Pittsburgh Years

Complexity

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etrochemical plant is the term used to describe both oil refineries and chemical plants and, often, a mixture of the two.  The primacy of Petro in the word tells us something about economics: Petroleum, as a feedstock, in the form of crude oil, produces gasoline, petrol, along with a host of other valuable products, key ingredients of our economy.  While chemicals, as a class, have nearly uncountable uses: they help to clean our clothes, bleach our paper, wash our windows, clean our teeth, seal our roofs, and so forth, they simply do not rise to the level of significance of petroleum; moving about quickly and keeping warm still trumps every other consideration in our lives.  The reason for the conjunction of Petro with chemical is that they have a great deal of commonality in the equipment and structures with which these materials are produced.  Looking at a petroleum refinery from the outside is very much like looking at most chemical plants.  Only one’s nose knows the difference for sure.

Were you to enter such a plant for the first time you would be awed.  And what would elicit your wonder would not be the architectural brilliance of the structures, nor the elegance of the arrangement of its elements, nor the neatly trimmed green grass and trees, of which there are practically none, except probably for a small decorative strip near the office, a small nod to nature and order.  Nor would you discover any other trappings of city life or of the gathering places of people.  No, what would humble you is the sheer complexity and seeming disorganization of it all; how can this jumble of strange looking noisy and smelly stuff possibly create something useful and, for that matter, where is it, this material for which a great deal has obviously been spent in its production?

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Nothing in these plants is obvious; they are a rudely colorful jumble of tanks and towers, boilers and pumps, heat exchangers and compressors and generators, some roaring, some hissing and steaming, nearly all of them smelling; and the entrails of this strange organism, the piping, ducting, and electrical routings that stream among them seem as intestines of the strange organs that they attach to.  This complex has some of a city’s trappings: roads and smells and sounds and feverish, but here hidden, activity.  But it is very different than a city.  It is as though one had entered the corpus of a vast robotic, foreign entity growing on our land, one that seems to have its own inner logic, its own rational, which it is obviously pursuing with great vigor; but what is it, and is it benign?  After reverence would follow doubt, and a nagging question: can this vast Frankenstein possibly be beneficial to our delicate species? 

The structural supports of these plants, my particular interest, the sinews of this strange foreign body, the elements which hold everything in their proper place, are almost insignificant, their design incidental.  The process itself, all the required equipment and interconnections, has the leading role in this act of generation.  But these peculiar conglomerates have their attractions for a structural designer:

“Oh, you want this large tank of ammonia to be up there, 47ft. in the air? It weighs how much? But there is nothing under it!”

“Well it has to be up there.”

“All right, we’ll come up with something.”

A chemical plant, or a petrochemical plant—first cousins, the second focused primarily on petroleum and it’s byproducts—is surprisingly complicated.  There are all sorts of equipment in these plants, some of unusual shape, and often rather heavy, at least in comparison with the things in homes, office buildings and stores.  These components are typically arranged in unusual configurations, especially in the vertical dimension, arranged entirely to suit the requirements of the process, not to make it easy for the structural engineer.  Integrating all this equipment into a system, so that the process functions properly, is all the necessary interconnecting piping, electrical cables and conduits, and ducting. So intricate and congested is all this stuff that there existed at Blaw-Knox a department that made precisely scaled, and rather expensive, models, in plastic and wood, of the major processes of a specific plant. 

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Wood and plastic scale model
The models were made as the drawings were developed—they were made from the drawings, just as the real structure would be.  It was another sort of check on the drawings themselves.  The model accurately depicted each vessel, heat exchanger and tank, each pump and compressor, each girder, beam and column, every interconnecting pipe, duct and cable tray.  A scale model of a man with a hard hat and raised arm might be placed on one of the levels just to establish the proper size perspective.

