Brass fitting for fresh water with straight and tapered thread - how to?

[OneMoreFarang]

I am confused about straight and tapered threads on brass and stainless-steel fittings and how to connect them.

 

I looked at some YouTube videos and here is what I learned:

If the threads are tapered, then use Teflon tape (with some rules how to use that tape). 

If the thread is straight and there is a rubber or O-ring, then don't use Teflon tape. It's not needed because there is already a seal.

 

But how about a straight thread which does not have a seal included?

I tried to connect the following two parts first without any tape (for testing) and I can turn it 6 times until it is at the end of the thread.

And then I added 6 layers of Teflon tape, and I can still turn it with my hands until the end of the thread. I expected that I can only turn it maybe 4 times, but that is not what happened.

I guess I could add pipe dope. But I am not sure if that is the correct way to do that.

These connections have a straight thread.

 

 

 

 

And then there is the question of how to connect straight and tapered threads to each other.

It seems some of the fitting which I bought have a straight thread and some a tapered thread. I haven't worked out a logic what is what.

The valve in the below picture has a tapered thread. 

 

 

I know that maybe I should ask a plumber to do the job. But these are only 3 little connections, work for 10min. And I like to know myself how to do that.

Thanks

 

[Mike Lister]

Add more teflon tape, six turns isn't nearly enough, pack the stuff in there until it makes a seal..

[OneMoreFarang]

6 minutes ago, Mike Lister said:

Add more teflon tape, six turns isn't nearly enough, pack the stuff in there until it makes a seal..

Thanks, I just tried 10 layers. And now I can't turn it to the end anymore with my hands.

Maybe I will try one more with 15 layers or so.

I better test this dry on my desk before I do this with the real water connections... 

 

[Wobblybob]

Tapered threads you use pfte tape and parallel threads you use washers, but of course if you use a washer you will need something for it to abut to.

This is the type we used.

 

 

[Morch]

I think we had that problem during the house build. I I remember correctly there's a connector part for the straight-tapered thing. Just wasn't that common to find at shops, at least the size we needed. The terminology used at shops was more like male-female, female-female etc. Never found out which was which, or if it was the same in all places. I'd take the parts you need to assemble and ask someone - even at Global House or one of the others. For us there's a nearby big hardware shop, guy knows everything.

[Elkski]

I think the better thing is to show us what you are trying to do!   Tapered threads are usually fir the line runs and straight threads are fir the final end parts.   Are you making a bum gun? 

No plumbing should need more than 4 turns of good thick teflon.  Like blue monster brand.  I'm loving it. Never use that thin crap teflon that comes with fixtures from china. I plumb water at 120 Psi most days 5 months of the year. Many connections would require a total rebuild if they leak. So on metal to metal, and metal to plastic  NPT i have started using pipe dope on top of the teflon because sometimes these chinese parts quality isn't very good.  

have you ran into the issue of metric and imperial sized straight threads?  This was an issue for me installing a chinese bum gun temp mixer valve for a bum gun here  

[Wobblybob]

The golden rule. Just for ease of clarity the female is the one with the hole and the male fits inside the female.😉

 

"The golden rule is straightforward: a tapered male can fit a tapered or parallel female.

That is, a BSPT (tapered) male thread can fit both a BSPT (tapered) and a BSPP (parallel) female since the taper of the male will fit equally into a cylindrical thread. In the case of using a tapered tap on a parallel female, sealing material is recommended to ensure the tightness of the joint."

 

https://redfluid.es/en/differences-bspp-gas-bspt-npt-threads/#:~:text=The golden rule is straightforward,equally into a cylindrical thread.

[OneMoreFarang]

10 minutes ago, Elkski said:

I think the better thing is to show us what you are trying to do!   Tapered threads are usually fir the line runs and straight threads are fir the final end parts. 

Ok, here is one of the thinks which I want to do.

 

I want to exchange the existing chrome stop valve with a smaller valve to the side.

This is behind the washing machine and the washing machine should be near the wall.

I am not sure if I need the extension before the valve to have a little more distance to the wall so that it is easy to connect the pipe from the washing machine. The part to the right is just a converter for 1/2" to 3/4" which is what the washing machine pipe uses.

