How to stop leak from 1 inch pipe in plastic tank.

[Sakeopete]

I have been trying to stop a  leak from the one inch PVC pipe with metal threads that is connected to the supply at the bottom of a plastic 1000 l tank. I have removed it several times and added thread tape but it keeps leaking. There must be a trick to stop the leak. Any ideas?

[Nojohndoe]

It may be that the brass fitting that is/was imbedded in the plastic surrounding it has become detached.That could give the appearance that the inserted fitting in it is leaking. If so  then it could be possible to remedy but difficult access internally to do so. .

Perhaps a large washer of a pvc  material with liberal pvc pipe cement between the insert  fitting and the tank fitting  and allowed to cure for a while  might be a cure?Or. there is  crack in the threaded part of the pvc fitting ? that has caught me more than once ! The quality of pvc pipe fittings is very variable plus thread tape makes it too easy to over tension and basically tear them apart.

I always now look for pvc threaded fittings that have a subtle incremental tapered thread as an equivalent to original  bsp metalic ones whereas many are totally even and do not progressively tighten. Becoming increasingly prevalent too are fittings which are  metric in diameter and fail due to being fractionatly smaller if used in conjunction with  bsp fittings regardless of  how  much thread tape is wound on in high pressure situations.

In the event of home handyman lack of success tanks of that size are not so inexpensive now

Good luck and hope you  get better opinion for  solution.

 

 

[Yellowtail]

First, as indicated above, make sure you know where it is leaking. 

 

If it is leaking between the brass and plastic threads, I think the easiest thing to try would be to replace the fitting on the pipe with a new PVC fitting with plastic threads and try again. 

 

Are the threads in the tank plastic? 

 

As as pipe threads are tapered, the brass (male?) threads on the pipe may have expanded the the plastic (female?) threads on the tank. If so, you can trim the end of the new PVC thread 3-4mm and it should tighten it up. It can be tricky to get it started back in so do not force it. 

 

 

[Cake Monster]

11 minutes ago, Yellowtail said:

First, as indicated above, make sure you know where it is leaking. 

 

If it is leaking between the brass and plastic threads, I think the easiest thing to try would be to replace the fitting on the pipe with a new PVC fitting with plastic threads and try again. 

 

Are the threads in the tank plastic? 

 

As as pipe threads are tapered, the brass (male?) threads on the pipe may have expanded the the plastic (female?) threads on the tank. If so, you can trim the end of the new PVC thread 3-4mm and it should tighten it up. It can be tricky to get it started back in so do not force it. 

 

 

I have to say that not all Pipe threads are tapered.

If the Thread is a British Standard 1 " Thread, there are 2 options for this .

The first is BSPP ( British Standard Pipe Parallel )

and the second is BSPT ( British Standard Pipe Tapered ) The Taper on this thread will be pronounced and you will see it visually.

The same applies to all British Standard Pipe Threads, which are the Norm in Thailand.

I have yet to see a Tapered Pipe Thread in Thailand, and most are just Parallel Threads where the slack between Male and Female is taken out with PTFE Tape.

Tapered Male and Female threads are far superior in both their strength and sealing ability over the Parallel Threads, however they tend to be more expensive to machine, and thats why we have to struggle sometimes with the parallel fittings..

 

 

 

[Sakeopete]

1 hour ago, Yellowtail said:

First, as indicated above, make sure you know where it is leaking. 

 

If it is leaking between the brass and plastic threads, I think the easiest thing to try would be to replace the fitting on the pipe with a new PVC fitting with plastic threads and try again. 

 

Are the threads in the tank plastic? 

 

As as pipe threads are tapered, the brass (male?) threads on the pipe may have expanded the the plastic (female?) threads on the tank. If so, you can trim the end of the new PVC thread 3-4mm and it should tighten it up. It can be tricky to get it started back in so do not force it. 

 

 

Tank threads are brass, I've tried both PVC threads and Brass thread fitting.  

[carlyai]

Just keep adding more white tape.  As long as you haven't stripped the thread ...heaps more tape ...more than you thought will do the job, eventually does it. ????

