Thoughts on Graduation and Starting Engineering Career

Subtitle: Go With What You Know

This article is for the new engineering graduates, but also applies to those with a year or two of industrial experience.   Some of this may seem quite obvious, but perhaps some will be useful.

I  was invited in 2015 to speak for an hour to the AIChE student group at University of California at Irvine, or UCI.  The topic was Engineering Ethics.  During the question and answer period afterward, I was asked what was the most unexpected thing I encountered after graduation.  My reply was, I did not expect to be so unprepared for the variety and depth of topics in the industrial world.   I gave a few examples to illustrate.

My engineering degree is from The University of Texas at Austin, one of the top engineering schools in the country, if not the world.  I learned what they taught, but the fact is that the engineering curriculum cannot possibly teach everything one needs to know in only 4 years of study.    The amount of knowledge that an engineer should know increases yearly as more and more fields are created (e.g. environmental engineering, bio-engineering, nano-materials) and existing fields are expanded.

What the new engineer should know can be viewed as 1) the fundamentals are key, 2) a vast body of topics exists and should be studied, and 3) time is your ally if used properly.

A brief side-bar on my career start: my first job was as a process engineer in a chlor-alkali plant in a medium-sized chemical company that no longer exists.  The plant is still operating, though, after being sold to other companies.   For details, the plant was designed and built by Diamond Shamrock Corporation of Cleveland, Ohio, and was known as the Battleground Plant after the nearby San Jacinto Battleground and monument in LaPorte, Texas – just east of Houston.   This was a merchant plant, in that the products were sold on the open market and not used internally by the company.

My first problem was understanding what a chlor-alkali plant did, and how it did it.  An engineer would do well to understand what his (or her) plant does.  Chlorine, caustic, and hydrogen are produced via electrolysis of sodium chloride dissolved in water.  I did not recall that electrolytic cells were mentioned in the undergraduate courses I took, not in chemistry, nor in reactor design.   It was all foreign to me.   At that time (1978), two technologies existed for chlor-alkali plants, diaphragm and mercury cells.  The company had both types in its fleet of plants, but the Battleground Plant had the diaphragm cells.

The solution to curing my ignorance of chlor-alkali technology was in two steps: 1) attending the mandatory safety orientation class, and 2) reading in the Perry’s Chemical Engineering Handbook.   The safety orientation class gave a good overview of the chemical plant, but was mostly concerned with the dangers and toxicity of the various processes and chemicals.  The chlor-alkali plant had plenty of dangers and toxicity: deadly DC current at 800 volts and 90,000 amps in the cell room; chlorine gas is toxic and can be deadly; caustic soda even in dilute strength (cell liquor) is hot, corrosive, and can blind the eyes; hydrogen is invisible, auto-ignites, and the flame is a pale blue that is essentially invisible in daytime.  The plant also used asbestos in creating the diaphragms.  There was also sulfuric acid in one process area, with the acid strength ranging from 70 to 98 percent.   There were also the usual dangers in a process plant, steam at various pressures, fuel gas, AC current at various voltages, and rotating machinery, to name just a few.  (As a side-note, we also had a small process in which CO2 in gaseous form was absorbed by a weak solution of sodium hydroxide and water to form sodium bicarbonate.  This would later become an important issue in the raging debate about capturing CO2 from a process furnace’s stack gases)

After gaining an appropriate respect for the hazards I would face on a daily basis, the next task was to read the Perry’s, where Electrochemistry was discussed in a few pages.  However, the Perry’s treatment was mostly theoretical and I was not much wiser for having read the material.  I then turned to another favorite, Chemical and Process Technology Encyclopedia by D. M. Considine (McGraw-Hill 1974).   This excellent resource had what I needed: about half a dozen pages on chlorine production, including a process flow diagram.  (readers should note the time frame, 1978.  At the time, there was no internet with vast resources.)  Finally, the plant library had design books specific to the Battleground Plant, with process flow diagrams and material balances.

This brings me to point 1) from above, the fundamentals.  I finally had a grasp of the fundamentals of electrochemistry and how a chlor-alkali cell operated.   In its simplest form, DC current passed through a conductive brine attracts the chlorine ions, Clˉ, to the positive electrode, and the sodium ions, Na+, to the negative electrode.   The chlorine ions combine to form a molecule of Cl2, while the sodium ions combine with OHˉ ions to form NaOH.  The left-over hydrogen ions combine to form a molecule of H2.   From there, the products Cl2, NaOH, and H2 were processed, purified, and condensed (the chlorine) into products for sale or internal use.

The new engineer must, in my opinion, gain a good understanding of the fundamentals of his (or her) assigned process, no matter what that process is.  The above outlines the steps I took to gain an understanding.  Next, the fundamentals of engineering are key to success.  No matter what field or area one is working in, the various laws apply: material balance, heat transfer, mass transfer, equilibrium, fluid flow, etc.

Now to point 2), a vast body of topics exists and should be studied.   The list below includes a number of topics that are common to the process industries, both batch processes and continuous processes.  Budgeting, Control and Instrumentation, Corrosion, Cost Estimation, Economics (especially incremental economics),  Environmental, Equipment, Feed Specifications, HazOps, Laboratory,  Maintenance,  Metallurgy,  Operations,  Optimization, People, Pinch Technology, PFD & PIDs, Plant’s Design, Project Implementation, Product markets, Product Specifications,  RAGAGEP,  Regulations, Safety,  Technical Plan, and Trade Offs.    These are the main issues that a plant process engineer will encounter.  Those working in other areas will have different issues to learn.  Engineers also work in EPC companies, Engineering/Procurement/Construction, research, catalyst development and production, technical sales, government agencies, and others.

Point 3) from above, time is your ally if used properly.  A new engineer could, and should in my opinion, strive to learn as much as possible as quickly as possible about the areas in which he (or she) is deficient.   Time for such learning can be found by arriving an hour early to work, at the lunch break, and staying an hour after formal work hours.   A study plan can be developed that will encompass the topics.   Another way to increase knowledge is regular attendance at AIChE monthly chapter meetings where continuing education credits are given.  Many times, these meetings include a presentation or lecture by industry experts on a particular subject.   Reading industry literature, including magazines or e-zines is especially helpful.

A brief expansion on the additional topics to be studied is shown below.

