Installing 6" Spiral Pipe - crimp or coupling?

[Rob Beaupre]

As the title says, I'm starting to install 6" spiral duct (26ga) - (right now its collecting dust on the outside (on the ground) vs installed)

I wanted to know people's experience with installing Spiral pipe. Should I avoid crimping the pipe ends where needed?
I believe I've read that crimping can add a small amount of resistance, not sure if it'd be significant enough to worry but should I always use couplings instead of crimping ?

I can get (and have bought a few) of the proper couplings from my HVAC supplier. I've attached a picture. These aren't overly expensive, but these along with all other fittings, the $$$ is adding up.

In the pic, if the air is following the arrow, I was thinking also to cut off, or flatten the crimping on the Left side, to reduce as much resistance. I believe without the crimping, I can still get the pipe over the coupling.

I guess what I'm asking is, if I use these couplings, am I adding just as much resistance as crimping the pipe itself.?

Is it worth worrying over? Thanks for any and all feedback.

430935

[Jim Becker]

Coupling for sure, but smooth ones. If they are sized correctly, I don't believe any crimping should be needed. Just mastic/foil tape.

[Andrew Seemann]

I'd go with regular straight couplings. They will have less resistance, and I can't imagine that spiral pipe would be that fun to crimp. If you have gone to the expense of spiral pipe and fittings, might as well do the whole thing right. Crimping here and there probably doesn't matter at the hobby shop level when you are using 6 inch pipe, at that point you are pretty oversized for most things. Same with that little bulge on the coupling to keep the pipes centered on the coupling.

In general, my experience using both was that the spiral pipe and fittings were a lot easier to use than HVAC pipe and crimping.

Did the couplings come with the crimping on them? The ones that I got from Spiral Mfg. did not have any crimping on them.

[Darcy Warner]

They make a simple external ring, cheap, but not as easy as those.

[Rob Beaupre]

Yes, they did come with the crimping on them. I might ask if they have couplings without crimping, but it'd be quicker for me to just hammer the crimping flat, rather than try to exchange, especially with the restrictions around Covid.

[Jim Andrew]

My metal vise has a flat spot behind the jaws for using like an anvil. I have hammered out the crimps using that. Spiral pipe does not really work crimping, as the ridges are so high. I have used couplers instead of crimping, and when reconfiguring, the couplers are handy for joining 2 pieces of pipe previously cut.

[Rob Beaupre]

Thanks to all for the feedback. I'll be looking to install everything with couplings, you're right Andrew if I've already gone this far, why stop short now.
Jim Andrew, thanks for the comment on using the vice. I'll do that for sure.