene One of the key design concerns for drinking water infrastructure design and installation is leakage. When one turns on the tap for potable water, there is a cost associated with the acquisition, treatment, and supply (pumping) of the waster. If a water distribution system leaks, the lost water can become an extremely high cost. In arid areas, where costs to acquire water can be exorbitant, leaks can be an expensive proposition. A 4-inch leak in their 24-inch diameter iron pipe can result in the loss of 3 to 5 million gallons of water per day.

HDPE has a slight advantage in leak resistance over PVC. This is because it can be delivered in longer lengths, minimizing the quantity of joints. Furthermore, the butt or electro-fusion processes used to join HDPE provides stronger, tighter, more leak proof joints compared to the bell and spigot joints used in PVC pipe for mains or the solvent glue joints used for smaller distribution. The longer length of HDPE can require longer trenches to be open at a time, but its length and flexibility can allow for trench less procedure, particularly in sewer replacement. HDPE’s greater flexibility and resilience (particularly at lower temperatures) also make it less susceptible to surge and hammer shocks or to damage from digging. HDPE’s flexibility and resilience has made it increasingly popular in earthquake territory or other areas where soils can shift. For larger diameters, the fusion technique requires a fusion machine, which might be problematic in cramped spaces. For smaller diameter pipes, a handheld device can be used to weld/melt the pipe lengths together. Mechanical couplings are available for HDPE, though some of these couplings may be made of PVC.

PEX is another form of polyethylene that retains HDPE’s flexibility and chemical resistance while providing resistance to higher temperatures for which HDPE is not suitable. It is coupled with either fusion techniques or mechanical crimp couplings. Due to its higher temperature ratings it was initially used in radiant and district heating system applications, but is now also beginning to be used more widely in water supply and gas distribution systems.

Ductile Iron (DI) has significantly higher tensile strength, making it more capable of handling higher pressures, crushes and hammer than PVC. DI does not lose strength at high or low temperatures as PVC does. Ductile iron is impermeable to hydrocarbons and other groundwater contamination unlike PVC or other plastic pipe. “There has been much debate over the durability and expected lifespan of each of these materials. The life of a pipe system depends on not only the material, but also the installation and the surrounding environment. All these types of pipe have been on the market for over 30 years, and while there are examples of pipe failures for each of them, this study did not find conclusive evidence to suggest that one material has a significantly different lifespan from the other. When properly designed and installed, pipe systems of any of these materials can be sufficiently durable to withstand many decades of services.”

OIL FIELD

2010-10-21T23:25:00.000-07:00

OIL FIELD

Moving fluids through pipe in the oil field demands the utmost in flexibility, reliability and performance. That is why Polyethylene is the best choice for the energy business. High-density polyethylene (HDPE) pipe provides superior flow characteristics, extended life, durability, and reduced maintenance than traditional piping materials, anywhere in the oil patch.

A wide selection of HDPE pipe can meet the needs for any oil field applications.

Polyethylene has products specifically for the oil and gas industry for gas gathering, crude transmission, water lines and auxiliary lines.

Polyethylene will not rust, rot, pit or corrode because of chemical, electrolytic or galvanic action. Chemicals that pose potentially serious problems for polyethylene are strong oxidizing agents or certain hydrocarbons. These chemicals may reduce the pressure rating for the pipe or be unsuitable for transport. Either can be a function of service temperature or chemical concentration. Continuous exposure to hydrocarbons can lead to permeation through the material or electrometric gaskets used at joints. The degree of permeation is a function of pressure, temperature, the nature of the hydrocarbons and the polymer structure of the piping material. The chemical environment may also be of concern where the purity of the fluid within the pipe must be maintained. Hydrocarbon permeation may affect pressure ratings and hinder future connections.