Budgeting – the engineer should know that a process plant has at least one budget, there being typically three or more.  These include a) annual operating budget, b) capital budget, c) local spending budget (under the control of the plant manager).  Learning what each budget controls, the budget size, and how the budgets are prepared are all vital to understanding the plant’s operation.

Control and Instrumentation – many times, the new engineer has had a course in the basics of process control and instrumentation; if not, he or she should study this.  The basics include (but certainly are not limited to) the four basic controlled parameters: temperature, flow, level, and pressure (and note there are several others); the measurement instruments that collect the signal; the controller that processes the measurement and sends out the correction signal; the control device (usually a control valve but not always); and the actuator that moves the control device.  In addition, the engineer should understand the basics of various control schemes, and why each controller exists at that particular point in the process.  Higher (and lower) levels of instrumentation and control exist, including safety and machinery health (bearing temperatures, shaft vibration), DCS (distributed control systems), advanced process control (computerized integration of basic controls with process models including optimization and constraints).   Other areas include inferential controls, analyzer-based controls, to name just two.

Corrosion – the measurement and management of corrosion in a process plant is extremely important, even vital.  The engineer should read and understand the basics of corrosion – it is simply a rather slow chemical reaction that (typically) removes molecules from the corroded surface and results in thinning (usually) and weakening of the material.  The corroded material may be a process vessel, a pipe, or other equipment.  Corrosion control and management may include passivating chemicals added to slow down the corrosion rate, upstream removal of corrosive molecules (e.g. sulfur and salts), and temperature control to keep the corrosion rate manageable.  Wall thicknesses are measured during periodic shutdowns.

Cost Estimation – the new engineer almost always has some experience in cost estimation in undergraduate studies, but the employer likely has its own cost estimation philosophy and software.

Economics (especially incremental economics) – the new engineer also likely has some experience with economics in undergraduate studies.  The process plant likely has various criteria that the engineer is required to use for economic studies, including a list of values (or prices) for each utility, feedstock, intermediate streams, products, and process unit operating costs.  Sometimes feeds, intermediates, and products prices are confidential and guarded with great secrecy.   Incremental economics must be understood, as these are quite different from average values.   It is also crucial to understand that not all energy is equal, as a BTU (or kW) saved in one area may actually have zero value.   In addition, the cost to install equipment to save energy, or increase yield, or improve product separations may greatly exceed the benefits.   Some plants have a strict guideline that no potential project is to be advanced for consideration that has greater than two years simple payout.

Environmental – the new engineer should learn what environmental issues exist in his or her plant, with the three standard classifications of air, water, and solids.  Typically, the plant has one or more permits from state or federal agencies that list the quantity of allowable emissions for each pollutant.   Potential modifications to the plant, e.g. adding a new fired heater, may require expensive and time-consuming revisions to the environmental permits.

Equipment – the new engineer likely has a good understanding of the basic equipment types from undergraduate work.  The plant likely has equipment that was not included in the classwork, and almost certainly has variations on familiar equipment.  As an example, there are many types of pumps (centrifugal, positive displacement) with several variations of each.  The same is true for relief valves, control valves, block valves, compressors, heat exchangers, filters, separator vessels, fired heaters, boilers, piping, fittings, turbines, electric motors, reciprocating engines, and many more.

Feed Specifications – each plant, and each unit within a plant, will have one or more feed specifications.  The engineer should understand what each specification is, what the allowable limits are, and how that item is measured.   Equally important, the engineer should know what the ramifications are when a feed specification is above or below the limit.

HazOps – or hazard and operability study, is an important part of a process plant’s safety plan.  This should be thoroughly understood by the engineer.

Laboratory – the plant laboratory, the samples, and analytical tests should be understood by the engineer.  The plant may have a laboratory on-site, or may send samples to off-site labs for testing.  Many laboratory tests are described by an ASTM number (American Society for Testing and Materials), or other designation.   Reference books exist that describe each test; these should be on the engineer’s bookshelf and be read and understood.

Maintenance – the plant maintenance is one of the three major organizations in a typical plant (the others are Operations, and Technical Services).   Maintenance is a vast, complicated, and essential aspect of a process plant’s success, safety, and profitability.  The engineer should learn the essentials of the plant’s maintenance organization and program.  Typically, maintenance is organized by craft: millwrights, electrical, instrumentation, and piping.   Safe shutdown and isolation procedures must be understood by the engineer, as well as startup procedures once the maintenance is completed.

Metallurgy – the engineer should understand the metallurgy and other non-metallic materials used in the plant.  Typically, various metallurgies could be used in a plant, and the choice is made based on several considerations: safety, cost, durability, corrosion, and others.

Operations – plant operations is one of the big three organizational arms in a plant (Maintenance and Technical Services are the other two, typically).  The engineer should get to know the operations staff, from the Operations Manager to Unit Supervisors, to shift staff.  Typically, the shift staff has a Shift Supervisor, each unit has a Lead Operator (or other title such as Head Operator), and Unit Operators and helpers.   The engineer should understand the role of each.   Terminology for the various operating positions can vary by industry and by plant.  For example, there may be one or more Board Operators and Outside Operators where the Board Operator remains at a computer control console in a central control room, while Outside Operators (as the title suggests) work outside among the equipment.

Optimization – the engineer should learn as much about optimization as possible, including what optimization systems and procedures are in place, and what they accomplish.  Optimization is a vast topic.  One thing a new engineer should know is that seasoned veterans in the Operations and Technical management are usually distrusting of new optimization schemes – especially the benefits that supposedly derive from the optimizer.

A paper on optimization; (see link) to my March 1998 article in Hydrocarbon Processing, “WHY A SIMULATION DOES NOT MATCH THE PLANT,” in which process plant simulations and optimizations are discussed.   An excerpt from the article:

“. . . there are many reasons why a process simulation doesn’t match the plant. Understanding these reasons can assist in using simulations to maximum advantage.

The reasons simulations do not match the plant may be placed in three main categories: 
1) simulation effects or inherent error,
2) sampling and analysis effects or measurement error, and 
3) misapplication effects or set-up error.”
The article then discusses these three categories.

People – people skills are essential to success, not just in engineering but in almost every endeavor.  The new engineer would do well to focus on what may be called “human engineering,” or practical psychology.  This is a vast topic, but crucial to success.  Stating one’s views in a meeting, learning how and when to disagree without offense, learning how to network effectively, all are important aspects.   Dealing with incredibly difficult people is to be expected.   One good source for process industry engineers is the “You And Your Job” series of articles in Chemical Engineering magazine (online and archived in libraries).

