Titanic tourist sub goes missing sparking search

[Akimbo]

Something creepy about trusting an o ring in that situation. Wow.

@Lorenzoid explained the viewport design but remember that O-rings seal all the penetrators and main hatch. The main hatch is pressure-seated but is unlikely to form a reliable metal-metal seat unless thick and conical like most of the extremely deep submersibles — as-in 6,000m/20,000'+.

The electrical penetrators are not pressure seated (in terms of O-ring design) and depend on a piston or face seal secured by threads. I have seen very large high-pin pressure-seated connectors with a bolt-flange arrangement but not for decades.

Very high pressure connectors are made by machining a metal (typically a stainless or titanium alloy) body and very precise stepped holes are drilled for each electrical pin. Gold plated pins, usually the same material as the body, are dipped in liquid nitrogen to cool/shrink. The connector body is heated to pretty high temperatures (but not enough to deform) and the glass tubes are inserted in the holes and the pins inserted in the glass tubes. Everything equalizes to room temperature to make a hermetic seal — the body shrinks squeezing the glass and pin so tight it makes a pressure tight seal. Glass has incredibly high compressive strength. There are no O-rings on the pins, just the connector body.

 

[Dan]

I thought it was only 13 prior Titanic dives, not counting shallow test dives in Puget Sound and deep dives in the Bahamas. Were there 10 test dives?

In Stockton Rush interview by David Pouge of CBS, he mentioned it made 6 dives to the Titanic in 2021 and 7 in 2022.

A second Titanic tragedy: The failure of OceanGate's Titan

David Pogue, who rode in the same underwater vehicle that perished last week, looks back on the controversial submersible, and his conversations with the man who built it.

www.cbsnews.com

Also from Titan submersible implosion - Wikipedia

"Dives to the Titanic​

Titan dives to Titanic took place during multi-day excursions organized by OceanGate. According to reporter David Pogue, OceanGate did five Titanic excursions during the summer of 2021 and five excursions during the summer of 2022.[33]

Passengers would sail to and from the wreckage site aboard a support ship and spend approximately five days in the ocean above the Titanic wreckage site. Two dives were usually attempted during each excursion, though dives were often cancelled or aborted due to weather or technical malfunctions.[33] Titan made its first dive to the Titanic in July 2021.[34] According to Rush OceanGate completed a total of 13 dives to the Titanic: six in 2021 and seven in 2022.[35] In June 2023 CBS news reported that OceanGate had a total of 12 successful dives to Titanic in 2021 and 2022.[36]"


This 2023 fatal dive is dive # 14 (2023 Mission V), according to the following article:

How many expeditions did OceanGate submersible make to see Titanic? When were they?

The Titan tragedy came some two years after the OceanGate submersible had made its first visit to the wreckage of the Titanic, on the Atlantic seafloor.

en.as.com

 

[Dan]

Some learning points from the fatal dive:

 

[chillyinCanada]

Some learning points from the fatal dive:

Good find and share. Thanks Dan.

 

[chillyinCanada]

This is Jake's (YouTube Channel DALLMYD) exclusive footage of his trip to ride Titan Mission III, few days before the fatal Mission V trip to the Titanic wreck. His description of the video: "In this video I share my personal experience with OceanGate Expeditions during Mission III, 2023 My condolences goes out to the people who passed away and their family members."

This is already posted up-thread.

 

[Dan]

This is already posted up-thread.

Sorry about that. Please delete it.

 

[Still Kicking]

I saw an interview with another submersible "pioneer" who said he went on a deep test dive in the Bahamas after Rush's first solo deep dive. Rush warned him that he should expect to hear "fireworks" going off as the hull absorbed the pressure. The interviewee described them as small caliber pistol shots.

If all the warnings from experts in the submergence field didn't give Rush pause, those noises should have. He was beyond reckless.

 

[chillyinCanada]

I saw an interview with another submersible "pioneer" who said he went on a deep test dive in the Bahamas after Rush's first solo deep dive. Rush warned him that he should expect to hear "fireworks" going off as the hull absorbed the pressure. The interviewee described them as small caliber pistol shots.

If all the warnings from experts in the submergence field didn't give Rush pause, those noises should have. He was beyond reckless.

He seems to have believed those were the weak fibers and unnecessary, or some weird statement to that effect. Smh

 

[Gone for diving]

I saw an interview with another submersible "pioneer" who said he went on a deep test dive in the Bahamas after Rush's first solo deep dive. Rush warned him that he should expect to hear "fireworks" going off as the hull absorbed the pressure. The interviewee described them as small caliber pistol shots.

If all the warnings from experts in the submergence field didn't give Rush pause, those noises should have. He was beyond reckless.

So the lesson here is,
when there are no more fibers letting go... the end is near,

Boy do I like steel!!!!

 

[Dan]

I saw an interview with another submersible "pioneer" who said he went on a deep test dive in the Bahamas after Rush's first solo deep dive. Rush warned him that he should expect to hear "fireworks" going off as the hull absorbed the pressure. The interviewee described them as small caliber pistol shots.

If all the warnings from experts in the submergence field didn't give Rush pause, those noises should have. He was beyond reckless.

Indeed, it’s beyond reckless. Those “fireworks” are the sound of the carbon fiber delaminating (breaking up), which is way beyond the yield strength of the material. What I learned in my sophomore year of Materials Science & Engineering in University of California at Berkeley, a safe operation of the material under pressure cycles should be done within the modulus of resilience of the material, the linear zone of stress-strain curve of the material, O to A zone, in the Chicago Cuve figure, below.

Courtesy of Exploring the Stress / Strain Curve for Mild Steel - The Chicago Curve

The maximum allowable working pressure (MAWP) should be at 2/3 of the test pressure. That means if the test is done at 4000 m depth, the MAWP is at 2,667 m depth. If MAWP is at 4000 m depth, you need to test it to 6000 m depth. The test pressure should be under the yield strength (point A in the figure, above), within the modulus of resilience. Those “fireworks” occur at point E in the figure, above. Nuts!

Increasing the MAWP can be done by material thickness and structure (sphere is stronger than cylinder, flat plate being the weakest).