High Density Polyethylene (HDPE) is available for all pipe applications. Being non-chlorinated, requiring fewer additives, and having a much higher recycling rate, it is considered a more benign plastic than PVC. PVC is more resistant to combustion, but smolders at a lower temperature than HDPE and releases toxic hydrochloric gases before combustion. Cross-linked polyethylene (PEX) is a polyethylene similar in many characteristics to HDPE but with molecules cross-linked to improve its ability to handle higher temperatures. Copper is highly recyclable but copper leaching into water supplies can be harmful to aquatic life. Copper also has significant life cycle problems in its mining, manufacture. Concrete, iron and steel have significant embodied energy usage, and their manufacture is not environmentally benign. However, all of them (with the exception of ABS) are generally considered environmentally superior to PVC. Aside from concrete, the primary PVC free alternatives are consistent with state government and professional association Environmentally Preferable Purchasing (EPP) guidelines (http://www.apwa.net/Documents/GovtAffairs/Policies/SolidWaste/solid-environpolicy.pdf). Steel, HDPE and copper pipe or conduit may all contain recycled content in the product. Quantities and post consumer content will vary with application and manufacturer. Alternative materials comparison issues The long-term durability of piping systems depends on many factors, including the soil environment, proper installation, material properties such as corrosion resistance, chemical resistance and strength and the performance of joints. Each of the primary PVC free materials has benefits that have kept them as significant market players.

FLUID FLOW

2010-08-16T02:28:00.000-07:00

FLUID FLOW

Polyethylene has an extremely smooth surface resulting in a very low coefficient of friction and a minimal loss of head pressure due to frictional losses. This, combined with excellent corrosion and abrasion properties, results in excellent flow characteristics throughout the life of the pipe. for pressurized systems, a Hazen-Williams "C" factor of 150 is used.PE3408/3608 Extra High Molecular Weight (EHMW) Black Pipe - a premium quality, high density, extra high molecular weight, and polyethylene pipe specifically designed for the rigors of the oil field. It is produced from PE3408/3608 resin containing not less than two percent (2%) carbon black for superior resistance to UV degradation. This pipe offers outstanding environmental stress crack resistance (ESCR), the best chemical resistance of any polyethylene pipe and high impact resistance. Polyethylene® oil field products are available in diameters from 1/2" CTS to 6" IPS coiled and straight lengths from 1/2" through 65" IPS.

FLUID AND GAS FLOW++

2010-08-04T02:41:00.000-07:00

FLUID AND GAS FLOW

Polyethylene pipes are used extensively in gas distribution applications worldwide. In USA and Canada over 90% of the natural gas distribution system is in plastics pipes with polyethylene representing 99% of the installations. The use of polyethylene in natural gas distribution systems is growing rapidly.

PE is lightweight, flexible and available in long coils minimizing the number of joints. It is ideally suited for a wide range of service conditions requiring very little maintenance. It has good abrasion resistance, flexible not effected by soil shift and temperature fluctuations.

Polyethylene pipe is recommended by PIPA for use in compressed air installations.

USES AND APPLICATIONS

2010-07-30T11:22:00.001-07:00

The effect of installation procedures on the field performance of existing high-density polyethylene (HDPE) pipe used for drainage applications on highway projects was investigated. A total of 45 HDPE pipes were inspected at sites in South Carolina that were statistically selected based on geographical location, pipe diameter, use, and age. The condition of each pipe was not known prior to selection for inspection. Both the external and internal conditions of the pipe were evaluated with respect to AASHTO and ASTM specifications, measurements of pipe deflection with a mandrel set to 5% deflection, and visual inspections of the pipe interior using a video camera. The video camera inspections revealed circumferential cracks in 18% of the pipes, localized bulges in 20% of the pipes, and tears or punctures in 7% of the pipes. Deflections greater than 5% were observed in 20% of the pipes. Installation problems such as poor preparation of bedding soils, inappropriate backfill material, and inadequate backfill cover contributed to the excessive deflection and observed internal cracking in pipes with observed damage. Appropriate construction procedures are essential in achieving a proper installation.

