Annex B defines pipe. Tubular-shaped product of circular cross section.
tubular. Tubular products is a generic term for a family of hollow section products of varous cross-sectional configuration, The term pipe denotes cylindrical products to differentiate from square and retangular hollow section products. However, a tube or tubing can also be cylindrical. User should note the AISC designation of tubular sections.
It has been my experience that many tubular products are made from plate or sheet ASTM standards while pipe has is own material specification. Tubular products are usually used in structural applications while pipe may be used in structural or pressure piping application.
Yours is not an easy question to answer.
In the UK, where they speak English as mother language, the applicable British Standards (BS) for pipe, which I've had in my hands, say that, for the purpose of the standard, there's not any difference between pipe and tube.
In Italian, Spanish and Portuguese languages, there's no word for "pipe". The only word is for "tube": TUBO, in the three languages. The only exception is the Spanish speaking country of Argentina, where PIPE is CAÑO and TUBE is TUBO.
In the USA, the best definition, in my opinion, is the one I found out in a glossary of terms, where PIPE is defined as "a tubular product whose dimensions follow the applicable ANSI standards". Tube dimensions, we can deduct, do not follow any ANSI standard.
The often heard definition that pipe size corrisponds to the approximate inside diameter, whereas tube size corrisponds to the outside diameter is a nonsense, because pipe size of 14 inches and over corrisponds exactly to the outside diameter.
I'll take the liberty of desagreeing with a statement from Mr. Johnson. Tubes ARE used very often to carry on liquids at high pressure, as for example in boilers and heat exchangers.
Giovanni S. Crisi
Sao Paulo - Brazil
Just to confuse things a bit more...
tube is measured in OD (3-1/2" tube has OD of 3-1/2"), while pipe is NPS (nominal pipe size - 3 inch pipe has OD of 3.5", but standard wall thickness would give an ID close to 3")
Pipe is generally above ground, has ANSI dimensions, while oilfield tubing is below ground in the well, is almost always threaded, and made to API specifications.
Beginningn to think that the definition of tubing depends on which segment of industry you are dealing with!
ASME Section 1 - Power Boilers - also has a definition, and uses slightly different formula for tube and pipe thickness. Just going off memory, but if I recall correctly, tube was something that tranferred fluid for the purposes of exchanging heat, while pipe was used for only tranferring fluid.
Perhaps someone has an ASME I handy and could confirm how bad my memery is?
Let's confuse things even more..........
As I said above, pipe made to ANSI specifications which is 14 inches and above in size is measured by the OUTSIDE diameter.For example, a 14 or 24 inches pipe has an outside diameter of exactly 14 and 24 inches.
And what about API 5L specification for LINE PIPE, which sizes the pipe by the OUTSIDE diameter as well? The line pipe to API 5L is usually welded and runs below ground, as in the gas and oil pipelines. One exception is the Trans Alaska pipeline which runs above ground. It was decided like that in order to facilitate the detection and repairing of any possible leak in that remote location and extreme conditions.
Giovanni S. Crisi
It would appear that the difference between "PIPE" & "TUBE" is the application. I often use pipe for fabing structures and we use tubeing for oil pipes. There is a term "mechanicle tubing" that from my experience is a heavy wall seamless pipe that we have used for machine parts.
Forum
