is it the same?

[BQ340]

Pipe is measured by the nominal ID, not OD. Different material pipe has different wall thicknesses. Only tubing is measured by OD.

MikeB

[Tony Hwang]

Hi, Is one equal to one and quarter? No.

[tnom]

Yes

[rb]

I'm seeing pipe which measure 1.25" outer diameter. Is this the same as what I call 1" pipe?

[Grunpy]

Pipe as commonly known as pipe it would be measure ID steel, brass,copper, aluminum, ETC. Tubing known as tubing it is always measure OD regardless of material is made of. Copper tubing comes in three thickness but the OD remain same. Electrical Pipe it is also measure in ID. Note; but EMT is measure in OD.

[Grunpy]

but the OD changes>

[mm]

I don't know the answer to this question, but.

He didnt' say others had measure it by the OD, only that he had. Or thats was specified by the OD, or even that the OD was listed anywher. Only iiuc that when he measured the OD, it was 1.25".

According to Tnom's chart, pipe that is nominally 1" is 1.315 is diameter. That's close. Maybe rb measured wrong? Maybe he was talking about tubing but called it pipe? Maybe it's red Chinese pipe, and doesn't meet standards?

[salty]

Pipe with 1" I.D. might very well measure 1.25" O.D.

Pipe sizes are usually given based on I.D.

In fact, due to the high price of copper, you'll find that current 1/2 inch copper tubing is slightly more than 1/2" ID, because they are making the walls thinner to save material, but still need it to be compatible with standard fittings and older plumbing.

Another example is 1" PVC pipe, which is 1" I.D. and 1-5/8" O.D.

[DD_BobK]

OP-

wow...you sure have gotten a range of replies but to address your original question

"I'm seeing pipe which measure 1.25" outer diameter. Is this the same as what I call 1" pipe"

well....it depends. what job is this "pipe" doing? what is the apparent material? and how did you measure the OD? (tape? circumferential wrap? caliper?)

If it is truly "pipe" ...... there is no standard Imperial sized pipe having an OD of 1.25". Maybe your measurement is lacking in accuracy?

One inch pipe has an OD of 1.315" (pretty close to 1 5/16").

Pretty much all pipe (brass, aluminum, steel, stainless, PVC) have precise agreed upon OD specs such that threaded fittings can be used on OD of pipe, independent of pipe schedule.

3/4" pipe 1.049" OD 1" pipe 1.315" OD 1 1/4" pipe 1.660" OD

cheers Bob

[Ed Pawlowski]

Have you measured 1/2" copper tubing recently?

[Stormin Mormon]

Ah, that would be water copper that Ed mentions? Refrigeration and AC tubing is actual OD.

1/2" nominal water copper is actual 5/8.