• Gas Gathering

• Crude Oil Flow

• Water Flood

• Saltwater Disposal

• Supply Water

• Fuel Transfer

• Main Lines

2010-07-25T10:58:00.000-07:00

GENERAL

Polyethylene (PE) is a thermoplastic material produced from the polymerization of ethylene. PE plastic pipe is manufactured by extrusion in sizes ranging from ½" to 63". PE is available in rolled coils of various lengths or in straight lengths up to 40 feet. Generally small diameters are coiled and large diameters (>6" OD) are in straight lengths. PE pipe is available in many varieties of wall thicknesses, based on three distinct dimensioning systems:

• Pipe Size Based on Controlled Outside Diameter (DR)

• Iron Pipe Size Inside Diameter, IPS-ID (SIDR)

• Copper Tube Size Outside Diameter (CTS)

PE pipe is available in many forms and colors such as the following:

• Single extrusion colored or black pipe

• Black pipe with co extruded color striping

• Black or natural pipe with a co extruded colored layer

The Visco-elastic Nature of Polyethylene

2010-07-23T02:26:00.000-07:00

VISCO-ELASTICITY

Polyethylene pipe is a visco-elastic construction material . Due to its molecular nature; polyethylene is a complex combination of elastic-like and fluid-like elements. As a result, this material displays properties that are intermediate to crystalline metals and very high viscosity fluids. The visco-elastic nature of polyethylene results in two unique engineering characteristics that are employed in the design of HDPE water piping systems, creep and stress relaxation. Creep is the time dependent viscous flown component of deformation. It refers to the response of polyethylene, over time, to a constant static load. When HDPE is subjected to a constant static load, it deforms immediately to a strain predicted by the stress-strain modulus determined from the tensile stress-strain curve. At high 12 introduction loads, the material continues to deform at an ever decreasing rate, and if the load is high enough, the material may finally yield or rupture. Polyethylene piping materials are designed in accordance with rigid industry standards to assure that, when used in accordance with industry recommended practice, the resultant deformation due to sustained loading, or creep, is too small to be of engineering concern. Stress relaxation is another unique property arising from the visco-elastic nature of polyethylene. When subjected to a constant strain (deformation of a specific degree) that is maintained over time, the load or stress generated by the deformation slowly decreases over time. This stress relaxation response to loading is of considerable importance to the design of polyethylene piping systems. As a visco-elastic material, the response of polyethylene piping systems to loading is time-dependent. The effective modulus of elasticity is significantly reduced by the duration of the loading because of the creep and stress relaxation characteristics of polyethylene. An instantaneous modulus for sudden events such as water hammer can be as high as 150,000 psi at 73°F. For slightly longer duration, but short-term events such as soil settlement and live loadings, the short-term modulus for polyethylene is roughly 110,000 to 120,000 psi at 73° F, and as a long-term property, the modulus is reduced to something on the order of 20,000-30,000 psi. As will be seen in the chapters that follow, this modulus is a key criterion for the long-term design of polyethylene piping systems. This same time-dependent response to loading also gives polyethylene its unique resiliency and resistance to sudden, comparatively short-term loading phenomena. Such is the case with polyethylene’s resistance to water hammer phenomenon, which will be discussed in more detail in subsequent sections of this article.

CONSTRUCTION ADVANTAGES HDPE

2010-07-20T10:16:00.000-07:00

FATIGUE RESISTANCE AND FLEXIBILITY HDPE

Pipe can be field bent to a radius of 30 times the nominal pipe diameter or less depending on wall thickness (12” HDPE pipe, for example, can be cold formed in the field to a 32-foot radius). Willoughby, D. A. (2002). Plastic Piping Handbook, McGraw-Hill Publications, New York.

SEISMIC RESISTANCE

The physical attributes that allow HDPE pressure pipe to safely ac commodate repetitive pressure surges above the static pressure rating of the pipe, combined with HDPE’s natural flexibility and fully restrained butt fusion joints, make it well suited for installation in dynamic soil environments and in areas prone to earthquakes or other seismic activity.

