Sloppy ball valve to skin fitting joint!

[xeitosaphil]

Having just come ashore to antifoul and polish I thought I would replace the two ball valves to the Heads ( toilet inlet and Basin outlet) as I don’t know their age and I have had them for 5 years anyway.
Having removed the old ball valves decided to re bed the existing basin skin fitting as it moved when removing the ball valve. Having purchased two new ball valves of the Hattersley type DZR ball valve I thought it would just be a simple change over?
Wrong!
Screwing the ball valve onto the existing skin fitting threads, I found that the valves are very loose?
Maybe PTFE around the threads is what others have used and I thought that would sort it.
Wrong!
Having wound 10 wraps of PTFE around the threads it still hasn’t taken up the sloppiness.

Question: Would it be ok to use Boss white and Hemp? The only thing it needs, is something to take up the slack in the threads and Boss white does actually set. I don’t like to use Sikaflex or the like because of future removal and need to set valve short of the internal seat for orientation purposes.

Insidently both Skin fitting and Ball Valve threads are ¾”, but appear different sizes? Mind One is probably English ( the original one ) and the new ones are Italian.
Don't know if that makes any difference, it shouldn't?

 

[lpdsn]

Having just come ashore to antifoul and polish I thought I would replace the two ball valves to the Heads ( toilet inlet and Basin outlet) as I don’t know their age and I have had them for 5 years anyway.
Having removed the old ball valves decided to re bed the existing basin skin fitting as it moved when removing the ball valve. Having purchased two new ball valves of the Hattersley type DZR ball valve I thought it would just be a simple change over?
Wrong!
Screwing the ball valve onto the existing skin fitting threads, I found that the valves are very loose?
Maybe PTFE around the threads is what others have used and I thought that would sort it.
Wrong!
Having wound 10 wraps of PTFE around the threads it still hasn’t taken up the sloppiness.

Question: Would it be ok to use Boss white and Hemp? The only thing it needs, is something to take up the slack in the threads and Boss white does actually set. I don’t like to use Sikaflex or the like because of future removal and need to set valve short of the internal seat for orientation purposes.

Insidently both Skin fitting and Ball Valve threads are ¾”, but appear different sizes? Mind One is probably English ( the original one ) and the new ones are Italian.
Don't know if that makes any difference, it shouldn't?

They shouldn't be sloppy. The threads are all precisely defined so the nationality shouldn't matter. You should be able to tighten them up without PTFE tape. PTFE tape is only used so that you can tighten up the ball valve with the handle exactly where you want it.

Are you sure they are both the same size?

Other than that the only other thing I can think of is that they are not the same type. There is the BSP thread and a tapered thread BSTP (I think). Are they of different types?

 

[PuffTheMagicDragon]

Is the male thread on the skin fitting still in a good condition or has it lost some material from the ridges due to dezincification?

 

[xeitosaphil]

They are these http://www.hattersley.com/documents/Fig_100_100EXT_Ball_Valve_Hattersley_0813_v3(1).pdf

In fig 100 - ¾” fitted to a standard ¾” skin fitting .
They do tighten up tight, if run to the end of the threads, but I want to stop them short as you suggest due to the orientation of handle and PTFE doesn’t seem to be enough. Or it might be in excess of 10 wraps?

They shouldn't be sloppy. The threads are all precisely defined so the nationality shouldn't matter. You should be able to tighten them up without PTFE tape. PTFE tape is only used so that you can tighten up the ball valve with the handle exactly where you want it.

Are you sure they are both the same size?

Other than that the only other thing I can think of is that they are not the same type. There is the BSP thread and a tapered thread BSTP (I think). Are they of different types?

 

[lpdsn]

From that data sheet it looks like the thread of your ball valve is tapered. The skin fitting thread almost certainly isn't. Try a ball valve with a normal BSP thread.

 

[xeitosaphil]

It didn't look too bad when I wire brushed the threads up after removing the old valve and the old valve was tight although it did have a combo of PTFE and silicone on it. I did measure the O/A of the thread with a Micrometer just to make sure it was 3/4" and it held up 1015 Thou, 3/4" being 1041 Thou so a tad smaller but not enough to equate to the amount of slop it has.

My thought were to use some Boss white and hemp to bulk up the threads - what do you think!!

 

[VicS]

They are these http://www.hattersley.com/documents/Fig_100_100EXT_Ball_Valve_Hattersley_0813_v3(1).pdf

In fig 100 - ¾” fitted to a standard ¾” skin fitting .
They do tighten up tight, if run to the end of the threads, but I want to stop them short as you suggest due to the orientation of handle and PTFE doesn’t seem to be enough. Or it might be in excess of 10 wraps?

