What Rail Diameters are available near you, outside the US?

I want to make a rail change, and in the US the next size up rails are,
EMT conduit, 29.5mm OD
DOM Steel tube, 31.75mm OD 1.2mm-2mm wall thickness

Conduit is the better choice, available at nearly every hardware store, dirt cheap, doesn’t rust, extremely rigid.

What is available in your area, closest to either of these, critical dimension is OD?

This says, https://infocomm.org/filestore/av-math-online/groups/62.html, “Outside the US, conduit sizes are typically measured in millimeters and are based on the outer diameter. Some common metric outer diameter sizes are 20 mm, 25 mm, 32 mm,”

You mentioned commonly available gas pipe before?

Already considered square tube, and/or a bunch of L brackets fastened together in various orientations and/or combinations to form some kind of rigid beam?

Some pipe supplier options.

Gas pipe, thick walled conduit, regular pipe are not good. We need thin walled Conduit, tubing, or DOM tubing.

Square also does not work for a few reasons.


In Brazil, we have ease access to 25mm conduit tubes.

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Thank you!

In Germany, 20mm and 25mm OD are equally common and easy to obtain in almost all hardware stores. Stainless steel tubing in 25x2mm (25mm OD, 2mm wall thickness), surface sanded to K240, is available at ~10,70€ per meter up to 6m in length right now (March 2024).

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Great news, thanks!

Yes, please stick to 25 for Germany… :smiley:

Zero options for what you call conduit, as far as I can tell. I’d personally be VERY skeptical of anything that says things like ‘outside the US, these sizes are common’. As I’m sure you’ve seen, it varies wildly based on location. Prices given in NZ$, multiply by ~0.6 to get to USD.

Short answer:
25.4mm OD is by far the most available here in NZ with the widest range of options in terms of material, wall thickness, surface finish, construction etc.
25mm is unrealistic here and would likely prevent people from being able to successfully construct anything.

Options that seem decent:

25.4mm OD general purpose steel tube. Available from Bunnings Warehouse (local hardware store) in 2m lengths and 1.2mm wall thickness. NZ$15/m. Also available from EasySteel as ‘precision tube’ in 1.2, 1.4, 1.6, 2.0 wall thicknesses. Unsure of the price.

25.4mm OD Stainless is readily available in multiple wall thicknesses from 1.2mm to 2mm. Available from most places in several forms. Used a lot in the dairy/food industry as well as for hand rails, Industrial Tube in Hamilton apparently have visually blemished stock available for close to steel prices.

25.4mm OD 4130 (Chromoly) is readily available in multiple wall thicknesses but expensive. Available from Steelcuts and most local steel suppliers. Ranges from NZ$40/m for 0.6mm wall to NZ$64/m for 1.6mm wall and beyond.

26.70mm line pipe is available in various options (schedule 40/80, seamless etc.). Also available as 21.3mm. Available from Easysteel and presumably most local suppliers. Not sure what the wall thicknesses are here, though.

Not so good options:

25mm Hydraulic tube - 2.5mm wall, available from NZ Steel and tube. Seems ‘rare’ or at least limited stock for special applications. NZ$13/m so it was super cheap on a ‘per mass’ basis, but limited stock so shipping was painful.

26.9mm OD general purpose steel pipe is commonly available in 2.6mm wall, as is 21.3mm OD. Black/galv are both options. Available from Steelcuts, EasySteel and presumably most local suppliers. Anything thinner wall seems to be uncommon/unavailable in this size.

26mm x 2.15mm galv steel pipe is available from a local cheap importer at $21/m cut with decent shipping.

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It isn’t that wild though. There are only a couple (2) standards, the issues are the places that do not legally use metal for electrical conduit then we need a substitute.

For the last 9 years everywhere, but the US used 25mm and 25.4mm.

CRAP… I screwed up the first post. I will edit it.

I would like to go to 29.5mm OD (US 1" EMT). So I am hoping everyone can get 30-32mm?

Maybe not varying ‘wildly’ in size alone, but taking into account purpose, construction and material it seems remarkably variable. I also think that it seems more stable because 25mm and 25.4mm are a common node in so many places, outside that it seems to become more variable again.

Ah, goddamnit.

Thin walled conduit or DOM TUBING, (that is Drawn over mandrel, not welded). Tubing gives a more precise Outside diameter, pipe give inside diameters with varying Outside diameters.