CONSTRUCTION ADVANTAGES HDPE

Pipe’s combination of lightweight, flexibility and leak-free, fully restrained joints permits unique and cost-effective installation methods that are not practical with alternate materials. Installation method such as horizontal directional drilling, pipe bursting, slip lining, plow and plant, and submerged or floating pipe, can save considerable time and money on many installations. At approximately one-eighth the weight of comparable steel pipe, and with integral and robust joining methods, installation is simpler, and it does not need heavy lifting equipment. Polyethylene pipe is produced in straight lengths up to 50 feet and coiled in diameters up through 6”. Coiled lengths over 1000 feet are available in certain diameters. Polyethylene pipe can withstand impact better than PVC pipe, especially in cold weather installations where other pipes are more prone to cracks and breaks.

DURABILITY OF POLYETHYLENE

Polyethylene pipe installations are cost-effective, have long-term cost advantages due to the pipe’s physical properties, leak-free joints, and reduced maintenance costs. The polyethylene pipe industry estimates a service life for HDPE pipe to be, conservatively, 50-100 years if the system has been properly designed, installed and operated in accordance with industry established practice and the manufacturer’s recommendations. This longevity confers savings in replacement costs for generations to come. Properly designed and installed PE piping systems require little on-going maintenance. PE pipe is resistant to most ordinary chemicals and is not susceptible to galvanic corrosion or electrolysis.

HYDRAULICALLY EFFICIENT

For water applications, HDPE pipe’s Hazen Williams C factor is 150 and does not change over time. The C factor for other typical pipe materials such as PVC or ductile iron systems declines dramatically over time due to corrosion and tuberculation or biological build-up. Without corrosion, tuberculation, or biological growth HDPE pipe maintains its smooth interior `all and its flown capabilities indefinitely to insure hydraulic efficiency over the intended design life.

TEMPERATURE RESISTANCE

PE pipe’s typical operating temperature range is from -40°F to 140°F for pressure service. Extensive testing at very low ambient temperatures indicates that these conditions do not have an adverse effect on pipe strength or performance characteristics. Many of the polyethylene resins used in HDPE pipe are stress rated not only at the standard temperature, 73° F, but also at an elevated temperature, such as 140°F. Typically, HDPE materials retain greater strength at elevated temperatures compared to other thermoplastic materials such as PVC. At 140°F, polyethylene materials retain about 50% of their 73°F strength, compared to PVC which loses nearly 80% of its 73°F strength when placed in service at 140°F .

As a result, HDPE pipe materials can be used for a variety of piping applications across a very broad temperature range. The features and benefits of HDPE are quite extensive, and some of the more notable qualities have been delineated in the preceding paragraphs.

DUCTILITY

Ductility is the ability of a material to deform in response to stress without fracture or, ultimately, failure. It is also sometimes referred to as trainability and it is an important performance feature of PE piping, both for above and below ground service. For example, in response to earth loading, the vertical diameter of buried PE pipe is slightly reduced. This reduction causes a slight increase in horizontal diameter, which activates lateral soil forces that tend to stabilize the pipe against further deformation. This yields a process that produces a soil-pipe structure that is capable of safely supporting vertical earth and other loads that can fracture pipes of greater strength but lower strain capacity. With its unique molecular structure, HDPE pipe has a very high strain capacity thus assuring ductile performance over a very broad range of service conditions. Materials with high strain capacity typically shed or transfer localized stresses through deformation response to surrounding regions of the material that are subject to lesser degrees of stress. Because of this transfer process, stress intensification is significantly reduced or does not occur, and the long-term performance of the material is sustained. Materials with low ductility or strain capacity respond differently. Strain sensitive materials are designed based on a complex analysis of stresses and the potential for stress intensification in certain regions within the material. When any of these stresses exceed the design limit of the material, crack development occurs which can lead to ultimate failure of the part or product. However, with materials like polyethylene pipe that operate in the ductile state, a larger localized deformation can take place without causing irreversible material damage such as the development of small cracks. Instead, the resultant localized deformation results in redistribution and a significant lessening of localized stresses, with no adverse effect on the piping material. As a result, the structural design with materials that perform in the ductile state can generally be based on average stresses, a fact that greatly simplifies design protocol. To ensure the availability of sufficient ductility (strain capacity) special requirements are developed and included into specifications for structural materials intended to operate in the ductile state; for example, the requirements that have been established for “ductile iron” and mild steel pipes. Similar ductility requirements have also been established for PE piping materials. Validation requirements have been added to PE piping specifications that work to exclude from pressure piping any material that exhibits insufficient resistance to crack initiation and growth when subjected to loading that is sustained over very long periods of time, i.e. any material that does not demonstrate ductility or strain ability. The PE piping material validation procedure is described in the chapter on Engineering Properties of Polyethylene.

