Valve Symbols Chart (Printable)
The valve symbols instrumentation buyers meet on P&IDs — simplified conventional basic forms as widely published, alongside what each symbol does not tell you. These are simplified basic forms; ANSI/ISA-5.1 official drawings govern, and project P&IDs may use owner variants — always read the drawing's legend.
Basic valve symbols
| Symbol | Valve | What it tells you | Catalog |
|---|---|---|---|
| Gate | Full-bore isolation valve — the symbol names the family only, not the class or ends. | Ball valves carry most instrument isolation duty | |
| Globe | Linear-stem throttling valve; the center line marks the globe body form. | HP globe valve | |
| Ball | Quarter-turn shutoff; the circle is the ball seen end-on. | Ball valve category | |
| Plug | Tapered or cylindrical plug, quarter-turn; the solid block is the plug. | Quoted per RFQ | |
| Butterfly | Disc-in-body quarter-turn valve for larger line sizes; the diagonal is the disc. | Quoted per RFQ | |
| Check | One-way flow; the flap line sits against the seat line. Direction comes from the drawing's flow arrow, not the symbol. | Check valve category | |
| Needle | Fine-metering globe-family valve; the fine stem mark distinguishes it on instrument sheets. | Needle valve category | |
| Diaphragm | Flexible diaphragm isolates the fluid; the arc above the body is the diaphragm. | Quoted per RFQ | |
| 3-way | Three ports; the drawing's arrows show the flow path in each position — the symbol alone does not. | 3-way ball valve | |
| Safety / relief | Overpressure protection; the spring above the angle body is the release element. | Quoted per RFQ |
From symbol to RFQ: what the drawing omits
A valve symbol names the valve family — nothing more. The P&ID does not carry the pressure class, end connection, seat material or trim, and those are the numbers that make a valve quotable. Reading a symbol to write an RFQ means adding, per line: the working pressure and temperature (the class question covered inball valve ratings), the end connections and size, the seat and seal materials, and the flow direction where a check or needle valve makes direction matter. Send the symbol list with those additions and the quote comes back matching the drawing. From our guides:needle valve vs globe valve,types of stainless check valves.Request a factory quote.