3 ms·

I witnessed the converse of this in the recent Mario Brothers movie. There is a scene where steam piping is about to overpressure and it shows a pressure safety

I witnessed the converse of this in the recent Mario Brothers movie. There is a scene where steam piping is about to overpressure and it shows a pressure safety valve lifting. Well that pressure safety valve is an accurately drawn ASME I BPVC open-bonnet PSV with test lever. The open bonnet is to expose the spring to air so it is kept cool and therefore has the correct force downwards on the seat. If you specify a closed-bonnet PSV (like the vast majority of PSVs) for steam service then the whole valve body can get up to the steam temperature, including the spring, and it doesn't lift until a much higher pressure than your bench test indicates. Quite remarkable that they found someone to help them on this 5-second bit of animation who had experience with using steam in an industrial process plant or boiler, and not just a domestic plumber.

PcChip 3y ago
That makes me want to watch the movie
- iamthemonster 3y ago
  The movie is great fun but its accurate ASME I BPVC code compliant pressure safety valves really are limited to a single 2-second scene I am afraid.
  - bombcar 3y ago
    Now I find I want you to write a review blog in the format of Old Man Murray’s crate test, but all you do is rate the depictions of steam equipment. Probably a short enough list of depictions - does IMDb list them?
    - nottorp 3y ago
      All those (semi) abandoned factories where the final fight takes place should provide a lot of material?
genter 3y ago
You sure that the artist didn't just choose it because the visible spring makes it look more interesting?
- iamthemonster 3y ago
  On reflection they might have just googled "steam safety valve" and copied the first image they saw, they probably didn't need an expert involved. They hadn't insulated their piping, which would have led to condensate forming in deadlegs and causing steamhammer issues, but to be fair I don't believe the Mario Bros had designed or installed this system, and it was exploding at the time.
Animats 3y ago
Well, the Mario Brothers are plumbers, remember. ("Musta been a non-union job." - Super Mario Bros., 1993, looking at some pipework).
bombcar 3y ago
Reminds me of the YouTube channels that try to play what the animated piano or guitar is playing, and it’s almost always wrong. But sometimes, in surprising situations, it was animated correctly.
- soupfordummies 3y ago
  That sounds dope, got any examples? Unrelated kinda - does anyone remember seeing some videos of a guitarist basically PLAYING some speeches? Like, there was a background of a speaker giving a speech or dialogue in a movie and this dude is PLAYING the speech with really weird jazz chords and they’re notated on the top of the screen. Very weird and specific I know LOL
  - tshaddox 3y ago
    EMCproductions’ “Drums are Never Animated Correctly…Right?” series is the one I know of: https://youtube.com/playlist?list=PL3GY86ziPu8UJjggF4AxMKvRloJY3-f7A https://youtube.com/playlist?list=PL3GY86ziPu8UJjggF4AxMKvRl...
  - saghm 3y ago
    This in turn reminds me of this analysis scissors emojis on each platform: https://wh0.github.io/2020/01/02/scissors.html https://wh0.github.io/2020/01/02/scissors.html I remember something similar for train emojis, but I couldn't find it from a quick search
  - bombcar 3y ago
    https://youtu.be/08tK1RBTJRg https://youtu.be/08tK1RBTJRg https://youtu.be/qn0jtZwpe8A https://youtu.be/qn0jtZwpe8A
soultrees 3y ago
There are services that exist to hunt down any scene details like this and at this point is pretty standard. The thinking behind it is that even though most people won’t notice or care, the ones that dk notice will care, and if it’s wrong then it could be the single defining thing that pulls them out of the story. That and the pressure of the film industry in general and bringing bad press to a film. There’s always someone who notices every mistake and then they take to twitter over and on the other end of that message is some poor art director or continuity coordinator who’s losing their shit. Perfect example, you seem to be someone specialized in a field that would exist somewhere in the same vector map as plumbing. Not plumbing but pipes, so therefore it’s in the studios interest to ensure the specialized feel recognized as well. Had it been so obviously fake CSI Miami style, you might not feel the same about the movie, or maybe you’d not care and still enjoy the movie but you sure wouldn’t be in HN singing it’s praise. So it’s all upside for the studio to ensure you don’t get pulled out of the story or at the very least don’t talk to your friends who also live in the same vector map as you. Not saying it’s wrong as it’s cool to see effort put into the creation process but it’s definitely thought of ahead of time.
almostnormal 3y ago
> If you specify a closed-bonnet PSV (like the vast majority of PSVs) for steam service then the whole valve body can get up to the steam temperature, including the spring, and it doesn't lift until a much higher pressure than your bench test indicates. That was surprising. With a quick search about temperature and springs I found 3 items: 1 Spring constant descreases with temperature, not much at small increases but significant at much higher temperatures (that would make it open at lower temperatures than expected) 2 Spring gets longer at increased temperatures (that would make it open at higher temperatures) 3 Durability issues Is effect 2 stronger than 1 at the relevant temperatures? If there's a fixed relation between steam temperature and pressure it should be possible to design one to open at the correct pressure at the temperature that this pressur occurs at?
- iamthemonster 3y ago
  Yes definitely - the vendors of the PSVs will calculate for you a special compensation factor that allows you to test the PSV at normal room temperature, but still have it open at its set pressure when it is at a higher operating temperature. They call it the "cold differential set pressure". You can calculate your own cold differential set pressure just as a cross-check against the vendor's calculation to make sure there are no misunderstandings but ultimately you should just use the vendor's value. In the case of steam, because it is obviously non-toxic and non-flammable you can just let it go to atmosphere in an emergency, so the best thing is just to let the spring of the PSV be exposed to atmosphere rather than some variable operating temperature.

