Packing Nuts!

[do it easy]

I was rebuilding an AL80 this weekend, and I couldn't get the packing nut to stop leaking. I replaced the copper washer, but I got the tiniest stream of bubbles out from the packing nut. I put a bunch of torque on the nut and it's still a slight flow. I could probably leave it all year and not worry, but does anyone have any suggestions?

I got another cooper washer and ordered a new packing nut. I was hopign that if I replaced them both, I might get lucky. Are there any tricks? Is there any danger to overtightening, besides rounding my nuts?

 

[Creed]

Is there any danger to overtightening, besides rounding my nuts?

Man........that would be a problem.......

 

[Leadking]

I was rebuilding an AL80 this weekend, and I couldn't get the packing nut to stop leaking. I replaced the copper washer, but I got the tiniest stream of bubbles out from the packing nut. I put a bunch of torque on the nut and it's still a slight flow. I could probably leave it all year and not worry, but does anyone have any suggestions?

I got another cooper washer and ordered a new packing nut. I was hopign that if I replaced them both, I might get lucky. Are there any tricks? Is there any danger to overtightening, besides rounding my nuts?

What valve are you rebuilding? Some use a teflon packing along with the copper crush washer. They both should be repalced. In Thermo valves the o-ring, crush washer, and teflon packing should be replaced. Any chance the stem is bent? There is a torque spec on the bonnet nut of 35-40 lbs.


Lee
www.seapearls.com

 

[do it easy]

What valve are you rebuilding? Some use a teflon packing along with the copper crush washer. They both should be repalced. In Thermo valves the o-ring, crush washer, and teflon packing should be replaced. Any chance the stem is bent?

Lee
www.seapearls.com

It's a Thermo 3000 psi provalve. I replaced the o-ring, copper washer, teflon, and seat, but kept the original stem. I did have a tank that had a slow leak, but I don't think it was this tank. It looks like the leak is coming from the threads of the packing nut.

 

[do it easy]

I just wanted to clear up any confusion- the packing nut is probably more commonly referred to as the bonnet.

 

[XS Scuba]

Hey do it easy:
Here are a few more ideas for you.
1. Check in water to confirm the leak point
2. Is the valve leaking only when a regulator is attached and pressurized?
3. Check that the old copper crush washer was removed and you don't have two washers stacked up
4. Look at the copper crush washer seating surface within the valve body. A good scratch here will cause the leak. BTW: this is usually caused when removing the old crush washer with a metal tool.
5. As Lee posted you need to torque the bonnet to 35 to 40 foot pounds. This is best done with the valve screwed in a cylinder (empty) and a deep wall socket / torque wrench.
6. Also, as Lee said it could be a bent stem.
7. If all else fails, valves are cheap. Just replace it.

I hope this helps. Also, I've attached a cut away image of the PRO valve.

It's a Thermo 3000 psi provalve. I replaced the o-ring, copper washer, teflon, and seat, but kept the original stem. I did have a tank that had a slow leak, but I don't think it was this tank. It looks like the leak is coming from the threads of the packing nut.

 

[do it easy]

Thanks for the info. I have a few new parts on the way, so we'll see if that fixes the problem.

edit: OK, I did some early morning trouble shooting- the valve leaks only when it's open (reg attached) and the bubbles are coming out of the threads in the bonnet, not the stem. I think this indicates the crush washer/bonnet.

 

[do it easy]

I finally swapped out the bonnets and the leaks stopped. I guess I had a pair of bad bonnets. Thanks for all the advice and suggestions!