Water Pipe Repairs

[DrTuner]

1 hour ago, Pattaya Spotter said:

If using metal valves, how do you fit them to the plastic PVC pipes?

Use PVC connectors and pick the ones that have brass threads. It's hard to get good teflon tape here (these are not tapered), the SCG tape is the only one that sort of works. I ordered thicker teflon tape from Amazon US but that was before they started snatching passports.

 

The PCV parts also have quality differences - look for the ones with shiny finish (forgot the brand) and do remember to scour the plastic before applying the glue. I've got enough battle scars to know it makes a difference.

[sometimewoodworker]

1 hour ago, Moonlover said:

You cannot 'melt the glue' because it isn't glue at all. It's a solvent that softens the the surface. When you make the joint the two parts blend together and harden again. It essentially becomes one piece of pipe.

No it doesn’t become a single piece of pipe, the join is microns thin

 

The only water pipe that actually becomes one at the join is PP-R. I have taken cut ends of blue PVC pipe out of well glued fittings several times when I didn’t have that particular fitting in stock.

 

It’s reasonably easy for most fittings using a heat gun and a pair of long nosed pliers. You do need to be careful not to use too much heat or you can deform the fitting. You deform the cut pipe to take it out.
 

The fittings are usually perfectly usable after disassembly.

[Pattaya Spotter]

1 hour ago, teacherclaire said:

It's pretty easy to work with these PVC pipes.

 

Give it a try and use some better valves that do not fall apart after one month.

I've lived in this house for over 10 years...this valve is probably due for replacement.

[Moonlover]

2 hours ago, sometimewoodworker said:

No it doesn’t become a single piece of pipe, the join is microns thin

 

The only water pipe that actually becomes one at the join is PP-R. I have taken cut ends of blue PVC pipe out of well glued fittings several times when I didn’t have that particular fitting in stock.

 

It’s reasonably easy for most fittings using a heat gun and a pair of long nosed pliers. You do need to be careful not to use too much heat or you can deform the fitting. You deform the cut pipe to take it out.
 

The fittings are usually perfectly usable after disassembly.

If you can separate a joint by the method you have outlined, then that joint was not made properly in the first place. (I encountered quite a few of them in the old house that we've renovated)

 

The 3 common mistakes are a. lack of preparation of the surfaces (cleanliness) insufficient solvent on the surfaces and then the most common mistake of all, turning the water too early.

 

A properly made PVC joint becomes 'welded' at a molecular level and cannot be separated.

[sometimewoodworker]

34 minutes ago, Moonlover said:

If you can separate a joint by the method you have outlined, then that joint was not made properly in the first place. (I encountered quite a few of them in the old house that we've renovated)

 

The 3 common mistakes are a. lack of preparation of the surfaces (cleanliness) insufficient solvent on the surfaces and then the most common mistake of all, turning the water too early.

 

A properly made PVC joint becomes 'welded' at a molecular level and cannot be separated.

I know that the joints I have separated were prepared correctly, had sufficient new glue and did not have the water turned on too soon. They did not leak, were in service for a short, reasonable or long time. They all came apart.

 

I also have come across joints that were not correctly done, not these.

 

Your experience and mine are clearly different, I know that I have taken well made joints apart, you know that it can’t be done.
 

Are we both reporting our experiences? Yes. 
 

Why are they so different? I don’t know. It could be technique. It could be glue used. It could be pipe. It could be preparation, etc.

 

you are assuming that the joints I took apart were badly made, I know they were not.

[DrTuner]

4 hours ago, Pattaya Spotter said:

Guess I didn't look close enough ???????????? I was only thinking of the long straight pipe lengths and not that I can make custom threaded ends by cementing appropriate fittings to the ends of them.

BTW IMHO the best selection of PVC pipe parts in Pattaya (I assume you're here) is at Thai Watsadu on Sukhumvit: https://goo.gl/maps/eHWYJu5oGC2SiuWk8

 

Walk in and all the way to the back, there are racks of the stuff on the right side.

https://goo.gl/maps/LBatXQ6G7YzGPLHN9

Edited August 28, 2020 by DrTuner

[Pattaya Spotter]

3 hours ago, DrTuner said:

BTW IMHO the best selection of PVC pipe parts in Pattaya (I assume you're here) is at Thai Watsadu on Sukhumvit: https://goo.gl/maps/eHWYJu5oGC2SiuWk8

 

Walk in and all the way to the back, there are racks of the stuff on the right side.

https://goo.gl/maps/LBatXQ6G7YzGPLHN9

I assume that's the one on Sukie past Lotus Jomtien going south.

[johng]

8 hours ago, Pattaya Spotter said:

I assume that's the one on Sukie past Lotus Jomtien going south.

Its on the northbound carriageway  of Sukhumvit.