 

Now:

 

This is what I want, maybe with the extension or without. 

 

 

[Elkski]

I would think the wall is male tapered thread?  So use a street elbow tapered then your valve which is tapered then use the final piece that converts to straight thread.  Usually washer hoses have a place for a rubber   washer.  So your final piece needs to he called an adapter.  Going from tapered female thread to male hose thread. 

it looks like your SS elbow is male straight to female tapered.   Then you need an adapter.  But that just extends it out further, and not what you want.  In USA i can order in Amazon and get these things same day or next on most things.  Amazing. Of course I go to the supply house or home Depot 1-2 rimes many days  

[OneMoreFarang]

9 minutes ago, Elkski said:

I would think the wall is male tapered thread?  So use a street elbow tapered then your valve which is tapered then use the final piece that converts to straight thread.  Usually washer hoses have a place for a rubber   washer.  So your final piece needs to he called an adapter.  Going from tapered female thread to male hose thread. 

 

Thanks

Something like this female thread with PP-R pipe is in the wall.

 

[Elkski]

Then a "street elbow" is what you want then your valve then " adapter".  Assemble it all first then screw on wall because the valve knob may hit the wall if you put it in after the elbow. 

[OneMoreFarang]

2 minutes ago, Elkski said:

Then a "street elbow" is what you want then your valve then " adapter".  Assemble it all first then screw on wall because the valve knob may hit the wall if you put it in after the elbow. 

Thanks.

Now what is a "street elbow"?

Is the one in my picture a street elbow? 

[Elkski]

A street has tapered both the female and male ends.  Your looks like straight male. 

We really should turn the washing hot and cold on and off after every use but my mom nor I have never done this in 63 years.   Trouble is at our current house the mess is below the top of the machines.  

[Elkski]

Your elbow is to be used in the opposite flow direction.   Attaching onto male ouoe stub then using a hose gasket connection like a bum gun   here in USA the washer hose is usually a 5/8" size like all garden hoses. Our kitchen flexible hoses are similar to what is in Thailand. 

[xtrnuno41]

1 hour ago, OneMoreFarang said:

 

Thanks

Something like this female thread with PP-R pipe is in the wall.

 

It is a 1/2 inch pipe connection with a straight 20mm metric thread. It could be, the S2.5 will be the pitch.

But it is blurry on what 20 mm, what pitch. G pitch? BPSP pitch, however that would in Inches?

It ends with a flange on which you should put the gasket and use a connector also with flange to hold the gasket and close the connection, like this. You have to screw it in, all.

 

 

 

You never use tapered in straight or vv. If you need to change, you use adapters. 

You also use the right thread to make it, so not use, like for instance 1/4 NPT(National Pipe Tapered) on 1/4 BPST (British Standard Pipe Tapered) or vv.

It could fit, but not right. NPT has 60 degree angle on pitch, BPST 55 degree pitch. 

IF you mix them up and fitten all , thread can be damaged.

 

Mostly in Thailand you see from wall NPT, so that is tapered thread. I doubt if the connector picture is in your wall.

 

With tapered you use teflon for seal off. Just 2/3 winding enough. Some stupid liquid seal off is harder to get off and you will now when you have to replace. 
in my working time we got instruments with venting plug, but we changed those ones to other plugs, a crime to get it loose.

 

Straight thread doenst have teflon as locking,as it is by gasket. 

Of course you put fitting in, but not with immense forces. Just put it in by hand to stop and then maybe 1-2 turns.

Dont put too much stress on plastic pipe, glue connection of pipe. 

 

[OneMoreFarang]

2 hours ago, Elkski said:

Your elbow is to be used in the opposite flow direction.   Attaching onto male ouoe stub then using a hose gasket connection like a bum gun   here in USA the washer hose is usually a 5/8" size like all garden hoses. Our kitchen flexible hoses are similar to what is in Thailand. 

 

Thanks for all your information.

I will check about the "street elbow".

Do you know if what you write is also plumbers' (shop) common knowledge in Thailand? Or will they be confused when I ask them about a "street elbow"?

