Have written software for a pig tracking company for the past few years. I'm always surprised at the amalgamation of low and high tech. On the one hand, some pigs can detect leaks in the line and map the pipe's dimensions. On the other hand, the industry often takes speed measurements via listening for a pig to pass a weld joint (which you can hear from far away) with a stopwatch.
The pig does often get stuck, so much so that there's a "Pig Stopped" button which influences ETAs. Every blue moon a pig really gets stuck for days or breaks in the pipe. Techs might have to use estimated locations and dig in someone's back yard.
Years into our contract, my girl friend was reporting on something farming related and said "hey can I pick your brain on raising pigs, I know you've been working with those farmers". Different type of pig tracking
Pigs do get stuck, and I STILL remember when I joined an O&G software company more than 20 years ago, and how hilarious it was to see the reportin output "Pig stuck in pipe."
For a second there I thought O&G was a weird spelling of OG. Took a moment to realize it's Oil and Gas indurstry after I read another comment. Today I learned.
some use more advanced approaches like this, but the conditions in a pipe are pretty brutal, plus the low-tech solutions often work "good enough". The entire upstream O&G industry is this weird mix of some of the most advanced technology in the world (like space exploration level) and basic non-technological solutions like drilling speed / weight "by feel". It was really cool to experience.
Similar experience here - I was making changes to the internal phone directory program and seen an entry for the “Pig Launcher” on a platform. As someone new to oil and gas, I thought it was quick funny.
I would assume they just dump a few handfuls of ice in the disposal and turn it on with water running over it. When the beaters break the ice it will form sharp edges for a short period of time that remove any material buildup inside the disposal.
It's less the sharpness than the solidity. An integral mass hitting clog or debris will scour those off regardless of how sharp the edges are. It's a bit like the principle noted in the meterological sector regarding hurricanes wind speeds: it's not that the wind blows, it's what the wind blows.
Ice is good for cleaning garbage disposals. Citrus peels (lemon especially) is good at improving their odour.
I will always associate pipe pigs with the opening scenes of Living Daylights where they exfiltrate a defector through a gas pipeline. Ridiculous but memorable.
I always remember my friend who works in VFX telling me he spent all week working on James Bond riding a pig. Which gave me some high hopes for the movie!
> I always remember my friend who works in VFX telling me he spent all week working on James Bond riding a pig. Which gave me some high hopes for the movie!
I think that was Sean Connery in his swansong as Bond.
He meets a rat in that scene (with a nice callback to it in the epilogue), but he shorts out the welding pig to attract service personnel to get him out.
Diamonds is a flawed movie and one of the weirdest Bonds, but it's my favourite because it's so weird.
A customer at a previous job was a fuels distributor. They told me that there is usually some leakage around the pig seals, so the gasoline near the pig might be contaminated with some other fuel - diesel, jet fuel, or whatever. And that the discount gas stations buy it ("Cheap Joe's Discount Gas"), but the major brands won't.
In cargo movements a simple foam pig pushed by compressed air or nitrogen is often used to clear the line after the pumping is finished and the pump has been turned off. In those cases where the line leading from the tank to the vessel was empty at the start of the movement, for best accounting you want the line to be empty afterward, and allow product settling time before the gager climbs the tank and takes their readings.
This can also facilitate sequential movement of different cargoes using a single line, after the pig has been caught and removed from the transfer path, the dry nitrogen then is used to purge the line until it is bone dry. To reduce cross-contamination, like if you were loading a parcel of acetone for one client followed by a parcel of ethanol from a different tank on the same clean-product manifold after that.
In the really long fuel pipelines, inspection or cleaning pigs can be used in the different legs but any one pig usually can not make it the entire length that the product will be traveling from entrance to exit. Foam pigs neither to better separate different grades of fuel so without a pig in between grades they end up with "transmix"[0] as the interface between gasolines and distillates becomes more blurred during the sequential transfers. As the transmix starts to appear at the receiving end it is diverted from the specification tank into its own smaller tank, rail cars, or trailers. Then subject to further processing back into two separate commodities again.
Players can implement "sushi pipelines" (pipes which transfer multiple fluids), e.g. [1]. It's fairly impractical, though; for a variety of reasons, most players prefer trains for long-distance transport of liquids.
Oh man that’s so cursed, but somehow also elegant.
For other readers, it’s called “sushi pipelines” because there’s a somewhat more common practice called “sushi belts” which is making transport belts that have every kind of item, and then filter inverters just take what they want, like at one of those sushi restaurants.
Sushi pipelines seem multiplexed more in the time domain than sushi belts (each square of belt can have up to 8 items at a time IIRC, so if you want to have more than 8 item types on it they’re also time-multiplexed, but that’s just a factorio implementation detail)
I like this theory, very creative. However I don’t think it would work unless you control both ends of the pipeline, since you need flow in the pipeline to move the pig and this flow would be noticeable along the entire pipeline.
As an electrician we used to pig conduits 50mm-200mm in diameter by wrapping rope around a bunch or commercial rags and tightly duct taping the middle of the pig. The head and tail would then compress to the diameter of the conduit and would be flexible enough to go around tight bends. Very effective
As a side note, in James Bond movies using a pipeline and a pig either as a tool or as an obstacle is a recurrent theme. It started with Diamond's are forever.
