1. PURPOSE
1.1 This engineering standard defines a common system of terminology and abbreviations to clearly and accurately communicate engineering information on project flowsheets (F/S) and/or piping and instrumentation diagrams (P&IDs).
2. Scope
2.1 This standard applies to all project flowsheets/P&IDs unless otherwise required by a customer.
2.2 Refer to the ASHRAE and BSI information sources, listed in Section 3, for Standard (SI) Units of Measure.
3. RELATED DOCUMENTS
3.1 Air Products Engineering Documents 3SEF0011 Fluid Codes for Use on P&IDs
3.2 American Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc. (ASHRAE) 1993 ASHRAE Handbook Fundamentals I-P Edition
3.3 British Standards Institution (BSI) BS ISO 80000-1 Quantities and Units – Part 1: General
3.4 The above listed documents are referenced herein and shall apply as specifically designated. Latest edition and addenda in effect shall apply.
4. GENERAL
4.1 Terms that may be abbreviated on project flowsheets/P&IDs are listed in Table 1.
4.2 Abbreviations that may be used on project flowsheets/P&IDs are listed in Table 2.
4.3 Letters are sometimes used to form parts of some other symbols, as in the case of instrumentation. These letters are not considered abbreviations and are not identified in this standard. Refer to a standard ANSI/ISA or DIN flowsheet legend to determine the meanings of symbols.
4.4 Refer to 3SEF0011 for fluid/service abbreviations.
4.5 Unless otherwise indicated, the same abbreviation shall be used for all tenses, for participle endings, for the possessive case, for singular and plural, and for the noun and the modifying forms of a term.
4.6 An abbreviation of a word combination shall not be separated for use individually. For example, the abbreviation FH (flexible hose) shall not be split to use F for flexible and H for hose.
4.7 Abbreviations listed in this standard may be used on project flowsheets/P&IDs with or without explanation.
4.8 Abbreviations that are not listed in this standard may only be used if their meanings are given in a legend that is included on the project flowsheet/P&ID. If this new abbreviation needs to be part of this standard, contact the owner of this standard for approval.
Table 1 Terms and Their Abbreviations
| Term | Abbreviation |
| Aboveground | AG |
| Bottom Dead Center | BDC |
| Bottom of Line | BOL |
| Bubble Diagram | BBD |
| Building | BLDG |
| Burner Management System | BMS |
| Calorimeter | CAL |
| Car Seal Closed | CSC |
| Car Seal Open | CSO |
| Cathode Ray Tube | CRT |
| Central Plant Monitoring | CPM |
| Central Processing Unit | CPU |
| Close | CLS |
| Closed | CLD |
| Cold Box | CB |
| Column Can | COL CAN |
| Compander | COMPDR |
| Compressor | COMPR |
| Computer | COMP |
| Computer Automatic Manual Station | CA/M |
| Computer Manual Station | CM |
| Crossover | XOVER |
| Crude Argon | CAR |
| Current To Pneumatic Transducer | I/P |
| Defrost | DF |
| Distributed Control System | DCS |
| Drain | D |
| Duplex Temperature Element | DTE |
| Electric Trace | TEL |
| Electrical | EL |
| Enclosure | ENCL |
| Expansion Joint | EJ |
| Fail Closed | FC |