There were several aims here: to be sure that one element of the design didn’t unintentionally run into another which, in a congested area, is a rather difficult thing to determine from a set of two dimensional drawings; to provide a three dimensional view of the process that was then available to all the various parties contributing to the effort, not excluding the client; to provide the field construction crew the same benefit of visualization: the models were shipped to the field when they were complete and as construction began.

Few of the liquids and solids and gases that circulate within petrochemical plants are benign.  Some of them, such as chlorine, if let on the loose, can kill you, but even most of the others would certainly not be good for you.  Even water, one of the most gentle substances known to man, can become quite dangerous when, as is often the case in chemical plants, it is heated to high temperature steam.  Chemical plants can, and often do, leak, sometimes burn and, though rare, they occasionally even explode, liberating noxious gases and liquids and jeopardizing the people that operate the plant, and perhaps even others in the vicinity. 

Yet another purpose of model building had to do with piping: before modeling became common, “orthographic” piping drawings were required to be made to indicate how the piping was to be run.  An orthographic drawing is made as though looking down on the piping from above, much like a house plan, except instead of walls and doors and windows and suchlike, what is viewed is piping.  These drawings were labor-intensive to make and susceptible to error because not all of the piping is running flat; it often goes every which way: up, down, and at odd angles.  An equivalent task would be to make a flat drawing, as though a looking down from an airplane, of a very complex highway interchange that has many levels and roads passing over and around each other.  It is difficult to represent this sort of complexity on paper.  Using models helped a great deal because one could visualize the process in three dimensions.

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A Piping Isometric Drawing
Once a model is built, orthographic drawings become unnecessary.  Instead, many, small “isometric” drawings are made that show each element of piping in a pseudo three-dimensional view.  These drawings can be made from the model itself without developing orthographic drawings first, the traditional way, since each line can be visualized by the draftsman directly from the model.  From the isometric drawings the piping can be fabricated directly in a pipe shop.  Most piping in a chemical plant is welded.  Screwed piping, as is common in plumbing is not customary in these facilities.  Each isometric drawing shows a single “spool piece”, at each end of which is welded the heavy steel flange with which the pipe spool can be bolted—with a gasket—to an element of equipment, to a valve, or to another spool.  Each such piece is welded together in lengths that can be shipped by train or by truck.  I don’t know, but I suppose that these elements are called “spool pieces” because a small one, with a flange at each end, looks remarkably like a rather large version of your grandmother’s spool of thread—just a guess.

Years later, after I had left the Civil Engineering Department and had become sort of the company’s computer guru, I shopped around for a computer program that would make these sorts of isometric drawings on a computer-driven plotter.  The “draftsman” then would simply entered the coordinates of each bend,  specify each valve and provided certain other information to the system, and the isometric drawing would be produced automatically, the computer making the calculations, and the pen plotter producing the physical drawing.  This was an interesting bit of shopping, because I had to go to England to do it.  This was my first overseas trip and it was very illuminating in several ways:

The airplane, a Boeing 747, left JFK Airport in New York bound for Manchester England.  For some reason it had to be re-routed to London instead.  After we landed at the airport—a rather rough landing, but not too bad—the pilot announced that the airplane had landed itself automatically, a process that was required to be done every so many flights in order to test the system.  I noticed that we were only given this information after we had successfully landed.  But this information was interesting in that even in those early days, one could see the extent of automation then dawning on world.

From London we were given railroad tickets to Manchester, several 100 miles away.  I was quite impressed with the British railroad system which traveled through a very green countryside, one I had not expected to find in industrialized England.  In the dining car, we were served a rather elegant meal, as it seemed to my Midwestern taste anyway; I remember corned beef and cabbage with boiled potatoes served by a middle aged gentleman with a white napkin draped on his forearm.  While eating this meal, and watching the green countryside flow by, I thought to myself, These British certainly do know how to travel.  It was my first bit of international travel, and my first trip of any extent on a railroad.  It was, all together, an interesting adventure for the young man from the corn country of Naperville.