Pipelines, More Complicated Than You Thought

Unlike a spares pipeline, a transportation pipeline is a conduit for the long distance transportation of gases, liquids, and slurries (solids suspended in liquid). Pipelines are one of the modes of transportation recognized by by the US Department of Transportation. According to the US-DOT Pipeline and Hazardous Materials Safety Administration (PHMSA), “The energy transportation network of the United States consists of over 2.5 million miles of pipelines. That’s enough to circle the earth about 100 times. These pipelines are operated by approximately 3,000 US companies” (http://www.phmsa.dot.gov/).

Pipelines are categorized into crude oil lines, natural gas lines, products (petroleum, food, water, etc.), and natural gas liquids (NGL). Then there are distribution mains, transmission pipelines, facility piping, and gathering/flow lines. Items “shipped” usually come in ‘batches’ or ‘pools’ for inventory purposes. Different products often flow one behind the other without using a separator; causing some mixing of products. This ‘transmix’ can sometimes be used as is, or will be refined again into separate products. Mechanical devices called “Pigs” are also sometimes inserted into the pipeline to separate different products, scrape/clean pipe walls, monitor condition, perform repairs, plug the pipe, check for leaks, and to propel James Bond 007 and his latest female interest at ridiculous speeds toward a ubiquitous gratuitous explosion. Pigs are serious business as can be seen at the Pigging Products & Services Association (PPSA) website: http://www.ppsa-online.com/about-pigs.php Plus, they look really cool when they explode in a fireball on screen.

One pipeline already built and operating in Northern conditions is the Trans Alaskan Pipeline Service (TAPS) Alyeska oil pipeline in Alaska. This pipeline has been raised above ground level because the heated oil would otherwise melt the permafrost, resulting in damage to the pipeline support base and ultimately damaging the pipeline itself. It also had to be built high enough for migratory animals to pass under (Moose and caribou are very tall animals)(http://www.alyeska-pipe.com/).

Before the Alyeska pipeline was built, Boeing proposed a series of twelve-engine tanker aircraft to carry the oil. These Alyeska Pipeline statistics show why a pipeline was the better logistics solution:

Area covered by the pipeline system: 16.3 square miles
Length: 420 miles above ground / 376 miles below
Right-of-Way Width: 54’ buried, 64’ elevated.
Average flow rate: 20,520 gal/min; $1.5 M/min
Total oil travel time: 10 to 12 days
Inside Pipe Diameter: 48 inches
Reliability Rate: 97.71% in 2010
Construction cost: $8 billion
Operating cost: $210 M/year
Velocity; 2.7 to 3.5 mph
Vertical Support Members: 78,000
Number of Valves: 178 mainline / 83 check / 71 gate
Oil temperature: 112oF at source / 54oF at destination
Internal Volume: 9.04 million barrels (42 gal/bbl)
Maximum Grade: 145% (55o) at Thompson Pass, AK
Volume: 17% of the US domestic crude oil production (and falling)

There are many types of pipelines. Short distance ones include the pneumatic tube at your drive-up credit union that literally sucks your paycheck right out of your wallet. Long distance commercial pipelines are often common carriers; which means that anyone’s product could be flowing through it at any time. Refinery products all flow through the same pipes: They buy “time” on the pipeline, For instance, if they insert 30 minutes of gasoline into the pipe, they then pull 30 minutes worth of gasoline out the other end at the same time, regardless of who refined it (Gasoline is all made to the same initial specifications, and any unique advertised additives are added just prior to sale).

From a reliability standpoint, the biggest cause of pipeline failure mode is a leak or rupture. There are some moving parts that break (valves, pumps, etc.), and when a petroleum pipeline catches fire, the flame front will travel a specific number of feet, compressing the ullage space until the pressure reaches a point where the the pipeline explodes a hole just big enough to relieve the pressure, but not enough to put out the flame – which continues down the pipe to repeat the process until stopped. Even buried pipelines need access for maintenance, so they appear on aviation maps as cleared forest areas. Also, aircraft fly at treetop level to inspect the pipelines, and mileage markers are provided that can be read from the air. – Logistics in Action.

Courtesy of SOLEtter, Oct ’15