Minor process line symbol
Also called Utility line, Secondary line
A minor process line carries secondary or utility flows: small bypasses, drains, vents and utility connections.
What the minor process line symbol means
A minor process line carries secondary or utility flows: small bypasses, drains, vents and utility connections.
How it is drawn
A thinner solid line than the main process lines, still with a line number.
The minor process line symbol in each standard
Drawn as on most US-style legend sheets.
Signal lines are not part of ISO 10628-2. They come from IEC 62424 or ISA 5.1.
German (DIN): Nebenleitung. See DIN P&ID symbols.
Where you see it on a P&ID
For utilities, drains, vents and small connections.
Tag codes
The minor process line is commonly tagged:
- Line number
Tag formats follow the project numbering procedure. For instruments, the letters follow ISA 5.1, explained on the instrument symbols page.
Related symbols
Frequently asked questions
What does the minor process line symbol look like on a P&ID?
A thinner solid line than the main process lines, still with a line number.
What is a minor process line used for?
A minor process line carries secondary or utility flows: small bypasses, drains, vents and utility connections. You will find it for utilities, drains, vents and small connections.
What tag does a minor process line have?
It is commonly tagged Line number. The exact tag format comes from the project numbering procedure and the legend sheets.
Is the minor process line symbol the same in ISA and ISO?
Signal lines are not part of ISO 10628-2. They come from IEC 62424 or ISA 5.1. Companies vary the details, so always check the legend sheets at the front of the P&ID set.
What is the minor process line called in German?
Nebenleitung. On a German R&I-Fließschema it is drawn to DIN EN ISO 10628-2.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016