Introduction
Plastic : A material which contains as an essential ingredient an organic substance of high to ultrahigh molecular weight, is solid in its finished state, and at some stage of its manufacture or processing can be shaped by flow. The two general types of plastic are thermoplastic and thermosetting.
There are many types of plastic pipe, both rigid and semirigid. Under normal conditions, rigid plastic pipe can be supported using conventional supports with the spacing half that used with steel pipe or as recommended by pipe manufacturers.
The support of plastic pipe or tubing should be continuous if, owing to the nature of the plastic, it will become flexible from elevated temperatures or from line contents. The continuous support can be in the form of a light angle or channel into which the plastic pipe is laid.
In some cases, wear shoes or pads should be added to plastic pipe where it may rub against steel supports. The use of wear pads will prevent the abrasive action caused by thermal movement, thus preventing damage to the pressure boundary.
It is suggested that recommendations of the manufacturer of the specific plastic
pipe also be followed.
Plastic piping is made from either of two basic groups of synthetic materials, thermoplastic and thermosetting. Thermoplastics can be softened and reshaped repeatedly by the application of heat. In contrast thermosetting materials are irreversibly set, or cured, or hardened into a permanent shape during factory manufacture.
Once hardened into their final shape, thermosetting products cannot be softened and therefore may not be reshaped by heating. Thermoplastic materials include minimal reinforcements, whereas thermosetting resins are almost always combined with reinforcements (such as glass fibers) and sometimes fillers (such as sand) to produce structurally integrated composite constructions.
Due to its excellent material characteristics and its outstanding price / performance ratio, until today PVC is the most used material worldwide for pipes or profiles made from plastics.
As the market is very competitive manufacturers of RPVC/UPVC pipes or profiles have been exposed to increasing pressure on prices and costs for years.
At the same time higher and higher demands are made on the product quality.
Plastic Pipe and Fittings :
General. Plastic pipe is manufactured in a great variety of compositions, many of which are suitable for plumbing systems. The applicable code is the most important factor in selecting the type of plastic pipe for any specific purpose. All plastic pipe, components, and jointing methods used in potable water systems must be approved by the NSFI. Plastic pipe must be closely integrated with the selection of hangers and the entire pipe support system.
The advantages of plastic pipe include excellent resistance to a wide variety of chemical and waste effluents, resistance to aggressive soils, availability in long lengths, low resistance to fluid flow, and low initial cost. Disadvantages include poor structural stability (requiring additional supports), lower pressure ratings at elevated temperatures, susceptibility of some types of plastics to physical changes due to exposure to sunlight, low resistance to solvents, and production of toxic gases released upon combustion of some types of plastics.
Three designations are used to express pressure rating and wall thickness: schedule (dimensions are outside-diameter-controlled, matching iron pipe size); standard dimensional ratio (SDR) (a pressure rating only); and dimensional ratio (a pressure rating only using nonstandard dimensional ratios). Where the pressure rating is the prime consideration, the abbreviation PR is used.
Polyvinyl Chloride (PVC) Pipe: PVC is used for potable water and drainage systems. It is one of the most widely used of the plastic pipes. It has a low pressure and temperature rating and very poor resistance to solvents.
PVC pipe and fittings must conform to the following standards:
1. ASTM D 1785, PVC Plastic Pipe, Schedules 40, 80, and 120
2. ASTM D 2241, PVC Pressure-Rated Pipe (SDR Series)
3. ASTM D 2466, PVC Plastic Pipe Fittings, Schedule 40
4. ASTM D 2467, Socket-Type PVC Plastic Pipe Fittings, Schedule 80
5. ASTM D 2665, PVC Drain, Waste and Vent Pipe and Fittings
Chlorinated Polyvinyl Chloride (CPVC) Pipe : CPVC is used for potable water and drainage systems. It has the same characteristics as those of PVC and is used where a stronger piping system with higher pressure and temperature ratings is required.
CPVC pipe and fittings must conform to the following standards:
1. ASTM F 441, CPVC Plastic Pipe, Schedules 40 and 80
2. ASTM D 2846, CPVC Plastic Hot and Cold Water Distribution Systems
3. ASTM F 439, Socket-Type CPVC Plastic Pipe Fittings, Schedule 80
Polypropylene (PP) Pipe: This material is widely used for chemical drainage piping systems. PP pipe and fittings are manufactured from flame-retardant material and are available in Schedule 40 or 80. Joining methods include solvent cement joints, threaded joints, or mechanical-type joints. (Only Schedule 80 can be
threaded.)
Polyethylene (PE) Pipe: It is widely used for underground fuel gas and foundation drainage piping. It is joined by socket and butt heat fusion. .
Acrylonitrile-Butadiene-Styrene (ABS) Pipe : ABS is widely used as drainage pipe and is available in Schedules 40 and 80 with plain or socket ends. Joints are made by either solvent cement or threaded connections. Only Schedule 80 can be threaded.
ABS pipe and fittings must conform to ASTM Standard D 2661, ABS Schedule 40 Plastic Drain, Waste, and Vent Pipe and Fittings.
IN BRIEF
• What Is the Manufacturing Process for PVC Pipes?