[rwill]

I don't think I have seen tapered threads here.  Pain it the butt.  Most people here wind about half a roll of tape on the fitting.

[CharlieH]

My suggestion......

 

https://s.lazada.co.th/s.VtPtH

[YayaManos]

Firstly check threads of the tank, trying using PTFE paste compound on the 1 inch nipple with PTFE tape this would stop the leak. It will work. Apply the paste all around threads of the nipple than go with white tape.

[Yellowtail]

1 hour ago, Cake Monster said:

I have to say that not all Pipe threads are tapered.

If the Thread is a British Standard 1 " Thread, there are 2 options for this .

The first is BSPP ( British Standard Pipe Parallel )

and the second is BSPT ( British Standard Pipe Tapered ) The Taper on this thread will be pronounced and you will see it visually.

The same applies to all British Standard Pipe Threads, which are the Norm in Thailand.

I have yet to see a Tapered Pipe Thread in Thailand, and most are just Parallel Threads where the slack between Male and Female is taken out with PTFE Tape.

Tapered Male and Female threads are far superior in both their strength and sealing ability over the Parallel Threads, however they tend to be more expensive to machine, and thats why we have to struggle sometimes with the parallel fittings..

That just has not been my experience. Below is an SCG 1" PVC threaded adaptor. These are arguably standard of the industry in Thailand and the threads are clearly tapered. 

 

 

 

[Yellowtail]

54 minutes ago, rwill said:

I don't think I have seen tapered threads here.  Pain it the butt.  Most people here wind about half a roll of tape on the fitting.

Now you have....

 

(just kidding)

[Yellowtail]

1 hour ago, Sakeopete said:

Tank threads are brass, I've tried both PVC threads and Brass thread fitting.  

I assume the tank threads are female, yes?

 

Assuming it is, do the threads go all the way through or do they end?

 

You should be able too put a straight-edge on the threads and see if they are tapered. 

 

Again, make sure it is not leaking out around the OD of the brass insert. 

[Speedhump]

1 hour ago, CharlieH said:

My suggestion......

 

https://s.lazada.co.th/s.VtPtH

Hello Mr. Heath-Robinson. ????

[Speedhump]

16 hours ago, Nojohndoe said:

It may be that the brass fitting that is/was imbedded in the plastic surrounding it has become detached.That could give the appearance that the inserted fitting in it is leaking. If so  then it could be possible to remedy but difficult access internally to do so. .

Perhaps a large washer of a pvc  material with liberal pvc pipe cement between the insert  fitting and the tank fitting  and allowed to cure for a while  might be a cure?Or. there is  crack in the threaded part of the pvc fitting ? that has caught me more than once ! The quality of pvc pipe fittings is very variable plus thread tape makes it too easy to over tension and basically tear them apart.

I always now look for pvc threaded fittings that have a subtle incremental tapered thread as an equivalent to original  bsp metalic ones whereas many are totally even and do not progressively tighten. Becoming increasingly prevalent too are fittings which are  metric in diameter and fail due to being fractionatly smaller if used in conjunction with  bsp fittings regardless of  how  much thread tape is wound on in high pressure situations.

In the event of home handyman lack of success tanks of that size are not so inexpensive now

Good luck and hope you  get better opinion for  solution.

 

 

Hi. A polite question and not meant to cause offence, do you live in Thailand? Plastic piping/joints may be BS or metric, and in my experience it's usually impossible to know which you're buying. The idea of tapered threads sounds like something from another planet. ????

[dlclark97]

First check that there is nothing cracked in either the female or male fitting.  Yes it is common to use a lot of tape here.  In the USA there is a liquid teflon paste that I use.  Actually had some sent over.  It is possible there is something similar here but I've never seen it.  Not knowing your DIY abilities, are you wrapping the tape in the right direction?  If wrong, the tape will only roll up as you thread it in and not make a good seal.  Once the wrapping is correct, 10-12 or more complete wraps may be needed.  Most of the teflon tape I find here is very thin and typically about a half inch or less wide.  Have not seen it myself but have been told some stores carry a thicker tape up in widths from about the half inch to one inch wide.  A friend here had a leak around the tank fitting.  Actually there was a crack under the fitting that he could not see.  He tried numerous ways (various glues etc) to repair it with no luck.  He called the tank manufacturer and they sent a service person who fixed it up in an hour.  The fitting had been over tightened.   Good luck.     