 

https://www.google.com/maps/place/ไทวัสดุ+สาขาพัทยาใต้,+Thai+Watsadu+South+Pattaya/@12.8869821,100.8975336,3a,75y,335.12h,87.71t

 

[Pattaya Spotter]

59 minutes ago, johng said:

Its on the northbound carriageway  of Sukhumvit.

 

https://www.google.com/maps/place/ไทวัสดุ+สาขาพัทยาใต้,+Thai+Watsadu+South+Pattaya/@12.8869821,100.8975336,3a,75y,335.12h,87.71t

 

I believe that's the only Thai Wasuda in town.

[Yellowtail]

I like the PVC valve for applications where the valve is only used occasionally. 

 

I agree joints can be taken apart, but (IMO) only as a last resort. 

 

You can just cut out the old valve and splice in a new one using PVC unions:

 

 

 

 

[sometimewoodworker]

29 minutes ago, Yellowtail said:

I agree joints can be taken apart, but (IMO) only as a last resort. 

Absolutely. I only do it if there is no shop open and I really need that particular fitting.

[Yellowtail]

12 minutes ago, sometimewoodworker said:

Absolutely. I only do it if there is no shop open and I really need that particular fitting.

And then it's a krap-shoot...

Edited August 29, 2020 by Yellowtail
deletion

[bankruatsteve]

1 hour ago, Yellowtail said:

I like the PVC valve for applications where the valve is only used occasionally. 

My experience has been that if not used, they end up getting stuck in whatever position they are in (probably from lime scale) and if not really careful to get the valve loose, the valve will break away from the lever and leak.  (from a few drips to an all out geyser)

[DrTuner]

3 minutes ago, bankruatsteve said:

My experience has been that if not used, they end up getting stuck in whatever position they are in (probably from lime scale) and if not really careful to get the valve loose, the valve will break away from the lever and leak.  (from a few drips to an all out geyser)

Lime scale and silt. The plastic valves are simple, just a ball with a hole in it and some o-rings. When there's accumulation on the ball and you twist it, the o-ring gets scraped and eventually it starts to leak. The good brass valves have a piston type mechanism that's much more reliable.

[Seeall]

On 8/28/2020 at 2:24 PM, johng said:

Its supposedly possible to heat the joints and "unglue" them  but I had no success with that method  using a LPG blow torch   a hot air paint stripper or  soldering station with variable temperature might do better ?

The heat also damaged another part stuck in the wall so I couldn't actually glue the new bit in without leaks

however the every usefull 2 part epoxy resin soon did the trick  it even sets  with water in the pipes...not under pressure just  no need to totally dry the joints like you do with PVC glue.

 show us your epoxy resin please

[Seeall]

On 8/28/2020 at 4:58 PM, Pattaya Spotter said:

Maybe I'm missing something...I understand the metal valves are threaded but I've never seen threaded PVC pipes...only smooth ends.

Go look again...

 

Hey, you guys are going to put the pipe guy out of work!!!

[Seeall]

On 8/28/2020 at 6:43 PM, DrTuner said:

Use PVC connectors and pick the ones that have brass threads. It's hard to get good teflon tape here (these are not tapered), the SCG tape is the only one that sort of works. I ordered thicker teflon tape from Amazon US but that was before they started snatching passports.

 

The PCV parts also have quality differences - look for the ones with shiny finish (forgot the brand) and do remember to scour the plastic before applying the glue. I've got enough battle scars to know it makes a difference.

Why not use the metal taps.. I cant see them having a problem for decades..

[DrTuner]

2 hours ago, Seeall said:

Why not use the metal taps.. I cant see them having a problem for decades..

Yes brass valves, but also brass threads on the PVC side. There are two types of threaded PVC parts, ones with plastic threads and ones with brass threads. The plastic ones are easy to strip or skip a thread, the brass ones tend to need more teflon tape to make watertight. I prefer the brass ones because it's harder for the somchai that sneaks in in the middle of the night just to screw your pipes to destroy the thread. He can, though.

 

I mean these:

Edited August 31, 2020 by DrTuner

[johng]

11 hours ago, Seeall said:

 show us your epoxy resin please

The "Draga"  is slightly more viscus than the "Bosny"  but both are very runny

and somehow go absolutely everywhere, I've had some success containing the stuff with cling film/plastic wrap before it starts to set (makeshift shuttering) then you have a  short while where it's like putty before being too far set to be useful.   clean up before it dries with  lots of washing up liquid and scouring pad rinsed with water..

 

for a pipe glue/fix only a very small amount was needed I roughened both surfaces with sand paper and cleaned and dried as far as possible then applied with wooden BBQ skewer a thin coat of epoxy to  the male PVC pipe leaving about  the first 5 mm with no epoxy and then coating the 5-15mm part then just assemble as you would with glue except probably quite a lot of epoxy will spill out and you need to leave it to set for a good few hours before turning on the water.

 

Did I mention it goes everywhere !!!! ????

