Water & Sewer Glossary



Air ValvesAir Valves allow the ingress/escape of air either when filling or draining a pipeline or whilst in operation under working pressure.
Anti-clockwise close (valves): Spindle rotates in an anti-clockwise direction, when viewed from above, to the closed position
Allowable operating pressure
Abbreviation: PFAMaximum hydrostatic pressure that a component is capable of withstanding continuously in service [EN 545]
Allowable test pressure
Abbreviation: PEAMaximum hydrostatic pressure that a newly installed component is capbale of withstanding for a relatively short duration, in order to ensure the integrity and tightness of the pipeline[EN 545]
Allowable maximum operating pressure
Abbreviation: PMAMaximum pressure occuring from time to time, including surge, that a component is capable of withstanding in service [EN 545]
Adjustable flangeAn adjustable flange consists of a ring, in one or several parts assembled together, which bears on an end joint hub and can be freely rotated around the pipe axis before jointing.


Butterfly Valves: A butterfly valve is a valve used for flow regulation in which the flow control takes the form of disc. Operation is similar to that of a ball valve, which allows for quick shut off. Butterfly valves are favoured because they are lighter than ball valves. A plate or disc is positioned in the center of the pipe. Passing through the disc is a rod connected to an gear box or actuator on the outside of the valve. Rotating the rod turns the disc either parallel or perpendicular to the flow.
Backfill: Material used to refill an excavated trench, in particular the material between the embedment material and ground level
BS EN 545: British ratified European Standard for 'Ductile iron pipes, fittings, accessories and their joints for water pipelines - Requirement and test methods'
BS EN 598: British ratified European Standard for 'Ductile iron pipes, fittings, accessories and their joints for sewerage applications - Requirement and test methods'



Clockwise close (valves): Spindle rotates in a clockwise direction, when viewed from above, to the closed position



Depth of coverVertical distance from the top of the pipe barrel to the surface
Ductile ironAn iron/carbon/silicon alloy. When magnesium is added to the molten iron the graphite forms in spheres rather than flakes. This transformation virtually eliminates brittleness and produces a strong ductile material
DNNominal diameter
DWIDrinking Water Inspectorate - administers the compliance of materials to Regulation 31: all materials that can come into contact with potable water, including pipe linings, lining repair material, joints and jointing lubricants must comply with the requirements of Regulation 31 of The Water Supply Regulations, England and Wales (6), or The Water Supply Regulations for Scotland (7).



External diameter [OD]External dimension of the pipe barrel at any cross section.
EmbedmentFill material around the pipe including bedding, sidefill and initial backfill
EPDMA type of synthetic rubber(ethylene propylene diene monomer) widely used for gaskets in contact with potable water. 
EPDM has a low compatibility with oils and aromatic hydrocarbons and is not generally recommended for use with effluents (use nitrile rubber gaskets)



Flap ValvesThe primary application of flap valves is for surface water drainage associated with rivers, estuaries and sea water outfalls to prevent reverse flow conditions. Flap valves can also be utilised on final effluent outfalls for sewage treatment plant to prevent flood damage within the works.
Fabricated PipeSaint-Gobain PAM UK offers a range of fabricated pipe tailored to customer requirements. Flange spigot, flange socket and double flanged pipes are available in a variety of lengths in diameter range DN 80-DN 2000 for both water and sewer application.
FlangeFlat circular end of a pipe or fitting extending perpendicular to its axis, with bolt holes equally spaced on a circle.- Note: a flange can be fixed (e.g. integrally cast or welded) or adjustable; an adjustable flange consists of a ring, in one or several parts assembled together, which bears on an end joint hub and can be freely rotated around the pipe axis before jointing.



Gasket: The rubber sealing component of a joint



Internal diameter [ID]Internal dimension/diameter of the pipe
InvertLowest point of the internal surface of the barrel of a pipe or channel at any cross section
Initial backfillLayer of backfill material immediately above the crown of the pipe



JointConnection between the adjacent ends of two components including the means of sealing



KameleoModular and variably angled, Kameleo offers contractors the real possibility of saving time, effort and money, even on challenging sites.
Normally, a combination of hard bends (45°, 22.5° and 11.25°) are used to connect pipes which do not make a specific angle. Kameleo is different - its continuously variable angle from 0 to 45° means that using two, three or more bends is a thing of the past. Kameleo is a variable angle bend with a variety of connection kits for the ultimate in flexibility and simplified logistics.



Length, effectiveIn practical terms, the effective length of a pipe or fitting is the increase in layed length of a pipeline from installation of the pipe or fitting.
For flanged pipes and fittings, the effective length L, is the same as the overall length.
For socketed pipes and fittings, the effective length Lu, is equal to the overall length minus the maximum spigot insertion depth.



Nominal diameter [DN]Nominal internal diameter (DN/ID) or external diameter (DN/OD)
Nitrile: Acrylonitrile Butadiene Rubber, usually shortened to Nitrile, was developed in 1941 as the first oil resistant rubber. It is the recommended gasket material for effluent applications because of its resistance to oils and aromatic hydrocarbons.
Non-return valveA non-return valve (also known as a check valve, or one-way valve) is designed to allow liquid to flow through it in only one direction.


Pipe barrelCylindrical part of the pipe excluding socket and spigot
Puddle flange: Where pipes pass through the wall of a building or chamber, a puddle flange may be required to reduce the risk of water passing through the wall. A puddle flange is a plain flange fitted to the barrel of the pipe, which is cast into the structure wall.
PFA: see 'Allowable operating pressure'
PEA: see 'Allowable test pressure'
PMA: see 'Allowable maximum operating pressure'




Resilient Seated Gate ValvesResilient seated gate valves are designed to isolate one section of pipeline from another. The resilient seated gate valve wedge is fully rubberised with vulcanised rubber.
Repair ClampsFor the temporary repair of localised cracks and breakages in pipelines.
Resistivity, soilSoil resistivity is a function of soil moisture and the concentrations of ionic soluble salts and is considered to be most comprehensive indicator of a soil’s corrosivity. Typically, the lower the resistivity, the higher will be the corrosivity. We offer a soil resistivity survey service that is WRc approved and a range of proven external active and barrier coatings to suit all ground conditions.




Swing Check Valvesee 'Non-return valve'
Sewerage Air ValveThe valve is suitable for the bulk release or ingress of air whilst filling or draining the line and the release of trapped air whilst the line is under operating pressure. Fouling of the orifice is eliminated by the use of a large float chamber which confines the liquid within the bottom, therefore preventing any leakage of solids into the atmosphere.
SewerPipeline or other construction, usually underground, designed to carry wastewater from more than one source
SidefillMaterial at the side of the pipe between bedding and initial backfill
Spheroidal graphite ironAlternative name for ductile iron. See entry for 'Ductile iron'
SpigotMale end of a pipe or fitting
SocketFemale end of a pipe or fitting to make the connection with the spigot of the next component