PcChip 3y ago

That makes me want to watch the movie

iamthemonster 3y ago
The movie is great fun but its accurate ASME I BPVC code compliant pressure safety valves really are limited to a single 2-second scene I am afraid.
- bombcar 3y ago
  Now I find I want you to write a review blog in the format of Old Man Murray’s crate test, but all you do is rate the depictions of steam equipment. Probably a short enough list of depictions - does IMDb list them?
  - nottorp 3y ago
    All those (semi) abandoned factories where the final fight takes place should provide a lot of material?

genter 3y ago

You sure that the artist didn't just choose it because the visible spring makes it look more interesting?

iamthemonster 3y ago
On reflection they might have just googled "steam safety valve" and copied the first image they saw, they probably didn't need an expert involved. They hadn't insulated their piping, which would have led to condensate forming in deadlegs and causing steamhammer issues, but to be fair I don't believe the Mario Bros had designed or installed this system, and it was exploding at the time.

Animats 3y ago

Well, the Mario Brothers are plumbers, remember. ("Musta been a non-union job." - Super Mario Bros., 1993, looking at some pipework).

bombcar 3y ago

Reminds me of the YouTube channels that try to play what the animated piano or guitar is playing, and it’s almost always wrong. But sometimes, in surprising situations, it was animated correctly.

soupfordummies 3y ago
That sounds dope, got any examples? Unrelated kinda - does anyone remember seeing some videos of a guitarist basically PLAYING some speeches? Like, there was a background of a speaker giving a speech or dialogue in a movie and this dude is PLAYING the speech with really weird jazz chords and they’re notated on the top of the screen. Very weird and specific I know LOL
- tshaddox 3y ago
  EMCproductions’ “Drums are Never Animated Correctly…Right?” series is the one I know of: https://youtube.com/playlist?list=PL3GY86ziPu8UJjggF4AxMKvRloJY3-f7A https://youtube.com/playlist?list=PL3GY86ziPu8UJjggF4AxMKvRl...
- saghm 3y ago
  This in turn reminds me of this analysis scissors emojis on each platform: https://wh0.github.io/2020/01/02/scissors.html https://wh0.github.io/2020/01/02/scissors.html I remember something similar for train emojis, but I couldn't find it from a quick search
- bombcar 3y ago
  https://youtu.be/08tK1RBTJRg https://youtu.be/08tK1RBTJRg https://youtu.be/qn0jtZwpe8A https://youtu.be/qn0jtZwpe8A

soultrees 3y ago

There are services that exist to hunt down any scene details like this and at this point is pretty standard. The thinking behind it is that even though most people won’t notice or care, the ones that dk notice will care, and if it’s wrong then it could be the single defining thing that pulls them out of the story. That and the pressure of the film industry in general and bringing bad press to a film. There’s always someone who notices every mistake and then they take to twitter over and on the other end of that message is some poor art director or continuity coordinator who’s losing their shit. Perfect example, you seem to be someone specialized in a field that would exist somewhere in the same vector map as plumbing. Not plumbing but pipes, so therefore it’s in the studios interest to ensure the specialized feel recognized as well. Had it been so obviously fake CSI Miami style, you might not feel the same about the movie, or maybe you’d not care and still enjoy the movie but you sure wouldn’t be in HN singing it’s praise. So it’s all upside for the studio to ensure you don’t get pulled out of the story or at the very least don’t talk to your friends who also live in the same vector map as you. Not saying it’s wrong as it’s cool to see effort put into the creation process but it’s definitely thought of ahead of time.

almostnormal 3y ago

> If you specify a closed-bonnet PSV (like the vast majority of PSVs) for steam service then the whole valve body can get up to the steam temperature, including the spring, and it doesn't lift until a much higher pressure than your bench test indicates. That was surprising. With a quick search about temperature and springs I found 3 items: 1 Spring constant descreases with temperature, not much at small increases but significant at much higher temperatures (that would make it open at lower temperatures than expected) 2 Spring gets longer at increased temperatures (that would make it open at higher temperatures) 3 Durability issues Is effect 2 stronger than 1 at the relevant temperatures? If there's a fixed relation between steam temperature and pressure it should be possible to design one to open at the correct pressure at the temperature that this pressur occurs at?

iamthemonster 3y ago
Yes definitely - the vendors of the PSVs will calculate for you a special compensation factor that allows you to test the PSV at normal room temperature, but still have it open at its set pressure when it is at a higher operating temperature. They call it the "cold differential set pressure". You can calculate your own cold differential set pressure just as a cross-check against the vendor's calculation to make sure there are no misunderstandings but ultimately you should just use the vendor's value. In the case of steam, because it is obviously non-toxic and non-flammable you can just let it go to atmosphere in an emergency, so the best thing is just to let the spring of the PSV be exposed to atmosphere rather than some variable operating temperature.