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- - By Ehsan (*) Date 01-24-2011 08:45
Whats the different between Tube & Pipe?
Parent - - By aevald (*****) Date 01-24-2011 12:25 Edited 01-24-2011 12:40
Hello Ehsan, welcome to the forum! To answer your question: mainly the way that it is sized and secondly, possibly the way that it is manufactured. Google a pipe chart and then google a tube chart, you will notice quite a difference in how the two are described, you will also notice that "tube" might reference square, rectangular, or round shapes. Generally a 6" nominal pipe size isn't 6" OD(it's greater) but a 6" round tube is, this changes when you hit a particular nominal OD size in pipe, the pipe will then actually be the stated OD. I believe 14" is the transitional size. I have included a site that explains and lists some of the size and description differences. Best regards, Allan

http://www.alro.com/DATACatalog/CatalogPages/007-TubingAndPipe.pdf#page=34
Parent - - By 803056 (*****) Date 01-24-2011 12:37
Pipe is sized by the nominal diameter and the wall schedule (thickness). You will have to look up the wall schedule for each pipe diameter to see what the actual thickness is.

Tube is specified by the diameter and the actual wall thickness.

Best regards -Al
Parent - By swnorris (****) Date 01-24-2011 13:20
One difference is the material grade.  For example, structural pipe is typically ASTM A53 and structural tubing is typically ASTM A500 grade B.
Parent - By js55 (*****) Date 01-24-2011 14:20
Tube is pronounced toooob. Pipe is pronounced pyp.
And I'm only partially facetious.
There are several definitions, Al provided the best. But in the end there are exceptions that break down any absolute definition. In the end the most accurate may very well be Scott's. They are specified through different specifications.
Also, I believe there have been discussions on this in here before. Do a search.
Parent - - By welderbrent (*****) Date 01-24-2011 14:32
Welcome to the AWS Welding Forum.

I'm wondering if you would mind sharing rather there is a particular reason you are asking?  We may be able to be more accurate in some of our examples and explanations if we knew what type of application your question had.  Or rather it is part of a discussion you got involved in?  Or the way something was called out for a particular job?

Scott did seem to hit the nail very square.

Except for the specs they are called out under there would be many overlapping areas.

But for the average usage everyone has given you some good ideas that should help keep them straight.

Hope we have been of some help.

Have a Great Day,  Brent
Parent - - By Bob Garner (***) Date 01-24-2011 21:27
AISC now has their "new" designations.  Now there is pipe (same as the old pipe), but they're calling tubes, HSS (hollow structural shapes).  There is round HSS and square and rectangular HSS.  Something few people know is that the wall thickness of HSS is usually something like 97% of the callout thickness.  This is due to plate thickness tolerances used for fabricate the HSS.

Bob G.
Parent - - By welderbrent (*****) Date 01-25-2011 02:51
Bob,

Not sure how many years exactly, but they have called the Structural Tube out as HSS for quite some time.

And I know I have been battling the tolerance issue for about 10 years.  Just as an example, 1"X2"X.083 TS is only about .075-.078 thick. 

Make sure you compare any job specs with your steel supplier specs because there are times I have had to order the next size up on material thickness.

Now, most structural that is 3/16" thick or more in the first place doesn't seem to vary much from true measurement.  Only the gauge thicknesses.  So it has not been a problem on Structural Steel fabrication. 

Have a Great Day,  Brent
Parent - - By Superflux (****) Date 01-25-2011 04:33
I was not aware of the discrepancy on the Gauge thicknesses. Help me make sure I've got this correct.
So, if a spec calls for a certain gauge then per AISC it is OK for it to be 97% under sized? But if the spec calls for .083 WT, then you HAVE to order a heavier gauge which might then be thicker than specified.
Where might one find this info? Is it available online (i.e. free, or must one have to purchase the applicable reference book).
Does AWS D9.1 sheet metal welding code address this?

