BSP Parallel Thread Male x BSP Parallel Female Thread - Gas Fitting Sealing

[Deleted member 36384]

I have a BSP Parallel Thread Female x BSP Taper which seals with simply making up and with some PTFE tape or liquid sealant. I also have a BSP male and female parallel threads. The male thread bottoms out in the female bushing and I am wondering if I need a flat washer to seal where the male bottoms out in the female segment, or should I just use sealant tape or liquid sealant? It is a gas system and I have both the correct tape tape and liquid for sealing. I am wondering because I have a recollection (which may be wrong) that a flat washer is used on parallel to parallel threads to make the seal. The taper is easy to understand but the fact that the parallel threads bottom out rather loosely is what is making me wonder about the flat washer. All the stuff was bought from a reputable supplier and no flat washer was provided with the fittings. The actual fitting is a Cleese valve (BSP parallel female) to a hose spigot (BSP parallel male). My current plan is to use 'Clessetite Thread Sealant For Metallic Pipework and Equipment', which is rated for LPG and make up until the male bottoms out on the female bush and then just nip up a bit more.

Any comment or advice is welcome, thanks, BlowingOldBoots

 

[philwebb]

I have a BSP Parallel Thread Female x BSP Taper which seals with simply making up and with some PTFE tape or liquid sealant. I also have a BSP male and female parallel threads. The male thread bottoms out in the female bushing and I am wondering if I need a flat washer to seal where the male bottoms out in the female segment, or should I just use sealant tape or liquid sealant? It is a gas system and I have both the correct tape tape and liquid for sealing. I am wondering because I have a recollection (which may be wrong) that a flat washer is used on parallel to parallel threads to make the seal. The taper is easy to understand but the fact that the parallel threads bottom out rather loosely is what is making me wonder about the flat washer. All the stuff was bought from a reputable supplier and no flat washer was provided with the fittings. The actual fitting is a Cleese valve (BSP parallel female) to a hose spigot (BSP parallel male). My current plan is to use 'Clessetite Thread Sealant For Metallic Pipework and Equipment', which is rated for LPG and make up until the male bottoms out on the female bush and then just nip up a bit more.

Any comment or advice is welcome, thanks, BlowingOldBoots

 

[philwebb]

Hi Blowingoldboots, your plan sounds Ok. You could do a pressure test afterwards or just put some soapy water on the joint
afterwards ( with gas pressure on) and check for bubbles which would indicate a leak. You can buy leak detector spray from
a plumbing shop if you are worried. Loctite 55 is also good for sealing threaded joints for water or gas. It is a string a bit like dental floss which is very good for sealing joints.
Regards Phil

 

[Topcat47]

Your local plumber's merchant will have some magic Silicone sealant called "Fernox LSX". I use it for all gas and water connections and even hull fittings. The great beauty of it is that if you break a joint made with it, the residue will peel off with a rub of your fingers, clean and ready for a fresh application. Much better than thread tape.

Fairey liquide and a little water makes a great solution for bubble testing gas system joints, too. it foams if there is any leak.

 

[NorthUp]

Cut the last thread off the male taper, use the liquid sealer or the ptfe- not both together.

 

[colhel]

I have a BSP Parallel Thread Female x BSP Taper which seals with simply making up and with some PTFE tape or liquid sealant. I also have a BSP male and female parallel threads. The male thread bottoms out in the female bushing

Its normal practice when sealing BSP parallel to seal it on the shoulder using something like a Dowty Seal. http://www.ashtonseals.com/images/ashton-seals-logo.gif

 

[Giblets]

From one who used to to this on a daily basis Loctite 55 is the best way forward. The advantage being that you can back the joint slightly if needed. It can be used on both water & gas.

LSX should not be used on gas as it is only suitable for water. Remind me to moor well away from Snark in Cherbourg!

 

[ianj99]

Its normal practice when sealing BSP parallel to seal it on the shoulder using something like a Dowty Seal. http://www.ashtonseals.com/images/ashton-seals-logo.gif

That is my understanding too. Not good practice to rely on sealant on a bottomed out thread.

 

[Heckler]

I have a BSP Parallel Thread Female x BSP Taper which seals with simply making up and with some PTFE tape or liquid sealant. I also have a BSP male and female parallel threads. The male thread bottoms out in the female bushing and I am wondering if I need a flat washer to seal where the male bottoms out in the female segment, or should I just use sealant tape or liquid sealant? It is a gas system and I have both the correct tape tape and liquid for sealing. I am wondering because I have a recollection (which may be wrong) that a flat washer is used on parallel to parallel threads to make the seal. The taper is easy to understand but the fact that the parallel threads bottom out rather loosely is what is making me wonder about the flat washer. All the stuff was bought from a reputable supplier and no flat washer was provided with the fittings. The actual fitting is a Cleese valve (BSP parallel female) to a hose spigot (BSP parallel male). My current plan is to use 'Clessetite Thread Sealant For Metallic Pipework and Equipment', which is rated for LPG and make up until the male bottoms out on the female bush and then just nip up a bit more.