Pinch Technology – the engineer should understand Pinch Technology, (developed years ago by Bodo Linhoff) and how it applies to process heat transfer and other areas.   PT has many articles and publications that the engineer can read for an understanding.

PFDs & PIDs – the engineer likely has a basic understanding of Process Flow Diagrams (PFD) and Piping and Instrumentation Diagrams (PIDs) from undergraduate work.  The process plant will have detailed drawings of each, which should be read and studied until the engineer is completely familiar with each figure on the drawings.   (Note that PID has a different meaning in the process control context, where it means Proportional, Integral, and Derivative).

Plant’s Design – where possible, the engineer should know the basics of the plant’s design – the capacity basis, the choices among various technologies, storage and inventory quantities (i.e. number of days’ storage for feedstock and for products).   Unit constraints are also important.

Project Implementation – the engineer should learn how a project is implemented in the plant, whether a capacity expansion, or other type of project.  There may be a separate group for project work, or the engineer may be expected to develop and manage a project.  The area of project management is (or can be) complicated, with construction contracts, project schedules, disruption to the existing plant, and many other aspects to consider.

Product Markets – the engineer should understand the market or markets for the plant’s products.  This could include the historic demand, projected demands, whether his or her plant is a low-cost producer or a marginal producer, and especially: how disruptive technologies could make the plant obsolete.   This last point is rather important to chemical engineers.

Product Specifications – similar to the above on feedstock specifications, the engineer should know and understand the specifications on each product.  At times, no variations in product specifications are tolerated.  In other plants, there may be incentives for higher purity and lower prices for selling a product with lower purity.

RAGAGEP – the engineer should understand RAGAGEP (Recognized And Generally Accepted Good Engineering Practice) and how it applies in the plant. RAGAGEP are “engineering, operation, or maintenance activities based on established codes, standards, published technical reports or recommended practices (RP) or a similar document.” They “detail generally approved ways to perform specific engineering, inspection or mechanical integrity activities such as fabricating a vessel, inspecting a storage tank, or servicing a relief valve.” (source: OSHA NEP for refineries, 2007)

Sources of RAGAGEP are many. Examples are the API Standards (American Petroleum Institute), ASME Code, CCPS (AIChE’s Center for Chemical Process Safety), OSHA, NEC (National Electric Code), NFPA (National Fire Protection Association), and other engineering disciplines such as ASCE (American Society of Civil Engineers).

The intent of RAGAGEP is to ensure that process plants, manufacturing plants, structures, civil works, electrical works, and other things designed and built are as safe as possible. This extends to ongoing repairs and maintenance, alterations and changes, inspection and testing.

Regulations – the engineer should develop at least a basic understanding of the multitude of government regulations that apply to the plant.  These likely include (but are not limited to) environmental, OSHA, FTC, labor laws, and others.

Safety  – the engineer should understand the basics of the plant’s safety program.  Safety should be first, as the slogan says (Safety First).  Whether the engineer is designing a new process, a modification to an existing process, or reviewing operating procedures, safety is critical.

Technical Plan – the Technical Plan is (or could be) a part of the Technical Services division.  The engineer should become familiar with the tasks or projects that are underway or were recently completed, and those that are contemplated for future work.  Unless the plant is recently completed and started up, the engineer will find there is a legacy of studies, projects, and reports for each that can be read and studied.

Trade Offs – the engineer should know what trade-off opportunities exist in the plant (this is a subset of the Economics and the Optimization areas above).  Trade-offs exist for making or purchasing utilities, feedstocks, and processing or selling intermediate streams.

Roger Sowell

Copyright © 2017 by Roger Sowell, all rights reserved

Join the conversation; leave a comment. What are your thoughts on starting an engineering career?


Top Ten Issues – River Mouth Osmosis

Subtitle: Renewable Energy from River Mouth Osmosis

I was asked in January, 2014  to speak to the student chapter of AIChE at UC-Irvine in California (American Institute of Chemical Engineers, at University of California at Irvine).  The students requested I speak to them on TopTen Issues in Chemical Engineering.  I was happy to speak to them, as usual.  I have spoken to that group three times in the previous 12 months.  Previous speeches discussed Peak Oil and US Energy Policy, and Practical Chemical Engineering Tips.  While the speeches are great fun, the questions and answers portion is always my favorite.  Students have some of the best questions.


Nile River Delta credit: Chris Hadfield  – NASA

One of the issues in the Top Ten speech is the subject of today’s article: Renewable Energy from River Mouth Osmosis, (RMO).   RMO is not a novel idea, having been discussed over many years.  The basic idea is to generate power from the fact that river water is fresh (contains very little salt) but the ocean into which it feeds is saline.  A suitable permeable barrier placed between fresh and salt water will allow the salt water to pull fresh water through the membrane.  Water will flow through the membrane even when the salt water is under pressure, if the pressure is not too great.

In practice, one version of a RMO system would have all or a portion of the river enter a vertical shaft or pipe, with its lower end placed at a depth in the ocean.  The river water, pulled by gravity, flows through a conventional hydro power plant located near the bottom of the shaft, with a water turbine that spins a generator.  The water exiting the turbine would flow into a chamber that is vented to the atmosphere.  The water in the chamber then flows through osmosis membranes in the floor and walls of the chamber and into the ocean.   With careful design, the flow of water through the membranes will equal the flow of river water into the vertical shaft.   Essentially, the power generated is virtually free, produces zero pollutants, and is inexhaustible.   In a world where so much debate occurs over green power, renewable power, and carbon dioxide regulations, the RMO system receives little attention.

The items of interest to chemical engineers in a RMO system include conditioning the river water so that the osmosis membranes have a long life, and the design of the membranes.   River water is not usually very clean at the river’s mouth, having acquired silt, chemicals, and debris from upstream.  Osmosis membranes are rather finicky, and must have fairly clean water.  Filthy water causes the membranes to plug, which requires cleaning or replacement.

Therefore, chemical engineers would be required to design screening systems to remove the larger debris, a system to prevent fish from being harmed, filtering systems to remove the silt and suspended solids, and ph adjustment to meet the membrane requirements.  The RMO membranes would have water flow in reverse direction compared to the traditional reverse osmosis membranes.  This will also require engineering to optimize the membrane.

