Member postings for Hopper

If the pump is attached to or near the boiler, locally recirculating the same small amount of water might raise its temperature enough to cause cavitation in the pump on the suction stroke as gasses/vapour flash off under low pressure conditions. High temperature with low pressure makes it worse. This could cause the pump to lose suction and stop feeding water to the boiler, or at least slow down the delivery rate.  Cavitation can be what causes that rattling noise in pumps that are losing suction.

Edited By Hopper on 25/06/2023 02:09:16

Yes that is the point. We were led by the media to believe for several days that those people were alive and desperately banging on the hull for rescue until the air ran out. An instantaneous catastrophic implosion is in fact good news under the circumstances.

Edited By Hopper on 25/06/2023 02:06:52

With the exception of the last line of the last quote from the US submariner, which was included to explain the pervasiveness in the media of statements about turning to dust, the discussion here is purely the engineering aspect of what happened to the vessel itself from a technical viewpoint. And nobody is claiming to know everything. Quite the opposite in fact. Your personal insults are quite out of line.

This stuff is going to be all over the media for the next six months and more as the official inquiry and various legal actions etc proceed. This obscure thread makes not one jot of difference in the overall picture.

Edited By Hopper on 25/06/2023 00:54:27

Looking forward to hearing what he says. Well done.

THIS BBC article contains the following, from a retired submarine officer:

....................................................................

Which is probably the source of the "turned to dust" that seems to be mentioned everywhere on the media. Sounds like something crews are all taught at submarine school.

But is a submarine the same situation? Depth is nowhere near the Titan's, so pressure would be far less. Submarine is much larger, giving more time and distance for the water to accelerate before meeting the oncoming water, so possibly higher velocity.

And the auto-ignition of hydrocarbons under compression in the air in a sub is probably not relevant to the Titan. Submarine is full of all sorts of oils and solvents and possibly diesel fuel for standby generators etc. Certainly a conventional sub is awash in diesel fumes from the main engines and their fuel supply, some of which inevitably ends up down in the bilge before being run through a separator and stored in a tank to be environmentally consciously disposed of in port. My ex-submariner co-workers at the shipyard building Collins subs told me the stink of diesel fuel was a pervasive fact of life in a sub, rivalled only by human flatulence, which was elevated to an artform as the main source of entertainment. They were all crazy.

Edited By Hopper on 25/06/2023 00:24:50

Edited By Hopper on 25/06/2023 00:26:46

IN that case, all you can do is bigger drill I suppose. Can you measure how big the existing hole is? And what is the exact size of the nominal 7mm HT cable? Might give some idea of how much bigger drill you might need.

Maybe test drill in some scrap to establish exactly what size you need.

I get :

Warning: Potential Security Risk Ahead

Firefox detected a potential security threat and did not continue to www.cowells.com. If you visit this site, attackers could try to steal information like your passwords, emails, or credit card details.

Edited By Hopper on 24/06/2023 14:19:25

I think it might be more complicated than that though. A google search for "fluid dynamics of implosion" reveals a world of head-achingly complex books, PhD theses and theories, like THIS one. It seems it is not necessarily a certain thing and depends on many factors.

Intuitively though, I would expect water to rush in simultaneously from the sides and bottom, not just the column from above, because pressure is virtually the same all round. Close enough to make no difference.

This paper HERE raises several interesting points. One is the compressibility of seawater at that depth and pressure means the fluid will initially expand as it is exposed to the low pressure void in the collapsing vessel, presumably adding to the kinetic energy involved. This results in a low pressure in the surrounding water, followed by a spike as the water rushing in hits other water and comes to a stop. The other point is that a brittle material (eg carbon fibre) will make the shock of the implosion greater than if it is a more ductile material such as a metal.

Still no clue as to where the various professors are getting specific figures for the speed of the water in an implosion at that depth. I suppose they could apply the old F = M*A and calculate something over the 20 milliseconds of time for velocity. No idea how you would apply it in a fluid situation like this. Its way above my pay grade.

Yes that sounds about right. (Not the elephant bit!) Water at the periphery would start off at 0kmh and accelerate from there. Still, with 6,000psi behind it, it will not be hanging about. Until it hits the water coming in from the opposite side, with literally crushing results for anything in between.

