Wot is this pipe and where can I get a replacement?

[lampini]

As title....

 

The blimmin’ joint is leaking.. sigh...

 

the good news news is I found the leak the evening we passed our Bss! ??

 

...or does the panel think it may be fixable with some PTFE tape....

Edited October 26, 2018 by lampini

[WotEver]

It looks like a flexible tap connector to me. Screwfix or any plumbers merchants (or even B&Q). Glad you passed your BSS although a leaking water system wouldn’t affect that of course. 

[matty40s]

It's only water,  what could go wrong......

 

Try tightening joints, try refreshing ptfe tape (use the yellow gas one!!), or you will probably sink within minutes ..

[stegra]

Standard flexible tap connector. Looks like it might be cross threaded at the filter end. If so the plastic may be damaged.

[lampini]

9 minutes ago, matty40s said:

It's only water,  what could go wrong......

 

Try tightening joints, try refreshing ptfe tape (use the yellow gas one!!), or you will probably sink within minutes ..

We tightened it and it got worse!!!! 

 

No sinking tho - water is isolated from tank atm... wasn’t going out to work with that leak still going! ?

[adrianh]

This hose has the wrong form on the end, it is meant to connect to the flat end of a tap and seal with a flat washer.

The standard connector for the filter has conical tapered end, so you are unlikely to get a seal with this set up.

The thread on the filter is 1/2" NPT I think, which is slightly different to the 1/2" BSP on the flexible pipe

If you check the Jabsco site you may see what adapters are available that fit the filter properly.

My setup uses the braided hose adaptor and flexible pipe ( with jubilee clips) to a hose tail on the rigid pipe work.

[sharpness]

The flexis come in different lengths so if you are getting a new one, get it longer so its not pulled round in such a tight bend.

[bizzard]

17 minutes ago, sharpness said:

The flexis come in different lengths so if you are getting a new one, get it longer so its not pulled round in such a tight bend.

Hear hear.

[dmr]

13 minutes ago, adrianh said:

This hose has the wrong form on the end, it is meant to connect to the flat end of a tap and seal with a flat washer.

The standard connector for the filter has conical tapered end, so you are unlikely to get a seal with this set up.

The thread on the filter is 1/2" NPT I think, which is slightly different to the 1/2" BSP on the flexible pipe

If you check the Jabsco site you may see what adapters are available that fit the filter properly.

My setup uses the braided hose adaptor and flexible pipe ( with jubilee clips) to a hose tail on the rigid pipe work.

Steady on a bit, this is a discussion forum, factual answers like that can totally prevent discussion (except for those who just ignore factual posts and just carry on regardless).

 

What is the history of NPT? I assume it came along after BSP so was it a slightly sick joke on the part of its (American) inventors.....lets design a thread that appears absolutely compatible with BSP but leaks a little bit????

 

.................Dave

[MtB]

54 minutes ago, lampini said:

..or does the panel think it may be fixable with some PTFE tape....

 

Quite the opposite actually. Adrian is on the money in post 6. The PTFE tape on the thread is supremely pointless as the thread is not where the water seal occurs. Undo the nut and remove the PTFE. The nut will be captive and free to spin on the end of the tap connector pipe. Inside the nut you'll see a neoprene washer designed to bed onto the plain threaded end of a tap as Adrian says. These sometimes seal adequately onto the (internally) chamfered end on fittings like the water filter, and sometimes not. Try it with no PTFE tape and it might be fine. If not, get e a file and file a mm or so off the end of the thread on the filter, to create a flat end. Get it nice and square and the tap connector will probably seal just fine. 

 

 

2 minutes ago, dmr said:

What is the history of NPT? I assume it came along after BSP so was it a slightly sick joke on the part of its (American) inventors.....lets design a thread that appears absolutely compatible with BSP but leaks a little bit????

 

My understanding is that due to the overwhelming need for pipe threads to be universal, it is identical to BSP but the yanks felt the need to call it something without the word "British" in it. 

 

I could be wrong though, and CBA to have a goggle. 

[Flyboy]

9 minutes ago, Mike the Boilerman said:

 

Quite the opposite actually. Adrian is on the money in post 6. The PTFE tape on the thread is supremely pointless as the thread is not where the water seal occurs. Undo the nut and remove the PTFE. The nut will be captive and free to spin on the end of the tap connector pipe. Inside the nut you'll see a neoprene washer designed to bed onto the plain threaded end of a tap as Adrian says. These sometimes seal adequately onto the (internally) chamfered end on fittings like the water filter, and sometimes not. Try it with no PTFE tape and it might be fine. If not, get e a file and file a mm or so off the end of the thread on the filter, to create a flat end. Get it nice and square and the tap connector will probably seal just fine. 

 

 

 

My understanding is that due to the overwhelming need for pipe threads to be universal, it is identical to BSP but the yanks felt the need to call it something without the word "British" in it. 

 

I could be wrong though, and CBA to have a goggle. 

NPT & BSP threads are not identical. They have different thread forms and pitches.  

