The Random Image Thread (keeping it PG-13 at the worst)

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dv
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matt wrote:
rjprice wrote:
Some of us really like cable knit sweaters. . .

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Oh God wearing that would be sensory hell.


Not really - you'd obviously wear unitard-like long underwear, sleeves, etc., underneath it. Otherwise you'd have to dry clean the damn thing every couple days. (Eeew.)

And sweaters by themselves aren't particularly warm without under-layers, imo.
obvs Social Distancing Grandmaster
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Oh no.

I hate static electricity and wool and yarn. Sweaters make it hard to breathe, so I don't wear them. I just wear cotton shirts and if I'm cold I'll wear a coat.

That would definitely be sensory hell.
dv
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matt wrote:
Sweaters make it hard to breathe, so I don't wear them.


My housemate has anxiety-induced asthma... (?)
obvs Social Distancing Grandmaster
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Not quite. Static cling causes a weird sensation where it feels like my throat is closing up, and it's always done that. Sweaters increase that significantly.
Some people are very sensitive to wool. I'm in the middle. It bugs me somewhat. When my wife knits sweaters for me, she avoids wool blends with more than 40% wool. ;)

That knitted item could be acrylic. That'd avoid the whole itchiness problem, most of the cleanliness issues (its tough and easy to clean) and sure as hell be much cheaper.

Yeah, since you mentioned it, it does look sorta like the Fremen stillsuit.
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mmaverick my steady systematic decline
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if I wore that wool thing I'd probably have a panic attack and die.
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Something funky going on with the server where this image originates? I can't make the small pic a link to the full size image, at any rate. Here is a link to a full size image
blurt mundus vult decipi
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blurt mundus vult decipi
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Fractionating column?
DukeofNuke FREE RADICAL
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wouldn't it have been easier to assemble that on-site?
jkahless Custom Title
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Potato gun. For reeeeeaaaally big potatoes.
Duke -

That depends . . mostly on the strength needed in the outer wall. Bleeding edge would be a no.

Then again, they could just make the walls a bit thicker and ship it in pieces to be welded on site, If the walls were thick enough the somewhat weaker welds would be strong enough.

So yeah, I don't really understand why it had to be done that way either.
Séamas Honorary Consul General
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Hope there are no sharp turns in the road.
ukimalefu want, but shouldn't, may anyway
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jkahless Custom Title
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Kirk wrote:
Duke -

That depends . . mostly on the strength needed in the outer wall. Bleeding edge would be a no.

Then again, they could just make the walls a bit thicker and ship it in pieces to be welded on site, If the walls were thick enough the somewhat weaker welds would be strong enough.

So yeah, I don't really understand why it had to be done that way either.


It's marked on it "Do not weld" and "Manufactured and something like "Supplied by Hitachi Canadian Industry Saskatoon".

It's definitely some sort of pressure vessel, there's photo's on Hitachi's website.


The sections are fabricated out of steel plate and bolted to each other. The resulting pressure vessel is too large to be heat treated by itself, that'd be why it's bolted together. That's also why it's marked "do not weld", so the steel's metallurgic characteristics aren't altered providing a weak spot for failure.

Mind you, this is all just conjecture from a semi-informed guy in industry.

http://www.hitachi-hpsca.ca/product/m-fabrication.php
You show decent metallurgical knowledge. A pressure vessel is one of those items which needs bleeding edge strength and so which we would want to avoid any processing which could change the steel's temper. Welding always affects the temper. The heat affected zone (HAZ), the weld itself and a small band on either side of the weld, will be back to or nearly back to the annealed condition. Heating to the molten state in the weld and somewhat less warmth in the nearby areas removes or reduced any work hardening or heat treatment previously done to the alloy. Annealed is much weaker than the heat treated or work hardened state. Some alloys can be reheat treated though rarely to the same high strength achievable the first time the alloy is heat treated. And of course work hardening on a finished item like a pressure vessel is impossible, beyond bead blasting the surface. Some alloys will only strengthen via work hardening. Some only via heat treatment. Steels fit into both categories depending on the alloy.

