Piping Systems
Throughout history, the need for freshwater has played a critical role in the development of human civilization. The Romans built massive gravity-fed aqueducts to direct water for farmland, mining, drinking, and even bathing pools and fountains. Innovations like the water wheel and mechanical pump further pushed water to new heights and applications. Eventually, the perfection of pipe has let us branch out across the world bringing our water supply along in tow.
Legacy Piping Systems
The origins of pipe date back to the Roman empire. Lead pipe was originally conceived for its ability to be easily formed and cost-effective maintenance. Despite our modern understanding of the health hazards associated with lead poising many of the adverse consequences of lead pipe were never fully understood. Lead water pipes have been installed in homes as late as the early 20th century and some lines remain in service today.
Wooden water mains have been known to be used as early as the 13th century to transmit water to villages. These systems were often made from Elm and originally relied on elevated streams to feed water with gravity. Boston was the first city in the United States to install wooden water mains in 1652 and was considered a pioneer in water infrastructure. There are many problems with timber piping including rotting, warping, and insects however some wooden water mains are still found in use today.
Steel pipe was then introduced to replace wood and lead in the early 17th century as our steel manufacturing processes improved. Steel pipe is very corrosive, so it was found not to be a good choice of material for long term service.
In the early 19th century, cast iron pipe was introduced in many cities. Made from grey iron, was found to be very long lasting and durable. The initial design called for a flange type (flat face) end, mated with another flange using an elastomer gasket to seal the pipe sections. Cast iron pipe was first made by horizontally casting, then vertical and eventually centrifugally casting method which is the most common manufacture used today.
Ductile Iron Pipe
Ductile Iron pipe was introduced in the 1970’s as an alternative to cast iron. With the application of magnesium and improved casting techniques, it was found to have better strength and ductility. Today, it is used as the primary piping material used to transport raw and potable water, sewage, slurries, and process chemicals.
Lighter, stronger, and more durable than cast iron, ductile iron pipe uses a bell and spigot type mating system. Using a gasket to join the bell end to the spigot end, pipe sections can quickly and easily be mated for installation. Other configurations like mechanical joints use a following gland to bolt the spigot end of the pipe to the mechanical side.
Ductile iron pipe is centrifugally cast with the integral bell manufactured conforming to standard ANSI C150.A21.0
Ductile iron pipe is made with a cement mortar lining interior to resist the corrosion process and can be made with different thicknesses (or grades), depending on what is specified by the engineer.
Pipe classes on small diameters range from class 350 to class 56, higher classes having a thicker interior lining. Larger diameter pipe ranges from class 150 to class 56.
The outside of the pipe is generally applied with an asphalt coat to deter corrosion from the soil. Other available outside coatings include zinc, asphalt, or even water-based paints. If extra protection is required, Ploy sleeving (poly wrap) can be used to encase the pipe to protect from adverse soil conditions.
Ductile iron pipe is usually manufactured in 18’ or 20’ lengths and is available in 3”- 64” outside diameters. The spigot end of the pipe can be used with a mechanical joint or slip-on type fittings if the pipeline must curve or branch off for other transmission lines. Pipe can be manufactured as unrestrained or restrained using special gaskets and end configurations. Flange piping is also available (usually CL53 and above) cut to specific lengths for field cuts or inside work.
Ductile iron pipe is rated to have a 100 year plus life with the benefit of low maintenance. This makes ductile iron pipe more superior to other products on the market today. The manufacturing process for casting ductile pipe supports a controlled outside diameter. This allows for the pipe to mate with standardized fittings, couplings, and other ancillary piping products.
