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grillster posted:I see your subtle attempt at a 2.5 page keyboard preference detail It’s a honeypot to identify the wasps.
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May 13, 2020 16:51
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https://i.imgur.com/dSKZ9Pi.mp4 Quarry workers using personal trucks on the rails to return from work. The handle in the middle is the handbrake.
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May 13, 2020 17:07
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Hey OSHA-adjacent question involving some math and industrial poo poo and I know loads of people who would know how to calculate stuff like this frequent this thread. 10 inch pipe got contaminated and needed cleaning so a foam pig was sent through and pressurized air was used to push it through the pipe and clean it out. The pipe is 4700ft long and the pig went through in 7 minutes (way too fast) which is like 11.2f/s. the PSI of the air was definitely greater than 20, what we need to know is how much pressure was used because it went way too fast and destroyed the pig and I guess caused some other fuckup (I don't have all the details). My father works in industrial safety for his company and is looking into this and wants to know and asked me... but this smells like calculus so I'm out of my depth. If anyone can give me the info I'll drop you an av cert or something.
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May 13, 2020 18:06
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Cyrano4747 posted:It’s a honeypot to identify the wasps. Whatever do you mean by that, human?
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May 13, 2020 18:14
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Resting Lich Face posted:Hey OSHA-adjacent question involving some math and industrial poo poo and I know loads of people who would know how to calculate stuff like this frequent this thread. I think there's some information missing here, specifically how much time it normally takes for the pig to travel through the pipe at the safe 20psi pressure.
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May 13, 2020 18:36
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norton I posted:This is a common myth, this class is now mostly used as part of seed treatment, to prevent insect damage to very expensive modern seed. Where did you get that idea from?
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May 13, 2020 18:45
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haveblue posted:I think there's some information missing here, specifically how much time it normally takes for the pig to travel through the pipe at the safe 20psi pressure. I do not know what the correct pressure for this to be done at is so the greater than 20 PSI figure shouldn't be taken as gospel. It's supposed to be done at about 10 ft per minute so 7.83 hours for a 4700ft length. I haven't done calculus and neither has dad so I don't really know what exactly is needed to figure out how much pressure, roughly, was put behind the thing (the guy that did it didn't have guages on the system to measure anything). I can tell it's calculus because it involves some constantly changing variables but that's about the extent of it. My understanding is since the job was done so much faster than it should have been the question is whether the pipe's integrity might be hosed so they need a pressure figure before they go putting petrochemicals through it.
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May 13, 2020 18:46
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haveblue posted:I think there's some information missing here, specifically how much time it normally takes for the pig to travel through the pipe at the safe 20psi pressure. Also what's the relationship between increasing psi and speed. I bet it's not that straightforward.
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May 13, 2020 18:47
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Atticus_1354 posted:Also what's the relationship between increasing psi and speed. I bet it's not that straightforward. I'm concerned we need a friction coefficient and a bunch more info I don't have.
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May 13, 2020 18:49
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Resting Lich Face posted:I do not know what the correct pressure for this to be done at is so the greater than 20 PSI figure shouldn't be taken as gospel. It's supposed to be done at about 10 ft per minute so 7.83 hours for a 4700ft length. I haven't done calculus and neither has dad so I don't really know what exactly is needed to figure out how much pressure, roughly, was put behind the thing (the guy that did it didn't have guages on the system to measure anything). I can tell it's calculus because it involves some constantly changing variables but that's about the extent of it. Just measure the distance it landed at and how long it was in the air. 
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May 13, 2020 18:49
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Sagebrush posted:WE! DO NOT! TALK ABOUT! THE ORANGUTAN! Here's the whole piece, well worth a read: https://winchysteria.tumblr.com/post/168634371438/ossacordis-crockpotcauldron
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May 13, 2020 18:49
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Resting Lich Face posted:My understanding is since the job was done so much faster than it should have been the question is whether the pipe's integrity might be hosed so they need a pressure figure before they go putting petrochemicals through it.
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May 13, 2020 18:55
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Ignore the pig, calculate the pressure needed to reach that fluid velocity with compressed air through an unobstructed pipe and take that as a lower bound. Based on this calculator very roughly it looks like you hit at least 160psi, realistically probably a multiple of that https://www.copely.com/tools/flow-rate-calculator/
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May 13, 2020 18:58
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zedprime posted:Hydro and leak check it if you don't do any other NDT. There's no math that's going to make anyone safe or warm and fuzzy here. but this is the real answer
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May 13, 2020 19:03
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Resting Lich Face posted:I do not know what the correct pressure for this to be done at is so the greater than 20 PSI figure shouldn't be taken as gospel. It's supposed to be done at about 10 ft per minute so 7.83 hours for a 4700ft length. I haven't done calculus and neither has dad so I don't really know what exactly is needed to figure out how much pressure, roughly, was put behind the thing (the guy that did it didn't have guages on the system to measure anything). I can tell it's calculus because it involves some constantly changing variables but that's about the extent of it. I don't have any training in this area (though I do a lot of fluid mechanics on a much, much smaller scale), but there should exist some chart or standard with the math already worked out for you, especially for something like petrochemicals.
