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Safety Moment #65: Personal Protective Equipment (PPE)

PPE process safety management

We are writing a series of posts to do with the ‘New Normal’ and the effect of the current pandemic on industrial safety, particularly process safety. (We also have a series for people of faith and the New Normal. This week’s post is The Parable of the Green Car.)

This week we will take a break from that discouraging topic and publish another Safety Moment. You will recall that these Safety Moments can be used for those situations where you may be called upon to start a meeting with a few words to do with safety. The first 52 Safety Moments (one for each week) were collected and are available as an ebook. We are working on a follow-up ebook, 52 More Process Safety Moments. Some of the recent Safety Moments that are available at no cost are listed here.

Let’s look at an important safety topic, one that is currently in the headlines, Personal Protective Equipment (PPE).

PPE is the last line of defense for keeping a person safe. Every effort should be made to protect the wearer ahead of time. (We see a simple example of this approach today when we visit a doctor’s office; before entering the office they check our body temperature. If the temperature is too high then the patient is denied entry, regardless of the PPE that everyone is wearing.)

The Irish Health & Safety Authority provides the following precautionary statements with regard to PPE.

  • PPE only protects the wearer.
  • It is ineffective if not working or fitted properly.
  • Theoretical levels of protection are seldom reached in practice.
  • The use of PPE always restricts the wearer to some degree.
  • The psychological effect of PPE may be such that the individual wearing the PPE feels more protected than he or she actually is.
  • In Europe the PPE should carry the ‘CE’ mark.

It is generally the responsibility of the employer to provide, maintain and repair the PPE that workers need. In the United States, for example, OSHA’s 29 CFR 1926.95 OSHA states,

. . . the protective equipment, including personal protective equipment (PPE), used to comply with this part, shall be provided by the employer at no cost to employees.

Further information to do with PPE can be found in the book Plant Design and Operations.

Book Plant Design and Operations

The following is an extract from Chapter 14 of that book.

Standard PPE typically includes:

  • Hard hat.
  • Full cover shoes. They should have non-slip soles. Many companies require that shoes always have toe protection — often in the form of a steel toecap.
  • Safety glasses with side shields.
  • High visibility clothing that may also be fire resistant in areas where flammable materials are being handled.
  • Life jackets when working around ships or on docks.

Gloves and hearing protection should be readily available, even if they are not used all the time.

The second type of PPE is situation-specific. For example, if a worker is catching a sample of a hazardous chemical he or she must wear protective gloves that are resistant to that particular chemical.

There are many regulations and standards to do with PPE. Some of them are listed in Table 14.1 of the book, the first page of which is shown below.

PPE for process safety management PSM

The New PSM Normal (3) — Peak Oil

Energy Returned on Energy Invested

This post is the third in a series in which we consider how our approach to industrial safety, and process safety in particular, may change in response to the COVID-19 pandemic. It is early days — no one knows what the ultimate health and economic effects of this frightening event will be. But it seems likely that we are entering a ‘New Normal’. So much has happened so quickly that it is hard to visualize how we can return to the ‘Old Normal’. All of us wish for a quick, V-shaped recession, after which the economy comes roaring back, more vibrant than ever. But, as discussed in the first post, The New PSM Normal (1) — Deflation, it seems more likely that we are entering a period of long-term deflation, possibly leading to a Depression such as took place in the 1930s.

There has rightly been much discussion in recent weeks to do with the pandemic and its direct effects. Not only have many people died or suffered from severe illness, we can be sure that more suffering is on the way. The actions that we have taken so far, particularly physical (not social) isolation and distancing, have helped slow down the rate at which the disease is spreading. But such actions cannot actually stop the spread; unless and until a vaccine and/or a cure is found, more and more people are going to be stricken. We are all vulnerable — no exceptions. It’s not a question of “if”, it’s a question of “when”.