The reason this process, RMO power, made the Top Ten list is not so much for the chemical engineering challenges, but for the large impact the technology could have on future power production.  While the RMO process would not be feasible in some rivers, especially those that empty into shallow seas, the rivers where the right conditions exist are numerous.   There may be some rivers where the economics are not favorable, such as where treating the river water to remove impurities is too expensive compared to the value of the power produced.

Work and research are proceeding on the RMO systems, as shown in this recent publication on membrane research.

There are variants on the process, such as a water surface system where fresh water flows through the membrane into brackish or seawater.  The seawater volume increases, which increases the pressure.  The pressurized water then flows through a hydro turbine that spins a generator.

Environmental concerns arise where the river enters an estuary.  It is not clear how much the ecosystem would be changed due to a RMO plant.

For now, the RMO process shows some promise as a means to generate clean, renewable energy.  It is also worth noting that many population centers are located at the mouth of a river.  This reduces or eliminates the need to invest in long-distance transmission lines from remote power plants such as windturbines or solar plants.  Examples include New York City (Hudson River), New Orleans and surrounding area (Mississippi River), Cairo and Alexandria (Nile River), Buenos Aires (Rio Plata), and Shanghai (Yangtze River).  The world’s largest river by flow, the Amazon, has a very small city near its mouth (Belem, Brazil).  That could change if abundant and low-cost electric power were produced there.

I expect to write more in future on the Top Ten Issues facing chemical engineers.


  1.  My list of the Top Ten Issues Facing Chemical Engineers includes:Fresh, Clean Water from Wastewater
  2. Process Plant Scale-Up
  3. Large Complex Process Optimization
  4. Coal Gasification / Liquefaction
  5. Low-Cost Manufacturing  –  Drugs
  6. Process Safety via Artificial Intelligence
  7. Unlimited Renewable Energy  (RMO is but one form of this)
  8. Nullify Atomic Weapons
  9. Low-Grade Heat Upgrade
  10. Improved Corrosion Prevention via Coatings   

    For those who want to read more about the process, a US utility patent 3,906,250  from 1975 has a good description. see link.    In this patent, the process is referred to as Pressure-Retarded Osmosis.   More than 50 subsequent patents are listed.

Roger Sowell

Copyright © 2014 by Roger Sowell, all rights reserved

Join the conversation; leave a comment.  What are your thoughts on this River Mouth Osmosis, and other forms of renewable energy?  How can chemical engineers be involved?



On Nuclear Reactors as Refinery Process Heaters

Chemical engineers hear this from time to time, how great it would be if only the oil refineries would install small nuclear reactors (presumably modular) to provide the process heat to the different refinery units.  The nuclear reactors would replace the existing furnaces and heaters that burn hydrocarbons.  The selling points were: almost zero operating cost for the nuclear reactors, and zero pollution from the heaters.   In earlier days, that meant real pollution such as sulfur oxides, nitrogen oxides, and sometimes particulate matter (PM) if heavy oil was a fuel being burned.   More recently, the nuclear advocates have added carbon dioxide to the list of pollutants that would be avoided.

Chemical engineers devote a considerable amount of time to researching and engineering ways to improve the process.  These ways typically include reducing operating costs, improving yield, reducing feedstock required, reducing process upsets, and others.   The small nuclear reactors would, supposedly, reduce the operating costs.

I first ran across this in my process engineering days in 1982, while working at an oil company that owned three refineries.

We were less than impressed with the capabilities, the cost, and the severe limitations of small nuclear reactors to provide process heat.

The first limitation was the temperature that could be provided by the reactors.  That turned out to be much, much lower than most of those that the fired heaters achieved.  As just two examples, and these are the two largest heaters in most refineries, the atmospheric crude unit heater had an inlet temperature of approximately 540 degrees F, and an outlet temperature at least 100 degrees hotter.   The second example is in the same range, a catalytic reformer first reactor heater has an inlet temperature of approximately 850 degrees F, and an outlet temperature of a bit more than 900 degrees F.   These two fired heaters, the crude unit and reforming unit, were the largest in heat load (Btu/h) and thus were the best candidates for the nuclear reactors.

The nuclear proponents then explained that the reactor produced a hot water stream at approximately 615 degrees F.  That hot water would be used in a heat exchanger to heat the oil, or whatever else we needed heating.   We were a bit puzzled.  Even if a heat exchanger had superb design, the hottest we could bring a process stream to would be no more than 550 to 560 degrees F.    So, we asked why the outlet temperature was so low in a nuclear reactor.

It turns out that the nuclear reactor has hundreds of fuel rods that contain the uranium that actually undergoes fission.  The fuel rods are made of a special metal, zircaloy, that must not be allowed to exceed a certain temperature.  If the zircaloy overheats, the water around the fuel rods begins to react with the zircaloy metal.   The oxygen in the water combines with the metal alloy, and the hydrogen forms a gas.   So, we could not obtain the hot water at any higher temperature.

Then, we asked about the cost of a nuclear reactor, even knowing the entire exercise was pointless.    For a crude unit fired heater at 300 million Btu/h fired duty, or approximately 80 MW of process heat, the cost was estimated back then at $200 to $250 million.

We never got around to the questions of temperature control, how long for startup and shutdown.

We said Thank you very much.   And the nuclear proponents left.


Roger Sowell

Copyright © 2017 by Roger Sowell, all rights reserved



The Four By Sixteen Rule for Pipe Flow

Subtitle: Easily Compute Pipe Diameter in your Head

There are dozens, if not hundreds, of quick-and-easy methods to estimate the required size for process and mechanical equipment.  This article addresses a very fast, easy, and accurate method to determine pipe size in a process plant.   The method requires no calculator, no spreadsheet, as it can be done mentally.  It is especially useful for sitting in a meeting and answering a question that may be posed, or quickly verifying a statement made by another in the meeting.

The method is one I call “Four by Sixteen”, or the 4×16 Rule.   I have never seen this anywhere published, but perhaps it is.   (note: this was originally published April, 2014 on SowellsLawBlog)

The basic concept for the 4×16 Rule is, at a flowing velocity of 7 feet per second through a pipe of circular cross-section (most pipes), 4,000 gallons per minute will flow through a 16-inch diameter pipe.  A flowing velocity of 7 feet per second is generally considered optimum, or close to optimum for pipe in a process plant where velocity is provided by a pump. (see caveats below)

Engineers can quickly compute that 4,000 gpm in a 16 inch diameter pipe will provide less than 7 feet per second.  The flow is actually 6.38 feet per second.  However, with 16 inch pipe, the outer diameter is 16 inches, and wall thickness is approximately one-quarter inch, leaving an inner diameter of 15.5 inches.   For the 15.5 inch ID, the flowing velocity is 6.8 feet per second, very close to the optimum of 7.