Edited By Hopper on 24/06/2023 13:17:16

So you are pushing the HT lead into a blind hole? If so, could it be air pressure preventing it travelling any further, if a tight fit?

Vaseline? (or its more sophisticated cousin silicone grease?)

Another great video below of him making a very similar shaft from scratch. Using induction-hardened chromed rod. The guy is a defiinte craftsman. Well worth watching. It is big stuff but lots of little tricks there relevant to the home workshop. He certainly screwcuts at a good clip, both RPM wise and depth of cut wise. Fits it to the nut and finishes it off with a file along the peaks and emery tape.

Seems like an ordinary straight bladed guillotine would do the job. Holds the stock clamped flat Cuts off a flat strip in one blow. Yes there is a small burr along the edge but that can be removed.

You want the proper gullotine where the straight blade comes straight down, hits the full length all at once. Not the shear type that has a scissor action that leaves a curled offcut.

I don't think it is registered anywhere. Could not get certification. Legal action may end up in the USA where the company is based and lawyers are more abundant even than AR15s. Investigation is being run by the Canadian Transport Department and the US Coast Guard. They both have a dog in the fight as they provided most of the rescue support, at a cost of millions. Legalities may depend too on what country waivers and contracts were signed in etc. As you say, it will be messy.

Interesting reports keep referring to the US's "top secret listening device" that picked up the sound of an implosion on day one. Pretty sure that is defence-speak for a submarine. It is what they do. But you never give away their location. It is all smoke and mirrors with those guys.

I have heard of guys de-rusting the insides of motorbike petrol tanks by the same method. Said to be highly effective.

LOL that is funny. Bless their little hearts, gotta love the meeja. When I worked in the print publishing industry, the journalists were all equally oblivious to anything mechanical, or mathematical. They were all the kids at school who did well in English but failed to grasp percentages and fractions. Every year or so they seriously reported a local nutjob/conman who claimed he had made a machine that produced more electricity than it used and could thus be used to supply remote towns from a minimal supply. They religiously reported it as a scientific breakthrough every year -- as he announced he just needed a bit more financial backing from investors to market his machine. They could not be convinced it defied the laws of physics and continued to provide the charlatan with free publicity.

It looks like he does contract work for the mining industry someplace like Western Australia. Multi-multi-million dollar industy where, as you say, it is tiny money. Every hour that machine is out of action is probably costing many many thousands of dollars in lost revenue. So turnaround time to ship/fly a new nut from the USA would be a consideration too. Or even to fly/truck it from within Australia. That is one reason Australia and NZ have such a well established culture of making new parts rather than buying.

But like all industries, even big industries are run by bean counters these days, so if they can save a few thousand on a repair job over and over again, they will. It's good work for Curtis.

Yes, looks much like John Stephenson's work but on a larger scale. Guys who can fix stuff will always be in demand. Problem is today that most of those guys are our age and retiring. Not many of Curtis's generation are picking up the reins. And that is a shame.

HERE is a thread on my experience with Evaporust restoring the above pictured dividing head and a vertical slide. Admittedly , a lot of the rust in the "before" pic came off with a long soaking in my parts washer solvent tank. So it was maybe a combination of rust, ancient oil and grease and dust and dirt from a farmer's opensided shed. But the second half of the thread shows clearly the wonderful job Evaporust did on those exposed parts that were seriously genuinely rusted anyway. Quite miraculous in my opinion, as the pics show. Now wire buffing wheel required afterwads. Just a rinse and then a quick wire-brush by hand to remove any residue from the Evaporust. Very, very pleasing result.

I have no experience with oxalic acid or molasses. But previously found that vinegar is good for cleaning up old tools etc but it can etch into the parent metal if left too long, and does not leave the nice shiny surface that Evaporust does.

Evaporust is expensive, specially in the smaller containers. But the time it saves is worth it.

Edited By Hopper on 24/06/2023 10:03:22

Yes you would think so. Equally deadly to human life but not such a catastrophic implosion perhaps, you would think.

A few good sized commercially made jobs here, part of a turbine tool kit.

Hex nut also spreads the load/damage across six points rather than two if you just machine two flats.

Edited By Hopper on 24/06/2023 09:44:06