LIFE CYCLE COST SAVINGS

2010-07-15T11:34:00.000-07:00

LIFE CYCLE COST SAVINGS

For municipal applications, the life cycle cost of HDPE pipe can be significantly less than other pipe materials. The extremely smooth inside surface of HDPE pipe maintains its exceptional flown characteristics and butt fusion joining eliminates leakage. This has proven to be a successful combination for reducing total system operating costs.

LEAKS FREE, FULLY RESTRAINED JOINTS HDPE

Heat fusion joining forms leak-free joints as strong as, or stronger than, the pipe itself. For municipal applications, fused joints eliminate the potential leak points that exist every 10 to 20 feet when using the bell and spigot type joints associated with other piping products such as PVC or ductile iron. As a result of this, the “allowable water leakage” for HDPE pipe is zero as compared to the water leakage rates of 10% or greater typically associated with other piping products. HDPE pipe’s fused joints are also self-restraining, eliminating the need for costly thrust restraints or thrust blocks while still insuring the integrity of the joint and the fl own stream. Notwithstanding the advantages of the butt fusion method of joining, the engineer also has other available means for joining HDPE pipe and fittings such as electro fusion and mechanical fittings. Electro fusion fittings join the pipe and/or fittings together using embedded electric heating elements. In some situations, mechanical fittings may be required to facilitate joining to other piping products, valves or other system appurtenances. Specialized fittings for these purposes have been developed and are readily available to meet the needs of most demanding applications.

CORROSION & CHEMICAL RESISTANCE

HDPE pipe will not rust, rot, pit, corrode, tube roulade or support biological growth. It has superb chemical resistance and is the material of choice for many harsh chemical environments. Although unaffected by chemically aggressive native soil, installation of PE pipe (as with any piping material) through areas where soils are contaminated with organic solvents (oil, gasoline) may require installation methods that protect the PE pipe against contact with organic solvents. Protective installation measures that assure the quality of the fluid being transported are typically required for all piping systems that are installed in contaminated soils

WHAT IS POLYETHYLENE

2010-07-11T05:17:00.000-07:00

WHAT IS POLYETHYLENE

Polythene resins are milky white, translucent substances derived from ethylene (CH2=CH2). Its chemical formula is [─CH2─CH2─]n (where n denotes that the chemical formula inside the brackets repeats itself to form the long chains of plastic molecules).

n CH2=CH2  [─CH2─CH2─]n

When Hogan and Banks first created a reaction between ethylene and benzaldehyde using two thousand atmospheres of internal pressure, their experiment went askew when all the pressure escaped due to a leak in the testing container. On opening the tube, they were stunned to find a white waxy substance that looked a lot like some form of plastic. After repeating the experiment, they discovered that the loss of pressure was not due to a leak at all, but was a result of the polymerization process. The residue polyethylene (PE) resin was a milky white, translucent substance derived from ethylene (CH2=CH2). Polyethylene was produced with either a low or a high density.