From this, we can easily determine the pipe size required for other flow rates.  This is based on the property of pipes, that if one doubles the diameter, four times the flow results for the same flowing velocity.  This also works in reverse, if one halves the pipe diameter, only one-fourth the flow results.  Using numbers, an 8 inch pipe is half of the 16 inch, therefore the flow will be one-fourth of 4,000 gpm, or 1,000 gpm.

What happens if we want to double the flow from above, for example, we want 2,000 gpm?  For this, we use a rough approximation for the square root of 2, that approximation being 1.4.  The pipe size for 2,000 gpm is then the 8 inch pipe times 1.4, or 11.2 inches.  We generally round up to even numbers for pipe sizes, therefore a 12 inch pipe would be selected.

This works in the upward direction quite easily, too, so that a 32 inch pipe will carry 4 times that of a 16 inch, or 4 times 4,000 gpm or 16,000 gpm.   Or, we can use the 1.4 factor to compute the diameter required for a doubled flow, from 4,000 to 8,000 gpm.  The 16 inch pipe is multiplied by 1.4, resulting in 22.4 inch pipe.  This would be rounded down to 22 because it is so very close to 22 inch and would not be rounded up to 24 inches.

How does one multiple 1.4 times a number in one’s head?   An example shows this:  take the 8 inch pipe from above, then multiply 8 by 0.4 to give 3.2.  Then add 3.2 to 8, to provide 11.2.

This method is also very useful for validation checks on computer output.  Experience has shown that computers should be trusted only after very thorough and careful validation.

A few caveats for the 4×16 Rule.  As stated earlier, this is for process plant piping where 7 feet per second is the accepted optimum.  That optimum is for standard pipe, typically made from mild carbon steel and non-corrosive fluids at 500 pounds per square inch pressure, or less.   For substantially different conditions, for example stainless steel piping at much higher pressures, a detailed economic analysis is required to determine the optimum flowing velocity.

Also, for petroleum pipelines, the flowing velocity is a bit higher, for example the Alaska Pipeline was designed for flow of approximately 16 feet per second.  The Alaska Pipeline is a  48-inch pipe with a design flow of 3 million barrels per day.  With the pipe having 48 inch OD and half-inch thick walls, as I recall, the flow is 87,300 gallons per minute at a flowing velocity of 16 feet per second.

In hopes that this article helps the various process engineers, in whose shoes I also once walked.

This same procedure works quite well for SI units, also.  The starting point is a 400 mm ID pipe, carrying 16 cubic meters per minute, at a flowing velocity of 2.1 meters per second (same as 7 feet per second).

A similar procedure for heat exchangers is shown — see link.

Roger Sowell

copyright © 2014 by Roger Sowell, all rights reserved

The View from a Process Engineer

Subtitle: Seven Steps to Good Evaluation
by Roger Sowell [1]

This article delves into the world of one of the most practical of all engineering disciplines: the chemical process engineer.   I hope to explain how we process engineers do at least some of the things we do, and why.  The examples shown here may have applicability to those who read and write on subjects such as climate change, nuclear power, renewable energy, water shortages, and many others.   (This article was originally published in June, 2015 on SowellsLawBlog.   see notes and references below)

First, what is a chemical process engineer?  He, or she is a person with a degree in chemical engineering who practices his or her engineering skills in process plants.   Process plants encompass quite a variety of industrial plants, such as petroleum refineries, natural gas plants, petrochemical plants, basic chemical plants, air separation plants, synthetic fiber plants, agricultural chemical plants, agricultural or crops processing plants (i.e. corn refineries that produce ethanol), synthetic fertilizer plants, soaps and detergents plants, adhesives plants, and many more.  My own career to date has given me first-hand experience in many of those categories, including petroleum refineries (of four types), natural gas plants, petrochemical plants (of many types), basic chemical plants, and air separation plants.

The process engineer (leaving off the word ‘chemical’) typically addresses a problem or considers a new idea via a seven-step process.  These are, in order,
1) is it physically possible,
2) can it be made safe,
3) can it operate reliably over time,
4) can environmental impacts be mitigated, including post-operating life cleanup,
5) can it make a profit,
6) can it compete for scarce capital resources, and
7) is it the best among the available alternatives.

Each of these steps is discussed below.   It is important, to a process engineer, to take the steps in order and not skip any steps.

Physically Possible

This step may appear unnecessary, even ridiculous, but it is amazing (to me) how many people (typically non-engineers) who believe in and then advocate for processes or an article (meaning a thing) that violates one or more of the laws of physics.  Consistency with the laws of physics is the meaning in this context of “physically possible.”   One sometimes hears, for example, that “everything is possible.”  That is just not true.    There are many, many laws of physics, chemistry, and thermodynamics, that are immutable.  As I mention in my speeches, no one has ever found a violation of the Second Law of Thermodynamics.  I encourage the students and practicing engineers at my lectures to notify me at once if and when they encounter a Second Law violation, because I want to congratulate them, and be the one that notifies the Nobel Prize committee on their behalf.    Once a potential idea, or problem solution, is examined and found not to violate any physical laws, and only then, does the process engineer move on to the next step.

Can It Be Made Safe

Safety in a process plant is not only required by law, it is critical to success.  Success may be defined in many ways, but in this context it is sufficient to have success mean long-term profitability.   This ties in somewhat to the next step, reliable operation.  An unsafe plant typically has unexpected production disruptions, perhaps explosions and fires, process areas that will not function, injured or killed employees, and a host of other undesirable outcomes.

The process engineer examines the potential idea and evaluates the safety aspects.  There may be, for example, high temperatures, high pressures, corrosive or abrasive materials, toxic gases or vapors, and unstable chemicals that could violently expand, explode, or spontaneously ignite.  Other dangers could include very low temperatures, a tendency to solidify and block the flow, or emissions of dangerous radiation.  This is only a partial listing of the many and varied dangers that exist in a process plant.  There may be design or operating decisions that can eliminate the safety concerns, or mitigate them sufficiently to move on to the next step.   If the safety concerns cannot be overcome, the process engineer stops the evaluation.