Any comment or advice is welcome, thanks, BlowingOldBoots

Fibre washer is the way to go.
S

 

[Deleted member 36384]

Thanks folks for the advice, I will source a Dowty Seal and fit that as well on Cleese Valve.

Fairwinds, BlowingOldBoots

 

[RichardS]

Cut the last thread off the male taper....

Why would the OP want to shorten the taper?

Apologies if I have misunderstood.

Richard

 

[prv]

Parallel threads are not designed to make a seal, even if it's possible to bodge one with various tapes and fluids. Parallel threads are designed purely to draw two parts together so that another surface (not the thread) can make a seal. Usually this means a washer (rubber, fibre, copper, etc) though there are other possibilities.

Pete

 

[Heckler]

Thanks folks for the advice, I will source a Dowty Seal and fit that as well on Cleese Valve.

Fairwinds, BlowingOldBoots

Be careful with a dowty seal, the seal bit is in the middle, not the edges, if the threaded male bit is thin it wont land on the sealing bit. The old gas fittings used red fibre washers
S

 

[Deleted member 36384]

Be careful with a dowty seal, the seal bit is in the middle, not the edges, if the threaded male bit is thin it wont land on the sealing bit. The old gas fittings used red fibre washers
S

Thanks, I have ordered both, the red fibre seals and a pack of stainless Dowty Seals, apparently the Dowty type are the self centring style.

 

[rob2]

Over a lifetime of handling and building kit for all sorts of gases - some of which you really don't want to escape! - I have acquired a reasonable knowledge of the parts which fit together and those that don't. One of the cardinal rules though is that anything that requires sealant isn't a proper seal. PTFE tape does help to make a seal, but really only by lubricating the thread such that it can be brought up tighter, making the seal. Even if that is only a half truth (probable) it is a good principle to work by.

What worries me is that in these days of Nanny State when advice is that a professional should be employed to fit things, the basic skill set is being lost by the DIY owner. Similarly one sees more and more questions about how to fix expensive electronic kit which only a white collar worker can afford, so they don't have the background to understand it. More worrying perhaps is the example of a friend's caravan which he has "serviced" annually - after which half the kit doesn't work! Perhaps the basic skill set is being lost by the professionals as well, just a symptom of the throw away economy.

Rob (having a bad day)

 

[Heckler]

Over a lifetime of handling and building kit for all sorts of gases - some of which you really don't want to escape! - I have acquired a reasonable knowledge of the parts which fit together and those that don't. One of the cardinal rules though is that anything that requires sealant isn't a proper seal. PTFE tape does help to make a seal, but really only by lubricating the thread such that it can be brought up tighter, making the seal. Even if that is only a half truth (probable) it is a good principle to work by.

What worries me is that in these days of Nanny State when advice is that a professional should be employed to fit things, the basic skill set is being lost by the DIY owner. Similarly one sees more and more questions about how to fix expensive electronic kit which only a white collar worker can afford, so they don't have the background to understand it. More worrying perhaps is the example of a friend's caravan which he has "serviced" annually - after which half the kit doesn't work! Perhaps the basic skill set is being lost by the professionals as well, just a symptom of the throw away economy.

Rob (having a bad day)

And that is why it saddens me when I see old time served artisans like me, not being replaced by the same. The old time skills and knowledge that is in our heads is slowly being lost as we peg it.
This is a typical thread, peeps dont know what to do. I do, because I learned it off a similar old gimmer when I was a lad. Silly things like when opening a wheel valve. open it all the way, then close it half a turn. It means the valve wheel is loose, a sure signal to the next guy that touches it that the valve is open. If it was opened all the way to the stop, it is then tight, then when someone tests it they dont know whether it is open or not! Learned on the first day as a bushy tailed apprentice!
S

 

[prv]

Silly things like when opening a wheel valve. open it all the way, then close it half a turn. It means the valve wheel is loose, a sure signal to the next guy that touches it that the valve is open. If it was opened all the way to the stop, it is then tight, then when someone tests it they dont know whether it is open or not! Learned on the first day as a bushy tailed apprentice!

They still teach that to divers, for opening the valve on an air cylinder . The supposed reason is that it can stick if opened all the way to the stop and not backed off. I still find myself doing it with taps etc.