IANAME (...Mechanical Engineer), but I'll bet "generally no". A pig is propelled by the pressure difference across it, in the pipeline. Having two pigs in the line means they're splitting the available pressure drop - and the line is only rated for so much pressure.
(Yes, in "no other way" situations you might deploy a far more complex, battery- or remotely-powered "snake pig". That'd be really cool & interesting...but also a much more expensive and unpredictable scenario. And pipelines are a big thing because they're cheap and reliable.
"Pigging station". I remember seeing these a lot as a kid, and I was always wondering what their function was. Finally.
Interesting section:
> There are four main uses for pigs:
> 1. Physical separation between different fluids flowing through the pipeline
> 2. Internal cleaning of pipelines
> 3. Inspection of the condition of pipeline walls (also known as an inline inspection (ILI) tool)
> 4. Capturing and recording geometric information relating to pipelines (e.g., size, position).
--
The topic interested me, so I looked around and found an article in a German newspaper [0], related to the Nordstream pipeline, it is from 2014. I asked ChatGPT to shorten and translate it because some might find the data interesting (prompt: `Shorten each paragraph to a maximum of 3 sentences and translate all to English, leave title and introduction unsummarized. Focus on the facts, numbers are important, pressures and speeds with their corresponding units as well: ...`):
--
OSTSEE-PIPELINE: Pipe Cleaner and Smart Crawler
The gas pipeline through the Baltic Sea is monitored by a special device called a "Molch" (crawler). This device inspects the pipes from the inside. The results of the measurements have now been released.
Pipeline condition must be regularly checked for sea floor changes or damage from trawling nets and anchors. External checks occur every two years using remotely-operated underwater vehicles. Steffen Paeper, responsible for inspections at Nord Stream, says the unique challenge was the pipeline's length.
The Molch was specifically developed for this task by the Rosen Group. Before deployment, it underwent extensive testing in a pipeline with a 1,153 mm diameter. Steffen Paeper stated that larger diameters could theoretically be used but are impractical with current ships.
The Molch detects early corrosion and material loss. It also checks for pipe deformations and curvature radii compliance. Although the pipes are coated with synthetic resin, the coating is absent at welding points, making them susceptible to rust.
The pipes are fitted with sacrificial anodes designed to prevent rust for at least 50 years. Nord Stream keeps a reserve of 480 pipes for any required repairs.
Wheels on the Molch measure the distance covered, enabling location-specific measurements. Mechanical devices with sensors capture the inner geometry, detecting even bumps smaller than 1 mm. These create a 3D image of the entire pipe.
The Molch uses magnetic flux sensors to detect steel corrosion and material loss. This magnetic field is calibrated to work with various wall thicknesses. It also creates a 3D image for future comparison.
Magnetic flux technology isn't new but needed adaptation for this large pipeline. Wall thicknesses range from 41 mm to 27 mm. Gas is pumped in Russia at about 220 bar but arrives in Germany at approximately 110 bar.
The Molch travels at 1.5 meters per second, powered by gas pressure, and reaches its destination in nine days. It generates about 1 TB of measurement data and operates on batteries.
The Molch is inserted and removed through locks with gate valves. It's 6.6 meters long and weighs over 7.3 tons. The worst-case scenario is getting stuck inside the pipeline.
Before the smart Molch's deployment, smaller, simpler versions are sent through. These are one-third the size and weigh 1.5 tons, helping to gauge potential obstacles.
Before inspections, a cleaning Molch removes dust and debris. It takes three to four days to reach Germany, where the collected material is analyzed.
Nord Stream is satisfied with the results. The first line had 8 kg and the second 4 kg of particles, which Steffen Paeper says is minimal given the pipeline's length. No signs of saltwater or corrosion were found. The next inspection is planned in 7 to 10 years.
---
A piece of information that went missing a bit was regarding `Wall thicknesses range from 41 mm to 27 mm. Gas is pumped in Russia at about 220 bar but arrives in Germany at approximately 110 bar.`
> In the Nord Stream pipeline, the Molch has to deal with four different wall thicknesses - from 41 millimeters of steel to 34, 31, and 27 millimeters. This is because the pressure of the gas decreases along the route.
The varying wall thickness is interesting. Presumably they reduced the thickness the further they got from Russia, as the pressure drops. One of the methods used for clearing a stuck pig is reversing the flow.
I wonder how reversing flow works mechanically? Does Russia pump out of the pipe, reducing pressure, or would the receiving end increase pressure? Up to 220 bar, or would they have to stop lower?
I think the latter, since you can only reduce the pressure to the vapour pressure of the fluid. You get more bang for your buck pushing than pulling.
Also the pressure can generally be raised above the design pressure for short periods, pipes are generally hydro tested at 125 - 150% of the design pressure.
This is timely. My partner and I have been watching the Saw movies, and we use the term "pigging" to mean "abducting" (as abductors wear pig masks in the series). Everytime someone is abducted we say they're "getting pigged".
The pig does often get stuck, so much so that there's a "Pig Stopped" button which influences ETAs. Every blue moon a pig really gets stuck for days or breaks in the pipe. Techs might have to use estimated locations and dig in someone's back yard.
Years into our contract, my girl friend was reporting on something farming related and said "hey can I pick your brain on raising pigs, I know you've been working with those farmers". Different type of pig tracking