Reliable Operation Over Time

A process plant must operate reliably over time to be useful and profitable.  The question is how to define “reliable.”   Process engineers usually define reliability by a percentage of time that a plant operates.  Operating ninety percent of the time is a typically acceptable reliability.  A process plant typically must be shut down at intervals to allow equipment to be repaired, cleaned, or have other services performed.   Plants that operate with frequent but unplanned shutdowns have a low reliability and will suffer a reduced profitability.  Profits are decreased as production decreases, from increased cost of repairs, and sometimes from re-processing unsuitable production.   A process can have multiple negative impacts where unreliable operations combine with unsafe conditions, as above.  Only where an idea can be designed and operated with sufficient reliability does the process engineer move to the next step.

Environmental Impacts Mitigated   

A modern process plant must meet certain environmental requirements as defined in a multitude of laws.  An idea for a new process must be evaluated for environmental impacts.  There are at least three ways to eliminate or mitigate environmental impacts, including capturing and properly disposing the pollutants, dispersing the pollutants so that any toxicity is reduced or eliminated, and designing the process so that the pollutants are not produced at all.  This last means is sometimes known as “green chemistry.”

The process engineer examines the various regulated pollutants and evaluates the available means to meet the emissions requirements.   The concept of Best Available Control Technology, or BACT, is common in the environmental world.   As examples of “capture and dispose”, toxic dusts may be captured in a filtering system, gaseous pollutants may be physically absorbed or chemically converted to benign chemicals, and liquids that have objectionable acidity or alkalinity (low or high pH) can be neutralized.

Dispersing pollutants is generally a last resort, but such systems are occasionally allowed.  Examples include saline brine from desalination plants where the saline brine is introduced gradually and at multiple points into the ocean, treated water from a waste-treatment plant is also introduced slowly and over a wide area into a body of water (the Pacific Ocean receives treated water from a large waste treatment plant on the coast near Los Angeles, California), and tall smokestacks are required to allow the wind to disperse emissions.

Environmental impacts must include mitigating any impacts when a process plant is shutdown after its viable life expires.  The US history is replete with hundreds of petroleum refineries and various chemical plants that have shut down permanently.  Many of those sites required extensive and costly mitigation to clean the soil.  Other process plants may have toxic areas that require special remediation.

Only where the process engineer can determine acceptable ways to design and operate a plant that meets all the environmental requirements does the next step occur.

Operate Profitably

The goal of (almost) every process plant is to make a profit, and a process engineer evaluates each idea with that in mind.  Where the idea is physically possible, can be made adequately safe and reliable, and meets environmental requirements, the process engineer examines the potential profitability.  This almost always includes an evaluation of capital costs, operating costs, and expected revenues.    Importantly, an idea that requires a lengthy construction period will also incur substantial financing costs.

Many economic aspects of a new idea will be evaluated, including considering various sizes to take advantage of economy of scale, possibly modularized construction, competing technologies (if any exist), fees or royalties, plant location with respect to feedstocks and markets, plus many more.  It may be possible to improve profit for plants that have high electrical power requirements when they can be located near sources of low-cost electricity, such as hydroelectric dams.

A key aspect is the cost to achieve improved reliability, especially long-term reliability due to corrosion.  Process engineers understand that corrosion is a function of the material chosen for the various pipes and equipment (note, there are also many other aspects that impact corrosion).  It may be possible to build a plant that does not corrode, if one had unlimited money and constructed the plant with titanium.  At the other extreme, one could build a plant of carbon steel and replace the various equipment and pipes just before the corrosion renders them unsafe and unreliable.

The process engineer evaluates all the above, and many others, to determine the likely profitability of the new idea.   Several measures of profitability are usually calculated, with one of the most commonly used being the simple payout time.  A process engineer simply divides the capital cost by the annual net income (revenues minus operating costs) to obtain the number of years that would be required to pay off the capital cost.  For example, a new idea that would cost $10 million to install, and has $2 million per year net income would have a 5 year payout.

Only where the simple payout time is sufficiently small, perhaps 2 or 3 years, does the process engineer move on to more sophisticated calculations of profitability.

Compete for Scarce Capital Resources

Next, a new idea is evaluated against other potential ideas or projects.  It is common that only a finite capital budget exists, but the combined cost of the numerous ideas greatly exceeds the capital available.  The process engineer then must evaluate the various new ideas and select those for implementation.   The selection criteria and process may be complicated and require careful evaluation from many people in the organization.

One criterion that a process engineer uses is the simple payout time from above.   Projects with shorter payout times almost always win over those with longer payout times.

Best Among the Available Alternatives

The final step taken by the process engineer may appear to be identical, or similar, to the Compete for Scarce Capital Resources step just above.   However, in this context, the process engineer considers the overall wisdom of proceeding with the new idea.  Even if the new idea could be built according to all the above criteria (physically possible, safe, reliable, environmentally adequate, profitable, and more profitable than competing ideas), the process engineer considers whether the new idea shouldbe built.

There may be compelling reasons one might not want to build the new idea.  Perhaps the new idea consumes resources that could be used in a different way or for a different purpose.  Natural gas, for example, has been decried as a heating fuel and as a power generation fuel because it has great value as a building block for pharmaceuticals, agricultural chemicals, and synthetic fertilizer.   Coal as a resource is also limited to approximately 50 years at this time, with its primary use as power generation fuel.[2]   It might be wise to reduce coal use as a power plant fuel and use it instead as a petrochemical precursor.

Another aspect is anticipated government regulation that would cut short the operating life of a new process plant or idea, such as occurred with mercury-based chlorine plants, plants that produced certain refrigerants, plants that produce lead-containing products, and plants that produce asbestos-containing products.

Application to Other Areas

The above discussion shows seven steps employed by process engineers.   These steps are proven over many decades.  But, are they applicable to non-process plants?  The list at the beginning included climate change, nuclear power, renewable energy, and water shortages.   Each is discussed below.

— Climate Change

In climate change, the science is so shaky, so uncertain that it scarcely deserves consideration. [3] [4] (see link and this link).   When one considers how the climate data was and still is tortured, how definitive statements of man-made climate change are made – and then revised – and then revised again and again, how modern instruments with global reach show zero warming for almost two decades, how the best “climate models” disagree with modern temperatures, it is a wonder that climate change is considered a problem in the first place.   Yet, solutions to any actual global warming, and more importantly, global cooling, can be addressed via the above seven steps.  One must, first, reliably identify whatever is a substantial factor in causing global warming – or cooling.   To date, global warming advocates believe that increased carbon dioxide in the atmosphere is causing unstoppable global warming.  There is no evidence to support that belief, however.