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May 13, 2020 19:03
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shame on an IGA posted:Ignore the pig, calculate the pressure needed to reach that fluid velocity with compressed air through an unobstructed pipe and take that as a lower bound. Based on this calculator very roughly it looks like you hit at least 160psi, realistically probably a multiple of that Decent enough. Apparently we only needed to know if pressure exceeded 80 sooooo.... Got a throwaway email for an av cert since you've not got plat?
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May 13, 2020 19:19
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I am totally not an engineer, but work in fire protection piping design so don't listen to a word I'm about to type, but I do spend a lot of time filling sprinkler pipe with compressed air. I just googled industrial pigs and found this site https://pigsunlimited.com/pigging-formulas.php Which might have the answer you are looking for. I'm not sure that you should be looking for a constant pressure in PSI as much as a volume fill rate in something like GPM or CFM. As you want to push the pig down the chamber you need to fill up the clean side of the pipe volume to a certain pressure that will overcome the friction of the pig against the wall at a certain velocity. I went with the third link which is volume in cubic feet per minute and put in the numbers you gave, and added in a totally fake differential pressure of 10psi and a .16 feet per second and it came up with a reasonable 8.8 cfm (cubic feet per minute). What was your air source and how was it being regulated?
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May 13, 2020 19:25
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I think not enough attention is being paid to the fact that the guy doing it didn't have any gauges and he just eyeballed how much air he should pump in like Charlie counting the gas as it was being poured in always sunny.
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May 13, 2020 19:36
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Thinking about this a bit more, is there any chance that the pig was the wrong size? A poor fit could reduce the friction enough that it traveled way faster than expected? I put the pipe into my cad program and am showing a volume of 20,820 gallons? What kind of device are they using to fill that entire space with compressed air in 7 minutes? That is a fuckload of CFMs even at basically no pressure. edit: this is like 400 cfms at 1psi SpaceCadetBob fucked around with this message at 19:42 on May 13, 2020 |
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May 13, 2020 19:37
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OSHA IV: Ignore the pig
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May 13, 2020 19:38
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Cojawfee posted:I think not enough attention is being paid to the fact that the guy doing it didn't have any gauges and he just eyeballed how much air he should pump in like Charlie counting the gas as it was being poured in always sunny. At least one head is definitely gonna roll. A gasket was blown and caused a spill which is never a cheap, safe, or easy thing to deal with in petrochem. If the national-level operations and safety guy is involved you hosed up. SpaceCadetBob posted:Thinking about this a bit more, is there any chance that the pig was the wrong size? A poor fit could reduce the friction enough that it traveled way faster than expected? The pig probably wasn't too small because it was utterly destroyed rather than just going through too fast. I have no idea what the setup is I just got texted the details we have and asked if I could calculate it. I cannot so I was like hey I'll ask the OSHA thread because there's all sorts of goons with specific industry knowledge that might be able to help. Resting Lich Face fucked around with this message at 19:43 on May 13, 2020 |
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May 13, 2020 19:39
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Cojawfee posted:I think not enough attention is being paid to the fact that the guy doing it didn't have any gauges and he just eyeballed how much air he should pump in like Charlie counting the gas as it was being poured in always sunny. It'll be fine, they know how to count 
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May 13, 2020 19:43
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SpaceCadetBob posted:I just googled industrial pigs and found this site If you plug 10 inches and 4700 feet into the Time of Pig Run calculator, the gallons per minute of liquid required to get a transit time of 7 minutes is around 2,750 gallons per minute. Since the calculator uses liquid (which is orders of magnitude less compressible than air) instead of compressed air, the PSI on the compressed air is going to be absolutely ridiculously high. McGavin fucked around with this message at 20:00 on May 13, 2020 |
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May 13, 2020 19:49
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McGavin posted:If you plug 10 inches and 4700 feet into the Time of Pig Run calculator, the gallons per minute of liquid required to get a transit time of 7 minutes is around 2,750 gallons per minute. Since the calculator uses liquid (which is orders of magnitude less compressible than air) instead of compressed air, the PSI on the compressed air is going to be absolutely ridiculously high. The rediculously high part is the issue I'm having since well a lot of large air compressors only come with so much CFMs (like a brief google search brings up 1600cfms on a mobile device) but even a big one would have a hard time getting 21K gallons of pipe over 80 psi in 7 minutes. I feel like i'm missing something, but again I don't work in that specific industry.
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May 13, 2020 19:54
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McGavin posted:If you plug 10 inches and 4700 feet into the Time of Pig Run calculator, the gallons per minute of liquid required to get a transit time of 7 minutes is around 2,750 gallons per minute. Since the calculator uses liquid (which is orders of magnitude less compressible than air) instead of compressed air, the PSI on the compressed air is going to be absolutely ridiculously high. One hell of an av/post combo there.
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May 13, 2020 19:55
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OSHA IV: WE! DO NOT! TALK ABOUT! THE PIG!