 

And in general: If I (or anybody else) have at the time of installation only some parts with straight thread, is there a way to do this work also with straight threaded parts? Or is that bad work and should be avoided? Thanks! 

[OneMoreFarang]

10 minutes ago, xtrnuno41 said:

Mostly in Thailand you see from wall NPT, so that is tapered thread. I doubt if the connector picture is in your wall.

 

Thanks for your detailed comment.

This is what is in my wall. I made that picture when they built is. It is from that position.

 

[Sigma6]

Parallel threads should seal at the bottom or on the shoulder using either dowty seal (bonded washer), O'ring, copper washer etc

 

Tapered threads use PTFE tape, or liquid thread sealant, like loctite

Folk using PTFE tape on parallel threads are cowboys - and yes it may work, if the pressure is low enough, and you jam enough in, but it isnt as per the intention.

 

As someone else stated; mixing between the 2 most common pipe threads (NPT and BSP) isnt ideal either.

One of those connectors in your pics looks like it may be a hose type connector.

The wall connector you have will be 1/2" NPT or BSP (Im not sure what is prevalent here, but someone else said its NPT, which is the American standard)

[xtrnuno41]

24 minutes ago, OneMoreFarang said:

 

Thanks for your detailed comment.

This is what is in my wall. I made that picture when they built is. It is from that position.

 

Pic is too blurry to make anything of it. Tried sharpening it, but nope.

I can see some of PP-R , but numbers not possible.

I think you have to take off the wall valve and see what is there. If you want a swimming pool then dont put off the main valve of the water, otherwise first switch off main valve water.

 

IF you want to mix, ok with me, I dont have water damage maybe later on, 555

straight in tapered maybe one turn. Hardly a seal.

Tapered in straight maybe 3 turns.

But then you get situation of putting on 10 rounds of teflon,

Both not my cup of tea.

If I see your connectors, they all look (!) like straight ones, only the valve is wrong then, replace that one with straight threads. Left overs from your other project? 555

BUT on straight threads you need gaskets and has to fit in somehow to make closure!

[OneMoreFarang]

5 hours ago, xtrnuno41 said:

Pic is too blurry to make anything of it. Tried sharpening it, but nope.

I can see some of PP-R , but numbers not possible.

I think you have to take off the wall valve and see what is there. If you want a swimming pool then dont put off the main valve of the water, otherwise first switch off main valve water.

 

IF you want to mix, ok with me, I dont have water damage maybe later on, 555

straight in tapered maybe one turn. Hardly a seal.

Tapered in straight maybe 3 turns.

But then you get situation of putting on 10 rounds of teflon,

Both not my cup of tea.

If I see your connectors, they all look (!) like straight ones, only the valve is wrong then, replace that one with straight threads. Left overs from your other project? 555

BUT on straight threads you need gaskets and has to fit in somehow to make closure!

Thanks, I will look for a better picture or make one.

With the parts I just bought in HomePro and a little shop around the corner something which I might need/use.

I.e. I asked them for a 1/2" elbow and that is what they gave me. Nobody mentioned different options for the thread.

But now I am aware of the difference, and I know what to look for. There are always some new "discoveries" with something I never did before.

The parts are luckily cheap. No problem if I buy a few and don't use them. 

[OneMoreFarang]

Now that I am aware of the different threat types, how to identify them?

Here are 3 links from HomePro about 90 degree elbows. Where can I see in the description or picture what thread they have?

Thanks

 

ELBOW THREAD MF BRASS SOCKET CITY 1/2" (homepro.co.th)

MPT-FPT BRASS ELBOW PIPE FITTING 90-DEGREE ANA 1/2IN (homepro.co.th)

ELBOW PIPE CONNECTOR ANA BRASS MF 1/2IN CHROME (homepro.co.th)

 

[Daffy D]

Don't use one of those small handle taps, after a while when the tap gets stiff there is not enough leverage to turn it.

 

If you can use tap with a normal size handle.

 

If there is space restriction behind the machine and wall, use an elbow and have the tap going up, down or left, right against the wall so the handle moves up/down or left/right and not in/out towards the machine.

