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View Full Version : Compresson Fitting vs. Slip Fix


reb12
10-13-2007, 12:49 PM
OK, my son and I are having an argument on which is best to use on a 2" PVC mainline. He says, a slip fix is fine if your connect it fully extended. I say for this repair you should only use a compression fitting. What say you???, and why??? Thanks!

PurpHaze
10-13-2007, 01:02 PM
You'll get arguments both ways as this has been hotly debated here before. Personally, we never install Slip Fixes on pressure lines (but use them all the time on lateral lines) and stick with either compression couplers or Dresser couplings depending on line size. I've replaced way too many Slip Fixes installed by our district plumbers in the past when they were initially maintaining our irrigation systems years ago.

Wet_Boots
10-13-2007, 02:00 PM
What about using a pair of sch 80 unions?

Dennis Spencer
10-13-2007, 02:28 PM
We use short pipe with bell end and a coupling.Once you start glueing no stopping.

FIMCO-MEISTER
10-13-2007, 03:04 PM
We use short pipe with bell end and a coupling.Once you start glueing no stopping.

Do not like this method. Involves going all the way down and pulling the bell forward which I think destroys the integrity of the glue joint. I would use slipfixes before this method. 4 ells is the best solution in my opinion.

reb12
10-13-2007, 03:55 PM
Meister, 4 elbows is going to hurt pressure. This is a main that feeds a ton of distant laterals on a high rise condo.

Wet_Boots
10-13-2007, 04:21 PM
Try the two unions, then. Flow is unaffected.

Mike Leary
10-13-2007, 04:47 PM
Try the two unions, then. Flow is unaffected.

I would agree..slip fixes are fine for low pressure mains & laterals, but I've
had them leak at 60 psi & up.

Mjtrole
10-13-2007, 05:38 PM
Ive used both but prefer the comp. fittings, the only downside to them on larger piping is that they need to be thrust blocked so they don't blow off or get pushed off the spot they are repairing, wood is no good because eventually it may rot and allow the comp. fitting to move off of its spot.

FIMCO-MEISTER
10-13-2007, 09:55 PM
Meister, 4 elbows is going to hurt pressure. This is a main that feeds a ton of distant laterals on a high rise condo.
What is the pressure like now? I guess the best solution would be Purps but if you use a comp fitting let me throw a thought out there for the skeet shooters here to fire at. Assuming this is a 2" pipe cracked or whatever and the nearest elbows and/or tees are not known. Take 2 2" crosses, glue in 2' of pipe on on opposite ends with caps glued on basically making it a cross turned into a coupling. glue those on each side of the coupling repair about 3-4' away. Then pour a bag of concrete around each cross/ coupling with the comp coupling in between. This would certainly prevent any shifting either way on the pipe. I've seen pipe shift inside concrete so the cross would add extra strength.

Good idea or bad idea? Better way?

Critical Care
10-14-2007, 12:51 PM
Try the two unions, then. Flow is unaffected.

Well... flow is of course affected to a point, but not as much as other ways. Who knows, you could put this unioned section in a valve box and innerchange it with a unioned quick connect for blowing out or for just water access.

That was really more of a joke, but in the right situation who knows.

Kiril
10-14-2007, 01:21 PM
Or perhaps you could use a couple of Wyes (Spears #P600-020) with a 1/16 street bends (Spears #P326-020) once you cut out the damaged area.

Kiril
10-14-2007, 01:39 PM
Or perhaps you could use a couple of Wyes (Spears #P600-020) with a 1/16 street bends (Spears #P326-020) once you cut out the damaged area.

Some alternate Spears Part numbers would be Wye #475-020 and possibly a 22 1/2 degree street elbow #442-020 or whatever it takes to get the repair section coming off wye parallel with the existing pipe.

First post part numbers are listed in their DWV fittings, the above numbers in their SCH40 PVC fittings.

Mike Leary
10-14-2007, 06:07 PM
Some alternate Spears Part numbers would be Wye #475-020 and possibly a 22 1/2 degree street elbow #442-020 or whatever it takes to get the repair section coming off wye parallel with the existing pipe.

First post part numbers are listed in their DWV fittings, the above numbers in their SCH40 PVC fittings.

More words of wisdom from the human parts catalog.:laugh:

jerryrwm
10-15-2007, 09:21 AM
Or perhaps you could use a couple of Wyes (Spears #P600-020) with a 1/16 street bends (Spears #P326-020) once you cut out the damaged area.Not sure it would be advisable to use DWV fittings on a pressurized main line. Don't believe they are pressure rated fittings.

Kiril
10-15-2007, 01:32 PM
Not sure it would be advisable to use DWV fittings on a pressurized main line. Don't believe they are pressure rated fittings.

Hence the second post. :)

Critical Care
10-15-2007, 01:40 PM
DWV fittings are for non or low pressure applications up to 25 psi.

Wet_Boots
10-15-2007, 02:48 PM
Two sch 80 unions and a bit of pipe are cheap enough, and the sch 80 repair should be stronger than the sch 40 pipe it goes onto.

