[ P&ID SYMBOLS · STANDARD ]
ISO 10628 P&ID symbols
ISO 10628-2 is the international standard for the graphical symbols on process flow diagrams and P&IDs in the chemical and petrochemical industry. It is the basis for equipment, valve and piping symbols on most European legends and on many international projects. Its symbols look different from US practice in a few important places: gate and check valves, control valves, pumps and compressors.
- Full title
- ISO 10628-2:2012, Diagrams for the chemical and petrochemical industry, Part 2: Graphical symbols
- Latest edition
- 2012. Part 1, the rules for drawing the diagrams, is ISO 10628-1:2014
- Published by
- ISO, committee TC 10/SC 10, process plant documentation
- Covers
- About 300 symbols in 29 groups: vessels, columns, heat exchangers, furnaces, filters, separators, pumps, compressors, valves, fittings, piping and more
- Does not cover
- Instruments and signal lines. ISO-based P&IDs show these with IEC 62424 or ISA 5.1
- National versions
- EN ISO 10628-2 in Europe, DIN EN ISO 10628-2:2013 in Germany, see DIN symbols
Valves ISO 10628
About valves- Gate valveValve, gate typeX8074
- Globe valveValve, globe typeX8068
- Ball valveValve, ball typeX8071
- Check valveCheck valve (general)X8077
- Butterfly valveValve, butterfly type (form 1)X8075
- Needle valveValve, needle typeX8076
- Angle valveValve, angle type (general)2102
- Three-way valveValve, three way type (general)2103
Control and actuated valves ISO 10628
About control and actuated valvesSafety devices ISO 10628
About safety devicesPumps and compressors ISO 10628
About pumps and compressors- Centrifugal pumpPump, centrifugal type2322
- Positive displacement pumpPump, reciprocating piston typeX8094
- Gear pumpPump, gear type8091
- Screw pumpPump, screw type8092
- Centrifugal compressorCompressor, centrifugal typeX8179
- Reciprocating compressorCompressor, vacuum pump, reciprocating piston typeX8097
- Fan or blowerBlower, fan (general)X8164
- TurbineTurbine (general)2571
- AgitatorAgitator (general), stirrer (general)2672
Vessels and tanks ISO 10628
About vessels and tanks- Vertical vesselTank, vessel with dished ends2062
- Horizontal vesselTank, vessel with dished ends2062
- ColumnTray column (general)X8101
- Cone roof tankTank with conical roof and flat bottomX2063
- SphereSpherical vessel on legsX8010
- Open tankContainer, tank, cistern2061
- Silo or hopperBunker with conical bottom2064
Heat exchangers ISO 10628
About heat exchangersFilters and strainers ISO 10628
About filters and strainersInstruments ISO 10628
About instrumentsLine types ISO 10628
About line typesPiping and fittings ISO 10628
About piping and fittings- Concentric reducerReducer516
- FlangeFlanged connection511
- Blind flangeFlanged dummy cover517
- Spectacle blindInterchangeable disc (blind disc)2044
- Expansion jointCompensator533
- Flexible hoseHoseX411
- Steam trapSelf-operating release valve (steam trap)2181
- Sight glassViewing glass2034
- DrainFunnel2040
- VentVent (outlet to atmosphere for steam/gas)2039
ISO registration numbers
Every symbol in ISO 10628-2 has a registration number, which is how legends and P&ID software refer to it. Most symbols come from the ISO 14617 series of graphical symbols for diagrams, and the number shows where each one comes from:
- A plain number, such as 2101 for a valve, is a symbol from ISO 14617.
- A number starting with C, such as C0096 for an orifice plate, is a preliminary ISO 14617 symbol.
- A number starting with X2, such as X2125, is an example built from ISO 14617 symbols.
- A number starting with X8, such as X8074 for a gate valve, is an example drawn for ISO 10628-2.
How ISO symbols differ from ISA and US practice
- Gate valve: ISO adds a short bar across the centre of the two triangles (X8074). On US legends a plain body is a gate valve; in ISO the plain body is a valve in general (2101).
- Check valve: ISO marks it with a small solid dot on the inlet corner (X8077), not a filled half or an arrow.
- Control valve: ISO draws a diagonal arrow through the valve body (X8087) and no actuator. The control is shown with the instrumentation.
- Pumps: a circle with two lines meeting at the outlet. The centrifugal pump adds a line through the middle (2322). US legends draw a circle with a tangential outlet and a base.
- Compressors and fans: a circle with two lines narrowing towards the outlet, without meeting (2302, X8179). A fan adds a rotor (X8164).
- Safety valve: the spring sits on a globe body with a dot in the centre and a heavy bar on the outlet side (X2124, X2125).
- Instruments are not part of ISO 10628-2 at all.
Side by side drawings for every symbol are on the ISA vs ISO comparison.
The 29 symbol groups
ISO 10628-2 sorts its symbols into groups: vessels and tanks, columns, heat exchangers, steam generators and furnaces, cooling towers, filters, screening devices, separators, centrifuges, driers, crushing and grinding machines, mixers and kneaders, shaping machines, liquid pumps, compressors and vacuum pumps, blowers and fans, lifting and conveying equipment, feeders, engines, valves, check valves, valves with safety functions, fittings, piping, apparatus elements, internals, agitators and internal characteristics.
The legend on this page shows the symbols that appear on most oil, gas and process P&IDs, with their registration numbers.
Frequently asked questions
What is ISO 10628?
ISO 10628 is the international standard for diagrams in the chemical and petrochemical industry. Part 1 (ISO 10628-1:2014) sets the rules for flow diagrams and P&IDs. Part 2 (ISO 10628-2:2012) defines the graphical symbols.
Does ISO 10628 include instrument symbols?
No. ISO 10628-2 covers equipment, valves, fittings and piping. Instruments and control functions are drawn to IEC 62424 or ISA 5.1.
What is the difference between ISO 10628 and ISO 14617?
ISO 14617 is a general library of graphical symbols for diagrams in many fields. ISO 10628-2 picks the symbols needed for process diagrams from ISO 14617 and adds examples of its own, which carry numbers starting with X8.
How is a gate valve drawn in ISO 10628?
As two triangles meeting at their points with a short bar across the centre, registration number X8074. The plain two-triangle body is the general valve, 2101.
Is DIN EN ISO 10628 the same as ISO 10628?
Yes. DIN EN ISO 10628-2:2013 is the German adoption of ISO 10628-2:2012, with the same symbols.
The symbols on this page were drawn by Deskely to the forms of the standard and are free to use. Standards are revised and every project issues its own legend sheets, which take precedence.
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