25mm in the UK is a safe option.

How about 30?

Thin walled conduit does not exist for us. I’ve not really seen anything specifically defined as DOM, it tends to be either seamed or seamless, with the seamed being linear or spiral welded depending on purpose. I suspect seamless is the same thing, we just don’t use the DOM terminology.

I think the ID/OD comparison depends on the particular pipe standard being followed. Here we seem to have plenty of options for pipe sizes that are OD relative with varying IDs depending on material/expected use. My guess would be that it depends on how the connections are expected to be handled.

~30mm options:

Seamless line pipe: 26.7mm or 33.4mm OD
General purpose (AS1074): 26.9 x 2.3/2.6 or 33.7mm x 3.2, some places showing 33.7mm with ‘light’ or ‘super light’ options at 2.0/2.6mm wall.
Galvanized general purpose (AS1074): 26.9x2.6, 33.8x3.2. $18-24/m
Galv general purpose from Bunnings: 33.8x1.2mm - $20/m
Precision Tube/seamless (AS1450): - 28.6mm and 31.8mm OD with a range of wall thicknesses from 1.2mm to 2.5mm, quite a few different suppliers. Local manufacture and import.
ASTM A554 tube (handrail/ornamental tube): 31.8mm x 1.5mm wall thickness, 304 stainless. $30/m
Light wall black pipe: 26.9x2.3 and 33.7x2.7
Hygienic tube (AS 1528): 31.8 OD x 0.9, 1.2, 1.6mm wall. 304 Stainless. No idea of prices but likely not cheap unless a blemished source can be found.

So yeah, way, way more variable at that size.

31.8mm looks like the most common size for stainless at reasonable prices and wall thicknesses. 33.7mm or 33.8mm looks like the most common size range for galv/black carbon steel, but it’s pretty difficult to find thin-walled options here from steel suppliers. Bunnings appears to have the only readily available thin-walled option, which is good but seems like it might be somewhat vulnerable to shifts in chosen stock etc.

Edit: And I have seen absolutely zero options for 30mm or 29.5mm.

Here in Canada, US sizing is readily available, in fact moreso than most metric sizing. I havent checked the inventory that we sell at work (I work for a company that sells steel tube) for anything really other than the 1"(25.4mm) round tube, but I wouldn’t expect surprises. Probably though we don’t have 1.25" which would be a bit of a bummer. I can get the 1" round for less than the 3/4" conduit.

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How much are these?

The rest are alittle more than the DOM here. Seamless, steel.https://www.metalsdepot.com/steel-products/steel-round-tube-dom

Huh, weird that I didn’t add the wall thickness. Those are the heavy-wall options, so 2.9mm to 8mm depending on rating. Looks reasonably cheap, though. 33.4 OD x 3.38mm wall is $80/length so ~$15/m. 26.7 OD x 2.87mm wall is $60/length so $10/m.

Looking at the databook, the stainless handrail/ornamental tube is 31.75mm which is 1.25", which explains why some places list it as 31.8 and some as 31.7… Found a place that has that around $10/m for 2m lengths.

If you think the design is sensitive to wall thickness, I’d be tending towards that stainless option for NZ. Cheap and extremely common because it’s used for handrails. On the other hand, I believe this is a formed/welded product, so if the design is sensitive to roundness of the rails it may not be ideal? I’m not sure what the specs are for finished out-of-round.

Edit: The handrail pipe is made to ASTM A554, found some roundness specs:

OD tolerance is ±0.2mm, ovality tolerance is ‘twice the tabular outside diameter tolerance’, and ‘the average of the maximum and minimum outside diameter readings should fall within the outside diameter tolerances shown’. So ±0.4mm ovality… So I guess the smallest dimension could be -0.4mm and the largest +0.4mm from nominal in any given dimension, with the average being still ±0.2mm off nominal.

No, just try to stop people from buying solid rod thinking it is better.

It’s all relative. Round is more important than wall thickness, but conduit is thin and anything but round.

Don’t over think it. Just looking for the least expense material that is relatively easy to get that is near 30mm.

… That happens??

You asked what’s available, I’m just giving you a firehose of options and my opinion on what is ‘suitable’ from a local availability standpoint. I’m trying not to think about anything beyond that at all :slight_smile: