BSP threads

[rpt]

BSP female threads are always parallel but male can be parallel or taper. My understanding is that when connecting a male taper to a female you need to wrap PTFE tape as the seal is on the thread, but when using a male parallel a washer is required as the seal isn't on the thread. So why do I read so many people using PTFE tape on male parallel threads? Have I misunderstood?

 

[cnelsonplumber]

Good practice is to use PTFE on parallel threads as use of a washer requires a shoulder on the female to tighten the nipple or spigot against. (or Hemp and paste, but lets not get into that :shock: )

It all depends on the how long the threads are on the bit you are joining, but my advice is if using Stainless Steel PTFE is the way to go to avoid any leaks.
Winding the tape onto the male thread in the corect direction will make sure the tape stays in the joint.

 

[Andyhull]

Always use a BSPT and PTFE if you can, you will get a much better seal with a tapered fitting.

 

[rpt]

Good practice is to use PTFE on parallel threads as use of a washer requires a shoulder on the female to tighten the nipple or spigot against.

Is the shoulder inside or outside the female?

 

[wezil]

Hi inside in the end of the thread, if you look down it you'll see a ridge inside the 'nut' or half way down if it's a joining piece (long fitting designed to join two pieces of pipe on a long run) And I tend to concure that using ptfe as a matter of course is a good idea, it costs pennies a roll. (just think of the nuisance of stripping the fittings because of a leak)

 

[rpt]

So if I want to connect a ball valve with BSP female to a parallel nipple do I have to put a washer inside the tap female? Or can I use a lock nut and washer on the outside of the nipple? I thought it was the latter although a tap connector is like the former.

 

[Andyhull]

Buy a tapered nipple and just use PTFE no problem or risk of leak then :thumb:

 

[rpt]

That doesn't answer the question! I need to know how to connect up parallel nipples.

 

[Andyhull]

So a parallel nipple to a parallel female socket?
Just use plenty of PTFE tape or food grade silicone.
You don't use washers!!

 

[Vossy1]

BSP female threads are always parallel but male can be parallel or taper

BSP female are not always parallel and can be taper,
As per the previous advice, parallel to parallel use PTFE, taper to parallel use lots of PTFE :lol:
Taper aren't ideal as sanitary fittings as there will always be a space at the narrower tapered front which you can't really do anything about unless using liquid sealants. Using more PTFE at the front of a tapered fitting usually just means it'll be pushed up the fitting, though you can get it so it doesn't but it's very difficult.

 

[Vossy1]

So a parallel nipple to a parallel female socket?
Just use plenty of PTFE tape or food grade silicone.

Yup, you probably won't have to use that much as p to p is usually pretty tight. I'd try to avoid silicone if you can, I've yet to see one that wont go mouldy with time.

 

[rpt]

BSP female threads are always parallel but male can be parallel or taper

BSP female are not always parallel and can be taper,

In theory yes, but Wikipedia says they are rare and I have never seen one listed in any of the online catalogues I have looked at. Since you can use parallel female with both parallel and taper male but taper female can only be used with taper male, it makes sense that nobody bothers making taper female.

 

[rpt]

So a parallel nipple to a parallel female socket?
Just use plenty of PTFE tape or food grade silicone.
You don't use washers!!

I hate to contradict members who have infinitely more experience of plumbing than I do, but I don't believe that is correct. Since posting this question I have done some more googling and have found that the way to seal parallel threads is with either a washer/O-ring inside the female or with a nut and washer outside the male. What I'm not clear about is whether the particular female fitting determines whether or not to use an internal or external washer. I've also seen mention of cone seats which I don't understand.

One example of this is a standard plumbing tap connector. I think a tap has a 1/2" or 3/4" BSP male parallel thread. The tap connector is female with a washer inside.

 

[Andyhull]

I have been a mechanical engineer for many years and have done alot of pipe fitting in the past,
If you are using BSP threaded parallel fittings you "don't" use washers or cone seals!!!
You either use PTFE or a liquid sealent dependant on aplication!

If on the other hand you are refering to the plated brass compressed air type fittings then they have a machined in shoulder to accomodate an O ring.

Standard malliable steel or stainless steel BSP fittings do not have such a machined shoulder so cannot be used effectively with a washer (etc).

Andy

P.s. the type of parallel "long" thread you seem to be mentioning isn't a pressure safe aplication, it is used in connecting steel electrical conduit and is a 20mm thread, this is conected via an external face to face lock nut and a fibre washer, this will not seal a water tight system it will eventually leak.
For a BSP parallel or tapered thread you use PTFE Hemp and paste or a liquid type sealant!

If your asking for advice take the advice given rather than try to discredit it

 

[rpt]

If your asking for advice take the advice given rather than try to discredit it

I want to take the advice here as members have lots of experience. But when I read contradictory information it just increases the confusion. I need to understand this and get it right; I'm not trying to discredit it. So I am sorry if I have caused any offence.

I have been a mechanical engineer for many years and have done alot of pipe fitting in the past,
If you are using BSP threaded parallel fittings you "don't" use washers or cone seals!!!
You either use PTFE or a liquid sealent dependant on aplication!

Can you explain what a cone seal is?

If on the other hand you are refering to the plated brass compressed air type fittings then they have a machined in shoulder to accomodate an O ring.

Some of the information I have seen may have been this type of fitting.

Standard malliable steel or stainless steel BSP fittings do not have such a machined shoulder so cannot be used effectively with a washer (etc).

Andy

P.s. the type of parallel "long" thread you seem to be mentioning isn't a pressure safe aplication, it is used in connecting steel electrical conduit and is a 20mm thread, this is conected via an external face to face lock nut and a fibre washer, this will not seal a water tight system it will eventually leak.
For a BSP parallel or tapered thread you use PTFE Hemp and paste or a liquid type sealant!

Can you comment on this tap kit? It's using a long running nipple with two nuts and washers for either side of the boiler wall. It also appears to have another washer to seal the ball valve to one of the nuts.

Also this appears to be a similar type of bulkhead.

 

[Andyhull]

Am i on test here??????
I can describe all of the above but i think your a wind up merchant.

You never asked about using a cone seal so why the need to know now??????
For your information they are used usually on industrial soft aplications eg. in the fitting of a boiler sight glass.

They are also used on hydraulic sytems as a compression cone seal/seat gives a very high pressure seal.

As for your other questions . . . . .

The valve you have a link to is once again not relevant to your original post, that does have what is called a long thread fitted to the valve which is BSP, you could/should not connect this parallel thead to another piece of pipe as it would not be safe, the this is actually a bulkhead fitting but a none pressure type fitting, this will only work safely at atmospheric pressure.

The 15mm compression bulkhead fitting doeasnt have a BSP thread (no matter what the add says) but is usable on a 15mm compression valve with a piece of 15mm copper valve connecting the two!

Like i said i think your a windup merchant and i will not be answering any more of your questions. :nono:

 

[rpt]

I'm not a wind up merchant - I'm just trying to learn about plumbing so I can safely build my brewing equipment.

I'm just more confused than ever now.

 

[Andyhull]

Just use PTFE and you will be fine.

Have you baught your fittings yet?

 

[rpt]

Not yet. Hence all the questions.

Part of my problem is that I like to understand things rather than blindly follow someone else's recipe. Probably why my home made bread varies from fantastic to not so good.

My boiler has a 16mm hole for the current plastic tap. I'd like to avoid making the hole bigger so was thinking of using a 3/8" running nipple and then converting back to 1/2" on either side to use more "standard" fittings. This way I can always convert back to 1/2" in the future if I need to.

 

[wezil]

Hi I don't know about rpt but im very confused now! It might have helped if we knew what he was trying to make originally. As for a non mouldy silicone try one thats safe for fish tanks (they don't seem to go mouldy and they stick like s*it to a blanket on smooth surfaces)!