Eccentric reducer symbol
An eccentric reducer joins two pipe sizes with one side flat, so a pipe can stay level at the top or bottom. On pump suctions it is fitted flat side up to avoid trapping vapour.
What the eccentric reducer symbol means
An eccentric reducer joins two pipe sizes with one side flat, so a pipe can stay level at the top or bottom. On pump suctions it is fitted flat side up to avoid trapping vapour.
How it is drawn
A trapezoid with one side flat, often marked FOT (flat on top) or FOB (flat on bottom).
The eccentric reducer symbol in each standard
Drawn as on most US-style legend sheets.
ISO 10628-2 has no separate symbol for this. Check the project legend sheet.
German (DIN): Reduzierstück, exzentrisch. See DIN P&ID symbols.
Where you see it on a P&ID
On pump suctions and pipe racks.
Tag codes
The eccentric reducer is commonly tagged:
- FOT
- FOB
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 eccentric reducer symbol look like on a P&ID?
A trapezoid with one side flat, often marked FOT (flat on top) or FOB (flat on bottom).
What is a eccentric reducer used for?
An eccentric reducer joins two pipe sizes with one side flat, so a pipe can stay level at the top or bottom. On pump suctions it is fitted flat side up to avoid trapping vapour. You will find it on pump suctions and pipe racks.
What tag does a eccentric reducer have?
It is commonly tagged FOT, FOB. The exact tag format comes from the project numbering procedure and the legend sheets.
Is the eccentric reducer symbol the same in ISA and ISO?
ISO 10628-2 has no separate symbol for this. Check the project legend sheet. Companies vary the details, so always check the legend sheets at the front of the P&ID set.
What is the eccentric reducer called in German?
Reduzierstück, exzentrisch. 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