A AirA AbsoluteAC Air to CloseAC CombustionAC Air ConditionerAGA American Gas AssociationAI Instrument AirAISC American Institute of Steel ConstructionANSI American National Standard InstituteAO Air to OpenAP Plant AirAPI American Petroleum InstituteASA American Standard AssociationASME American Society of Mechanical EngineersASTM American Society of Testing MaterialsAWS American Welding SocietyAWWA American Water Works Association

BBE Beveled Both EndsBC Bolt CircleBF Blind / Blank FlangeBLE Beveled Large EndBLVD BeveledBOF Bottom of Face of FlangeBOP Bottom of PipeBSE Bevelled Small EndBW Butt Weld

C CentigradeC-C Centre to CentreCFM Cubic Feet per MinuteCI Cast IronCL Centre LineCr ChromiumCS Carbon SteelCS Cold SpringCSO Car-Seal OpenCTR CentreCV Control Valve

DIA DiameterDIM DimensionDS Dummy SupportDWG DrawingDRG Drawing

E EastE-E End to EndEL ElevationEL ElbowELB ElbowletELL ElbowERW Electric Resistance Welding

F FahrenheitFAB FabricationF&D Face & DrilledFF Face to FaceFF Flange FaceFF Flat FaceFF Full Face (of Gasket)FLG Flange FaceFOB Flat on BottomFOT Flat on TopFS Far SideFS Field SupportFTG FittingFW Field WeldG GasGalv GalvanisedGPM Gallons Per MinuteGR Grade

HDR HeaderHEX HexagonHg MercueyHPT Hose Pipe ThreadHP High PointHP High PressureHTR HeaterHVAC Heating Ventilation and Air Conditioning

ID Inside DiameterIE Invert ElevationIMP ImperialINS InsulationINST InstrumentationIPS Iron Pipe SizeIS&Y Inside Screw and YokeISO Isometric Drawwing

LA Level AlarmLC Level ControllerLG Level GuageLI Level IndicatorLP Low PressureLP Low PointLR Long RadiusLS Level SwitchLT Level TransmitterLT Light Wall (pipe)

M MeterMS Mild Steel

N NorthNC Normally ClosedNO Normally Open

NPS National Pipe SizeNPS Nominal Pipe SizeNPT National Pipe ThreadNRS Non Rising StemNS Near Side

OD Outside DiameterOS&Y Outside Screw and Yoke

P&ID Piping and Instrumentation DiagramPBE Plain Both EndsPC Pressure ControllerPCV Pressure Control ValvePE Plain EndPI Pressure IndicatorPOE Plain One EndPR Pressure RegulatorPRV Pressure Reducing ValvePS Pipe SupportPSI Pounds per Square InchPSV Pressure Safety Valve

R RadiusRED ReducerRED ReducingREF ReferenceREQ RequiredRF Raised FaceRJ Ring JointR/L Random LengthRS Rising StemRT Reducing Tee

S SouthS SteamSC Sample ConnectionSC Steam CondensateSCH ScheduleSECT SectionSMLS SeamlessSO Slip-OnSOL SockoletSP Sample PointSP Set PointSP Steam PressureSpec SpecificationSQ SquareSR Short RadiusSS Stainless SteelST Steam TracingSTD StandardSW Socket WeldSWG SwageSWP Standard Working Pressure

T ThreadedT Steam TrapT TemperatureTBE Threaded Both EndsTC Temperature ControllerTC Test ConnectionTE Threaded EndTEF TeflonTOC Top of ConcreteTOL ThreadoletTOP Top of PipeTOS Top of SupportTOS Top of SteelTPI Threads Per InchTYP Typical

UNC Unified Course ThreadUNF Unified Fine Thread

V ValveVERT Vertical

W WestW WaterW/ WithWC Water ColumnWE Wended EndWN Wenld NeckWOG Water, Oil, GasWOL WeldoletWP Working PressureWP Working PointWT Weight

XH Extra HeavyXS Extra StrongXXH Double Extra HeavyXXS Double Extra Strong