Are you fitting a female tapered thread onto a tapered male thread and trying to stop before they are fully enmeshed?

 

[Stork_III]

They are these http://www.hattersley.com/documents/Fig_100_100EXT_Ball_Valve_Hattersley_0813_v3(1).pdf

In fig 100 - ¾” fitted to a standard ¾” skin fitting .
They do tighten up tight, if run to the end of the threads, but I want to stop them short as you suggest due to the orientation of handle and PTFE doesn’t seem to be enough. Or it might be in excess of 10 wraps?

The valve is taper threads, the skin fitting is probably straight thread, they do not work together. "They do tighten up tight, if run to the end of the threads" but won't make a water tight or safe joint.

 

[xeitosaphil]

Sorry in my haste to get it on the website ,I may have put the wrong link on the post as I quickly looked for Hattersley valves.

Mine actually came from a Seaware Supplier so I think these might be the right ones in this link


http://www.seaware.co.uk/Products/HATTERSLEY-BALL-VALVE-34__10584.aspx

http://www.baysidemarine.co.uk/dzr-brass-ball-valve-417-p.asp

From that data sheet it looks like the thread of your ball valve is tapered. The skin fitting thread almost certainly isn't. Try a ball valve with a normal BSP thread.

 

[nigelmercier]

Don't use PTFE. Use Loctite 577: http://amzn.to/VDsh1L

People will say it goes off too quickly, just don't nip it up until the last minute.

 

[xeitosaphil]

VicS and Stork ,

I think I am going to have to go back to the supplier, our local Marine Engineering company C&O Engineering and see exactly what they have supplied me with?
I assumed I had Parallel threads as the links above, but what you describe actually sounds like I have tapered threads?

Thanks for your input and I will get back to you when I have more correct info.

 

[prv]

Tapered threads are designed to seal on the threads, preferably with both parts tapered. However, tapered male into straight female is acceptable. Straight male into tapered female is not, you end up with only a couple of turns of thread at the tip of the male actually engaging.

BSP straight threads are not designed to seal on the threads, they are designed to pull parts together so that a rubber O ring or fibre washer is pressed between two machined faces to make the seal. However, this is not the case with the skin fitting and ball valve combination universally used on yachts - on this side of the Atlantic the threads involved are invariably straight, but there is no O ring or washer and not really much of a sealing surface (the end of the skin fitting bottoming out in the skin fitting is all you get). Despite its wide application, this is really a bodge from an engineering point of view. We should all be fitting proper seacocks, which are bolted to the hull and then have the through-hull fitting (trimmed to length) screwed in from the outside just to line the passage through the hull and provide a little more security. The trouble is, they cost a bleedin' fortune and involve extra work, so nobody (myself included) does!

Seacock:

In practice, the through-hull fitting with backnut and a ball valve perched on the end is good enough (it's better if you trim away all the excess length from the through-hull to reduce the leverage a little). A good dose of PTFE tape (or appropriate loctite product as Nigel suggests) on the threads will seal it against the low pressures involved. You then need to screw the valve up hard against something to lock it in position and prevent it coming unscrewed again. If you don't care about the final orientation then simply bottoming out the threads is good - with careful trimming you get the lowest possible profile and minimise the dreaded leverage. If you do need the handle pointed in a particular direction, you thread on a second nut before the valve. Screw the valve down as far as possible while still ending up facing the right way, then move the extra nut back up to meet it and lock the two against each other. By carefully measuring a trial assembly, you can trim the through-hull so that when it's all done up there's only a millimetre or two of spare thread between the backnut that's against the hull and the backnut that's against the valve.

Pete

 

[xeitosaphil]

Thanks for your detailed explanation Pete, and Nigel for the link, that seacock ball valve certainly looks the business and expensive?

I think I may have a male skin fitting parallel thread, with a tapered female ball valve so not compatible but will have to check with supplier and get back to you.

Philip

 

[Plevier]

Don't use PTFE. Use Loctite 577: http://amzn.to/VDsh1L

People will say it goes off too quickly, just don't nip it up until the last minute.

I used 572 - slower setting version, again specifically for pipe thread sealing, not a normal thread locker.