 

I won't add my thoughts to the already too many confusing suggestions made regarding the connections. Except to say you're all over thinking it.

 

Anyways good luck 

 

 

 

 

[xtrnuno41]

12 hours ago, OneMoreFarang said:

Now that I am aware of the different threat types, how to identify them?

Here are 3 links from HomePro about 90 degree elbows. Where can I see in the description or picture what thread they have?

Thanks

 

ELBOW THREAD MF BRASS SOCKET CITY 1/2" (homepro.co.th)

MPT-FPT BRASS ELBOW PIPE FITTING 90-DEGREE ANA 1/2IN (homepro.co.th)

ELBOW PIPE CONNECTOR ANA BRASS MF 1/2IN CHROME (homepro.co.th)

 

Nr 1 would say it is a 1/2 "NPT , so tapered, to make a bend on 1/2" screwed pipe and the go out again to 1/2 "NPT.

nr 2 is a tricky one, i see male is straight(?), but female could be NPT to screw direct on NPT screwed pipe.

        so in that case the bend is also an adapter. You go from NPT to straight (?)on which you should put on your flex hose.

        flex hoses are with straight connection and a gasket.

nr 3 I would say that male is definitely straight, but then more luxurious. With (female) NPT screw to screwed pipe(wall)

 

You dont read anything about what thread it is, sadly. MF only stands for Male- Fmale nr 1

nr 2   MPT-FPT would stand for male female again p for pipe and T should be tapered, however I see male and that one could be  straight.

         It is difficult to see. According to (right description?) description MPT (male pipe tapered)it should be tapered. Again nothing mentioned. 

         Im doubting about male thread or the pic with that text, they could have made an error.  It looks similar to the chrome one, but then rough finish.

 

You send pic of wall mounting and the out fitting is FEMALE and what fits in female? MALE.

So at least you have to find a connector/adapter with MALE to screw in your wall out. Your valve in the wall will also have a male connection.

SO no clue what you want with nr 2 and 3, for another place then wall out? Or you think the wall out is still straight and you screw the straight in wall out and continu with NPT (maybe straight) to connect valve? But then you have wrong connector as there is no flange to put a gasket in between.

Then there should be inside the wall out a space to place a gasket. Or you tape the straight thread? What is in your mind?   

[OneMoreFarang]

I just removed the stop valve and made some pictures.

It seems to me the female thread in the wall pipe is straight. I can screw in a straight threaded part smoothly until the end.

 

The following are pictures from the pipe in the wall and from the stop valve which I removed.

It seems to me the Thai plumbing guy used a lot of Teflon tape. 

Until now, maybe a year after the installation, there was no leak.

 

 

 

[charleskerins]

On 11/2/2023 at 11:00 PM, xtrnuno41 said:

It is a 1/2 inch pipe connection with a straight 20mm metric thread. It could be, the S2.5 will be the pitch.

But it is blurry on what 20 mm, what pitch. G pitch? BPSP pitch, however that would in Inches?

It ends with a flange on which you should put the gasket and use a connector also with flange to hold the gasket and close the connection, like this. You have to screw it in, all.

 

 

 

You never use tapered in straight or vv. If you need to change, you use adapters. 

You also use the right thread to make it, so not use, like for instance 1/4 NPT(National Pipe Tapered) on 1/4 BPST (British Standard Pipe Tapered) or vv.

It could fit, but not right. NPT has 60 degree angle on pitch, BPST 55 degree pitch. 

IF you mix them up and fitten all , thread can be damaged.

 

Mostly in Thailand you see from wall NPT, so that is tapered thread. I doubt if the connector picture is in your wall.

 

With tapered you use teflon for seal off. Just 2/3 winding enough. Some stupid liquid seal off is harder to get off and you will now when you have to replace. 
in my working time we got instruments with venting plug, but we changed those ones to other plugs, a crime to get it loose.

 

Straight thread doenst have teflon as locking,as it is by gasket. 

Of course you put fitting in, but not with immense forces. Just put it in by hand to stop and then maybe 1-2 turns.

Dont put too much stress on plastic pipe, glue connection of pipe. 

