The Hydrolock - how to build a deep sea docking system?

[DeepSeaBase]

I call it the "hydrolock".

People may not realize, because often times "space" is considered the most difficult frontier, but there currently is no docking system for deep ocean. If you want to go to the deep ocean you have to enter a pressure vessel on the surface before your long descent. We are basically at the Mercury mission stage if comparing deep sea exploration to space exploration. Space was easy for a reason I'll mention below.

I've been working on this thought problem about how to create a docking system for deep sea bases. It's not as straightforward as one might originally think because the system has to:
1) maintain hull integrity the whole time.
2) transfer between extreme pressure differences while:
3) -not having any pumps capable of doing so.
4) maximum pump depth right now is 5,500 meters. And that's pushing the limits of 100 years of development. This pump is also centrifugal, meant to operate on liquids not gasses, and so there's a whole host of issues with a high pressure pump that might not even be applicable to a docking mechanism between huge pressure differences and between liquids and gasses.

So bottomline, you can't just pump your way out of the problem like in a normal airlock that transfers gas from one pressure to another pressure usually between 0atm to 0.3atm (or 0psi to about 5psi). And you therefore can't pressurize the gas, so the airlock can't be one contained system with pressure tanks.

So having mentioned the hurdles, here's the basic thought process so far.

1) Have two pressure hulls capable of maintaining 1atm at 1000atms (10,000meters seawater).
2) Have one of these hulls contain water.
3) Transfer water between these hulls to transfer a relatively incompressible material from one hull to the other.
4) Equalize pressure between the hull containing water and ambient pressure so its hatch can be removed.
5) Dock another pressure hull to the removed hatch.
6) Re-equalize the pressures again, back to 1atm.
7) Remove the water from the docking hull to the water tank.

I call this a "hydrolock". In principle it works much like a torpedo tube. The pressure hulls are subject to massive stress at the seams (where the spheres meet). I'm not sure if these seams would rupture or leak.

Seals are formed by metal-on-metal contact, so I believe that the greater exposed surface area will keep a strong metal-on-metal seal at the seams since the seams represent a very small amount of total surface area. This of course is the most crucial assumption. The settling of a spherical hull into the removed arc of the other spherical hull might create a fatal seam that has no strength against the pressures outside and form a leak. Now to make it "structural connected" I was thinking of magnetic locks. Magnets on either side of a nonmagnetic hull (titanium?) or magnets on one hull locking to the steel of the other....this would provide rigidity or locking in place...but it will NOT provide a pressure-lock. That has to come from pressure outside mating the metal-on-metal contact. So if that can't form at the seam, a leak will form.

 

@exchemist Unfortunately I can't answer you yet (cooldown on my posts), but I'll update here incase I forget. Firstly, I didn't choose the worst pump, I simply researched the highest pressure pump. This is used in the oil-industry at depth. So it may be worst for the application but it's, as far as I can tell, the highest operating pump pressure there is, at approximately 5500meters that's 550atm or 550 bar which are roughly equivalent. (500bar = 493 atmosphere to be precise).

The problem here is I want a system that works below that...10,000meters or 1,000atm or about 1,013.25 bar.

I don't know of any pump that can withstand that. But if we can find one we can start to consider it, and the hydrolock (torpedo tube) will probably still be necessary to reduce stress and increase safety and redundancies.

I need to evaluate the second stage you mentioned.

Edited May 6, 2021 by DeepSeaBase

[exchemist]

42 minutes ago, DeepSeaBase said:

I call it the "hydrolock".

People may not realize, because often times "space" is considered the most difficult frontier, but there currently is no docking system for deep ocean. If you want to go to the deep ocean you have to enter a pressure vessel on the surface before your long descent. We are basically at the Mercury mission stage if comparing deep sea exploration to space exploration. Space was easy for a reason I'll mention below.

I've been working on this thought problem about how to create a docking system for deep sea bases. It's not as straightforward as one might originally think because the system has to:
1) maintain hull integrity the whole time.
2) transfer between extreme pressure differences while:
3) -not having any pumps capable of doing so.
4) maximum pump depth right now is 5,500 meters. And that's pushing the limits of 100 years of development. This pump is also centrifugal, meant to operate on liquids not gasses, and so there's a whole host of issues with a high pressure pump that might not even be applicable to a docking mechanism between huge pressure differences and between liquids and gasses.

So bottomline, you can't just pump your way out of the problem like in a normal airlock that transfers gas from one pressure to another pressure usually between 0atm to 0.3atm (or 0psi to about 5psi). And you therefore can't pressurize the gas, so the airlock can't be one contained system with pressure tanks.

So having mentioned the hurdles, here's the basic thought process so far.

1) Have two pressure hulls capable of maintaining 1atm at 1000atms (10,000meters seawater).
2) Have one of these hulls contain water.
3) Transfer water between these hulls to transfer a relatively incompressible material from one hull to the other.
4) Equalize pressure between the hull containing water and ambient pressure so its hatch can be removed.
5) Dock another pressure hull to the removed hatch.
6) Re-equalize the pressures again, back to 1atm.
7) Remove the water from the docking hull to the water tank.

I call this a "hydrolock". In principle it works much like a torpedo tube. The pressure hulls are subject to massive stress at the seams (where the spheres meet). I'm not sure if these seams would rupture or leak.

Seals are formed by metal-on-metal contact, so I believe that the greater exposed surface area will keep a strong metal-on-metal seal at the seams since the seams represent a very small amount of total surface area. This of course is the most crucial assumption. The settling of a spherical hull into the removed arc of the other spherical hull might create a fatal seam that has no strength against the pressures outside and form a leak. Now to make it "structural connected" I was thinking of magnetic locks. Magnets on either side of a nonmagnetic hull (titanium?) or magnets on one hull locking to the steel of the other....this would provide rigidity or locking in place...but it will NOT provide a pressure-lock. That has to come from pressure outside mating the metal-on-metal contact. So if that can't form at the seam, a leak will form.

Where do you get this stuff from about the limits of pumps? And why choose the worst possible type of pump for dealing with big pressure differences? You would need a +ve displacement pump, not a centrifugal one. Injector pumps can manage well over 500bar. And surely by a 2-stage process you could reduce the stresses between each stage considerably, couldn't you? 

[DeepSeaBase]

22 hours ago, exchemist said:

Where do you get this stuff from about the limits of pumps? And why choose the worst possible type of pump for dealing with big pressure differences? You would need a +ve displacement pump, not a centrifugal one. Injector pumps can manage well over 500bar. And surely by a 2-stage process you could reduce the stresses between each stage considerably, couldn't you? 

As mentioned above I'm not really concerned with what is the "best" pump for a job, but what is the most powerful pump. The most powerful pump in the world currently seems to be somewhere around 690bar. ( https://www.castlepumps.com/pumps/pump/cat-plunger-pumps/ ) I haven't really found one more powerful than this. It is irrelevant if a pump is better at pressure differences or higher flows if the pump cannot handle the head pressure. Head pressure in Challenger Deep is approximately 1014bar.

There may be more powerful pumps, I just haven't found any yet. Was talking with a submarine buddy of mine (fire control), and he relates to my view of the torpedo tube analogy. Flooding simplifies the equalization of pressure, so should be able to flood and de-flood a pressure hull to expose it to ambient pressure. Just need a self contained water source because the inability to pump at those pressures prevents any open circuit to the ambient pressures outside. Hence the water tank in the design.

Stress and everything else as far as pumps are concerned seems to not be a concern because the 1014+ bar pressures well exceed any pump to-date?