Even so, all that would be required to create the pressure vessel on site via welding is to take this strength reduction into account. Start with pieces sufficiently thicker that the alloy in the annealed condition is strong enough. Shipping problem solved. I'm not sure why this particular pressure vessel could not be done that way. Perhaps the cost of shipping something this ungainly isn't as expensive as using more metal to make the pressure vessel out of an annealed alloy.
Geesie Couldn't hit it sideways
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jkahless Custom Title
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Kirk wrote:
You show decent metallurgical knowledge. A pressure vessel is one of those items which needs bleeding edge strength and so which we would want to avoid any processing which could change the steel's temper. Welding always affects the temper. The heat affected zone (HAZ), the weld itself and a small band on either side of the weld, will be back to or nearly back to the annealed condition. Heating to the molten state in the weld and somewhat less warmth in the nearby areas removes or reduced any work hardening or heat treatment previously done to the alloy. Annealed is much weaker than the heat treated or work hardened state. Some alloys can be reheat treated though rarely to the same high strength achievable the first time the alloy is heat treated. And of course work hardening on a finished item like a pressure vessel is impossible, beyond bead blasting the surface. Some alloys will only strengthen via work hardening. Some only via heat treatment. Steels fit into both categories depending on the alloy.

Even so, all that would be required to create the pressure vessel on site via welding is to take this strength reduction into account. Start with pieces sufficiently thicker that the alloy in the annealed condition is strong enough. Shipping problem solved. I'm not sure why this particular pressure vessel could not be done that way. Perhaps the cost of shipping something this ungainly isn't as expensive as using more metal to make the pressure vessel out of an annealed alloy.


Thanks, I'll take that as a high compliment, considering how basic my metallurgic training has been.

Obviously taking the strength reduction into affect would be possible, but for the amount of steel and the high pressure that's probably required, it's likely a high grade of steel that is significantly more expensive. If this was in a high density area that'd probably be cheaper, but Saskatoon is in Saskatchewan, which is prairie country. I don't imagine it'd be too much more expensive to ship as is and have the fabrication in a tightly controlled environment. The oil industry doesn't tend to skimp.

If I remember correctly, when welding a strength critical area, the steel is often preheated before welding, and is insulated or even heated over the cooling period using heating blankets to reduce brittleness and maintain the correct ratios of grain structure in the steel. That's a shipyard practice though, and I don't know if it'd transfer to terrestrial applications. There is no large scale welding in the civilian maritime world that I know of equals the type needed for a pressure vessel.
Ooooh, more than basic metallurgical knowledge. Yes, you are correct.
jkahless Custom Title
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More basic than you probably think. I just love stuff like this. It's been a couple years since I've heard the term HAZ. :p
So become a metallurgist or mechanical engineer. Those jobs remain in demand.
jkahless Custom Title
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Navigational officer is also fairly in demand. I'm not hurting for work.
jkahless wrote:
If I remember correctly, when welding a strength critical area, the steel is often preheated before welding, and is insulated or even heated over the cooling period using heating blankets to reduce brittleness and maintain the correct ratios of grain structure in the steel. That's a shipyard practice though, and I don't know if it'd transfer to terrestrial applications. There is no large scale welding in the civilian maritime world that I know of equals the type needed for a pressure vessel.


Not just ships yards but any time something like that needs done, an old old technique.
Cast can be repaired using the same method, in fact it's about the only shot you've got if the strength is needed.
The structural changes by applying heat to metals and different cooling methods is really interesting.
blurt mundus vult decipi
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Even that's not the whole change. The Sun is rotating around the galactic center. The Milky Way is expanding away from the Big Bang's original explosion point while looping in toward Andromeda. All that would be too much for a cartoon though.
ukimalefu want, but shouldn't, may anyway
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You wouldn't have that problem if you'd just slingshot around the sun in your starship.
DukeofNuke FREE RADICAL
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Just wait for a solar flair to warp the wormhole.
ukimalefu want, but shouldn't, may anyway
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DukeofNuke wrote:
Just wait for a solar flair to warp the wormhole.


Indeed
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John Scalzi and Jim C. Hines in a pose-off for charity:

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There are MORE to come! Remember: this is for CHARITY. Almost $7000 raised at the time I typed this.
ukimalefu want, but shouldn't, may anyway
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ukimalefu want, but shouldn't, may anyway
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The Random Image Thread (keeping it PG-13 at the worst)

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