[dmr]

12 minutes ago, Mike the Boilerman said:

 

Quite the opposite actually. Adrian is on the money in post 6. The PTFE tape on the thread is supremely pointless as the thread is not where the water seal occurs. Undo the nut and remove the PTFE. The nut will be captive and free to spin on the end of the tap connector pipe. Inside the nut you'll see a neoprene washer designed to bed onto the plain threaded end of a tap as Adrian says. These sometimes seal adequately onto the (internally) chamfered end on fittings like the water filter, and sometimes not. Try it with no PTFE tape and it might be fine. If not, get e a file and file a mm or so off the end of the thread on the filter, to create a flat end. Get it nice and square and the tap connector will probably seal just fine. 

 

 

 

My understanding is that due to the overwhelming need for pipe threads to be universal, it is identical to BSP but the yanks felt the need to call it something without the word "British" in it. 

 

I could be wrong though, and CBA to have a goggle. 

I'm pretty sure they have identical or almost identical diameter and pitch but a slightly different thread profile, BSP is sort of pointy so the threads more or less seal whilst NPT has a rounded tip on the crest of the threads so leaves a very small gap that can leak.   This is one of those situations were a bit of PTFE might actually help (where the threads are providing the seal rather than just a sealing force that is).

 

.............Dave

[bizzard]

I think that nut might be cross threaded, (quite easy to do on a plastic thread)  it doesn't look square on to me. Also I can see stress at the hose crimp which is also not quite square on due to the too sharp curvature of the hose.

[Sea Dog]

If fitted correctly, the strainer should be on the inlet side of the pump, keeping any crud from the fresh water tank entering the pump itself. As such, the line is only under the low pressure created by the head of water in the tank so I see no reason to have the braided wire reinforced line. If you're struggling to get a seal, it might be easier just to replace the line with food grade reinforced hose.

[matty40s]

Any thread involving BSP usually has Tree monkey all over it. Stick a log of strange wood over the leak and he will be along shortly.

[Flyboy]

8 minutes ago, dmr said:

I'm pretty sure they have identical or almost identical diameter and pitch but a slightly different thread profile, BSP is sort of pointy so the threads more or less seal whilst NPT has a rounded tip on the crest of the threads so leaves a very small gap that can leak.   This is one of those situations were a bit of PTFE might actually help (where the threads are providing the seal rather than just a sealing force that is).

 

.............Dave

  Some sizes do have the same TPI but most do not,  eg. 1/8", 1/4", 3/8" all have 1 TPI difference. 1/2" & 3/4" have the same TPI.

[lampini]

Thanks for all your thoughts guys, especially Mike - the placement of the ptfe was not making any sense to me! I will further investigate in the morning...

 

thanks again! Xx

[Ex Brummie]

MTB has already told you what you need to do. Anyone who has used flexible hoses to taps will know that the seal is made with a neoprene washer against the mating face. Clean off the ptfe, clean off the face and replace the washer. Screw the nut up to finger tight plus a 1/2 turn. If it leaks, tighten up a further 1/4 to 1/2. If you use a long spanner or grips until it moves no further, you will deface the washer to such an extent it will never seal. On domestic taps, a 1/2 turn past finger tight will hold against mains pressure, so your 30 psi is nothing.

[Dr Bob]

I'd just get rid of the flexible pipe and replace with clear braided pipe. That way you can diagnose problems as you can visibly see bubbles flowing in the pipe. Far too tight a bend on the pipe as well.

[MtB]

2 minutes ago, Dr Bob said:

Far too tight a bend on the pipe as well.

 

I'd say it probably isn't actually.

 

I don't think there is much stress on that joint as if you look carefully, the other end of the flexible hose is not in a fixed position, it is screwed into another, identical flexible hose just lying nice and unstressed under the pump motor. 

 

Even so, it would be better to add some extra pipework and not to have the bend. 

 

 

[dmr]

1 hour ago, Flyboy said:

  Some sizes do have the same TPI but most do not,  eg. 1/8", 1/4", 3/8" all have 1 TPI difference. 1/2" & 3/4" have the same TPI.

Just one TPI???,  a nice big spanner and you won't even notice. ?

 

1/2 and 3/4 are common domestic plumbing sizes whilst the smaller ones are a bit more engineering/instrumentation.....is this just a co-incidence????

 

.............Dave

[Flyboy]

On 26/10/2018 at 23:32, dmr said:

Just one TPI???,  a nice big spanner and you won't even notice. ?

 

 

 

You will when it leaks.

[bizzard]

Unless its a photo distortion thing  I'm pretty much convinced that its cross threaded.

[DandV]

The American Standard threads NF NC NPT have a 60deg thread form with truncated peaks. BS  threads have 55deg thread form and radius ends. Where the thread forms a seal generally copious PTFE tape, or if sealing against water, plumbers hemp,  can acheive a seal for these mismatched threads provided they have the same pitch. Attempting to match those with the mismatched pitch will result in damage.

 

 

Edited October 27, 2018 by DandV
50deg changed to 55deg

[lampini]

4 hours ago, bizzard said:

Unless its a photo distortion thing  I'm pretty much convinced that its cross threaded.

 

Mr Bizz may have a point - but I think the distortion is just that the gland (?) going into the bottom of the bolt is loose! 

 

Possibility - the PTFE was a bodge to get around the cross-thread or miss-matched thread (previous owner installed this!)

 

Possibility - neoprene washer is FUBAR due to my over tightening..

 

possibility - both of the above!

 

cheers gang... will investigate when it’s light... bloody shift work has one up n musing over a cuppa t at some odd times in the morning! 

Edited October 27, 2018 by lampini