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May 13, 2020 19:58
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SpaceCadetBob posted:Thinking about this a bit more, is there any chance that the pig was the wrong size? A poor fit could reduce the friction enough that it traveled way faster than expected? It probably ran into the blockage early, buddy is like loving come on, cranked it up without a regulator, blockage is cleared and bang boom a pipe pig is now travelling an average of 8mph through a pipe. Like I'm asking for x-rays as soon as a mangled pipe pig comes out the other end as fast as a forklift. Like I bet there was vacuum and some back blast cause the pig just took the gently caress off.
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May 13, 2020 20:00
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zedprime posted:I am in team why do math he just shot a pipe pig out of a mile long pipe, but applying dynamics the pressure probably didn't get applied to the full length of the pipe. He might have been using something like a site air reservoir which will hold a shitload of air at compressor pressure and different utility users hook in and regulate down. Instead of doing math I'd find out what he was using, find the highest number it could have possibly been because buddy clearly didn't care or regulate it, and go from there. Yeah, this feels gut right to me. Maybe it got a small way in before getting stuck and built up way to much pressure even if the in flow was the right CFMs. If there was no safety pressure relief that could go crazy high really fast if you are off a resevoir prefilled at 160 psi. Hey OP was the blown gasket at the near end of the pipe length?
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May 13, 2020 20:05
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Actually, if you plug 10 inches, 4700 feet, and 20 PSI into the Cubic Feet Required To Fill Pipeline calculator, the capacity of the compressor required to get a transit time of 7 minutes is around 500 cubic feet per minute, so it's entirely possible he was doing it at 20 PSI, he was just pumping way too much air in there. Instead of 500 cfm of air, he needed about 7.42 cfm to get a transit time of 7.83 hours. McGavin fucked around with this message at 20:12 on May 13, 2020 |
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May 13, 2020 20:09
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You guys have all the info I do. I can ask later. The 20PSI is what the gasket blows at so the actual desired pressure was pretty low.
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May 13, 2020 20:12
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Heh, I love playing with formulas that I have no idea are correct. here is off the last link that I put in. Numbers make sense to me, so maybe it did get to around 80 psi? The above shows that a 2000 cfm compressor will fill the volume to 80psi in 7 minutes. Kinda all works out.
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May 13, 2020 20:14
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SpaceCadetBob posted:Heh, I love playing with formulas that I have no idea are correct. I got the same numbers with 20 PSI and a 500 cfm compressor, so we need to know the capacity of the compressor he was using (it was definitely too high). McGavin fucked around with this message at 20:20 on May 13, 2020 |
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May 13, 2020 20:18
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McGavin posted:I got the same numbers with 20 PSI and a 500 cfm compressor, so we need to know the size of the compressor he was using. Yeah, that makes sense since psi and cfm are directly correlated. I was trying to more back figure how much of a cfm rated compressor would you need to get to the 80 psi in 7 minutes, which would be a 2000 cfm compressor.
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May 13, 2020 20:22
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Ol' boy from Arkansaw and ol' boy from Texas were trying to move a pig through 1mile of pipe, Arkansaw used 2700c feet of compressed air and that pig just dribbled out the other end. Boy from Texas said "yeah but it's deep too!"
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May 13, 2020 20:22
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It's possible it just got stuck early on, and the guy fuckin cranked it, which destroyed the pig and then shot it down the rest of the pipe.
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May 13, 2020 20:24
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The calculators not really constrained right for the problem statement but yeah if you had the flow rate of his source you might get something useful or maybe not because he almost certainly ran into the block and blew it past using something higher than the calc would spit out. Ok time for pig school folks Pig rule 1: always use water. Can't use water because it's incompatible with your service? Pay twice as much attention to rule 2 and 3 Pig rule 2: maintenance engineer tells you your max pressure. You don't go above the max pressure. Block doesn't clear at that pressure? Time to get out the roto rooter Pig rule 3: you have a pressure gauge at the throat, see if operations had any pressure gauges in the pipe network your pigging you can watch too in case of local overpressuring (if it was a good clean pipe with uniform flow you wouldn't be pigging it) and have relief valves and fail safe pressure controls that keep you below the pressure from rule 2. If any of the gauges show too high, even if your fail safe doesn't trip, you shut it down, let it settle, and start again from 0. If you can't clear it like this, refer back to the end of rule 2. Failure to pay attention to rules 2 and 3 nearly always end in pig potato cannon.
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May 13, 2020 20:30
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Finding out how much pressure would be required to give the pig an average speed of eleven feet per second is all well and good, but if you get an answer that is “it’s possible without exceeding safe pressure”, that doesn’t absolve anyone of exceeding the specs. I don’t care that the average temperature of my freezer in the last month met USDA guidelines. What matters is that it completely defrosted on the ninth. Everything is ruined.
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May 13, 2020 20:37
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You guys sure know a lot about getting your pipes cleared.
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May 13, 2020 20:38
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If the pig didn’t satisfy, you’ll be laying pipe.
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May 13, 2020 20:42
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chitoryu12 posted:OSHA IV: Ignore the pig seconded
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May 13, 2020 20:47
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