SPG Blew Off Under Pressure - Cause?

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CD24

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This weekend I was on a fun dive in Monterey with my LDS and the SPG blew off the HP hose underwater. I'm wondering if anyone has experienced this before or may have an idea of the cause?

Details:
It was a shore dive at McAbee beach and occurred 18 minutes into the dive at 28ft depth. I reached down with my left hand to look at my SPG and as I pulled up, it shot out of my hand, along with the spool. Fortunately I still had about 2,000 psi in the tank so was able to ascend and swim back to shore safely with my buddies. I wasn't able to recover the spg and only have the hose left to examine. My LDS inspected it and didn't note any scarring in the hose threads. Their assumption is that it wasn't properly torqued down and may have loosened over time.

It was a HOG 2" SPG attached to a 24" braided hose that I purchased from Piranha Dive Mfg a couple months ago. This was my second dive with it, so fairly new. Randy claims it's impossible for this to have occurred as the SPG was under pressure, but I have several witnesses that would disagree. My thought is perhaps the bolt snap location was partially to blame but am interested to hear other opinions. I have two more of these SPGs for my son and wife and want to ensure that they don't experience the same issue. Attached is a photo of the hose threads and an example of how I had the boltsnap connected. Appreciate any feedback.

Only other details I can think of that may be relevant is that the spg was connected to a D ring above my left hip and was still connected as I pulled up. I typically don't need to unclip the boltsnap to read the gauge. There were also no bubbles that I noticed which I would expect if the spg was partially unthreaded. I had also checked my gauge one time already during this dive.

Thanks!
 

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Was not tightens properly, and possibly was rotated when not pressurized, the bungee didn't let the hose thread spin, is my assessment.

But also I would not attach the bolt snap there. That is right in the swivel joint, use spool or cave line and attach higher or lower, my preference is higher.

Get you self 2 wrenchs and snug up the 2 hexs closest to the gauge.
 
They don't leak until they come apart. It wasn't tight. To blow off, you wouldn't have threads left in the hose end and you can see them in the picture.
 
It was probably a hanging on by a thread or 2 until it came loose.

With where the bolt snap was attached it probably prevented the swivel from swiveling making it so you where loosening it as you moved it around.
 
Yes, I had one come off near the end of a dive. In had unscrewed. Ever since if I need to rotate it I always turn it clockwise
Or just tighten properly. (Fairly snug.)

This is not a second stage, where a case could be made, to be hand tight in certain situations for certain reasons
 
This is not a second stage, where a case could be made, to be hand tight in certain situations for certain reasons
I know you used "could," but this practice has largely fallen out of favor and I'm not able to think of any current reasons. Carry an adjustable and a tarantool with some plugs and you're off to the races.

I do pull the faceplate retaining pins out of the SP regs that I use.
 
There were also no bubbles that I noticed
I just want to know who made those 'Godzilla' orings that refused to leak bubbles while unscrewing !! Puts my viton's to shame.
 
I just want to know who made those 'Godzilla' orings that refused to leak bubbles while unscrewing !! Puts my viton's to shame.
Haha I think we need to ask HOG. I'm impressed but also disappointed that the o-rings worked as well as they did. Some early signs of failure would have saved me from buying another SPG.
 
Thank you all for the replies. Sounds like the main culprit was improper torquing by Piranha Dive Manufacturing further exacerbated by me locating the boltsnap on the swivel. It's likely that the gauge had loosened and only had a couple threads holding it together before the dive.

Lessons Learned:
1) Even reputable dive shops can make mistakes -- don't assume because it came from the "factory" that all is well
2) Don't place bolt snaps on moving parts
3) Inspect equipment before each dive, including hose connections
 

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