Coupling Types - no hub, shielded, flexible ????

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Jasesun23

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Going to connect a 2" galvanized pipe to a 2" PVC pipe. Its above ground in my basement. I'm trying to get a firm understanding of the different types of connectors. I get that Name brands like Fernco and Mission used to mean certain models but they are really Brand names and both have all different types of couplings.
Please let me know if this is the correct way of looking at the different types. There are shielded and un-shielded couplings.
Un-shielded are sometimes referred to flexible but are pieced of rubber with a single metal strap at both ends to tighten. Basically these are not used anymore. But some location they are used underground outside?
Then there are shielded
No Hub shielded is for Cast iron to cast iron. It can have 2 to 4 tightening bands and the metal shielding is a corrugated looking piece of metal.
Then there is the shield with a solid metal shielding. This is not referred to as no hub and can be used for connecting cast iron to different materials?

If I'm correct why can't I use a no hub /corrugated shielded for galvanized to PVC. What exactly makes it only for CI to CI. The no hub is $3.50 and the solid shielding Proflex is $9. The money is not an issue as its my personal home and I have no problem spending extra money to do it right. I just really want to understand the difference in the two and why I should use one vs the other.

I've included pics of the two I'm talking about in my examples

mission-cp200.jpg
 

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Reach4

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I think you are right.

https://www.fernco.com/plumbing/shielded-couplings/proflex-couplings are the Fernco regular shielded couplings. Their 3000-22 would look to be the one for you.

PL means PVC or ABS plastic. XHCI is extra heavy cast iron, and CI is regular cast iron. So we can infer that this is not quite symmetrical, but the thing tightens over a range of diameters.

If you scroll farther down, you get diameters.
 

Jasesun23

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Reach thanks for the quick reply. I agree that the P3000-22 is the right one. It list that it can go from one material to another and the Fernco site you linked pic shows it going from CI to PVC.

I'm still curious why the corrugated shielded model , from what I can tell, called a no hub, which is 1/3 to 1/2 the price wouldn't be acceptable. Why is this one only for CI to CI? Why wouldn't it work for PVC to Steel which are both 2.375 OD.

Also the P3000-22 says from 2" CI,PL or ST to 2" CI, PL, or ST. Reading that it makes it seem it can go from any pipe to any pipe. That what end you use doesn't matter. Yet the sleeve inside has markings on each side. 1 side says 2 CI and the other says 2 PL. Should I assume the rubber coupling has different ID dimensions and one side should go on the PVC and the other go on the Galvanized pipe.

Pic attached of markings inside sleeve of solid shielded coupling. I attempted to use a digital caliper to measure ID of both rubber sides but its really impossible since they can flex.
 

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Reach4

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I'm still curious why the corrugated shielded model , from what I can tell, called a no hub, which is 1/3 to 1/2 the price wouldn't be acceptable. Why is this one only for CI to CI? Why wouldn't it work for PVC to Steel which are both 2.375 OD.
I don't know. Your logic is good. Maybe a different distribution channel?

Should I assume the rubber coupling has different ID dimensions and one side should go on the PVC and the other go on the Galvanized pipe.
The table below says one side is 2.28 and the other is 2.34. I presume these are the unstretched diameters, since each side can fit over 2 inch PVC and galvanized...

I would tend to put the bigger side on the one that is the hardest to work with, or on the one I put on first. Dish soap makes a good lubricant.

While we are discussing these, the tightening spec is 60 inch-lbs which is 5 ft-lbs. This is pretty easy to achieve with a nutdriver for an average person. If using a wrench, it is easy to overtighten. Some people have seen the 60 number and tried to crank to 60 ft-lbs.
 
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Jasesun23

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Look at that, I didn't scroll down all the way on the Fernco site you linked. They are different sizes, slight but different .
 

Jasesun23

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Well its doesn't leak, and its easily accessible so I can always change it to the more expensive solid shielded coupling.

If anyone can add exactly why the No Hub I used is wrong I'd like to know. Appreciate your help Reach4. Tighten to 60 in pounds with a torque wrench.

Jay
 

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Kreemoweet

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"designed to resist shear ..." is how the shielded, but not no-hub, couplings are described. That shear resistance would be very important
in underground installations and when using plastic pipe, as plastic can generate huge forces simply due to thermal expansion. No-hub
is typically used in commercial installs, is well-supported, and is largely accessible for repairs, unlike the minimal support requirements
(frequently disregarded) and zero access given to piping which is usual in residential construction.
Notice also how the metals used in the shielded couplings are specced as hi-grade stainless steels. I see none of that for the no-hubs.

Nonetheless, a no-hub may well work OK with plastic in some particular situations. It is "wrong" there only because it violates most
plumbing codes, which (quite reasonably) insist that devices be used according to their listings and manufacturer's instructions.
 

Terry

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What you have is a 2" hub there. I normally remove the pipe and the lead with packing and reinstall using a 2" cast iron hub Fernco insert and 2" PVC or ABS pipe.

washer-galv-abs-2.jpg


The old cast iron hub with lead.

washer-galv-abs-3.jpg


The new Fernco insert with 2" pipe.

washer-galv-abs-1.jpg


This is what I removed. You can guess that the washer was a bit slow draining.
 

Jasesun23

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So the solid metal shield is more resistant to sheer forces due to its slightly thicker solid piece of metal, where as the No Hub one with the corrugated metal shield has a thinner thickness of metal and its corrugated so its less strong especially with sheer force. I guess that makes sense.
 

Jasesun23

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I did that for a toilets a basement sink. My CI pipes are XH pipes and even standard XH donuts didn't fit well. Had to order special donuts and was a pain. I wanted to take the easy way out this time.
 

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