[Sakeopete]

I'm going to try this stuff.

https://www.lazada.co.th/products/55-50-loctite-no55-thread-sealing-cord-50m-i732014594-s1400982291.html?exlaz=d_1:mm_150050845_51350205_2010350205::12:13920044294!125392363912!!!pla-294682000766!c!294682000766!1400982291!172459525&gclid=CjwKCAjwmqKJBhAWEiwAMvGt6EoAW65sMxFPutnH8mNXnwlRB9gL6X5XALPqKJXggjfGWD_6mjV8IhoC2K0QAvD_BwE

[mikecha]

buy tape from global  that worked for us as ptfe tape here has  bad quality

 

 

never seen loctite thread anti leak here but i did bring 2 tubes last time 

works perfect  maybe lazada sells

[Yellowtail]

1 hour ago, Speedhump said:

Hi. A polite question and not meant to cause offence, do you live in Thailand? Plastic piping/joints may be BS or metric, and in my experience it's usually impossible to know which you're buying. The idea of tapered threads sounds like something from another planet. ????

Again, that has not been my experience. Below is the same SCG 1" PVC threaded adaptor pictured above. These are arguably standard of the industry in Thailand and the threads are clearly tapered in the picture above, and is clearly marked 25mm(1"). 

 

If something has a parallel threads, it must have an O-ring or some other compression-type seal, pipe sealant should not be used. 

[malthebluff]

Cut it out but leave around  4 inch of pipe then cut this pipe as close to the fitting as possible so you have small piece of pipe  then replace the faulty fitting  with new on the end  of this pipe and use a coupling with the small piece of pipe with new fitting connected to join existing pipe 

[Stevemercer]

I sometimes use that sticky fluid used for joining lengths of plastic pipes. I tape it up, drip on the fluid and screw it in. Mind you, this is a second-to-last resort as it may be impossible to remove. So I only use it when I know it is possible to saw off the leaking part and install new joints as a last resort. This may not be possible for a water tank.

[Speedhump]

34 minutes ago, Yellowtail said:

Again, that has not been my experience. Below is the same SCG 1" PVC threaded adaptor pictured above. These are arguably standard of the industry in Thailand and the threads are clearly tapered in the picture above, and is clearly marked 25mm(1"). 

 

If something has a parallel threads, it must have an O-ring or some other compression-type seal, pipe sealant should not be used. 

Well clearly you don't buy your plastic pipe and pipe reducers in Home Pro. 

[Yellowtail]

18 minutes ago, Speedhump said:

Well clearly you don't buy your plastic pipe and pipe reducers in Home Pro. 

Seriously? You crack me up.

 

[petermik]

Seems to me that the brass threaded insert has split,hence fitting more thread tape and tightening up only opens the split wider....either replace the tank fitting if you can or drain it off and use a good quality silicone sealant and give it enough time to cure properly before filling it with water again.

[DiDiChok]

You need a jointing compound.  In the UK we use "Boss White" particularly on half inch copper water pipe and central heating pipes.  It isn't sold here in Thailand but "Amerikem" black gunge is, complete with a brush attached to the lid.  Looks awful, seals perfectly and allows you to undo it later should you need to, but the mess needs wiping up.  Cheap & available in DoHome and good plumbing places.

 

 

[sometimewoodworker]

3 hours ago, Yellowtail said:

That just has not been my experience. Below is an SCG 1" PVC threaded adaptor. These are arguably standard of the industry in Thailand and the threads are clearly tapered. 

 

 

 

Un-tapered

the same fitting with the guide dowels in the wrong place seemingly tapered

 

so while tapered threads may be available they are far from standard.

