no-hub terminology

davefoc

Various terms are used to refer to no-hub type fittings.

no-hubs, sheilded no-hubs, ho-hub bands, mission couplings, fernco couplings

What do these terms mean? Mission and Fernco are the names of Manufacturers but the terms fernco connector and mission connector seems to be used to mean particular kinds of couplings. In common usage what do these terms mean?





In particular what is the generic name for the above coupling?


What is the generic name of the above coupling?

For plastic to plastic applications what types of couplings are allowed and are there any restrictions on either of them?

I like to use the non-shielded ones where there I want some flexibility in the connection like when connecting the shower drain that needs to be level to the usually not exactly perpendicular drain pipe. Is this allowed under UPC? Are there any restrictions for its use inside walls?

USP45

First pix is a Fernco coupling used soley for plastic, second is no hub used for cast iron and steel pipe. The reason the fernco can not be used for iron is there is no strenth there to keep the pipes at the same level. If you use the fernco on cast iron it tends to sag, causing a lip inside where trash can get trapped. The plastic (ABS, and PVC) is so light that it will not sag causing any lip inside. Make sense? During new construction neither is allowed inside a wall or anywhere else for that matter unless your tieing into existing and changing pipe types (cast to PVC, or PVC to cast) Remodeling they do allow as far as I know, and I have used them in remodeling, but I try to stay away from it when I can.

ranman469

the frenco was removed from the IPC code. due to sag.

davefoc

Thanks for the replies .

ranman, are the Fernco couplings not allowed at all by IPC even in vertical plastic connections? I couldn't find any mention of restrictions on the Fernco site (probably not too surprising) Is it possible for you to reference the relevant code? As a practical matter I think using them to relieve tension on the vertical drain pipe when the drain pipe is not perfectly vertical seems like a good idea. I used one to fix a bathtup connection where the hard plumbed in drain pipes had long ago cracked because drain pipe for the tub wasn't perfectly vertical.

I should have noted that the pictures above are from the Fernco site, so Fernco makes all three styles This image is also from the Fernco site:


Is this what is commonly known as a mission coupling?

I also came across the term CIT coupling. Is this the same thing as a Fernco coupling?

The terminology used in the UPC code seems to be molded rubber coupling joint (705.1.6) , shielded coupling joint (705.1.8) and hubless cast iron pipe joints (705.1.9). Unfortunately the information is limited there and it is hard (for me at least) to tell exactly how the UPC intends for these type of couplings to be used and even exactly what they mean by the terms. Hubless cast iron pipe joints probably means no-hub and the UPC seems to intend, as USPS45 suggested, for this to be the way to join hubless cast iron pipe.

USP45

I was not aware of this change, neither are the inspectors here

Marlin

Really? I just put about 1000 of them into a new construction building. The banded ones are used for cast iron no hub pipes.

I only use the ones with the band. They work on galvanized, cast iron, and PVC which all share a similar OD. They make special ones to go from galvanized/pvc/cast to copper. Those clamps have orange or yellow tags on them (as illustrated in your picture). And usually have a more solid looking band.

The ones with just two hose clamps look horrible, are more prone to being damaged, don't make as well of a seal (they will leak more easially), and are more prone to causing a clog. If you are doing your job right you shouldn't need the extra play that they give you. Somehow the guys fifty years ago did the job with galvanized pipe measuring and threading every connection. Why can't it be done now with PVC?

USP45

marlin, with the inspectors here they would rather see a system that is as tight as possible. They view the ferncos and no hubs as a possible week spot in the system. They do not really fail it for this, but theyd rather not see it.

Marlin

So you don't use no-hub cast iron? What do you use for commercial buildings (where plastic isn't allowed), copper?

I agree that a new system shouldn't be using no hubs to transfer from PVC to cast and such.

USP45

Commercial we use cast iron, residential we use PVC. If we need to use no hub bands in commercial its just try to do it with as few no hubs as possible.

ranman469

when we did our code up date last year where we go through all the changes. i was a member of the tri county plumbing inspectors. there it was pointed out. most would never catch it. most insp. missed it.
its the astm # that was removed, therefore makeing it not allowed.
it was addresed for the ftex and when it is used with diffrent materals. they wanted shielded bands.

jpplumber

The first one is the Fernco also called a "CT" which stands for clay tile and we use them here for exactly that, when we do a PVC to clay tile transition in the ground and some inspectors like to see a bag of cement poured under it to discourage sagging.(it will say 4" PVC to 4" clay tile on the coupling and flares out to accommodate the larger diameter of the clay tile)
The Fernco you show is for pipe of the same outside diameter (or close to the same but is still ironically called a CT) and some inspectors like to see those on repairs that are PVC to PVC or PVC to Cast Iron provided there is the addition of a shielded band around the middle (like a mission band) to discourage sagging.
The second one is a no-hub band used for hubless cast iron to cast iron and in my mind also acceptable for PVC to PVC when dropping in clean outs where none exist or on PVC repairs.
The third one is a generic mission band and the difference between generic and actual will be noticed if you compare the rubber portion. Mission bands have heavier sheet steel as compared to the no-hub bands and it is not rippled or wavy, but the rubber portion on mission bands are of different thicknesses (most noticeable on the 3" and 4") to accommodate for PVC to cast iron transition so the clamps tighten equally as cast iron typically has a smaller outside diameter then PVC. If you look on the inside of the rubber on a mission band it will have the initials C.I. on one side and PVC on the other, the generic ones to my knowledge lack this feature. Mission bands are typically required on repairs under a slab.

Marlin

JP, read the coupling in the picture. It's Cast/Plastic to Cast/Plastic. They do make them for clay tile to cast but that's not the only thing they're made for. In my opinion the only place those fittings should be used is underground. A bag of cement under it is a good idea.

jpplumber

Yes I noticed that, I was only trying to show that when you go to the supply house and ask for a 4" CT adapter they almost always give you the one he has pictured for pipes of near identical outside diameter unless you actually say "give me a 4" CT for PVC to clay tile"....and if you go to Home Depot they just give you a stupid look cause they don't know beans

davefoc

This is a link to a copy of the ICC listed Fernco parts (reissued Jan 1, 2007):

http://www.icc-es.org/reports/pdf_files/BNBC/97-29.pdf

The un-shielded no-hubs still seem to be listed for plastic to plastic applications, but I'm not knowledgeable enough to know whether this is the actual document that is relevant to IPC approvals of no-hubs.

There was a note attached to 1056 series ( unshielded no-hubs) which states that they weren't evaluated for cast iron to cast iron. Presumably this means that they aren't allowed for that purpose as several people have suggested above.

This is a UPC listing for Fernco manufactured parts:
http://pld.iapmo.org/file_info.asp?file_no=0001193

One of the things mentioned in this document is that parts without center stops aren't allowed for new construction. It seemed like all the un-shielded no-hubs that didn't change size were precluded by this restriction from new construction but using them for repair purposes in existing construction would be allowed, which is roughly what USP45 said previously.

davefoc

Thanks to everybody that replied. In reading through this forum I had been confused by the various terms for these kind of couplings and had difficulty running down what the preferred and allowed uses were for the various types. I think I get it now.

I have been checking out how the various hardware stores refer to these types of fittings. The ones I checked had standardized on the terms no-hub coupling, flexible coupling and heavy duty no-hub (to refer to the mission coupling).