| Fail Last | FL |
| Fail Open | FO |
| Field | FLD |
| Flexible Hose | FH |
| Flowsheet | F/S |
| Foundation Fieldbus | FF |
| Full Port | FP |
| Function Block Diagram | FBD |
| Gaseous Argon | GAR |
| Gaseous Nitrogen | GAN |
| Gaseous Oxygen | GOX |
| Heater | HTR |
| Helium Rejection Unit | HRU |
| High Point | HPT |
| High Pressure | HP |
Table 1 (continued)
| Term | Abbreviation |
| Inside | I/S |
| Inside Battery Limits | ISBL |
| Inside Cold Box | ISCB |
| Inside Diameter | ID |
| Inspection Port | IP |
| Instrument Air Supply | IAS |
| Instrument Control Tubing | ICT |
| Insulated | INS |
| Interlock Close | ILC |
| Interlock Logic Diagram | ILD |
| Interlock Open | ILO |
| Liquid Argon | LAR |
| Liquid Helium | LHe |
| Liquid Hydrogen | LH2 |
| Liquid Nitrogen | LIN |
| Liquid Oxygen | LOX |
| Load Relay | LR |
| Lock Closed | LC |
| Lock Open | LO |
| Low Point | LPT |
| Low Pressure | LP |
| Low Temperature Diode | LTD |
| Lower Explosive Limit | LEL |
| Main Air Compressor | MAC |
| Maintain De-energized | DE-EN |
| Maintain Energized | EN |
| Malfunction | MALF |
| Manhole | MH |
| Medium Pressure | MP |
| Millivolt to Current Transducer | E/I |
| Momentary Start Signal | MST |
| Momentary Stop Signal | MSP |
| Motor Control Center | MCC |
| Motor Operated Valve | MOV |
| Nitrogen Rejection Unit | NRU |
| Normally Closed | NC |
| Normally Open | NO |
| Open | OP |
| Opened | OPD |
| Operator Interface Unit | OIU |
| Ortho/Para | O/P |
| Outside | O/S |
| Outside Battery Limits | OSBL |
| Outside Cold Box | OSCB |
| Outside Diameter | OD |
Table 1 (continued)
| Term | Abbreviation |
| Piping and Instrumentation Diagram | P&ID |
| Process Flow Diagram | PFD |
| Pneumatic | PNEU |
| Pneumatic To Current Transducer | P/I |
| Pressure | PRESS |
| Pressure Tap | PT |
| Process Control Unit | PCU |
| Programmable Logic Controller | PLC |
| Pure Argon | PAR |
| Pushbutton | PB |
| Removable Spool | RS |
| Resistance Temperature Detector | RTD |
| Sample Point | SPT |
| Sanitary Sewer | SS |
| Seal Boot | SB |
| Selective Catalytic Reduction | SCR |
| Side of Line | SOL |
| Sight Glass | SG |
| Start | ST |
| Steam Methane Reforming | SMR |
| Steam Trace | STC |
| Stopped (Not Operating) | STP |
| Storage | STOR |
| Strainer | STR |
| Strainer (Y-Type) | STY |
| Tank | TK |
| Temperature | TEMP |
| Thousand | M |
| Tight Shutoff | TSO |
| Top Dead Center | TDC |
| Top of Line | TOL |
| Top of Pipe | TOP |
| Transition | TRANS |
| Transition Joint | TJ |
| Trap | TP |
| Underground | UG |
| Unspecified Size | UNS |
| Upper Explosive Limit | UEL |
| Utility Connection | UC |
| Vacuum | VAC |
| Vent to Safe Location | VSL |
| Vessel Trim | VT |
Table 2 Abbreviations and Their Terms
| Abbreviation | Term |
| AG | Aboveground |
| BDC | Bottom Dead Center |
| BLDG | Building |
| BOL | Bottom of Line |
| CA/M | Computer Automatic Manual Station |
| CAL | Calorimeter |
| CAR | Crude Argon |
| CB | Cold Box |
| CLD | Closed |
| CLS | Close |
| CM | Computer Manual Station |
| COL CAN | Column Can |
| COMP | Computer |
| COMPDR | Compander |
| COMPR | Compressor |