 

your preparation for picture methodology is not clearly correct, many fittings have a slightly larger base so giving an illusion of a taper if your chopsticks are too low. I don’t say that your fittings do not have a tapered thread, just that you haven’t made that as clear as you think.

Edited August 27, 2021 by sometimewoodworker

[Nojohndoe]

1 hour ago, Speedhump said:

Hi. A polite question and not meant to cause offence, do you live in Thailand? Plastic piping/joints may be BS or metric, and in my experience it's usually impossible to know which you're buying. The idea of tapered threads sounds like something from another planet. ????

No problem. Yes I live in Thailand. Until recent years all the pvc pipes and fittings were made standard to imperial threads and dimensions. (BSP/T British Standard Pipe Thread ) even if some were marked in metric equivalents. eg 1/2 inch or 20.99mm. Threads per inch TPI 14.

NOW I too have to check because every place I have purchased fittings has bins marked as  BSP .

Either there is an increase in very poor quality or there is an increase in random metric dimensional product which is incompatible with BSP in that they are a loose fit when using threaded parts.

Visually they look the same. My way to compensate is to take a known BSP fitting and "test" it against a product. The TPI may be the same  but even with hand tightening they will not be a proper fit.

There is also an American format NPT ( National Pipe Thread)which is still imperial dimension but the thread profile is slightly different which is important mostly using metallic parts. They are also invariably a tapered thread which assists in self sealing on tightening.

In the times when galvanized piping and fittings was standard a bit of grease was enough to help a good leakproof joint. The invention of thread tape  just made it less  messy. But thread tape for pvc is too often just a compensation for low quality manufacturing and so also often leads to over

tightening in attempt to stop a leak which results in stress crack failures often at the junction of where the threads meet the external body of the component. Less so now than in years past there are some "male"pvc fittings that  do have a subtle tapered thread but probably old stock lucky to be found.

In conclusion to my long winded explanation I can only hope the content of it is to some degree useful. I am not a Plumber but I am a retired development and production Engineer across a wide field. Also an ardent DIY-selferwhen I have the energy.

I happily and willingly defer to other comment, opinion,advice offered to the op's question which indeed may provide a simple solution.

 

 

 

 

 

 

 

 

[sometimewoodworker]

This shows the difference in diameter between the base and threads. It is obvious that there is not a 4^o taper

32.2mm thread

32.9mm base

base approx 32.4mm

Thread 32mm

Edited August 27, 2021 by sometimewoodworker

[3NUMBAS]

GUN GUM WORKS ON CAR RADS

[phetphet]

6 hours ago, Cake Monster said:

I have to say that not all Pipe threads are tapered.

If the Thread is a British Standard 1 " Thread, there are 2 options for this .

The first is BSPP ( British Standard Pipe Parallel )

and the second is BSPT ( British Standard Pipe Tapered ) The Taper on this thread will be pronounced and you will see it visually.

The same applies to all British Standard Pipe Threads, which are the Norm in Thailand.

I have yet to see a Tapered Pipe Thread in Thailand, and most are just Parallel Threads where the slack between Male and Female is taken out with PTFE Tape.

Tapered Male and Female threads are far superior in both their strength and sealing ability over the Parallel Threads, however they tend to be more expensive to machine, and thats why we have to struggle sometimes with the parallel fittings..

 

 

 

On my list for the next time I am able to return to UK: A mix of 1/2" and 3/4" BSPT brass fittings. Had a hell of a job fitting new bathroom taps. Kept leaking because of straight threads in to pipes in wall. Tapered would have done the job perfectly. Also some proper thread compound for domestic water.

[Elkski]

I suspect as much as the OP has tried to seal this that there is a crack in the fitting or the brass to tank weld has been abused.   Try a plug in the brass tank and try to observe where the leak is.    I've never heard a plumber or anything written to use 12-15 wraps of tape.   I'm quite the handyman plumber.  I did have something recently that said 4-5 turns but I've always been a 2-3 times a day type guy.  555

Edited August 27, 2021 by Elkski