Ductile Iron Pipe Manufacturing Standard
Ductile Iron Pipe is a centrifugally cast product. A controlled amount of molten iron is introduced into the rotating mold, which generates a centrifugal force that holds the iron in place against the mold until it solidifies. The pipe is then removed and furnace-annealed to obtain the prescribed physical properties. The following acceptance test requirements set forth by ANSI/AWWA C151/A21.51 must be met before the pipe is declared ready for shipment
1. Tensile test:
Ultimate strength: 60,000 psi minimum
Yield strength: 42,000 psi minimum
Elongation: 10% minimum
2. Impact test:
7 ft.-lb. minimum at 70°F
3 ft.-lb. minimum at -40°F
3. Hydrostatic test:
Every piece of Ductile Iron pipe is subjected to a hydrostatic test of at least 500 psi before it leaves the foundry. In addition to these acceptance tests, Ductile Iron manufacturers conduct additional quality control. Tests throughout the manufacturing process ensure the highest-quality castings
Ductile Iron Pipe Standards
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ANSI/AWWA C104/A21.4
American National Standard for Cement-Mortar
Lining for Ductile Iron Pipe and Fittings for Water
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ANSI/AWWA C151/A21.51
American National Standard for Ductile Pipe Centrifugally Cast, for Water
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ANSI/AWWA C115/A21.15
American National Standard for Flanged Ductile Iron
Pipe with Ductile or Grey Iron Threaded Flanges
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ANSI/AWWA C105/A21.5
American National Standard for Polyethylene
Encasement for Ductile Iron Pipe Systems
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ANSI/AWWA C153/A21.53
American National Standard for Ductile Iron
Compact Fittings for Water Service
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ANSI/AWWA C150/A21.50
American National Standard for the Thickness Design of Ductile Iron Pipe
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ANSI/AWWA C110/A21.10
American National Standard for Ductile Iron and Grey
Iron Fittings, 3-Inch through 48-Inch for Water
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ANSI/AWWA C600
AWWA Standard for Installation of Ductile Iron
Water Mains and Their Appurtenances
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ASTM A716
Standard Specification for Ductile Iron Culvert Pipe
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ANSI/AWWA C110/A21.11
American National Standard for Rubber Gasket
Joints for Ductile Iron Pressure Pipe and Fittings
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ASTM A674
Standard Practice for Polyethylene Encasement
For Ductile Iron Pipe for Water or Other Liquids
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ASTM A746
Standard Specification for Ductile Iron Gravity Sewer Pipe
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Ductile Iron Pipe Standards
Ductile Iron Pipe Pressure & Thickness Class
Ductile Iron Pipe Size, Dimension and Pressure Rating
Ductile Iron Pipe Joints
Push-On Joint
Push on pipe joints are the easiest and most common method of connecting ductile iron pipe. This joining method was developed in the 1950s to provide a faster and easier assembly. Connecting the pipes forces a bottle tight seal around the gasket allowing this system to be used in wet and even submerged applications.
Mechanical Joint
Mechanical Joints were originally developed for the oil and gas industry in the late 1920s but have found a preference in water works. Despite being commonly replaced by the push-on joint, the mechanical joint is a convention method for joining pipe.
Restrained Joint
The restrained joint is a special variation of either the push-on or mechanical joint. Used in addition with thrust blocks, the restrained joint provides support against thrust forces due to internal pressures. The design of the restraint fits further past the initial joining region to anchor the joint to a more secure part of the pipe.
Flanged Joint
Flanged Joints are use in applications where installations are not flexible a rigidity is important. This method is typically used for above ground systems including open bays and pipe galleries. The flange connection utilizes a gasket between the two mating flanges surrounded by a series of bolts to create a seal.
Ball-and-Socket Joint
The ball and socket joint provides a blotless solution to joining pipe while also offering the most flexibility and deflection ( up to 15° per joint ). These joints can be used with the addition of a restraint to help prevent joint separation and add more strength to the pipeline. The versatility of the ball and socket joint lends this joint to commonly be employed for submerged uses or in areas with erratic elevations and grades changes.
Miscellaneous Joints
There are a variety of different Joints that are modified styles of mechanical joint or stuffing box configurations. These miscellaneous joints were developed for use with tapping sleeves, repair sleeves, couplings, connectors, and other related products
Ductile Iron Pipe Gasket Material
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Description
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Maximum Service Temperature (°F)
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Uses
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Water & Sewer
Push-On &
Mechanical
Joint Gaskets
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Air
Push-On
Joint Gaskets
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Mechanical Joint Gaskets
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SBR
(Styrene Butadiene)
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150°
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150°
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125°
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Common:
Drinking Water, Sea Water,
Sanitary Sewage, Reclaimed
Ware, Raw Water, Storm
Water
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EPDM
(Ethylene Propylene
Diene Monomer)
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212°
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200°
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150°
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Common:
Alcohols, Dilute Acids, Dilute
Alkalis, Ketones (MEK, Acetone),
Vegetable Oil
Other Drinking Water, Sea
Water, Sanitary Sewage,
Reclaimed Water, Raw Water
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Nitrile (NBR)
(Acrylonitrile Butadiene)
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150°
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150°
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125°
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Common:
Hydrocarbons, Fats, Oils, Greases,
Chemicals, Oils & Fluids, Refined
Petroleum
Others:
Drinking Water, Sanitary Sewage,
Reclaimed Water, Raw Water,
Storm Water
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Neoprene (CR)
(Polychloroprene)
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200°
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180°
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150°
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Common:
Greasy Waste
Other:
Sea Water Sanitary Sewage,
Reclaimed Water, Raw Water,
Storm Water
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Viton
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212°
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300°
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300°
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Common:
Aromatic Hydrocarbons,
Fuels, Acids, Vegetable
Oils, Petroleum Products,
Chlorinated Hydrocarbons,
Most Chemicals and Solvents.