Low-density polyethylene (LDPE) has a density ranging from 0.91 to 0.93 g/cm3 (0.60 to 0.61 oz/cu in). The molecules of LDPE have a carbon backbone with side groups of four to six carbon atoms attached randomly along the main backbone. LDPE is the most widely used of all plastics, because it is inexpensive, flexible, extremely tough, and chemical-resistant. LDPE is molded into bottles, garment bags, frozen food packages, and plastic toys.

High-density polyethylene (HDPE) has a density that ranges from 0.94 to 0.97 g/cm3 (0.62 to 0.64 oz/cu in). Its molecules have an extremely long carbon backbone with no side groups. As a result, these molecules align into more compact arrangements, accounting for the higher density of HDPE. is stiffer, stronger, and less translucent than low-density polyethylene. HDPE is formed into grocery bags, car fuel tanks, packaging, and, of course, piping.

POLYETHYLENE PIPE

The history of the polyethylene (PE) pipe begins with early civilization's attempts to find a suitable transport medium that could move water and other fluids from one place to another. 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 piping, on the other hand, beginning with polyvinyl chloride or PVC in 1926, dates back to the 1930s, when it was utilized for sanitary drainage. Polyethylene was first developed in 1933 as a flexible, low-density coating and insulating material for electrical cables. It played a key role during World War II -- first as an underwater cable coating and then as a critical insulating material for such vital military applications as radar insulations. Because of its lightweight, radar equipment was easier to carry on a plane, which allowed the out-numbered Allied aircraft to detect German bombers under difficult conditions such as nightfall and thunderstorms.

POLYETHYLENE TIME LINE

1862 - Parkesine, the first synthetic plastic

1866 - Celluloid by John Wesley Hyatt

1891 - Rayon is used to make Cellophane

1900 - Celluloid is used for Film

1907 - Bakelite, the first thermosetting synthetic resin.

1918 - Polystyrene

1926 - PVC or Polyvinyl Acetate

1927 - Nylon - synthetic silk for stockings in 1939

1933 - Polyethylene

1935 - Low Density Polyethylene

1938 - Teflon

1951 - High Density Polyethylene

1957 - Velcro and Silly Putty

HISTORY OF POLYETHYLENE PIPE

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HISTORY OF POLYETHYLENE PIPE

The history of the polyethylene (PE) pipe began with early civilization's attempts to find a suitable transport medium that could move water and other fluids from one place to another. Concrete has, in some form or another, been around since the Assyrians, Babylonians and Egyptians, while steel was first patented in 1855. Plastic piping, on the other hand, beginning with polyvinyl chloride or PVC in 1926, dates back to the 1930s, when it was utilized for sanitary drainage. PE was first developed in 1933 as a flexible, low-density coating and insulating material for electrical cables.

HDPE, however, is quite a bit different material from the PE used in the 1930s. LDPE was discovered in 1935 and it was not until nineteen years later in 1954 that commercially available quantities of HDPE appeared on the scene. As a relative newcomer in the piping industry, PE is constantly making its way into applications normally reserved for the older piping technologies. Since the late 1950s and early 1960s, PE has made its way into every corner of our lives launching a multi-billion dollar industry. It is currently the largest volume plastic in the world. This is partly due to the fact that there are certain characteristics (or combinations of characteristics) of HDPE that make it an attractive alternative. Whether it is an issue of installing a new piping system or rehabilitating an existing system, there are certain requirements placed on the piping material: that it be simple to install, that it doesn't leak or cost a lot to maintain, and will last a very long time.

HDPE Pipe

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Features and Benefits of HDPE Pipe

When selecting pipe materials, designers, owners and contactors specify materials that provide reliable, long-term service durability, and cost-effectiveness. Solid wall polyethylene pipes provide a cost-effective solution for a wide range of piping applications including gas, municipal, industrial, marine, mining, electrical and communications duct applications. Polyethylene pipe is also effective for above ground, buried, trench less, floating and marine installations. According to David A. Willoughby, P.O.E., “…one major reason for the growth in the use of the plastic pipe is the cost savings in installations, labor and equipment as compared to traditional piping materials. Add to this the potential for lower maintenance costs and increased service life and plastic pipe is a very competitive product.

