O-Ring Rupture while Underwater?

[Wayward Son]

Most often, if an O ring is going to fail it does when pressurized or shortly after.

 

[Heffey]

The Challenger accident involved poor o-ring design and heat.)

I don't mean to hijack but I thought that the Challenger accident involved poor o-ring design which caused both the primary and secondary seals not to seal properly at low temperatures. :06:

Not that this makes a difference to your statement. Just a side note.

 

[mer]

I was on a dive boat a few weeks ago and someone's o-ring ruptured. It was on the boat, after the dive, and she started to remove the yoke before depressurizing.

*POP!*

Technically, this is not a ruptured oring. Due to not fully depressurizing or HP air getting under the oring, the air under the oring "pops" the oring out of its home. The pop is often rather loud, and will sometimes send the oring across the room/boat. Often this oring will still be intact after the experience.

 

[MEL-DC Diver]

Technically, this is not a ruptured oring. Due to not fully depressurizing or HP air getting under the oring, the air under the oring "pops" the oring out of its home. The pop is often rather loud, and will sometimes send the oring across the room/boat. Often this oring will still be intact after the experience.

Ok, we will call it 'O-Ring Extrusion' then

 

[Chad Carney]

I don't mean to hijack but I thought that the Challenger accident involved poor o-ring design which caused both the primary and secondary seals not to seal properly at low temperatures. :06:

Not that this makes a difference to your statement. Just a side note.

Heffy,

I think we're both partially right about the Challenger accident.

This is what I found with a quick search. There's a whole lot more at:

http://ethics.tamu.edu/ethics/shuttle/shuttle1.htm

Chad


The Space Shuttle Challenger Disaster

Department of Philosophy and Department of Mechanical Engineering
Texas A&M University
NSF Grant Number
DIR-9012252

Instructor's Guide

Introduction To The Case

On January 28, 1986, seven astronauts were killed when the space shuttle they were piloting, the Challenger, exploded just over a minute into the flight. The failure of the solid rocket booster O-rings to seat properly allowed hot combustion gases to leak from the side of the booster and burn through the external fuel tank. The failure of the O-ring was attributed to several factors, including faulty design of the solid rocket boosters, insufficient low- temperature testing of the O-ring material and the joints that the O-ring sealed, and lack of proper communication between different levels of NASA management.

 

[Azza]

I have had an o-ring crap out on me at depth in my early days of diving. I was down at 30 metres (100 and something feet) and wrestling with a crayfish in a hole when I wacked my reg against the ceiling of the hole. It moved my reg enough to blow the o-ring and massive amounts of air were spewing out. My buddy had decided to bugger off and look for cray's himself (Even though we were supposed to be watching each other) so I went for the surface. I was still getting air through my reg until I hit about 18 metres and just ESA'd from there.
Thats when I decided that I was changing to din regs and twins.
Dins are definantly safer as the o-ring is captured properly against the tank valve.

 

[Warlock]

I was diving a quarry one time and when I descended down to about 45' I heard a blast and my 1st stage started blowing air like it had blown the o-ring. I ascended and the flow slowed down at around 20' ar so. My buddy and I surfaced and shut the tank down and checked the o-ring and it was fine. After a visit to the dive shop where they pressure tested the whole reg set they said I had a IP leak in the 1st stage. That day in the water though it seemed exactly like a blown o-ring.

 

[KOMPRESSOR]

Skip the Yoke valve sets next time you get a new valve. Get DIN-valves. Less stuff that can break.

 

[Al Mialkovsky]

The shop I instruct for bought this package full of white O-rings and they were supposed to last nearly forever. A couple of months into their use, while looking perfect, they started to rupture during use. Two of them in the same pool session with students, one out in open water. We removed these expensive O-rings and went back to basic black.

I was there, one of those tanks in the pool was on my back. It deformed and just squeezed out. Nothing was done wrong.

 

[CJ-62]

I witnessed a similar event to Azza's once out of Dana Pt, CA. Diver in my group hit his yoke against the rocks while eyeballing some Garibaldi in mild surge conditions. Not a big deal since his buddy was attentive/close. Afterwards on the boat, it was surmised that the Yoke detent on the back of the valve (old rental tank) was worn enough to allow a slight misalignment and thus the blow out. That valve looked pretty beat up.

Incidentally when the oring failed, the tank took about 1 minute to empty, very impressive at ~60 fsw (my team was about 25' away and it got our attention!). Of course I am not sure how much pressure it had at failure and am not sure of how bad the displacement was. Those involved didn't make a scientific study of the system before tearing it apart. Never saw them again so no idea of any follow through by the rental shop.

Just sharing, no great insights.