Policy · published 2026-09-25

Terms of use

These terms exist to be understood, not to be agreed to carefully. They say what the numbers are for, what you may do with them, and what we do not promise.

What this site is for

It is a reference for pipe and tube dimensions: outer diameter, published wall thickness, and the inner diameter those two imply. It answers "what is the outside of this size" and "which standards use this outside". It does not answer whether a particular pipe is suitable for a particular job.

What we do not warrant

• Not engineering approval. Verify against the controlling specification and the marking on your own pipe before you cut, weld or order. That sentence is in the footer of every page for a reason.
• Not a pressure rating. Wall thickness is a dimension. A pressure rating depends on material, temperature, service conditions and safety factors that are not published here.
• Not a stock list. “Schedule 40” names a wall, not an item you can buy, and a size listed here may not be made in every material.
• Not complete. 213 wall values are published and gaps are named as gaps. An absent number is usually a decision: it did not clear the two-source rule. Read theaccuracy policy for what that means per series.

What you may do

Use the tables, print them, link to any page directly, and quote a value in a forum, a spec sheet or a purchase decision. Linking is always allowed and needs no permission.

If you republish a table, two things help everyone: say which standard and revision the values are from, and link back to the page it came from (the footer of every page carries a data version —v48d86b977106 today — that pins the exact set of numbers you copied). What we ask you not to do is present someone else's chart as your own independent verification: the whole value of these numbers is that two separate publications agree on them, and re-labelling a copy destroys exactly that.

The published data is also machine-readable at /data/index.jsonand per series; the dimension values themselves are facts from published standards, and we do not claim to own them. The arrangement, the prose, the derived columns and the calculations are ours.

Acceptable use

The site is static and cheap to serve; the contact form is not. Automated hammering of the form is rate-limited at the server and the mailer, and submissions that are empty, absurd or honeypot-triggered are refused rather than delivered. Reading the pages with a script is fine; flooding them is not.

Third parties

Every published value links to the publications it was checked against. Those are other people's sites, with their own content and policies; we do not control them and are paid nothing by anyone we link to.

Changes and contact

If a term here changes, the date on this page changes with it. Questions about reuse, or a correction to a number, go throughthe contact form — we deliberately publish no email address, and the form reaches the same person.

No governing-law or jurisdiction clause is stated here, deliberately: this is a reference table, not a contract with fine print you could not negotiate. See also the privacy policy and thecookie policy.