The Titan Submarine Imploded Due To Micro-Cracks In The Carbon Fiber Hull - Has A Carbon Fiber Bottle Broken/Exploded On Anyone?

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lbc_PSI said:
Interesting segment on CBS Sunday Morning. According to a retired sub captain interviewed the Titan was destined to fail. It was built with titanium, CF, and viewport of glass or plexiglass. 3 materials with different expansion contraction ratios. He summed it by saying subs only use one material for the hull for that reason. And finished by stating only a fool would have set foot in that submersible. The show had footage from a segment done about a year ago that showed the interior an build method. Also had the owner designer on..seem like someone that did things in unconventional ways..and bragged about it. He was the same guy that recently fired one of the project guys who raised safety concerns. Make one wonder
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2018
"During the meeting, Lochridge said he discovered that the Titan’s viewport was certified to a pressure of 1,300 meters below sea level. OceanGate intended to take passengers on the Titan down to depths of 4,000 meters."

However, Lochridge alleged that the company refused to pay for the Titan’s manufacturer to build a viewport that would meet the required standards for these depths.

He also said in the lawsuit that paying passengers would not be aware or informed of the Titan’s “experimental viewport design,” the lack of sufficient safety testing of the hull, or that hazardous flammable materials had been used in its construction. "

It was destined for doom from the get go and no Xbox controller was going to save that day .
 
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Hi all
Whatever happened was a great shame allround.
Without people pushing boundaries we would probably still be on terra firma.
Scientists tested carbon fibre in Portsmouth 10 yrs ago under water pressure and it failed.
Its mainly due to the glue in plain terms bonding it together' and under extreme cold and being pressurized and un pressurized can delaminate.
That's if it was the carbon fibre that failed.
I should imagine hpa air tanks and buddy bottles are made using tried and tested resin and well over engineered and must conform to a safety standard.
Even though he was an innovator I dont agree with the owner taking people on trips in a vessel he himself was not prepared to be certified or inspected as that alone rings alarm bells.
I'm sure we will find out the cause in due course.
So I personally wouldn't jump to conclusions just yet
 
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TN_Yankee said:
This link was posted here not too long ago. It's from Digital Wave, the original company authorized to do SCBA cylinder recertifications, and although not dated, it's likely about a decade old. It's 7 pages, but well worth reading, as it explains the history of the mythical 15-year life and general technology behind them. It is not an engineering paper - it's easy reading. A few key takeaways:

* The 15 year life for carbon fiber vessels is not
based on any experimental or historical data that
was performed using carbon fiber data.

* Three years of intensive studies requested by the
US Navy and DOT which followed ISO 11119-2
“at manufacture” testing procedures have
conclusively shown that the DOT-CFFC cylinders
can be safely used for at least 15 years beyond
their current lifetimes. (emphasis mine)

* The tests showed that the cylinders were still
meeting “at manufacture” design requirements,
even after 15 years of hard use (many of the
cylinders in the studies were from large
metropolitan fire departments and had seen
extensive use in the field). (emphasis mine)

* DOT-CFFC cylinders have been fatigued up to
24,000 cycles at developed pressure (5192 psi
for a cylinder with an operating pressure of 4500
psi), and did not have liner leaks. This number of
cycles, according to ISO 11119-2, results in an
infinite life cylinder. (emphasis mine)

My opinion is that even used fire department SCBAs are safe for our usage, for a long time to come. The paint ball cylinder mentioned in a post earlier in this thread that leaked was likely either significantly damaged (with the damage hidden by the wrap/bag it was in) or a poor grade, imported model.

https://docs.wixstatic.com/ugd/d00b78_72625b919876457fb9191418c1259c6b.pdf
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This is exactly why I choose to use firefighting SCBAs for my airgun adventures instead of the storage tanks being made for and marketed to the airgun community. The testing and certification is much more rigorous. I’ll take a used name brand firefighter SCBA over a new CF tank from overseas any day.
 
