Connecting cast-iron to ABS (or PVC) ...

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Old 02-11-09, 11:45 AM
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Smile Connecting cast-iron to ABS (or PVC) ...

Hi,

- I have had to replace a leaking horizontal portion of my bathroom drain pipe (4 in. cast iron) with ABS (4 in. also) and a Fernco shielded no-hub coupling.

question1 : Will such a shielded no-hub coupling hold up for connecting cast-iron to ABS ?

question 2: What is the difference between a flexible no-hub and a shielded no-hub coupling ?

question 3 & 4: I used a snap cutter to cut my cast-iron pipe. The cut is fairly clean, but not perfect. When I fit my cast-iron and PVC pipes together (just to do a match up test before applying the coupling), I notice that there are irregularities in the cast-iron piping circumference (1/8" at some places around the circumference). Will this have an effect on the efficiency of my Fernco shielded coupling? If so, is using a grider on the cast-iron to smooth it out recommended ?

Any feedback would be most appreciated.
 
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Old 02-12-09, 12:57 PM
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Cast Iron to ABS

watertight: Most of the time the shielded coupling is more heavy duty.

You can use a grinder on the cast iron, but don't get anal about it; your coupling will adapt to a certain amount of irregular spots on your cast, WEAR EYE PROCTION!!, luck.
 
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Old 02-13-09, 02:18 PM
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question1 : Will such a shielded no-hub coupling hold up for connecting cast-iron to ABS ? yes

question 2: What is the difference between a flexible no-hub and a shielded no-hub coupling ? a flexible one is thick rubber with a hose clamp at each end and will allow movement and under most codes is not to be used above ground. a shielded coupling is thinnner rubber with an aluminum shield that covers all of the rubber with 2-4 hose clamps on it making it more ridgid and less likely to allow pipe movement. the hose clamps are to be torqued to 60 in lbs

question 3 & 4: I used a snap cutter to cut my cast-iron pipe. The cut is fairly clean, but not perfect. When I fit my cast-iron and PVC pipes together (just to do a match up test before applying the coupling), I notice that there are irregularities in the cast-iron piping circumference (1/8" at some places around the circumference). Will this have an effect on the efficiency of my Fernco shielded coupling? If so, is using a grider on the cast-iron to smooth it out recommended ? yes and yes it is recommended
 
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Old 02-16-09, 07:36 AM
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Hi guys,

- Thanks you guys for the generous feedback. I did some digging around on the Fernco web site and contacted them. I had installed the wrong coupling. Things all look the same, but the devil is in the details. Actually, there are (as you all know) flexible and shielded couplings, however not all shielded couplings will support transitioning CI to ABS. And, I recall Plumberdanman stating the caution to make sure that the coupling indicates what it can transition to (CI-to-ABS, Copper, Clay, etc.). What I accidentally installed (and was recommended by a hardware store guy) was a shielded Fernco coupling, but only for mating CI-to-CO or ABS-to-ABS!

- Hence, I re-installed a flexible Fernco coupling that explicitly states that it can mate CI-to-ABS. Ideally, I would have preferred to install a CI-to-ABS shielded coupling, but I could not find any at h/w stores in my area. So, I put in a flexible CI-to-ABS Fernco coupling. I am aware that a shielded coupling would be best since I am working above ground, but since I am working on a horizontal portion, I think it could withstand a good rattle without leaking. I have supported the pipe before and after the transition with metallic hangers.

- Last, I saw that Fernco do make a specialized coupling, the "Proflex" series that supports both CI-to-ABS transitioning and is shielded, though my h/w store only sold those for 2in. pipes (and I need 4in.).

Watertight.
 
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