[h=1]LOCTITE 572[/h]

LOCTITE 572 for metal, slow cure thread sealant
Your benefits

• Suitable for coarse metal threads
• Ideal where slow cure is required for adjusting the alignment of fittings

Technical Data

• Maximum pipe size: 3"
• Disassembly strength: Medium
• Service temperature range: -50°C - +150°C
• Breakaway torque: 7 Nm
• Pack sizes: 50ml, 250ml

 

[xeitosaphil]

Ball Valve Update

It would appear that my ISIS Ball Valve (not a Hattersley by name anyway) is a tapered thread according to my Marine Engineers Supplier. He says he has not had any feed back or problems with these Ball Valves in all the time he has been supplying them. He did say though that they are fitted with new skin fittings and wound up tight to their seat and then the ball valve is orientated for the handle as a complete unit. He couldn’t answer my query about stopping the valve short in the taper so you could orientate the valve on the fixed skin fitting. Which would mean the parallel thread would be loose in a tapered valve?
Having rung Hattersley ( because I thought it was one of theirs) they also confirmed that they do not make Parallel thread Ball Valves, they also said they knew nothing of the company called ISIS?
I also rung Seaware at Penryn in Cornwall as they are a big distributer of chandlery, and low and behold their web site advertising Hattersley Ball Valves shows a picture of one with an ISIS green handle on it?
http://www.seaware.co.uk/Products/HATTERSLEY-BALL-VALVE-34__10584.aspx

The chap at Seaware also confirmed that they were tapered threads, having tried a skin fitting in it.

Having done some searches I have found that Hattersley and ISIS seem to be using an Italian Manufacturing Company called Effebi, or so it would seem by the casting emblem on both sets of Ball Valves. Spec available here
http://pdf.directindustry.com/pdf/effebi/general-catalogue/27169-294291.html#open

It would appear that there is also a S/S handle available for Marine use, which is a really good idea if you can get hold of them?

Our local Chandlers at Brixham has ¾” Ball Valves advertised as parallel female threads which also seem to be Effebi valves. Note emblem on casting in photo link and spec.
http://www.baysidemarine.co.uk/dzr-brass-ball-valve-417-p.asp

The Marine Engineers have offered me a refund if the tapered ones are not suitable, so I may except that, and go with the Bayside Marine ones.

Going back to my original question re the use of Hawk White and hemp to seal the loose threads here is a link to the spec of Hawk White. When used with hemp it is ok up to 7 bar pressure on water. 5 bar on gas ,LPG, steam and Brine.
http://www.castreekilns.co.uk/hawk-jointing-compound---white-997-p.asp

Is there any reason why this would not work ok, or are we just so used to using things specified as for “ Marine Use “.

I have wondered about the use of the suggested Loctite Thread Sealant but wonder if it is only suitable as a sealer for close fitting threads?

 

[VicS]

Ball Valve Update


Going back to my original question re the use of Hawk White and hemp to seal the loose threads here is a link to the spec of Hawk White. When used with hemp it is ok up to 7 bar pressure on water. 5 bar on gas ,LPG, steam and Brine.
http://www.castreekilns.co.uk/hawk-jointing-compound---white-997-p.asp

Is there any reason why this would not work ok, or are we just so used to using things specified as for “ Marine Use “.

I have wondered about the use of the suggested Loctite Thread Sealant but wonder if it is only suitable as a sealer for close fitting threads?

From the Loctite data sheet

LOCTITE® 572 is designed for the locking and sealing of metal
pipes and fittings. The product cures when confined in the
absence of air between close fitting metal surfaces

It will not be suitable for loose fitting joints. Its thread locker not a gap filler


That aside if you do not screw the valve onto the skin fitting fully you will have a poor or weak mechanical joint with only a small number of threads engaged with each other and only partly engaged at that.

Poor engineering but a common plumbing practice is to use a combination of parallel and tapered threads, only acceptable if screwed fully home.
The choice of thread sealant provided it has decent gap filling properties is of secondary or even minor importance.


My preference would be to use a valve with a parallel thread in combination with a lock nut to lock the valve firmly in the orientation required.

Run the lock nut onto the skin fitting. Apply a sealant to the skin fitting threads, screw on the valve as far as is possible but while still being able to orientate the handle as required.
While holding the valve body tighten the lock nut up onto it
.
Use the same sealant as you used for the skin fitting to hull joint.

 

[trthebees]

+1 for VicS...just about full thread engagement and lock nut to secure.

I rather like Fernox LS-X for these awkward jobs needing a bit of gap-filling. Clean/degrease first even if new. And cheap from screwfix.

 

[David2452]

Ball Valve Update

It would appear that my ISIS Ball Valve (not a Hattersley by name anyway) is a tapered thread according to my Marine Engineers Supplier.

When I have no room for Marelon I use stock and use ISIS valves, for the avoidance of doubt they are DZR (Bronze available from 2 1/2" BSPP up ) and female parallel thread to ISO 228/1(BS 2779) a very good valve in my view. I use a backnut and Clessetite sealant on the threads.