Pete

 

[Deleted member 36384]

They still teach that to divers, for opening the valve on an air cylinder . The supposed reason is that it can stick if opened all the way to the stop and not backed off. I still find myself doing it with taps etc.

Pete

..... and drilling engineers. We are taught to open valves on production trees, standpipe and choke manifolds fully (and count the number of turns), then close a quarter turn. The quarter is important as any more moves the gate into the flow stream and will cause turbulence and possible wear / erosion issues.

People should not fret too much about loss of skills because the internet is a resource that can be used. As long as one is not too proud and understands their limits (or level of competency) the DIYer can get answers quite easily. This thread and other threads does demonstrate though that a number of possible solutions can be offered and filtering out the unsuitable solutions is the challenge. As always DYOR (Google is wonderful) which pays dividends and allows the DIYer to filter with confidence.

Anyway my fibre washers arrived and they are too small. I ordered by nominal size, 3/8", but I need a larger ID for fitting over BSP male end. On ebay one of sellers actually explains this!

 

[Deleted member 36384]

To close out this thread, this is the assembly I am sealing: -

Clesse Valve 3/8" BSP Parallel Female and a 3/8" Fulham BSP Parallel Male Nozzle

Beside the Fulham Nozzle is a 3/8" Female Fibre Washer and a 3/8" Male Dowty Washer

Fibre Washer Seals Inside Of Female on end of Male

Dowty Washer Seals Outside of Male Against Top Of Female Bushing

The Final Assembly

Some points to note if you are in a similar situation: -

The Fulham Nozzle does not bottom out inside the female bushing so the fibre washer cannot be used, which is why the Dowty was recommended. I described the bottoming out wrongly in my OP. Subsequent measurement confirmed this is the case. I assumed that by design when the top touched the bottom touched as well, that assumption was clearly wrong.

Hamilton Gas Products describe the Fulham Nozzle as BSP Taper, but it is not, it is parallel, later in the item specific page on their website it is just described as BSP. Searching the web does identify tapered nozzles but not Fulham type. All the other nozzles that I could find which were BSP Taper Male had sharper serrations for gripping a hose; this is not correct for gas purposes. I understand that the Fulham is designed for gas hose and that the two round rings do not cut into the hose and thus reduce its wall thickness (pressure rating) and provide a double seal when the hose clamp compresses the hose.

The Dowty washer and Fibre washers are correctly described on ASAPs web page using the male and female designation, not anywhere else that I looked. The Dowty washers have stainless outer rims but most will be plain carbon steel, it took a bit of eBay work to find the stainless version.

Hope this helps anyone else. I have not pressure tested the assembly yet as the gas installation is still underway.

Once again many thanks for the advice given, it's much appreciated.

Fair Winds,

BlowingOldBoots

 

[Heckler]

To close out this thread, this is the assembly I am sealing: -

Clesse Valve 3/8" BSP Parallel Female and a 3/8" Fulham BSP Parallel Male Nozzle

Beside the Fulham Nozzle is a 3/8" Female Fibre Washer and a 3/8" Male Dowty Washer

Fibre Washer Seals Inside Of Female on end of Male

Dowty Washer Seals Outside of Male Against Top Of Female Bushing

The Final Assembly

Some points to note if you are in a similar situation: -

The Fulham Nozzle does not bottom out inside the female bushing so the fibre washer cannot be used, which is why the Dowty was recommended. I described the bottoming out wrongly in my OP. Subsequent measurement confirmed this is the case. I assumed that by design when the top touched the bottom touched as well, that assumption was clearly wrong.

Hamilton Gas Products describe the Fulham Nozzle as BSP Taper, but it is not, it is parallel, later in the item specific page on their website it is just described as BSP. Searching the web does identify tapered nozzles but not Fulham type. All the other nozzles that I could find which were BSP Taper Male had sharper serrations for gripping a hose; this is not correct for gas purposes. I understand that the Fulham is designed for gas hose and that the two round rings do not cut into the hose and thus reduce its wall thickness (pressure rating) and provide a double seal when the hose clamp compresses the hose.

The Dowty washer and Fibre washers are correctly described on ASAPs web page using the male and female designation, not anywhere else that I looked. The Dowty washers have stainless outer rims but most will be plain carbon steel, it took a bit of eBay work to find the stainless version.

Hope this helps anyone else. I have not pressure tested the assembly yet as the gas installation is still underway.

Once again many thanks for the advice given, it's much appreciated.

Fair Winds,

BlowingOldBoots

I love threads like this! Proper stuff!
S