 

"You never use tapered in straight or vv. If you need to change, you use adapters. "  Tapered isn't sweated ?    sharkbites available in Thailand?

[xtrnuno41]

6 hours ago, OneMoreFarang said:

I just removed the stop valve and made some pictures.

It seems to me the female thread in the wall pipe is straight. I can screw in a straight threaded part smoothly until the end.

 

The following are pictures from the pipe in the wall and from the stop valve which I removed.

It seems to me the Thai plumbing guy used a lot of Teflon tape. 

Until now, maybe a year after the installation, there was no leak.

 

 

 

Well there it is, indeed, amazing !, straight thread in wall out and the valve is tapered.

Then put on a lot of tape and keep on turning till it could shut off. Luckily for you it did and maybe it could do the job for many more years, but it is not the way. Also lucky they didnt ruin the thread and you can still fit in a straight one.

 

I see wall out has no space for gasket inside, so gasket must be on top of wall out, in between with the straight connector I showed with picture before. That would be the right combination. I showed it with rubber ring as gasket, but there are also ones with more common stiff gaskets.(several like a glassfiber gasket) Maybe even metal, like a soft copper ring, the one you use in oil plug types.

 

Take care of the surface of both holding the gasket, otherwise you could have leakage. Rubber could eliminate the tiny imperfections on surfaces. But not really to squeeze it hard, then you could damage (you squash it) the gasket and you have to start over with a new ring(gasket).

You have to find the straight connector, as shown, and then think how to go on. Wisely all straight, as you have straight connectors. Only valve is NPT, change that one then. That would be logical then, otherwise you should have all kinds of adapters to fit it right in. 

You have straight in wall, so make all straight in the rest of plumbing.

 

Straight with gaskets is the "new" method. Many years ago in industrie, the method was introduced. A crime as you have to watch out was used, it could be straight or tapered. Especial new installations were in straight.

And i have met mixings in my work, as simple reason no straight present, so use tapered.

So now it is also in household. Like I, said amazing to see straight in wall out, but then sadly next tapered.

Probably as they couldnt find straight thread valve, or ordered wrong. Or wall out was ordered wrong.

But ok, straight out , so all straight with gaskets ! Every connection needs a gasket.

[Muhendis]

On 11/2/2023 at 5:59 PM, OneMoreFarang said:

Teflon tape

It's PTFE

On 11/2/2023 at 5:59 PM, OneMoreFarang said:

But how about a straight thread which does not have a seal included

Ten turns of tape will do.

I have some old joints which can still be moved but don't leak.

You do not need to tighten them to maximum newton metres.

Tapered threads are for gas and shouldn't need tape.

It depends on how much water pressure is present but a few Bar is not normally a problem for a parallel thread with 10 turns of tape and no sealing washer. 

[Elkski]

You got this. 

Xtrnuno44 post is good. 

You can tell the posts with experience. 

I looked at your links of the  3 parts but its all Thai.    

Its easy to determine taper from straight threads i think the peoblem is there are 2 straight thread configurations.  

Since your wall female is straight thread and face sealing and won't be so tight try to run the valve and stuff to the right so gravity keeps it from turning loose. 

 

[xtrnuno41]

57 minutes ago, Muhendis said:

It's PTFE

Ten turns of tape will do.

I have some old joints which can still be moved but don't leak.

You do not need to tighten them to maximum newton metres.

Tapered threads are for gas and shouldn't need tape.

It depends on how much water pressure is present but a few Bar is not normally a problem for a parallel thread with 10 turns of tape and no sealing washer. 

The NPT/API standard is and still used for many years in oil/ chemical industrie and all tapered connections are with ptfe tape.

No matter it is air, gas or liquid. No matter it is 1 bar or 100 bars.

And again parallel thread needs NO ptfe, but do need a gasket.

NPT closure on threads, G or BPSP or any other straight on gaskets !

If you are clowning with 10 winds of ptfe tape, you dont know what you are doing.

Joints that move is not the right way of having connections, I hope it is not on your gas bottle.

If this was a clickbait, well you got me.

[Yellowtail]