But people in the process industries are also aware of a second change that has been creeping up on us, but that has suddenly (and ‘suddenly’ is the operative word in our New Normal) become its own crisis. I refer, of course, to the collapse in the price of oil.  For the last five years a barrel of light, sweet crude has been in the $50-60 range. But now it is down to $12, and we hear stories about traders actually paying to have the oil taken away.

At first, it all seems to be quite simple. The low price of oil is directly related to the pandemic. The logic is as follows,

  • The pandemic has led to an enormous and startlingly quick decline in economic activity.
  • Therefore, transportation of all types (trucks, trains, cruise ships, barges) has drastically reduced its use of refined oil products such as diesel, gasoline and bunker fuel.
  • Cutbacks in manufacturing have led to a significant reduction in the use of plastics and other petrochemicals that are derived from crude oil.
  • Hence there is an oversupply of crude oil.
  • Hence the price of crude falls to unimaginably low values, with some futures being in negative territory.
  • It all happened very, very quickly.

There are complicating political factors. The Russians and Saudis are seemingly engaged in a price war in order to control market share. But their real agenda — to drive the U.S. shale oil industry out of business — seems to be going according to plan.

It also means that the concerns that were expressed about ten years ago to do with Peak Oil were wrong. We are not running out of oil — indeed the opposite seems to be the case. There is a surplus of crude oil; only if we return to the ‘Old Normal” will prices rebound.

Not so fast.

Most of the discussions to do with the economic woes of the oil business have been to do with the fall in revenues linked to low prices. But it is the cost side that should receive more attention. What is hurting the oil companies just as badly is that the cost of finding and developing new sources of oil is high and is steadily rising. These costs are not driven by political or social issues such as the Russian/Saudi agreement; they are driven by the laws of physics and the realities of geology.

What we are learning is that

Peak oil does not mean that we run out of oil. Peak oil means that we run out of affordable oil. We will never run out of oil.

Crude oil is a finite, non-renewable resource. We have picked the easy, low-hanging fruit and now exploration and development costs are rising inexorably. Consider the two pictures shown below. The first is of a Texas oil well about 100 years ago. The oil was near the surface, under pressure and easy to extract. All you had to do was “stick a straw in the ground”. The second picture is of a modern offshore oil platform — it operates in very deep water, and the oil is thousands of feet below the mud line. Needless to say, finding and extracting this oil is very expensive. Eventually there comes a point where the energy company cannot make a profit.

Blowout Texas oilfield

Offshore platform low ERoEI

It might be thought that the energy companies, as their costs increase, could simply raise the price of their products such as gasoline and petrochemical feedstocks so as to ensure that they make a profit. The catch is that energy, particularly the energy provided by oil, is utterly fundamental to our entire economy. If the prices of oil products are increased too much, people cannot afford those products, demand falls, and so prices fall. We need to find a Goldilocks price for crude oil. That price is not too hot, and not too cold. It needs to be high enough for the oil companies to make a profit, but it needs to be low enough for the economy to function properly. But we are having trouble finding that Goldilocks price, as discussed by Richard Heinberg in his 2015 post Goldilocks is Dead.

To summarize:

  • The costs to do with finding and developing new sources of energy are steadily increasing.
  • The energy companies cannot raise prices because, if they do, the overall economy deteriorates, so prices fall due to reduced demand.
  • There is no longer a Goldilocks zone.
  • Profits are inexorably squeezed.

If the above logic is correct then the process and energy industries will be facing particularly severe economic challenges. Process safety professionals will need to adapt to those challenges.

A more fundamental way of looking at the oil price conundrum is to use the concept of Energy Returned on Energy Invested (ERoEI). It takes energy to find and develop new sources of energy. If we use most of our energy simply finding and developing those new sources of energy then the oil companies cannot make a profit. They are constrained not by political and social events, but by the basics of geology.

As time permits, we will discuss ERoEI in greater detail in future posts. We will also look at the “ERoEI Cliff” — the point at which there is no longer any justification for developing new sources of oil.

Boeing 707 and the start of low cost air travel

We are publishing another set of weekly posts for people of faith and the New Normal.  This week’s post is The New Normal (5) — Change Is In The Air.