Natural gas distribution was among the first applications for medium-density polyethylene (MDPE) pipe. In fact, many of the systems, currently in use, have been in continuous service since 1960 with great success. Today, polyethylene pipe represents over 95% of the pipe installed for natural gas distribution in diameters up to 12” in the U.S. and Canada. PE pipe has been used in potable water applications for almost 50 years and has been continuously gaining approval and growth in municipalities. The production, quality assurance and testing of PE gas pipes, including joints, are carried out according to international AWWA, NSF, and ASTM standards. The fear often expressed in the early days that HDPE would have insufficient resistance to the aromatics contained in natural gas (such as tetrahydrothiophene (THT), concomitant substances and condensates) has not been confirmed, either by laboratory tests, or by practical experience. Other material alternatives do not share PE’s advantages. For instance, there are about 23,000 fractures and corrosion failures of iron mains across the United Kingdom each year. Of these events, the majority are located and dealt with in a safe manner. However, on average, about 600 of these results in the leakage of gas into buildings and annually this results in 3 to 4 major incidents involving fire.

INTRODUCTION OF POLYETHYLENE

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Since its discovery in 1933, polyethylene (also known as polythene) has grown to become one of the world’s most widely used and recognized thermoplastic materials . The versatility of this unique plastic material is demonstrated by the diversity of its use. The original Application for polyethylene (PE) was as a substitute for rubber in electrical insulation during World War II. Polyethylene has since become one of the world’s most widely utilized thermoplastics. Today’s modern polyethylene resins are highly engineered for much more rigorous applications such as pressure-rated gas and water pipe, automotive fuel tanks and other demanding applications. Polythene’s use as a piping material was first developed in the mid 1950’s. In North America, its original use was in oil field production where a flexible, tough and lightweight piping product was needed to fulfill all the needs of a rapidly developing oil and gas production industry. The success of polyethylene pipe in these installations quickly led to its use in natural gas distribution where a coil able, corrosion-free piping material could be fusion joined in the field to assure a “leak free” method of transporting natural gas to homes and businesses. Polyethylene’s success in this critical application has not gone without notice and today it is the material of choice for the natural gas distribution industry. Sources now estimate that nearly 95% of all new gas distribution pipe installations in North America that are 12” in diameter or smaller are polyethylene piping .

The performance benefits of polyethylene pipe in these original oil and gas related applications have led to its use in equally demanding piping installations such as potable water distribution, industrial and mining pipe, force mains and other critical applications where a tough, ductile material is needed to assure long-term performance. It is these applications, representative of the expanding use of polyethylene pipe that are the principal subject of this article. In the chapters that follow, we shall examine all aspects of design and use of polyethylene pipe in a broad array of applications. From engineering properties and material science to fluid flown and burial design; from material handling and safety considerations to modern installation practices such as horizontal directional drilling and/or pipe bursting; from potable water lines to industrial slurries, all these things have led to the growing use of polyethylene pipes in the world .

Polyethylene Pipe

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The structure and the mechanical properties of a butt weld in a polyethylene pipe were examined and contrasted to non-welded PE pipe. X-ray diffraction, differential scanning calorimeter and Fourier transform infrared spectrometer measurements revealed details of axial amorphous and crystal orientation in the original pipe. Contrary to expectations considering the squeeze, flow nature of butt-welding, formation of randomly oriented crystal structure was determined in the weld region. Tensile and notched impact tests at ambient and sub-ambient temperatures and varying rates of impact showed that welding consistently reduced resistance to failure. Microscopic evaluation of the brittle fracture surfaces revealed the surface morphology of the welded zone to be coarser than the non-welded PE material.

