Article
The end of a pipe decides how it will be joined. Ordering the wrong end finish means extra machining at site, or pipes that simply cannot be used. There are three main options.
Plain end (PE)
The pipe is cut square with no preparation. Plain ends are used for:
- Socket weld fittings and flanges, where the pipe slides into a socket
- Slip-on flanges
- Mechanical couplings and grooved systems (after grooving)
- Pipes that will be cut to length and prepared at site
Bevelled end (BE)
The end is machined at an angle to make room for a full-penetration butt weld. Bevelled ends are standard for buttweld fittings, weld neck flanges and pipe-to-pipe welds, typically from 2" upward.
| Wall thickness | Standard bevel (ASME B16.25) |
|---|---|
| Up to about 22 mm | 37.5° ± 2.5° with 1.6 mm ± 0.8 mm root face |
| Above about 22 mm | Compound bevel: 37.5° then 10°, to reduce weld volume |
Very thin stainless pipes, such as SCH 5S and some SCH 10S, are often welded square-butt by TIG and may be ordered plain end.
Threaded end (TE)
The pipe is threaded, usually NPT (ASME B1.20.1) or BSPT (ISO 7-1), for screwed fittings. Threaded pipe is used in small sizes, typically 2" and below, for low-pressure utilities, instrument and drain lines. Threading removes wall thickness, so thicker schedules (SCH 80S) are normally used.
Other end options
- Threaded and coupled (T&C) – one coupling screwed on each length.
- Grooved ends – for mechanical grooved couplings.
- End caps – plastic caps to protect bevels and keep dirt out during transport.
How to write it
Pipe 6" SCH 40S, ASTM A312 TP316L, seamless, bevelled ends to ASME B16.25, with plastic end caps
Frequently asked questions
What is the standard bevel angle for pipe?
37.5° with a 1.6 mm root face, according to ASME B16.25, for walls up to about 22 mm.
When are plain-end pipes used?
For socket weld connections, slip-on flanges, couplings, and pipes to be prepared at site.
Which thread is used on pipe in the USA and Middle East?
Mostly NPT taper threads to ASME B1.20.1.
Key takeaways
- PE for socket weld and slip-on; BE for butt welding; TE for screwed joints.
- Standard bevel is 37.5° with a 1.6 mm root face.
- Specify ends and end protection in every pipe order.
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