As for the definition, I thought that Tubing has to be tubular, and pipe must be pipular....
Parent - - By welderbrent (*****) Date 01-25-2011 15:05
Super, and Bob,

According to the Thirteenth edition of the AISC Construction Manual 2005, on page 1-5  they go into HSS, Hollow Structural Sections.  Rectangular, Square, and Round.  According to the Glossary and both 1-5 & 1-6 Pipe can be considered as an Hollow Structural Section.  But pipe has it's own system of measurements as previously noted by others that also separates it from HSS Rounds. 

They also comment about using only .93 of the thickness for calculations for engineering purposes. 

It is noted from my own useage that much Tube Steel of lighter gage (16-10) no longer measures to previous standard dimensions.  They have gone lighter but still within what has for years been considered acceptable tolerance.  For example, TS 1X2X14 ga is 1X2X.083 according to the supplier book I generally reference when buying my steel. But, when you get it, measure, you will more than likely have .075-78.  On a chart in the back of my steel book for AISI thickness tolerance it says: 14 ga= .0747; range- .0817-.0677.  So, even though they call out their 14 ga tube steel as being .083 that is not what they have to supply.  And, with more accurate manufacturing abilities these days they go for the minimum allowable in order to make more tubing with the same amount of steel.  I have not had any problem with any tubing that was 3/16 wall or heavier.  They have always measured what was designated.

Now, since I don't use these gauges of tubing for structural purposes, I have never gotten nor checked upon the ASTM specs/tolerances to see if there is any thing in them that would specify thicknesses for these tubes.

Now, as to rather you HAVE to order heavier by any code???  I don't know that for sure.  As I stated, it is only going to be noticed in the lighter gauges, not the members normally covered by D1.1 as Structural Steel that most of us are welding for any building or equipment applications.  My comment was directed to making sure one takes note of how the material is specified and make sure what you order and use is compliant with those specs to the satisfaction of the engineer and inspectors.

I will have to take some time and go through D1.3 & 9.1 more carefully to see if they happen to deal with those tolerances.  I don't recall seeing it mentioned off the top of my head.  Maybe someone else has more knowledge about that or can look it up before I get a chance to. 

I hope my comment about the tolerance dimensions did not cause any confusion. 

Have a Great Day,  Brent
Parent - By Superflux (****) Date 01-26-2011 00:07
Brent,
Fairly sure I'm not any more confused than before. So, the design calculations have a "fudge factor" factored in. And there is manufactures' tolerances too. Thanks for the reference to the AISC 13th, 2005. Next AISC gig I'm on, I'll check in to that.
Parent - - By DaveBoyer (*****) Date 01-25-2011 02:55
As well as all the others have mentioned, at least in the smaller sizes, "pipe" has the same outside diameter regardless of wall thickness, so that it can be threaded to standaerd dimensions. All that I have seen has a visable seam on the inside, and is not held to close tolerance for roundness..

Round tube is made either seamed or seamless, and may be drawn over a mandrill, specified DOM. This operation gives closer tolerances in size and roundness.
Seamless tube is not always perfectly concentric from inside to outside.
Parent - - By 803056 (*****) Date 01-25-2011 12:49
ASTM A106 is seamless pipe. ASTM A53 can be welded pipe or seamless pipe. You need to review the applicable specification to know exactly what is ordered and what is delivered.

Seamless pipe has greater variations in the thickness of the pipe wall than welded pipe due to the manufacturing process.

You get what you order, sometimes.

Best regards - Al
Parent - - By Bob Garner (***) Date 01-25-2011 19:22
Brent,

You're right about the 0.93 wall thickness.  This is built in to the design tables so we at least we don't have to worry about it in engineering.

Bob
Parent - By swnorris (****) Date 01-25-2011 21:36
Something else to consider... pipe can be designed using the provisions of the AISC specification for round HSS sections as long as the pipe conforms to ASTM A53 Class B and the appropriate limitations of the specification are used.
Parent - - By DaveBoyer (*****) Date 01-26-2011 02:31
What specification does Sch. 40 pipe [1/8"-4"] like You get from the plumbing supply or a big box store fall under?
Parent - By 803056 (*****) Date 01-26-2011 13:48
Typically ASTM A53 for carbon steel pipe.

Best regards - Al
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