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KatoKevin454 said:
our Carbon fiber Tanks can withstand the pressure inside because the pressure is pushing outward on the material..... carbon Fiber is designed to be strongest when it is being pulled or Tension, so it is strongest with an outward pushing pressure or tensile Strength, the mistake they made on the Sub is Carbon Fiber is Weak with an Inward pushing pressure, it crushes very easily, when I seen the video of the sub, I knew right away that they made a terrible mistake in design. that is why Carbon fiber tanks will work in the vacuum of space and not in the high pressures of the deep ocean,
please note the resin used is only a binding agent use to keep the fibers in place, it has very little strength value compared to the Carbon fiber itself,

a good analogy: take a Rope and pull on it, it is strong when being pulled and has good structural tension, now take the same rope and push on it, it becomes slack and has no structural tension... thus the rope only has Tensile strength.
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We are talking about burst pressure on our tanks, not crush pressure as in the mini sub, IMHO the CF on the sub was worthless but then i don't have any engineering experience in either direction. My former employer made alum/fiber centrifuge buckets, spinning at 40k rpm, there were quite large appox. 8-10" OAL and 5' diameter
 
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jps2486 said:
There’s steel and then there’s steel. Lower grade steel alloys can have internal inclusions, processing stress cracks and is subject to fatigue failure. Higher grade steel alloys are better in those regards but are more costly. No material is perfect.
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I totally understand that.. totally true.. I don't work aluminum other than machining it.. but I have done a lot of welding and there common low grade steel and I really liked the high tensile steel.. a lot harder to drill but it could flex a lot and never crack.. even the welds, as long as you do correctly are very strong..
Mark
 
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The compressive strength of carbon fiber is not zero, it is 30-50% of the tensile strength. So to resist the same pressure differential you would need 2-3 times the thickness. Not sure why it was judged a good material for this application but I think it could have worked. We like carbon fiber in our tanks because they are lighter and thus easier to carry. But a sub needs to sink. More weight can be a good thing. My degree is mechanical engineering but I've never designed pressure vessels. But I would have thought hard about steel. I guess more weight would make the sub harder to handle on a boat, however. But I don't think carbon fiber construction needs to be an issue if it was done correctly with reasonable design margins. The results indicate an issue but I have no idea where.

I read the Navy report on extending the life of carbon reinforced air tanks and it is clear there is no technical basis to the 15 year life span the DOE specifies. Quality of manufacture is undoubtedly important and my one tank is an "expired" 45 minute Scott tank with no visible damage to the carbon fiber. The aluminum liner will not support much pressure on it's own, the carbon fiber must do that. So it is very important the carbon fiber is not damaged. I just opened the airtube of one of my PCPs on fathers day to replace O-rings and there was no sign of moisture. That is not the first and likely not the last time I will have one open and there has never been any moisture. I take seriously the need to filter the air going into my bottle and then my guns. I'll also replace my bottle if I ever see significant damage to the carbon fiber. I'm not worried about an explosion, I think that is very very unlikely, I just want it to work.
 
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look, the people knew the risks or at least they should have
it was not a game they were playing but at the same time they were in over their heads
the sub as far as i can tell had made the dive more than once but their luck ran out on them
the sub was made with fiber being wrapped at 90 degrees instead of 45 degrees, it was 5 inches thick there was a video of the manufacture of the sub
and most in the know, knew the sub was lost the first day
the best interview was with Bob Ballard and James Cameron for those who don't know Cameron built the sub that went to Challenger Deep at 35.876 feet
now the governments will have to make some better rules, hell all surface ships have guidelines but if you sign the waiver form stating you understand you could die well okay then and the subs owner was on the sub
 
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JimD said:
The compressive strength of carbon fiber is not zero, it is 30-50% of the tensile strength. So to resist the same pressure differential you would need 2-3 times the thickness. Not sure why it was judged a good material for this application but I think it could have worked.
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I agree. CF seemed like a weird choice for this application.

Different materials have different thermal expansion coefficients as @Hateful McNasty mentioned relative to the window (along with other comments he made on the window). This coupled with the wear on the epoxy that holds the CF together as @aroundlocks mentioned could also be a factor. As many have mentioned, there are a number of possibilities and obvious engineering "risks" they took where they absolutely shouldn't have. There were so many red flags here, it is truly sad.

marflow 777 said:
look, the people knew the risks or at least they should have
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My wife read me some excerpts from the waiver that they all had to sign, and it was pretty ridiculous. Worse than the waivers on some school field trips, I must say.

marflow 777 said:
the sub as far as i can tell had made the dive more than once but their luck ran out on them
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That is what I heard. I don't know how many times the head of the company made the trip, but I doubt he had been much if at all before. Ironic that he was on board during this tragedy and this would give the other passengers a false sense of security which is horrible.