Polyethylene (PE) pipes have been produced in Australia and New Zealand since the mid 1950s, initially in small diameters for industrial and agricultural applications. The first Australian Standard was released in 1962 and Iplex Pipelines (then Hardie Iplex) commenced production in the early seventies. Usage has grown rapidly with over 40,000 tones of PE pipes being produced annually in Australasia. Polyethylene has become one of the most widely used of all plastic polymers.

Terms frequently used to describe this material when used for engineering applications are high density (HDPE), medium density (MDPE) and most recently high performance (HPPE) polyethylene. Others such as low density (LDPE) and linear low density (LLDPE) are sometimes used for irrigation pipelines.

The Type 50 PE of AS1159, which was in common use until 1994, is an HDPE with a long-term design stress of 5.0 MPa. However, with the introduction of new Standards, terminology relating to density alone is no longer recommended. AS/NZS4130 and AS/NZS 4131 recognized this, allow for three specific classifications by material strengths, and sub classifications by performance at elevated temperatures. The higher strength PE 80 and PE100 compounds are sometimes referred to as second and third generation materials. They were introduced into general service in the late seventies and early nineties respectively.

POLI plex polyethylene is an integrated family of PE pipes produced by Iplex , based on PE 80B, PE 80C and PE100 materials. These are manufactured to AS/NZS 4130 from polyethylene complying with AS/NZS 4131. Diameters range from DN 16 to DN 1000 with pressure ratings of up to 2.0 MP a. Pipes up to DN 110 can be supplied in coils lengths of up to 300 meters in some diameters. Larger diameters are typically 12 m long although 15 m and longer are occasionally manufactured by arrangement. Note that the nominal diameter of PE pipes refers to the outside diameter in accordance with international practice.

Iplex THERMAPIPE is a white co-extruded PE developed by Iplex, designed for above ground pipelines in hot climates to significantly reduce the heating effect due to exposure to solar radiation, which occurs with the normal black pigmented PE. This allows the use of lower class pipes to give reduced purchase and operating costs.

POLI plex PE pipes may be joined economically using thermal butt welding equipment. However, diameters of up to DN 110 are more commonly joined using the Iplex Metric compression couplings. These provide an easy system for making joints quickly which can be undone and reused when altering the system layout. An alternative form of welding PE is the electro fusion system where heating elements are embedded in PE sockets. These sockets form part of a coupling or other fitting and require an electrical input to produce a welded joint. For pipes, which are, constantly being uncoupled and moved, shouldered ends can be provided to suit proprietary metal clamps. For bends and tees a range of both injection molded and fabricated fittings

I am obliged to express my thanks

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All praises to the almighty Allah, who induced the man with intelligence, knowledge, sight to observe and mind to think. Peace and blessing of Allah be upon the Holy Prophet, Hazrat Muhammad ( ) who exhorted his followers to seek for

Knowledge from cradle to grave.

I feel great pleasure in expressing my sincere gratitude and profoundest thanks to my project advisor Professor Sajid Hussain Shah, Department of Mechanical, Preston University, for his kind guidance, constant help, invaluable suggestions and unforgettable cooperation throughout my project work. I am very much obliged to Mr. Jahanzeb Ahmed, Mr. Muhammad Hafeez, Mr. Muhammad Ali and Madam Zenat Shahrazi, , for providing facilities to complete this work, and all other teachers of the Department for their help and encouragement.

I am obliged to express my thanks to Professor Dr.Muhammad Tahir Hussain, University of Textile Engineering Faisalabad. He has been sympathetic, amiable and very kind to me. He is always a source of aspiration for me.

I am thankful to my friends Ahmad Nadeem and Abdul Rehman for their cooperation and encouragement.

I express my feelings of gratitude to all the members of non-teaching staff of the Department for their constant help.

My special thanks are due to my parents, brothers, sisters, and wife for their full support, encouragement, and sincere prayers for my success.

(MUHAMMAD ABDUL RAUF)