| CPM | Central Plant Monitoring |
| CPU | Central Processing Unit |
| CRT | Cathode Ray Tube |
| CSC | Car Seal Closed |
| CSO | Car Seal Open |
| D | Drain |
| DCS | Distributed Control System |
| DE-EN | Maintain De-energized |
| DF | Defrost |
| DTE | Duplex Temperature Element |
| E/I | Millivolt To Current Transducer |
| EJ | Expansion Joint |
| EL | Electrical |
| EN | Maintain Energized |
| ENCL | Enclosure |
| FBD | Function Block Diagram |
| FC | Fail Closed |
| FF | Foundation Fieldbus |
| FH | Flexible Hose |
| FL | Fail Last |
| FLD | Field |
| FO | Fail Open |
| FP | Full Port |
| F/S | Flowsheet |
| GAN | Gaseous Nitrogen |
| GAR | Gaseous Argon |
| GOX | Gaseous Oxygen |
| HP | High Pressure |
| HPT | High Point |
| HRU | Helium Rejection Unit |
| HTR | Heater |
Table 2 (continued)
| Abbreviation | Term |
| IAS | Instrument Air Supply |
| ID | Inside Diameter |
| ILC | Interlock Close |
| ILD | Interlock Logic Diagram |
| ILO | Interlock Open |
| INS | Insulated |
| IP | Inspection Port |
| I/P | Current To Pneumatic Transducer |
| I/S | Inside |
| ISBL | Inside Battery Limits |
| ISCB | Inside Cold Box |
| LAR | Liquid Argon |
| LC | Lock Closed |
| LEL | Lower Explosive Limit |
| LH2 | Liquid Hydrogen |
| LHe | Liquid Helium |
| LIN | Liquid Nitrogen |
| LO | Lock Open |
| LOX | Liquid Oxygen |
| LP | Low Pressure |
| LPT | Low Point |
| LR | Load Relay |
| LTD | Low Temperature Diode |
| M | Thousand |
| MAC | Main Air Compressor |
| MALF | Malfunction |
| MCC | Motor Control Center |
| MH | Manhole |
| MOV | Motor Operated Valve |
| MP | Medium Pressure |
| MSP | Momentary Stop Signal |
| MST | Momentary Start Signal |
| NC | Normally Closed |
| NO | Normally Open |
| NRU | Nitrogen Rejection Unit |
| O/P | Ortho/Para |
| OD | Outside Diameter |
| OIU | Operator Interface Unit |
| OP | Open |
| OPD | Opened |
| O/S | Outside |
| OSBL | Outside Battery Limits |
| OSCB | Outside Cold Box |
| PAR | Pure Argon |
| P&ID | Piping and Instrumentation Diagram |
| P/I | Pneumatic To Current Transducer |
| PB | Pushbutton |
| PCU | Process Control Unit |
| PFD | Process Flow Diagram |
| PLC | Programmable Logic Controller |
Table 2 (continued)
| Abbreviation | Term |
| PNEU | Pneumatic |
| PRESS | Pressure |
| PST | Permit Start |
| PT | Pressure Tap |
| RS | Removable Spool |
| RTD | Resistance Temperature Detector |
| SB | Seal Boot |
| SCR | Selective Catalytic Reduction |
| SG | Sight Glass |
| SMR | Steam Methane Reforming |
| SOL | Side of Line |
| SPT | Sample Point |
| SS | Sanitary Sewer |
| ST | Start |
| STC | Steam Trace |
| STP | Stopped (Not Operating) |
| STOR | Storage |
| STR | Strainer |
| STY | Strainer (Y-Type) |
| TDC | Top Dead Center |
| TEL | Electric Trace |
| TEMP | Temperature |
| TJ | Transition Joint |
| TK | Tank |
| TOL | Top of Line |
| TOP | Top of Pipe |
| TP | Trap |
| TRANS | Transition |
| TS | To Stack |
| TSO | Tight Shutoff |
| UC | Utility Connection |
| UEL | Upper Explosive Limit |
| UG | Underground |
| UNS | Unspecified Size |
| VAC | Vacuum |
| VSL | Vent to Safe Location |
| VT | Vessel Trim |
| XOVER | Crossover |