marflow 777 said:
now the governments will have to make some better rules
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I understand that this was in international waters, so I don't think that there would be a "regulating body" involved here. It would have to be up to the individuals that were making the trip. You would have to be an informed consumer. Hopefully from this, there will be a push for some standards, like ASTM or CSA, or some such, that would certify certain portions of this type of vessel for safety that you could look for to know that it adheres to "some" standard of safety. This is the same conversation we will be having when consumer trips to space become more common.
"Sure, we can get you there in a trebuchet"​
"Is it safe?"​
"Uh, yea, sure it is. Just sign here"​
<THWACK!>​

Cue new regulation...(and the cycle of regulated exploration continues)
 
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SkeeterHawk said:
I agree. CF seemed like a weird choice for this application.

Different materials have different thermal expansion coefficients as @Hateful McNasty mentioned relative to the window (along with other comments he made on the window). This coupled with the wear on the epoxy that holds the CF together as @aroundlocks mentioned could also be a factor. As many have mentioned, there are a number of possibilities and obvious engineering "risks" they took where they absolutely shouldn't have. There were so many red flags here, it is truly sad.


My wife read me some excerpts from the waiver that they all had to sign, and it was pretty ridiculous. Worse than the waivers on some school field trips, I must say.


That is what I heard. I don't know how many times the head of the company made the trip, but I doubt he had been much if at all before. Ironic that he was on board during this tragedy and this would give the other passengers a false sense of security which is horrible.


I understand that this was in international waters, so I don't think that there would be a "regulating body" involved here. It would have to be up to the individuals that were making the trip. You would have to be an informed consumer. Hopefully from this, there will be a push for some standards, like ASTM or CSA, or some such, that would certify certain portions of this type of vessel for safety that you could look for to know that it adheres to "some" standard of safety. This is the same conversation we will be having when consumer trips to space become more common.
"Sure, we can get you there in a trebuchet"​
"Is it safe?"​
"Uh, yea, sure it is. Just sign here"​
<THWACK!>​

Cue new regulation...(and the cycle of regulated exploration continues)
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Hi all
Thick cf is more prone to micro buckling and microfissures .
So your scuba tank and buddy bottles are fine.
 
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Hi all
The titanic should be left alone.
There is enough footage and information on how she met her fate.
Anyone who took things from it was grave robbing in my opinion.
It should be a protected site to stop sightseers and treasure hunters.
Maybe a so called mummys curse awaits the thieves who take personal belongings of the lost souls.
I think this thread needs to disappear into the atmosphere now that unless your going shooting a mile or two underwater your hpa tank should be good to go.
let's get back to shooting and discussing airguns and let the maritime people do their thing" Amen
 
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Stubbers said:
"What happened to the bodies when the sub imploded?"

They went from biology to physics.
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Yea, that video that @Rudolph Hucker posted on Post #20 talked about the physics and it totally makes sense. When you go from high pressure to low pressure, you make "cold" (keeping physics simple), but when you go from low pressure to high pressure, the opposite it true that it creates heat. The passengers were cooked before they knew what happened.

aroundlocks said:
let's get back to shooting and discussing airguns
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I think that we answered the original question, so unless someone has something else useful to contribute, I am good with that.
 
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steve-l said:
You do not know what caused the implosion..........nobody does yet, if ever. The news media today is the least reliable it has ever been. Stop spreading bull poop!
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EXACTLY. Theories, ideas and circular reasoning and TADA it's all solved. The news media has proven their worth, the last few years as well as decades. But the masses continue to watch and hold their breaths at each word they report. Never underestimate the ignorance of people in large numbers.
 
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Richieg said:
Never underestimate the ignorance of people in large numbers.
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Such a true statement. I've seen Frankenstein as a matter of fact.

The small number of people on this forum have concluded that carbon fiber is meant to keep pressure in, not keep pressure out. We have also realized that if a carbon fiber bottle were to rupture, as stated from the experience of @Kraemer99 , that the carbon fiber will keep the rupture from being catastrophic. We have concluded that if you are using carbon fiber for the reason for which it was intended, that you will most likely not die when using it.

Regarding your statement of the net worth of the news media, I agree with you there too. Their opinions are worthy of being a copy of the paper on the back of the toilet, when you are out of paper otherwise 🤮
 
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