[quesera]

But 3/4" is also readily available, and much stronger. And of course larger gauges are available as well, just more difficult to bend with a standard manual bender.

I wouldn't use it for scaffolding(!) or anything supporting dynamic loads in the human-scale, but I've sistered three 3/4" EMT pipes together for an extremely strong, rigid, and inexpensive support pole.

[DannyBee]

Sure, you can use it for stuff, just don't expect it to hold anything real in any meaningful span.

Here's some real values for you:

2ft 3/4 EMT has an expected failure force of about 3300lbs (some studies found actual is around 3900-4200lbs).

4ft 3/4 EMT ha an expected failure force of about 2000lbs.

8ft 3/4 EMT has an expected failure force of about 450lbs.

So it is non-linear.

This is the point at which it fails catastrophically, not the point at which it starts sagging.

They are also not permanent load ratings, include no safety factors, etc.

Cost wise, 3/4 EMT costs 11 bucks for a 10ft piece at my home depot.

I can go to my local metal supply and get 3/4 square structural steel tube for < $1.00 a ft.

This is relatively in line with online suppliers so i believe it's not an exception: https://www.onlinemetals.com/en/buy/square-tube

This is structurally rated steel tube - it will hold much more than the EMT, it is meant for holding things, and being square, it's often easier to work with.

So i just don't know why i'd use the EMT.

[quesera]

EMT is light weight, readily available on weekend evenings, inexpensive, cuts easily, bends easily, is reasonably rustproof, and good enough for many applications.

It is "appropriate technology" for some applications, but of course there are better options when the requirements approach its critical limits!

I've used EMT to build big hoop trellises for growing vines. Bends smoothly into pairs of 10' arcs (using some ad hoc jigs), weighs almost nothing, requires minimal paint protection, supports more curcubits than our friends and family can consume, and lasts ~forever.

One of the tricks with EMT construction is to leverage the design for structural rigidity. E.g. geodesic domes with short members are extremely strong. Anything in compression will do well. If you need resistance to deflection across a long unsupported span, then I definitely agree -- EMT is not your material of choice!

[DannyBee]

(steel tubing is available on weekends and evenings too, fwiw)

I agree it's good enough for random aesthetic stuff, but even outdoor stuff is silly to use it for if you care about aesthetics. It really does rust pretty quickly these days. I have plenty of EMT that is 20 years old and not rusted, and plenty next to it that is 5 years old and rusty.

The latter is from different vendors, too. The specs over the years have gotten worse because nobody really uses EMT outdoors without painting it unless they are willing to accept it rusting to crap.

For your case, you could just use pvc pipe, cheaper, bends easier, cuts easier, can be glued directly, will never rust, you don't care about weight limits.

However, if you remember where we started, this article is about "structural pipe fittings" for EMT.

That is a horrible horrible idea.

[quesera]

PVC pipe does not survive outdoors, and the failure mode is messy.

"Structural" does not necessarily mean "very strong".

I think we mostly agree here though. I've used EMT for lots of things, and it has never ever let me down even slightly. I have also chosen square steel tubing for (less frequent) cases.

Choosing carefully is the key. When EMT fits, it's great stuff and preferable in many ways.

[happyopossum]

> PVC pipe does not survive outdoors, and the failure mode is messy.

That's just not the case - thousands of pool owners can point to 20+ year old PVC pipes and fittings in exposed pool equipment decks...

[quesera]

I hear this in other comments, but I cannot reconcile it with my own direct experience with brittle white PVC pipes.

There are a few grades of white PVC, including Schedule 40. There must be a subset of options which are appropriate for outdoor use.

[Edit: FWIW A superficial web search agrees with me that standard white PVC will degrade in UV. A common recommendation is to use "furniture grade" PVC, or to paint or wrap the pipe to protect it. In this context I'm mostly thinking about options available at ordinary hardware stores, not special order stuff, but apparently there are options.]

Other reasons to choose EMT though: thinner, more heat-resilient, less prone to sag, stronger by thickness, subjectively more attractive.

[hannasm]

Do you have a good source for these load calculations. I poked around on the site but didn't see anything representing an L/360 or other strength rating despite these fasteners being large enough to hurt people doing things if they don't know any better.

It would be great to just have one nice calculator to lookup trustworthy load data on standard home depot materials.