 

 

[DrTuner]

As far as epoxies go, I've found Scotch the best. It's not too runny, sets well without a sticky surface. Never tried on PVC though, I would think it's very important to scour the surface well to achieve adhesion. I use the usual PVC glue from Thai Pipe, when properly prepared the joint is so strong I've tried to chisel it out without any luck. It won't fill any gaps though, so epoxy might be useful in cases where it's impossible to get a tight join otherwise.

[Yellowtail]

What is the reason for using epoxy rather than the regular solvent glue?

 

I like the SCG high-pressure PVC glue that comes in a tube, much more viscous than the brush on...

 

Wish I could find a good brand that came in a decent brush-top can here...

[Pattaya Spotter]

I see on YT all the PVC tutorials use primer before the pipe cement...but not seen this in the stores. Is it recommended to prime before or is it unnecessary?

[DrTuner]

2 minutes ago, Pattaya Spotter said:

I see on YT all the PVC tutorials use primer before the pipe cement...but not seen this in the stores. Is it recommended to prime before or is it unnecessary?

Haven't found it in Thailand. Would use if I could.

 

EDIT: https://www.lazada.co.th/products/weld-on-p-70-primer-946ml-i552314064-s1006940290.html?exlaz=d_1:mm_150050845_51350205_2010350205::12:1498579383!58089999096!!!pla-294682000766!c!294682000766!1006940290!128036153&gclid=CjwKCAjw4rf6BRAvEiwAn2Q76mqklIebWopkNtobGWlBmS87uHT0PhYh5Z-UXo1F5L1cpF02CLn4mxoC5lAQAvD_BwE

 

And ordered.

Edited September 1, 2020 by DrTuner

[Yellowtail]

29 minutes ago, Pattaya Spotter said:

I see on YT all the PVC tutorials use primer before the pipe cement...but not seen this in the stores. Is it recommended to prime before or is it unnecessary?

 

SCG sells a primer.

 

I believe  that US (or at least CA)  code mandates primer be used for PVC joints. That said, I think the cement available in the US (or at least CA) is much "safer" than the cement available in Thailand which if probably why the primer is required. The primer in the US is tinted such that inspectors can confirm it was used. 

 

I've never use primer at hope or at the plant in the 20 years I've been here and as far as I know have never had a joint failure. 

 

 

 

 

[Yellowtail]

If you are going to use a primer, I would not use a different brand primer and cement. 

 

As with painting, I try to buy all materials from a single source when possible. I try to use all SCG pipe, fittings, walves and cement....

[DrTuner]

7 minutes ago, Yellowtail said:

If you are going to use a primer, I would not use a different brand primer and cement. 

 

As with painting, I try to buy all materials from a single source when possible. I try to use all SCG pipe, fittings, walves and cement....

I'll do a report once I get it. Interested to see just how much it softens the PVC. Could spare me the sandpaper step.

 

Some reading: https://www.plumbingsupply.com/the-great-pvc-primer-debate.html

Edited September 1, 2020 by DrTuner

[Yellowtail]

9 minutes ago, DrTuner said:

I'll do a report once I get it. Interested to see just how much it softens the PVC. Could spare me the sandpaper step.

 

Some reading: https://www.plumbingsupply.com/the-great-pvc-primer-debate.html

 

I just use a little acetone and one of these:

 

 

 

The primer might just acetone with color in it...

 

 

[DrTuner]

5 minutes ago, Yellowtail said:

The primer might just acetone with color in it...

Probably is. From what I read from the article, the joint will be weaker at first, which makes sense as it's softened the plastic, and ends up about the same after 24h. I'll get me that pipe reamer, thanks.

Edited September 1, 2020 by DrTuner

[Yellowtail]

5 minutes ago, DrTuner said:

Probably is. From what I read from the article, the joint will be weaker at first, which makes sense as it's softened the plastic, and ends up about the same after 24h. I'll get me that pipe reamer, thanks.

 

The reamer works surprisingly well on the half and three-quarter, pretty good on the one-inch. 

[sometimewoodworker]

3 hours ago, Pattaya Spotter said:

I see on YT all the PVC tutorials use primer before the pipe cement...but not seen this in the stores. Is it recommended to prime before or is it unnecessary?

The interesting conclusion of the linked article is

Quote

Conclusion

The purpose of this investigation was to determine the effect of primer on the strength of solvent welded PVC and CPVC joints. Was primer necessary to have better joint strength? The hypothesis was that if primer penetrates and softens the plastic surfaces prior to the application of cement, then the inclusion of primer in the solvent welding process should achieve maximum fusion and strength. This was not the case. In both tests, the primer had a negative effect on the strength of the pipes. In the compression test, more primed joints failed first than unprimed joints. In the torsion test, the primed joints overall took less force to fail than the unprimed joints. The primed joints also had a higher failure rate, although the rates were more equal than in the compression test.