If, and this is a big IF, it becomes necessary to reduce carbon dioxide inputs into the atmosphere, or remove some from the atmosphere, chemical engineers already know that it is physically possible to do so.  Safety is a major concern, especially for the processes that capture carbon dioxide and store it in liquid form deep in the earth.  A leak of liquid carbon dioxide into the atmosphere could and likely would suffocate thousands, if not millions of people.   Process plants that remove carbon dioxide from furnace exhaust stacks have existed for many years, and a modern plant is now running near San Antonio, Texas.   Reliability is not a major issue for these plants.  Environmental compliance is also not an issue, other than the massive leak from storage described above.  However, the cost to build and operate is a problem at this time.   The major issue, though, is whether the great cost to build enough plants to make a difference is justified, considering the questionable science surrounding the entire climate change and human contribution to any historical warming.

— Nuclear Power

Nuclear power is a frequent topic on SLB, and creates great disagreement and acrimony between proponents and opponents.   As readers of SLB already know, my position is a nuclear opponent.  The 30-article series on the Truth About Nuclear Power shows many excellent reasons why nuclear power plants should never be built. [5] (see link)

Yet, nuclear proponents continue with their beliefs that nuclear power is safe, affordable, and desirable.   Nuclear power can be considered as two categories: proven and unproven technologies.  As proven technologies, there are boiling water reactors and pressurized water reactors (BWR and PWR, respectively).  Unproven technologies include thorium, fusion, high temperature gas reactors, and small modular reactors.

The arguments made by proponents for expansion of PWRs is that newer models are less costly and safer.  Some even argue for relaxed regulations, and abolition of lawsuits during construction.  Applying the seven steps, it is seen that the reactors are physically possible, but clearly not safe and not very reliable – especially as the plants age.  Environmental risks and damage are very great, with highly toxic nuclear waste emitting dangerous radioactivity for hundreds and thousands of years.  Costs to build have not been reduced but instead keep increasing, even though huge plants are built to achieve economy of scale.   Finally, competing technologies for producing electrical power make nuclear plants not the best choice, including natural gas and renewable energy.

Unproven technologies barely pass the physically possible test, with fusion as yet only a theoretical but not demonstrated concept.[6]  Thorium plants also are physically possible but have major safety, reliability, cost and environmental concerns.[7]  The same is true for high temperature gas reactors [8] and small modular reactors.[9]  A major concern for thorium-based nuclear plants is the corrosion and cracking in the metallurgy that contacts the molten salt.  Every heat exchanger with tubes will eventually leak, with material at higher pressure leaking into the material with lower pressure.  The consequences of such leaks must be understood.   It is astonishing to me that a great number of nuclear proponents simply ignore this basic fact of process engineering.

The final verdict on nuclear power is that proven technologies are vastly uneconomic, require massive government subsidies, and leave behind highly toxic wastes that endure for generations.  Unproven technologies are even worse.

—  Renewable Energy

The renewable energy subject includes many technologies, solar in its various forms (photo-voltaic, concentrated solar, and solar ponds), wind both on-land and off-shore, ocean including waves, tides, sea-surface vs deep ocean temperature difference, and currents, river flow systems, pressure retarded osmosis at river mouths, [10] and bio-mass systems including land-fill methane capture, municipal solid waste burning, and water distribution pressure recapture.  Many of the above technologies require some form of energy storage and release to provide increased value to the untimely or intermittent nature of the energy source.  [11]

Physical possibility exists for all of the above renewable technologies.  Safety is adequate or can be made acceptable.  Reliability can also be made acceptable with sufficient design and investment.  Costs are rapidly declining in most technologies as experience is gained and economies of scale are captured.  Economy of scale exists for both larger individual units, and for mass production, and for single-events such as building transmission lines.    The lack of environmental impact, or very low impact, makes renewables especially attractive.  The eternal nature of the motive force, the sun, the wind, ocean waves, tides, and currents, and the essentially eternal production of municipal solid waste also make renewables especially attractive.  As installed costs continue to fall but costs of other forms of electric power increase, renewable energy plants become ever-more attractive.

— Water Shortages

Fresh water in adequate amounts is a greater and greater concern, even though some areas experience heavy rains and floods.  Providing adequate fresh water essentially reduces to three technologies: building dams and storage reservoirs to hold and retain water during abundant years; desalinating ocean waters; and collecting then transferring excess water from areas of abundance to areas of scarcity.  Those in the water industry also promote conservation, however that has a very limited benefit.   Pumping groundwater from aquifers to the surface is also common in many areas, however the aquifers are generally not replenished as rapidly as the water is pumped out.   Yet another (unpopular) technology is simply recycling treated water from waste treatment plants.   This last has the great risk of transmitting disease via unclean water.

Technologies exist and are therefore physically possible for each of the three technologies (dams, desalination, and water transfer).  (for water transfer, [12] see link) The technologies are safe and reliable when properly designed, built, and operated.  Certain dams have failed with harmful or even catastrophic results, but those can be minimized or eliminated with proper attention.  Environmental impacts are hotly debated, with some claiming great harm results from building dams and desalination plants.

The major issue with fresh water is cost, and in some cases, ownership of the plants.  Water is such a vital part of life that many consider it too precious to be privatized except in very limited and controlled ways.  However, some technologies are simply very costly at this time, especially desalination via reverse osmosis, RO, the most attractive process.  A few thermal desalination technologies also exist, but are generally less economic than electrically-powered RO.


The seven steps of process engineers, physically possible, safety, reliability, environmental impact, profitability, most economic choice, and wisest choice, are used to evaluate a new idea or process plant.  These steps should be used to evaluate other areas to provide a systematic and grounded conclusion.  Having a blind and irrational faith in future innovations is not a good basis for allocating resources of time, talent, and money.  Yet, a blind and irrational faith is what many people exhibit in their writings on many topics (especially climate change, and nuclear power).

At the same time, many people have far too little understanding of the technical and economic advances in renewable energy systems, and the associated energy storage and release systems.