Other:
Drinking Water, Reclaimed Water,
Raw Water, Storm
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Ductile Iron Pipe Linings
Ductile Iron Pipe installed in water systems today is normally furnished with a cement-mortar lining. Conforming to ANSI/AWWA C104/A21.4, the specifications for the cement-mortar lining strictly follow standards. Cement mortar lining prevents tuberculation by creating a high pH condition at the pipe wall as well as providing a barrier between the water and the pipe wall. Additionally, cement linings create a smooth surface inside the pipe, meaning less friction and thus less head loss. The Hazen-Williams coefficient, or “C” value, is 140 for Ductile Iron pipe with cement-mortar lining.
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Description
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Maximum Service
Temperature (°F)
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Uses
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Thickness
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Portland Cement Mortar
With Sealcoat
Without Sealcoat
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150°
212°
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Common:
Drinking Water
Sea Water
Non-Septic Gravity Sewers
Sanitary Sewers Force Mains
Reclaimed Water
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Standard or Double
(ANSI/AWWA C104/A21.4)
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Fusion-Bonded Epoxy
(Fittings Only)
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120°-150°
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Common:
Drinking Water
Non-Septic Gravity Sewers
Sanitary Sewer Force Mains
Reclaimed Water
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(ANSI/ AWWA C116/A21.16)
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Petroleum Asphalt
Coating
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150°
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Common:
Air
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1 mil (nominal)
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Ceramic Quartz Filled Amine Cured Novalac Epoxy
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120°-150°
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Common:
Septic Sewers
Acids
Alkali Waste
Pickling Brine
Other:
Reclaimed Water
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40 mil
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PVC Pipe
Piping systems used for our water and sewer infrastructure are designed to last. Our municipal infrastructure must be economical and demand a piping system proven to function without considerable service. PVC pipe has become the clear choice for many pipe systems. Today, PVC pipe is utilized over twice as much as any other pipe material for its durability, corrosion resistance and ease of installation.
PVC Pipe connections
The most common used PVC pipe available C900 for in 4”-60” at standard 20” lengths. PVC pipe is the same diameter as ductile and cast-iron pipe. This allows for it to be used with C153 standard mechanical joint fittings or C900 injection molded or fabricated fittings supplied with integral bell socket to accept spigot end. PVC is typicaly fitted with a Gasketed Integral bell (IB) and a standard SBR Gasket. Other options can be supplied with a one end restrained joint and a spigot joint on the other end.
PVC water Pipes are to NSF61 approved with cell classification of 12454 with ASTM D1784 conformance. Standard inside dimensions are DR51-DR14 which is based on pressure ratings (80-305PSI) with DR18 (235 PSI) being most used.
*SDR OR DR is the standard dimension or in other words, the ratio of pipe diameter to the wall thickness. The lower the SDR, the larger the wall thickness.
Another type of PVC pipe used, however less common, is D2241 water pipe. Available from in 1-1/2”-12” iron pipe size (IPS), it follows CL160 (SDR26) or CL200 (SDR21). This pipe is supplied with a gasketed integral bell and spigot end for joining. This pipe can also be used with mechanical joint fittings, but a transition gasket must be used due to being iron pipe size.
INTEGRAL BELL PVC PIPE
Integral Bell & Spigot design is excellent for open-cut applications where the affordability and durability of PVC are required.
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Pressure Pipe
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Pipe Size
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DR
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Pressure Class
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CIOD: AWWA C900
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30”, 36”
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51
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80 psi
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Potable Water
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16” – 36”
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41
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100 psi
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Force Main & Reclaim
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16” – 36”
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32.5
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125 psi
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4” – 36”
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25
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165 psi
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14” – 36”
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21
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200 psi
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4” – 30”
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18
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235 psi
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4” – 16”
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14
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305 psi
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IPS: ASTM D2241
Potable Water, Main & Reclaim
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1.5” – 12”
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SDR 13.5 – 41
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100 – 315 psi
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PSM: ASTM D3034
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4” – 15”
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SDR 35
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46 psi
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4” – 15”
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SDR 26
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115 psi
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4”, 6”
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SDR 23.5
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153 psi
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PSM: ASTM F679
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18” – 36”
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PS 46
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46 psi
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18” – 36”
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PS 115
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115 psi
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Types of PVC Pipe
Schedule Pipe
Schedule pipe comes is Iron Pipe Size (IPS) with an Outside Diameter (OD) and a wall thickness that matches the steel pipe sizes. This pipe is available in Schedules 40, 80, and 120. The higher the Schedule number, the thicker the pipe wall. Scheduled pipe pressure ratings vary with each pipe diameter with pressure ratings decreasing as pipe diameter increases. Most applications will focus on Schedules 40 and 80 PVC
Standard Dimension Ratio (SDR) Pipe
Standard dimension ratio (SDR) pipe is mostly based on the IPS-OD system. The SDR is the ratio of pipe diameter to the wall thickness or the OD divided by the wall thickness. For a given SDR, the pressure ratings and pipe stiffness values are constant for all pipe sizes. Nonstandard dimension ratios (DR) can be computed for any pipe OD and wall thickness.
