OT (kinda)---- How is DOM tubing made?

I know it stands for "Drawn Over Mandrel" but I have always wondered how they do it. If it's extruded how can they keep the bore size within 5 thou. or so?

I don't think it's welded because there is no visible seam......

It is often welded, then finished over a mandrel.

Regards.

Mike

Finegrain said:

It is often welded, then finished over a mandrel.

Regards.

Mike

Click to expand...

So they would form and weld it like tubing and then finish it over a mandrel?

ChipSplitter said:

So they would form and weld it like tubing and then finish it over a mandrel?

Click to expand...

Yes. There is also seamless DOM -- white-hot billet gets pierced by a mandrel and becomes tubing.

Regards.

Mike

If you want seamless, they take a hot rod and shove a long mandrel down it. Pretty neat process, videos are on YT.

I've purchased seamless pipe diameters to 12" for sure, maybe some 16 or 20....but that's getting pretty rare.

For seamless tubing the initial tube that gets drawn is made with a rotary piercing process:

Rotary piercing - Wikipedia

Cole2534 said:

If you want seamless, they take a hot rod and shove a long mandrel down it. Pretty neat process, videos are on YT.

I've purchased seamless pipe diameters to 12" for sure, maybe some 16 or 20....but that's getting pretty rare.

Click to expand...

B&W had a tube plant in Beaver Falls Pa, made nooklear grade seamless pipe.

My grandfather saved me a clipping about how they bought a foreign (European ?)
Extrusion press/process, and they were the first in this country to use it.

It showed the white hot tube emerging the press in a trough.

It used glass powder for a lubricant.

But yes, the "mandrel and double rollers" is the normal process, and they did most of their work this way (the neighbor described working at that machine).

So they basically punch the center out?

Even if it's 1" OD x .5" ID x 20' long...??

I'd like to watch that.....

ChipSplitter said:

So they basically punch the center out?

Even if it's 1" OD x .5" ID x 20' long...??

I'd like to watch that.....

Click to expand...

No.

In the case of the most common way seamless is made, it's a hot forging process using grooved rollers to force the metal over a "bullet shaped" mandrel. for DOM, usually a welded product is sent through a similar process, at "room temperature" .

Just go look at the videos!

digger doug said:

B&W had a tube plant in Beaver Falls Pa, made nooklear grade seamless pipe.

My grandfather saved me a clipping about how they bought a foreign (European ?)
Extrusion press/process, and they were the first in this country to use it.
).

Click to expand...

I don’t think so. Generally Shelby tube in Ohio is credited with pioneering the seamless process primarily for the manufacture of bicycle frames during the bicycle craze of the 1890s. See here

Then & Now: Ohio Seamless Tube in Shelby 1908 | Area History | richlandsource.com


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Also cool are extruded steel pipe fittings.

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Some videos:


This one is animated:

YouTube


About 1:25 here:

YouTube


A lecture:

YouTube


There are a lot more. But it seems that the exact way that a mandrel is held, and removed from the tube is not shown in great detail. I suspect some trade secrets here.

adh2000 said:

I don’t think so. Generally Shelby tube in Ohio is credited with pioneering the seamless process primarily for the manufacture of bicycle frames during the bicycle craze of the 1890s. See here

Then & Now: Ohio Seamless Tube in Shelby 1908 | Area History | richlandsource.com


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Click to expand...

Are you calling my grandfather and the newspaper a liar ?

Extruded hi temp steel pipe/tube.

Your linked article while filled with spamming pop ups, doesn't call out the process.

ChipSplitter said:

I know it stands for "Drawn Over Mandrel" but I have always wondered how they do it. If it's extruded how can they keep the bore size within 5 thou. or so?

I don't think it's welded because there is no visible seam......

Click to expand...

Interviewed as Plant Manager of a brand-new DOM factory - right near where my ancestor is buried - first settler. 1760's Jane Lew, WBGVA. about.... f**k me... 1974? forty-six years ago?

Our History

It for damned sure IS "welded". From flat sheet. Slit and formed. FAST!

That's the whole POINT!

Just waaaay faster and better than Old Bill over at the local steelyard runs his arc!

And yes, you can find the seam. If you know HOW to "look". Cheap import shite, there is even a blue-black heat line, outside, RUDE f**king raggedy-burr.. on the inside. Some shapes, similar process, (check Big Box squares) yah may draw THROUGH a mandrel (die..) or rollers as final-final rather than just OVER one. Whatever keeps the cost down ... and still sells ... for cheap office furniture legs and the like.

Jane Lew, WBGVA plant, Pittsburgh Tube, early 1970's "Made in USA"? No such crap. Serious nice goods!

Being used for stuff like HEAVY tandem-axle stone and coal-truck suspension trunnions, printing-press rollers.... So it hadda be right consistent and straight as well as strong.

Yah pay for what yah get..

A good reference describing the history and the details of the DOM process can be found in " The Making, Shaping, and Treating of Steel" .

The 10'th edition, published in 1984 and 1572 pages long, covers the process in chapter 32.

The first seamless tube plant in the US was established in 1895 in Elmwood City, Pennsylvania. The plant used a Stiefel disc piercer, developed in 1840, a Pilger milling roll, and a cold drawing bench. The early mills were limited to a 9 inch diameter and 30 foot pipe length.

In 1925 US Steel developed a double piercing process that produced tube diameters of up to 16 inches.

The original rotary piercing mills were later replaced by the double roller Mannesmann process patented in 1865. The early US Mannesmann mills made seamless tube of up to 20 inch diameter.

The US Steel rotary rolling mill was later developed and can produce seamless pipe of up to 36 inches in diameter. The large OD tube is used to connect the deep sea drilling platforms to the sea floor.

There is also a three roller modified Mannesmann process for producing tube with a better surface finish.

All of these methods develop the cylindrical cavity in a solid bar by continuously deforming the solid bar into a elliptical shape. This can be done with a hammer and anvil in a blacksmith's shop or with rotary forging in a steel mill. The forging process produces a steel tube that has uniform strength around the wall circumference and along the tube length. This is an advantage over plate welded tubing when the tube serves as a pressure vessel.

The finished dimensions are obtained by running the DOM tubing through a grooved rolling mill to control the outside diameter. If the inside diameter needs to be controlled the rolling mill can be equiped with a bar mandrel that sits inside the tube during the rolling process or the tube can be run through a tension reducing mill which stretches the tube as it is rolled. The rolling mill finishing step can handle tubes up to 16 inches in diameter.

Small diameter tubing is finished by cold drawing though a die with a mandrel in the tube. Tubing less than 2 inches in diameter can be finished without the mandrel by cold tension drawing to control both the OD and wall thickness.

For some alloys the rotary piercing process is replaced by a hydraulic ram which forces a mandrel through the center of the heated cast ingot. The punched ingot is then drawn and finished to size on a rolling mill with a floating mandrel.

The patents describing these and related tube drawing practices are available on the internet.