1. Chemical Combination :
Polyvinyl chloride (PVC) is created from a combination of vinyl and plastic. Experiments to create a vinyl chloride polymer were first done in the mid-1830s, but the solid product created in the lab was simply an oddity, without any apparent use at that time. Additional experimentation in the 1880s reproduced a solid that withstood high heat exposure, but it was ignored in commercial applications due to the inflexibility of the product. Not until the 1920s did scientists attempt to use co-polymers of vinyl chloride. These were easier to produce and created an extremely durable substance. The first experimental pipes made from a co-polymer of polyvinyl chloride were first produced in 1932. Three years later, commercial production began. The first commercial pipes were used in applications to transport water, sewage and waste water, and for the movement of chemicals.
2. Preparing Ingredients :
The first step in manufacturing PVC pipes is to prepare the ingredients. PVC is created in a chemical process that bonds the vinyl and chloride. The process involves the polymerization of monomer vinyl chloride (VCM). Most manufacturers use suspended polymerization that involves use of a polymerization reactor to mix chemicals and a polymerization initiator. The resulting PVC resin is suspended in water and then removed for degassing and water removal, which is accomplished by use of a centrifuge. The product is then dried and turned into a granulated dust for transportation to the manufacturing plant, where it will be heated to the melting point. Early manufacturing melted the dry powder as a sheet on a roll mill. Once this was done it was molded into a solid product that was ready to be rolled.
3. Additives :
Early PVC production created a rigid and stiff product. As a result of experimentation with other polymers and oil products during the 1950s and the subsequent decades, the PVC product improved dramatically. While formulas for PVC are patented by individual companies, most modern PVC ingredients include various types of stabilizers and lubricants to facilitate processing. Colors are also added during the manufacturing process to indicate the appropriate use of the piping. Dark grey pipe is used for industrial pressure applications, white and blue pipes indicate cold water uses, and green is used for sewer applications.
4. Extrusion :
While rolled PVC was produced beginning in the 1930s, no extrusion process to form PVC pipe was perfected until the 1950s and 1960s. Modifications to such processes are still underway, but today there are two predominant types of PVC pipe--cellular core and solid wall. Three separate layers are extruded to create the cellular core pipe, with hard outer layer walls sandwiching a cellular core center. All three layers are immediately incorporated into one pipe during the manufacturing process. Solid wall PVC pipes are formed in a single manufacturing step. PVC pipe is extruded to meet industry-standard 10 and 20 foot lengths. Pipes are tested for compliance with industry and government standards for durability and the ability to withstand pressure.
Plastic : A material which contains as an essential ingredient an organic substance of high to ultrahigh molecular weight, is solid in its finished state, and at some stage of its manufacture or processing can be shaped by flow. The two general types of plastic are thermoplastic and thermosetting.
There are many types of plastic pipe, both rigid and semirigid. Under normal conditions, rigid plastic pipe can be supported using conventional supports with the spacing half that used with steel pipe or as recommended by pipe manufacturers.
The support of plastic pipe or tubing should be continuous if, owing to the nature of the plastic, it will become flexible from elevated temperatures or from line contents. The continuous support can be in the form of a light angle or channel into which the plastic pipe is laid.
In some cases, wear shoes or pads should be added to plastic pipe where it may rub against steel supports. The use of wear pads will prevent the abrasive action caused by thermal movement, thus preventing damage to the pressure boundary.
It is suggested that recommendations of the manufacturer of the specific plastic
pipe also be followed.
Plastic piping is made from either of two basic groups of synthetic materials, thermoplastic and thermosetting. Thermoplastics can be softened and reshaped repeatedly by the application of heat. In contrast thermosetting materials are irreversibly set, or cured, or hardened into a permanent shape during factory manufacture.
Once hardened into their final shape, thermosetting products cannot be softened and therefore may not be reshaped by heating. Thermoplastic materials include minimal reinforcements, whereas thermosetting resins are almost always combined with reinforcements (such as glass fibers) and sometimes fillers (such as sand) to produce structurally integrated composite constructions.
Due to its excellent material characteristics and its outstanding price / performance ratio, until today PVC is the most used material worldwide for pipes or profiles made from plastics.
As the market is very competitive manufacturers of RPVC/UPVC pipes or profiles have been exposed to increasing pressure on prices and costs for years.
At the same time higher and higher demands are made on the product quality.
Plastic Pipe and Fittings :
General. Plastic pipe is manufactured in a great variety of compositions, many of which are suitable for plumbing systems. The applicable code is the most important factor in selecting the type of plastic pipe for any specific purpose. All plastic pipe, components, and jointing methods used in potable water systems must be approved by the NSFI. Plastic pipe must be closely integrated with the selection of hangers and the entire pipe support system.
The advantages of plastic pipe include excellent resistance to a wide variety of chemical and waste effluents, resistance to aggressive soils, availability in long lengths, low resistance to fluid flow, and low initial cost. Disadvantages include poor structural stability (requiring additional supports), lower pressure ratings at elevated temperatures, susceptibility of some types of plastics to physical changes due to exposure to sunlight, low resistance to solvents, and production of toxic gases released upon combustion of some types of plastics.