Roger E. Sowell
Marina del Rey, California
copyright (c) 2015 by Roger Sowell

Notes and references:

[1] Roger E. Sowell, B.S. 1977 in chemical engineering from The University of Texas at Austin, has worked as a Principal Process Engineer and consultant for 40-plus years in and with more than 75 oil refineries and petrochemical plants in a dozen countries on five continents.  Clients include major and independent oil and gas companies, world-scale petrochemical companies, and basic chemical companies.  Process plant assets ranged from the $100 million range, to $10 billion and higher.  He has performed hundreds of process studies in process design, operations, optimization, and economics.   Implemented projects have a cumulative value of the low hundreds of million dollars, and cumulative benefits exceeding $1.3 billion.  He is published in Hydrocarbon Processing and CryoGas International.  He has also taught engineering students at University of California at Los Angeles, University of California at Irvine, and made dozens of public speeches.  He is also a Council Member with Gerson Lehrman Group, providing expert advice to member clients.  He is also a California attorney-at-law, in Science and Technology Law, and publishes SowellsLawBlog.   He was recently (2016) requested to defend climate skeptics in United States RICO actions.   He is a founding member of Chemical Engineers for Climate Realism, a Southern California think-tank comprised of experienced chemical engineers.

[2] CalTech Professor David Rutledge,  “Estimating long-term world coal production with logit and probit transforms,”  International Journal of Coal Geology, 85 (2011) 23-33,  — discusses world coal deposits and economically recoverable coal.

[3] Sowell, R.  “Warmists are Wrong, Cooling Is Coming” see link

[4] Sowell, R.  “From Man-made Global Warmist to Skeptic – My Journey” this link.

[5] Abbot, D. “Is Nuclear Power Globally Scalable?” Proceedings of the IEEE, Vol. 99, No. 10, pp. 1611–1617, 2011,  see link)  also Sowell, R.  “Truth About Nuclear Power – Conclusion” (see link),  — Abbot discusses 15 reasons that nuclear fission power is not viable in the long term.

[6] Lawrence Livermore National Laboratory LIFE,  Laser Inertial Fusion Energy.  See link, also  Sowell, R.  “Power from Nuclear Fusion”,   see link  — Sowell’s summary of the LIFE process: Fusion is proceeding in research but has so many drawbacks it is almost a tragedy.  LLNL plan to split water into hydrogen and oxygen, isolate deuterium from normal hydrogen, freeze the deuterium, make spherical pellets of the deuterium, then load the sphere into a special chamber where high-powered lasers blast simultaneously on the sphere’s surface to induce a fusion reaction at the sphere’s core.    If it were not published by a US national lab, this would be the stuff of comic books and a mad scientist.

[7] Idaho National Laboratory, “Molten Salt Reactor,” see link  also Sowell, R.  “Thorium MSR No Better Than Uranium Process”   see link

[8] Nuclear Regulatory Commission, “HIGH TEMPERATURE GAS-COOLED REACTOR (HTGR) NRC RESEARCH PLAN” (2011)   see link  also Sowell, R.  “High Temperature Gas Reactor Still A Dream,”see link

[9] World Nuclear News, 2014, “Funding for mPower Reduced,” see link also Sowell, R.  “No Benefits From Smaller Modular Nuclear Plants,” see link

[10] US utility patent 3,906,250, also  Sowell, R.  “Renewable Energy from River Mouth Osmosis,” see link

[11] “Nobel Prize in Chemistry, 2000: Conductive Polymers” see link,  also Sowell, R. “This Battery Is A Game Changer,”  this link  — BioSolar’s novel battery with halogenated polyactylene cathode is to provide double the kWh capacity, less weight, fast charging, and at one-fourth the cost of commercial batteries used in the Tesla all-electric cars.  Other uses include grid-scale electricity storage at affordable cost.

[12]  Cohen, Lorraine Y. “Mid-west floodwaters, an ignored national resource,” see link, also   Sowell, R.  “Solution for Water in the West – NEWTAP,” see link  — Sowell’s concept for a national water transfer system, pipeline or canal, is described to economically transfer excess water from the Missouri River to Arizona’s Colorado River

Arctic Ice in 2017 – Normal

A little excursion to check on the progress of the Arctic ice, the Northern Hemisphere Total Ice from the U.S. National Ice Center,  The chart below shows the results, with the blue shaded area the maximum and minimum range for the past 10 years.  The 10-year average is the black dotted line.  The results for 2017 are shown in the blue solid line.    The black circle (added) shows the latest data for mid-July.   (link to the graph, which is updated regularly.)

We are right on the average, and have been so since the first of May.

What has this to do with chemical engineering?   Radiant heat transfer, and insulation, for starters.  Taking note of the data at the far left, from March 1 to about May 1, shows the 2017 data was slightly below the ten-year average.   Is that cause for alarm, is the Earth overheating and the ice melting away?    No.

Screenshot (229)

The reduced amount of ice typically leaves  open seawater, that loses heat to space in the dark winter.  Ice acts as an insulator, preventing or reducing the rate of heat transfer.  To the extent there is open water, heat is radiating from the water into deep space.

There are other data that show no warming.  These will be addressed in future posts.


Roger Sowell

copyright 2017 by Roger Sowell, all rights reserved







Welcome! To A Conversation w/ a ChE

This is the first post on CWChE, a blog where I will share what is interesting to me in several topical areas.   Chemical Engineering is my education and university degree; I have more than 40 years of work in that field in the USA and many other countries.  I’m also an attorney-at-law, but this blog will steer clear of legal topics.   Some readers may recognize my name from other blogs, and from my own SowellsLawBlog.   Topics for this blog will include energy in most forms, renewable, natural gas, coal, hydroelectric, and nuclear, plus grid-scale storage in several forms.   There will be articles on the science and data in climate science.  Other articles will address fresh water issues.   Some articles will address state-of-the art vehicles, such as pure electric vehicles, PEVs.   A few articles will consider topics with political implications, especially where issues that are important to ChEs are involved.

A note on comments, which I encourage.  Keep it civil or be gone.   Comments will be moderated.   This is intended to be a conversation, not a monologue.   Questions are encouraged.

So, what is a chemical engineer?  We are the engineers that have the math, physics, chemistry, and specific chemical engineering education, training, and experience to effectively analyze many processes and problems, design chemical plants and other processes, perform economic analyses, build the chemical plants and start them up, operate them, optimize them, and modify them as economics will justify.    Probably the most significant thing ChEs do is evaluate massive amounts of data to determine what is acceptable data, and what is Bad Stuff – known to us as BS.

That is all for now.  Much more will be posted later.


Roger Sowell