Pipe Markings
Fitting markings may vary slightly because of the limitation of space but in most cases, there will be some way of identifying the pipe. All PVC piping are marked with ASTM standards, manufacturer’s name, pipe size, material and certification organization where. Specific applications may show required codes such as reclaimed water or DWV.
DWV Pipe Markings
PVC Schedule 40 DWV piping is marked in several different ways depending on the piping pressure ratings and pipe structure. (There is 3.25-inch OD pipe, but it is rarely used in commercial or industrial construction.) Listed below are PVC DWV markings and pipe descriptions:
DWV—cellular core: ASTM F 891, PVC pipe with a cellular core has the PVCDWV along with additional marking “IPS SCHEDULE 40 SERIES COEX CELLULAR CORE PVC-DWV.”
DWV—dual marked: ASTM D 1785 and ASTM D 2665 conformance allows for Schedule 40 PVC DWV solid wall pipe to be dual marked for both DWV and potable water pressure pipe. Dual marked PVC DWV piping can be triple marked with the addition of ASTM F 480. None of the other DWV pipes are pressure rated.
Storm Sewer Pipe
Storm sewer pipe is available in concrete, PVC, clay, and HDPE pipe. PVC sewer pipe is most used in the sanitary sewer industry for residential and industrial application. The most commonly used pipe is SDR35 (46 psi) and SDR26 (115 psi) with gasketed integral bell and spigot end. This pipe is made in 4”-36” and is listed as D3034, cell class of 12454. Storm pipe is a fed gravity pipe and is not to be used in any pressure application. Standard lengths are 14’ or 20’ and often colored is green for identification purposes. This pipe is also available with solvent weld ends included with or without perforations for drainage applications. Gasketed and solvent weld fittings are available SDR35 and SDR26 in the form of tees, bends, adaptors, reducers/increasers.
Reinforced Concrete Pipe (RCP)
Introduced in the 1940’s, reinforced concrete pipe (RCP) is prestressed steel cylinder mesh surrounded by concrete. Pipe sizes available are 6”-144” with mastic ends or gasketed (O-ring) joint. This pipe has a bell on one end and a spigot on the other to join pipe. Fittings are available but usually used in a manhole to manhole connection. Pipe lengths are 8’ and are available in round or elliptical shape, designated with classes of I-V (1-5) depending on D-load required and bury depths and loads.
Clay Pipe
Clay pipe has been in use since the Mesopotamians, but first readily used in the 17th and 18th century for the removal of wastewater. The first use of clay pipe in the United States was in the 1850’s in Chicago, where it is still used for storm drainage. Clay pipe is available in 4”-24” and can be supplied with O-ring Joint for 8’ lengths. Clay pipe must conform to C425 standards for deflection. Clay pipe is generally used in storm sewer applications.
HDPE Pipe
HDPE pipe is another type of pipe available for storm use. Made from high density polyethylene (HDPE) pipe with corrugated outsides, it has a 100+ year life expectancy. HDPE pipe is available in 4”-60” diameters for 13’ or 20’ lengths in either single wall or dual wall (N-12 smooth wall interior) depending on drainage needs. This pipe can be supplied as plain end, soil-tight with integral bell or watertight with integral bell. Fittings come available in bends, tees, and adaptors. HDPE is used in manhole to manhole application as well as culvert pipe and to retention ponds or retention systems.
Steel Pipe
Steel pipe is also used in culverts and drainage applications. Corrugated metal pipe (CPM) is available in corrugated or smooth interior and has a life expectancy of 100+ years. This pipe is supplied in standard 20’ lengths but special lengths up to 40’ and smaller are available. Joining of the pipe is typically done with a steel coupling band with bolt and nut.
