ASTM F876/F877 (CTS) ·size chart
CTS 1 1/4 PEX outer diameter: 1.375 in / 34.925 mm
- OD (inches)
- 1.375 in
- OD (millimetres)
- 34.925 mm
- DN
- 32
- Wall
- not published
- Bore
- not published
Crosslinked polyethylene tubing in CTS (copper tube size) ODs, designated by SDR rather than schedule. For CTS 1 1/4 we can publish the outside, but no wall yet — the wall values in our sources did not reach two independent confirmations, so we are not guessing the bore.
| Nominal | DN | OD (in) | OD (mm) | Wall series published |
|---|---|---|---|---|
| 1 1/4 | 32 | 1.375 | 34.925 | none — 1 designation(s) awaiting a second source |
Why the wall is missing. 1 designation(s) (9) appear in at least one source for this size, but not two independent ones. Unverified values are kept out of the published set on purpose — the rule.
Same body, different material. steel 1 1/4 Sch 40 = STD, and stainless 1 1/4 Sch 40S are the same 0.140 in wall on the same 1.660 in / 42.164 mm body; steel 1 1/4 Sch 80 = XS, and stainless 1 1/4 Sch 80S are the same 0.191 in wall on the same 1.660 in / 42.164 mm body. A caliper cannot separate them — what the pipe is made of does.
The same nominal label in other standards
| Standard | OD (in) | OD (mm) | DN | Published wall series |
|---|---|---|---|---|
| ASME B36.10M · welded and seamless steel pipe | 1.660 | 42.164 | 32 | Sch 40 0.140 · Sch 80 0.191 · Sch 160 0.250 · STD 0.140 · XS 0.191 · XXS 0.382 |
| ASTM F876/F877 (CTS) · PEX tubing | 1.375 | 34.925 | 32 | no wall published yet (1 awaiting a second source) |
| ASME B36.19M · stainless steel pipe | 1.660 | 42.164 | 32 | Sch 5S 0.065 · Sch 10S 0.109 · Sch 40S 0.140 · Sch 80S 0.191 |
PEX vs steel — 1 1/4 (ASME B36.10M)
Measuring this size
- Measure across the pipe, not the fitting: that is the OD, and it is the number a clamp, a hole saw or an insulation sleeve has to match.
- Measured
34.925± a fraction of a millimetre points at CTS 1 1/4. Check which standards a measurement fits — the same OD can belong to more than one. - The bore decides flow; the wall decides pressure rating and how deep a thread cuts. Neither number is in the name CTS 1 1/4 carries.
Questions about CTS 1 1/4
What is the outer diameter of CTS 1 1/4 pipe?
1.375 in / 34.925 mm — but that is only true for ASTM F876/F877 (CTS). The same nominal label in ASME B36.10M (1.660 in / 42.164 mm) and ASME B36.19M (1.660 in / 42.164 mm) is a different pipe. Calipers measure this number; the name does not.
Is CTS 1 1/4 the same as DN 32?
DN 32 is the millimetre-family name for this size, so yes for the size — no for the number. DN is not the outer diameter and not the bore; CTS 1 1/4 measures 1.375 in / 34.925 mm outside. See the NPS ↔ DN table for the whole series.
No edition year is claimed. These values match ASTM F876/F877 (CTS) as published by the sources above, but the specific printing was not verified, so the standard is named without a year.
Next
- Full ASTM F876/F877 (CTS) chart (9 sizes)
- OD / ID / wall calculator — measure two, get the third
- About ASTM F876/F877 (CTS)