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big_gus

Active Member

1

Wednesday, January 18th 2006, 5:55pm

PVC Pipe Thread Suck!

Does anyone have a fail safe method for assembling PVC pipe Threads! I've gone through 2 rolls of Teflon tape with no luck. All my 3/4" threaded joints work, but the 1" mainline joints always seem to leak...

Here is what I've been doing:
1) Clean threads with dry cloth
2) Apply Teflon tape to thread at least 3 layers thick wrapping clockwise around the male threads applying tension to the tape to help it conform to the threads.
3) Assemble to finger tight
4) Turn 1.5 to 2.5 additional revolutions
5) Turn on water to find a slow leak (one drip every few minutes)
6) get mad, throw tools
7) Start over at step one, this time sitting in a mud puddle.

After a few attempts, I started to look at my fittings. The quality of the PVC threads is horrible. There is major flash and molding mis-match. Is this standard? Should I take these fittings back to the place I bought them?

In the interim, I've changed out as much of the threaded joints as possible, or converted them to brass and copper. However, this is expensive and I would prefer to use PVC in the future...

Any suggestions would be greatly appreciated...

Thanks

Wet_Boots

Supreme Member

Posts: 3,876

Location: Metro NYC

2

Thursday, January 19th 2006, 4:12am

Why would you even need one roll of teflon tape for a PVC sprinkler system? You could just about do the entire thing without any threaded joints under constant pressure. If you have some crappy-quality male adapters, by all means get good ones. Some female-threaded electric zone valves will require you to overload on the tape, because they are purposely made 'oversized' to guard against the threads from splitting.

big_gus

Active Member

3

Friday, January 27th 2006, 3:08pm

I guess I chose to use threaded joints because I thought that these joints would help make the system more serviceable.

I've Got Threaded Joints in the following locations:

CONSTANT PRESSURE:
1) At the main take-off: 1" Mips Copper Adapter to 1/4 turn PVC Fips Ball Valve
2) At the exit of my Ball Valve
3) At both sides of my Basket Filter

DOWN STREAM OF VALVES:
4) At every Sprinkler Riser
5) At the Pressure Regulators for the Drip Lines

I've can replace the PVC 1/4 turn Shut-off valve with a Copper one, but it's more expensive. I really don't want to buy another pricy filter to replace my plastic one.

Does Pipe dope work?

lush96

Advanced Member

4

Sunday, March 19th 2006, 5:33pm

pipe dope does work. be very carefull to read the can. some dopes can only be used on metal to metal fittings cause they expand and will crack your pvc. there is a GREAT pipe dope called "blue lock" that works fantastic on pvc threads. also......too much teflon is bad. it sounds like you are doing everything right. never overtighten!!!!! hand tight is usually good especially with dope added. you may need to replace certain fittings if you damaged the threads. try these methods as i have been putting together threaded pvc manifolds for years at my company and very rarely come across leaks. one more thing. if your psi is over 100, consider using glue fittings or switch to copper. hope this helps

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