Flexible Stuffing Box maintenance

vyv_cox said:
I thought that was what I said?
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Yes, but I think you were using the small differences as evidence of "no preferred solution" while I was using the general similarity as evidence of "clearly preferred solution". I think there is still a lot more variation in the shaft seals market. Lip vs face ought to have been settled by now!
 
Thanks to everyone for your helpful comments and suggestions. Having examined the gland and its nut in much closer detail (see pictures attached), it became clear that the packing is indeed in the nut and not in the gland. Furthermore, it actually seems to be in good condition.

What I think probably happened in the summer was that when I tried to tighten the seal, I did not realise that there was a locking nut - I thought it was a fixed flange. So when I tightened the nut, I only tightened it against the locking nut whereas I should have moved the locking nut, tightened the gland and then re-tightened the locking nut. Which has now been done.

Is this the correct diagnosis? I'll find out when the boat is relaunched in December!

Picture on the left shows the inside of the gland - solid metal as best we can judge. The picture on the right shows the inside of the nut which is definitely packing.

gland.jpgnut.jpg
 
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Thought so :) good chance to replace it, it's cheap and good time to measure the size you need and get some spare, even if it's just as an excercise, incase you ever need to do it in anger
 
Glad you solved it. I would now dig out the old packing and replace it with PTFE instead of graphite. If you're not familiar with that type it is white and looks as if it's covered in chewing gum. I like it because it is low friction and, unlike the traditional packing, it does not require any lubricants. Once it beds down you can gradually tighten the nut (over several sessions) until there are virtually no drips of water coming in without causing any damage to the shaft.
Not everyone will agree with this but it is what I have been doing ever since I was an apprentice and never had any problems; I'll be 69 in two weeks' time. ;)
 
With regard to "removing" the greaser ignore that comment, keep it and use it the grease will go both ways granted but it requires grease, otherwise you will be repacking every other trip.
 
PuffTheMagicDragon said:
Glad you solved it. I would now dig out the old packing and replace it with PTFE instead of graphite. If you're not familiar with that type it is white and looks as if it's covered in chewing gum. I like it because it is low friction and, unlike the traditional packing, it does not require any lubricants. Once it beds down you can gradually tighten the nut (over several sessions) until there are virtually no drips of water coming in without causing any damage to the shaft.
Not everyone will agree with this but it is what I have been doing ever since I was an apprentice and never had any problems; I'll be 69 in two weeks' time. ;)
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I am most definitely one of them. I repacked my 1 1/4" shaft gland using PTFE twice about two years ago. In each case I found it impossible to get it to run cool without a massive stream of water through it. The thermal conductivity of PTFE is extremely poor, which may be the reason. I then repacked for a third time using graphited cotton, which fixed it instantly to perfection.
 
PuffTheMagicDragon said:
Glad you solved it. I would now dig out the old packing and replace it with PTFE instead of graphite. If you're not familiar with that type it is white and looks as if it's covered in chewing gum. I like it because it is low friction and, unlike the traditional packing, it does not require any lubricants. Once it beds down you can gradually tighten the nut (over several sessions) until there are virtually no drips of water coming in without causing any damage to the shaft.
Not everyone will agree with this but it is what I have been doing ever since I was an apprentice and never had any problems; I'll be 69 in two weeks' time. ;)
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+1 I am 75, and still use grease as well LOL
 
vyv_cox said:
I am most definitely one of them. I repacked my 1 1/4" shaft gland using PTFE twice about two years ago. In each case I found it impossible to get it to run cool without a massive stream of water through it. The thermal conductivity of PTFE is extremely poor, which may be the reason. I then repacked for a third time using graphited cotton, which fixed it instantly to perfection.
Click to expand...

+1
 
Aeolus said:
Thanks to everyone for your helpful comments and suggestions. Having examined the gland and its nut in much closer detail (see pictures attached), it became clear that the packing is indeed in the nut and not in the gland. Furthermore, it actually seems to be in good condition.

What I think probably happened in the summer was that when I tried to tighten the seal, I did not realise that there was a locking nut - I thought it was a fixed flange. So when I tightened the nut, I only tightened it against the locking nut whereas I should have moved the locking nut, tightened the gland and then re-tightened the locking nut. Which has now been done.

Is this the correct diagnosis? I'll find out when the boat is relaunched in December!

Picture on the left shows the inside of the gland - solid metal as best we can judge. The picture on the right shows the inside of the nut which is definitely packing.

View attachment 54668View attachment 54669
Click to expand...

Glad to see that the problem is solved. The nut seems very short to have the usual three turns of packing inside it: without destroying what you have can you estimate how many there are?

If you agree I will add your photos to the website.
 
Hi Vyv,
Happy for you to publish the pictures. The nut does look too short for three turns but I decided not to investigate further and re-pack it because the packing looks to be in good condition and access is tricky in my engine bay. If it leaks when re-launched and I decide to re-pack, I'll let you know what I find.
Thanks......Jonathan
 
Looking at it again, the gland nut looks very short, I'd be surprised if it contained more than one ring of packing. The body however (the threaded part) looks excessively long for no apparent reason.
 
ghostlymoron said:
Looking at it again, the gland nut looks very short, I'd be surprised if it contained more than one ring of packing. The body however (the threaded part) looks excessively long for no apparent reason.
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I think that is an effect of the angle that the photo was taken and that the nut is really longer than it appears. You can just make out the cylindrical bit just behind the hexagon in the 2nd photo. I would suggest that it really looks something like the top part in this photo:

32.jpg
 
PuffTheMagicDragon said:
I think that is an effect of the angle that the photo was taken and that the nut is really longer than it appears. You can just make out the cylindrical bit just behind the hexagon in the 2nd photo. I would suggest that it really looks something like the top part in this photo:

32.jpg
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No, it is nowhere near as long as your example. I have added the pics to my website now https://coxengineering.sharepoint.com/Pages/Sternglands.aspx where you can see that the cylindrical part is about the same length as the hexagon flats. I concluded as ghostlymoron did.
 
vyv_cox said:
Glad to see that the problem is solved. The nut seems very short to have the usual three turns of packing inside it: without destroying what you have can you estimate how many there are?

If you agree I will add your photos to the website.
Click to expand...

That is very similar to mine which only has two rings of packing. Confused me When I repacked it but it has been ok so far for two years hard use.
 
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