FIMCO-MEISTER
10-15-2007, 02:50 PM
Two sch 80 unions and a bit of pipe are cheap enough, and the sch 80 repair should be stronger than the sch 40 pipe it goes onto.

Agree. Just need a precise cut.

Kiril
10-15-2007, 02:58 PM
DWV fittings are for non or low pressure applications up to 25 psi.

The Spears SCH 40 DWV (fabricated fittings) through 12" are pressure rated to 130 PSI.

Check out section 6.4:

http://www.spearsmfg.com/prod_dimensions_spec/FAB-7-0702_0807_web.pdf

Kiril
10-15-2007, 03:00 PM
Agree. Just need a precise cut.

Also agreed, and will be the easiest to put together assuming you can measure and cut accurately.

jimmyburg
10-15-2007, 03:10 PM
I have replaced more slip-fixes than compression fittings. My 2 cents.

irrig8r
10-15-2007, 03:17 PM
I don't like compression fittings on pressurized lines.The composition of the backfill material enters into it.

About 25 years ago we had a mainline out to a small apricot orchard that was 2" and was buried about 36" deep to give the tilling equipment plenty of room. A bad glue joint was replaced with compression fitting (sometimes called a "kubota"). The soil was a heavy clay and the swell and shrink from wetting and drying eventually allowed the fitting and pipe to shift and leak again. Granted this was unregulated pressure of about 120 PSI as I recall. Thrust blocks might have been a good idea if somebody had thought about it. The final repair we made used 4 ells.

jerryrwm
10-15-2007, 06:38 PM
The Spears SCH 40 DWV (fabricated fittings) through 12" are pressure rated to 130 PSI.

Check out section 6.4:

http://www.spearsmfg.com/prod_dimensions_spec/FAB-7-0702_0807_web.pdf
This is true...but there is a huge difference between 'Fabricated' fittings and 'DWV Molded' fittings. The molded are for "Drain, Waste & Vent" non pressure applications. Section 6.4 also says:

DWV Fittings - NPR
WYE, Combo WYE, etc. DWV - NPR

And yes I have seen what a 4" DWV ell looks like when it is subjected to 120 psi on a golf course. It makes a helluva hole when it comes apart!

Mike Leary
10-15-2007, 06:43 PM
And yes I have seen what a 4" DWV ell looks like when it is subjected to 120 psi on a golf course. It makes a helluva hole when it comes apart!

:laugh: :laugh: :hammerhead:

jerryrwm
10-15-2007, 06:52 PM
:laugh: :laugh: :hammerhead:Mike...The Chairman of the Greens committee called and said that I had made a faulty design and sold them defective fittings. (I was working for a supply house in So. Texas) They had put the system in themselves.
Drove the 100 miles -one way, to check out the problem. He took me over to a pile of pipe and fittings that they had taken out because of breaks.

I took one look at the fittings and told him that I hadn't sold the DWV fittings to him. He then remembered that they had messed up a few connections and had to cut them out. One of the members ran a hardware store and he brought them the needed fittings. Of course the only ones he had in 4" were DWV. Blew the end right out of the ells.

He apoligized and then took me to dinner at the Country Club. Rode in his restored '58 Vette convertible. Then we went a played a round of golf. All in all not a bad trip.

Mike Leary
10-15-2007, 06:59 PM
He apoligized and then took me to dinner at the Country Club. Rode in his restored '58 Vette convertible. Then we went a played a round of golf. All in all not a bad trip.

Great story Jerry, I bet your heart was pumping JUST a tad whilst driving
to the site. Steak & lobster...."waiter, more champagne".:laugh:

Kiril
10-16-2007, 08:59 AM
This is true...but there is a huge difference between 'Fabricated' fittings and 'DWV Molded' fittings. The molded are for "Drain, Waste & Vent" non pressure applications.

Agreed, NPR fittings have no place in any pressure scenario, use of low pressure DWV should be used with extreme caution, hence the reason for the second post with numbers to SCH 40 fabricated fittings.

The wye is rated to 235 PSI up to 2 1/2", the elbow at 280 PSI.

http://www.spearsmfg.com/prod_dimensions_spec/40-4-0507_0507_web.pdf

Wet_Boots
10-16-2007, 09:06 AM
How about never using DWV in pressure apps and leaving it at that? Back away from the catalogs....

FIMCO-MEISTER
10-16-2007, 09:20 AM
I've got so many Kiril pdf files on my desktop I've started a special file called:
THINGS FROM KIRIL

Kiril
10-16-2007, 10:58 AM
How about never using DWV in pressure apps and leaving it at that? Back away from the catalogs....

Did you miss the "SCH 40 fabricated fittings" part in my last post?

Knowing what materials are available gives you different options to approaching a problem. I did not say it was the preferred or best solution to the problem, just one approach. In fact, I probably wouldn't have even thought of it had I not run into a design problem with my houses central vac system.

Mike Leary
10-16-2007, 06:43 PM
Kiril knows the serial # of his pocket pen protector.

Wet_Boots
10-16-2007, 06:50 PM
that's harsh, bruddah :)

Mike Leary
10-16-2007, 06:54 PM
that's harsh, bruddah :)

That's how the west was won.:rolleyes: