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pretty_name: "Plumbing fitting and pipe thread standards"
license: other
license_name: source-terms-cited
license_link: https://referencesource.org/plumbing-fitting-thread-standards/
language:
- en
tags:
- reference-data
- provenance
- referencesource-org
configs:
- config_name: default
data_files:
- split: train
path: data/records.jsonl
---
# Plumbing fitting and pipe thread standards
**Canonical, always-current version: https://referencesource.org/plumbing-fitting-thread-standards/**
Machine-readable: https://referencesource.org/plumbing-fitting-thread-standards/data.json — this mirror is a point-in-time copy.
- **Last verified:** 2026-08-12
- **Stale after:** 2028-08-11 (past this date, prefer the canonical copy —
it re-verifies on a cadence this snapshot does not)
- **Records:** 97
Dimensional specifications for NPT and BSP pipe thread sizes used in plumbing, hydraulic, and gas fittings worldwide. For each nominal pipe size within each standard, gives threads per inch, pitch, major diameter, and minor diameter — the numbers needed to identify an unknown thread or confirm whether two fittings will mate. Combines American (ASME B1.20.1) and British/ISO (ISO 228, ISO 7) standards in one table so the critical differences are visible side by side.
## Provenance — what every record carries
Every record carries `source` (the URL the value was read from) and
`source_quote` (a verbatim quote from that page stating it). A value you
cannot check against its page is indistinguishable from an invented one;
these can all be checked. Each record is also individually addressable on
the canonical site at its `url`.
## Licence position
factual compilation of thread dimensions from public reference sources; facts cited with attributed quotes, no standard document reproduced
Facts are not copyrightable; what this dataset takes from each source is a
fact plus a short attributed quote linking back to the page that states it.
## Sources
- https://amesweb.info/Screws/BSP-Thread-Chart.aspx
- https://www.geminivalve.com/bsp-thread-vs-npt-fitting/
- https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings
- https://en.wikipedia.org/wiki/National_pipe_thread
- https://trimantec.com/blogs/t/thread-identification-guide
- https://www.machiningdoctor.com/charts/bsp/
- https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained
- https://en.wikipedia.org/wiki/British_Standard_Pipe
## Fields
See any record in `data/records.jsonl` — field names are self-describing,
and the canonical page for each record renders them with labels:
https://referencesource.org/plumbing-fitting-thread-standards/
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