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Terms and definitionsTerms and definitions usedthroughout this technical manualcomply (as much as possible) withthe latest terms and definitionsused in the European standards.Allowable operating pressure(PFA)Internal pressure, exclusive ofsurge that a component can safelywithstand in permanent service(see EN 805), often referred to asworking pressure.Allowable test pressure (PEA)Maximum hydrostatic pressurethat a newly installed componentcan withstand for a relatively shortduration, when either fixed aboveground level or laid and backfilledunderground in order to measurethe integrity and tightness of thepipeline (see EN 805), often referredto as test pressure.Note:This test pressure is different fromthe system test pressure (STP),which is related to the designpressure of the pipeline, and isintended to ensure the integrity andleak tightness of a certain fittinginstalled.Nominal pressure (PN)Numerical designation expressedby a number, which is used forreference purposes.Nominal size (DN diameter nominal)Numerical designation of size, whichis common to all components ina piping system. It is a convenientround number for referencepurposes and is only loosely relatedto manufacturing dimensions (seeEN ISO 6708).Outside diameter (OD)Outside diameter of the pipe(s) to beconnected.182Depth of engagementMinimum distance between anypoint of the spigot end and theinternal face of the joint gasket.Ductile ironCast iron used for pipes, fittings andaccessories in which graphite ispresent, mainly in spheroidal form.FittingCasting other than a pipe, whichallows pipeline deviation, changeof direction or bore. In additionflanged socket pieces, flangedspigot pieces and collars are alsoclassified as fittings.FlangeFlat circular end of a fitting or pipeextending perpendicular to its axis,with bolt holes equally spaced in acircle.Flexible jointJoint which permits significantangular deflection both during andafter installation and which canaccept a slight offset of thecentreline.GasketSealing component of a joint.JointConnection between the ends oftwo pipes and/or fittings in which agasket is used to effect a seal.Joint angular deflectionAngle between the axis of twoconnected pipe components, whicha flexible joint can accommodate.Joint gapMaximum axial distance betweenany point of the spigot ends of thepipes to be connected (coupling), or,maximum axial distance betweenany point of the spigot end of the pipeand the flange face (flange adaptor).Large tolerance couplingFitting intended for use with pipes ofvarious materials which:• is used in a pipeline to make theconnection between two spigotsof pipes, fittings or valves• allows for radial and axialdisplacements in order tofacilitate easy assembly.Large tolerance flange adaptorFitting intended for use with pipes ofvarious materials which:• is used in a pipeline to makethe connection with a spigot ofa pipe or a fitting and the flangeof another component of thepipeline (e.g. pipe, fitting, valve• allows for radial and axialdisplacements in order tofacilitate easy assembly.Large tolerance stepped or reducercouplingLarge tolerance coupling intended foruse with pipe components of differentnominal sizes.Performance testProof of design test, which is doneonce and is repeated only afterchanging the design.Restraint flexible jointFlexible joint in which a means isprovided to prevent separation of theassembled joint.Dimensions and unitsAll dimensions used in this catalogueor other documentation are indicatedin mm and/or inches and arespecified as nominal or standardsizes. We reserve the right to alterdesign of fittings.