Three designations are used to express pressure rating and wall thickness: schedule (dimensions are outside-diameter-controlled, matching iron pipe size); standard dimensional ratio (SDR) (a pressure rating only); and dimensional ratio (a pressure rating only using nonstandard dimensional ratios). Where the pressure rating is the prime consideration, the abbreviation PR is used.
Polyvinyl Chloride (PVC) Pipe: PVC is used for potable water and drainage systems. It is one of the most widely used of the plastic pipes. It has a low pressure and temperature rating and very poor resistance to solvents.
PVC pipe and fittings must conform to the following standards:
1. ASTM D 1785, PVC Plastic Pipe, Schedules 40, 80, and 120
2. ASTM D 2241, PVC Pressure-Rated Pipe (SDR Series)
3. ASTM D 2466, PVC Plastic Pipe Fittings, Schedule 40
4. ASTM D 2467, Socket-Type PVC Plastic Pipe Fittings, Schedule 80
5. ASTM D 2665, PVC Drain, Waste and Vent Pipe and Fittings
Chlorinated Polyvinyl Chloride (CPVC) Pipe : CPVC is used for potable water and drainage systems. It has the same characteristics as those of PVC and is used where a stronger piping system with higher pressure and temperature ratings is required.
CPVC pipe and fittings must conform to the following standards:
1. ASTM F 441, CPVC Plastic Pipe, Schedules 40 and 80
2. ASTM D 2846, CPVC Plastic Hot and Cold Water Distribution Systems
3. ASTM F 439, Socket-Type CPVC Plastic Pipe Fittings, Schedule 80
Polypropylene (PP) Pipe: This material is widely used for chemical drainage piping systems. PP pipe and fittings are manufactured from flame-retardant material and are available in Schedule 40 or 80. Joining methods include solvent cement joints, threaded joints, or mechanical-type joints. (Only Schedule 80 can be
threaded.)
Polyethylene (PE) Pipe: It is widely used for underground fuel gas and foundation drainage piping. It is joined by socket and butt heat fusion. .
Acrylonitrile-Butadiene-Styrene (ABS) Pipe : ABS is widely used as drainage pipe and is available in Schedules 40 and 80 with plain or socket ends. Joints are made by either solvent cement or threaded connections. Only Schedule 80 can be threaded.
ABS pipe and fittings must conform to ASTM Standard D 2661, ABS Schedule 40 Plastic Drain, Waste, and Vent Pipe and Fittings.
IN BRIEF
• What Is the Manufacturing Process for PVC Pipes?
1. Chemical Combination :
Polyvinyl chloride (PVC) is created from a combination of vinyl and plastic. Experiments to create a vinyl chloride polymer were first done in the mid-1830s, but the solid product created in the lab was simply an oddity, without any apparent use at that time. Additional experimentation in the 1880s reproduced a solid that withstood high heat exposure, but it was ignored in commercial applications due to the inflexibility of the product. Not until the 1920s did scientists attempt to use co-polymers of vinyl chloride. These were easier to produce and created an extremely durable substance. The first experimental pipes made from a co-polymer of polyvinyl chloride were first produced in 1932. Three years later, commercial production began. The first commercial pipes were used in applications to transport water, sewage and waste water, and for the movement of chemicals.
2. Preparing Ingredients :
The first step in manufacturing PVC pipes is to prepare the ingredients. PVC is created in a chemical process that bonds the vinyl and chloride. The process involves the polymerization of monomer vinyl chloride (VCM). Most manufacturers use suspended polymerization that involves use of a polymerization reactor to mix chemicals and a polymerization initiator. The resulting PVC resin is suspended in water and then removed for degassing and water removal, which is accomplished by use of a centrifuge. The product is then dried and turned into a granulated dust for transportation to the manufacturing plant, where it will be heated to the melting point. Early manufacturing melted the dry powder as a sheet on a roll mill. Once this was done it was molded into a solid product that was ready to be rolled.
3. Additives :
Early PVC production created a rigid and stiff product. As a result of experimentation with other polymers and oil products during the 1950s and the subsequent decades, the PVC product improved dramatically. While formulas for PVC are patented by individual companies, most modern PVC ingredients include various types of stabilizers and lubricants to facilitate processing. Colors are also added during the manufacturing process to indicate the appropriate use of the piping. Dark grey pipe is used for industrial pressure applications, white and blue pipes indicate cold water uses, and green is used for sewer applications.
4. Extrusion :
While rolled PVC was produced beginning in the 1930s, no extrusion process to form PVC pipe was perfected until the 1950s and 1960s. Modifications to such processes are still underway, but today there are two predominant types of PVC pipe--cellular core and solid wall. Three separate layers are extruded to create the cellular core pipe, with hard outer layer walls sandwiching a cellular core center. All three layers are immediately incorporated into one pipe during the manufacturing process. Solid wall PVC pipes are formed in a single manufacturing step. PVC pipe is extruded to meet industry-standard 10 and 20 foot lengths. Pipes are tested for compliance with industry and government standards for durability and the ability to withstand pressure.
No comments:
Post a Comment