The New PSM Normal (2) — Do Less With More

Manager and Just in Time philosophy

The COVID-19 pandemic has changed everything. When more than 22 million people in the United States alone lose their jobs in just a few weeks we have entered a new and different world. There is no going back to an ‘Old Normal’. In the first post in this series, The New PSM Normal (1) — Deflation, I suggest that we are entering a time of deflation, which is defined as a situation where goods and services are available but people do not have the money to purchase them. Even people who do have secure jobs or who have savings hold back on purchases, particularly large purchases such as automobiles; they adopt a “let’s wait and see attitude”. Consequently the companies that provide those goods and services have to cut back, which means that they lay off more people, which means that that there are even fewer customers, which means that — well, you get the idea.

Deflation may lead to lower prices. On the other hand, the financial authorities may decide that the only way they can reduce the massive amounts of debt that they have incurred will be through high inflation.

Last week I said that I hope that this analysis is incorrect. It would be great if we are merely in a V-shaped recession in which we can quickly find a vaccine and/or cure for the disease so that the economy can come roaring back. But I am dubious. The ‘Old Normal’ is in the rear view mirror.

Deflation and the Depression

A defining image of the Depression of the 1930s is the anecdotal story of dairy farmers producing milk that they wanted to sell. There were plenty of hungry people who wished to purchase the milk, but they could not do so because they were unemployed and so they had no money. Hence the farmers wound up pouring the milk down the drain. (I was put in mind of this story when I read about farmers in our time dumping milk because demand from restaurants has collapsed.)

Milk pouring down drain represents deflation

Pouring milk down the drain

In a parallel series of blogs to this one I am trying to determine what the ‘New Normal’ may look like for people of faith and for churches in general. I suggest that key features of their ‘New Normal’ will be Community, staying out of Debt and practicing Thrift and Frugality. The same general philosophies are likely to apply to companies in the energy and process industries.

For the process safety community it all creates a very different world. Means of improving safety will change while funds for safety projects, no matter how well justified such projects may be, will be ever more scarce.

In this post I would like to consider another feature of the ‘Old Normal’ that may be changing, and that is the philosophy of, ‘Do More With Less’. There are many aspects to this philosophy and, as time permits, we will discuss them in future posts. Let’s start with the fact that the virus has exposed problems with our global supply chains that may not go away and that will affect the way in which we manage industrial safety.

Just-in-Time Management

One feature of the ‘Do More With Less’ strategy is Just-in-Time (JIT) management. JIT calls on managers to “squeeze fat” out of the supply chains by reducing intermediate inventories and by delivering products to the customer “just in time” to meet his or her needs. This strategy forces managers at both ends of the supply chain to be ruthlessly efficient — they have to optimize their processes so that they operate without any glitches or hiccups. The fundamental value of JIT is not that it reduces the working capital needed for intermediate storage, that is a side benefit; the real value is that every manager in the chain is forced to make his or her process more efficient.

Note: The following example is to do with an onshore process plant. But the way of thinking that it discusses can be used in a much broader range of industries such as manufacturing.

Consider the following simple example. A chemical company operates two facilities: Units ‘A’ and ‘B’. Unit A manufactures an intermediate chemical used by Unit ‘B’ whose product is sold to the company’s customers. The intermediate chemical is a liquid, so an Intermediate Storage Tank, T-100, is provided between Units A and B. The chemical is pumped from T-100 to Unit B by Pumps P-101 A/B, each of which has 100% capacity — while one is operating the other is on standby. The pumps are identical; this allows the maintenance manager to minimize the spare parts needed, it reduces the number of operating and maintenance procedures that have to be written, one training program can be used for both pumps and management of change issues are minimized.

Intermediate Storage Tank illustrates process safety reliability

T-100 has a one-hour capacity, and is normally operated 50% full. This means that, if Unit A has an operating upset then Unit B can continue normal operations for 30 minutes while the upset is taken care of. Similarly, if B has a problem, A can continue normal operations for 30 minutes. It is this “fat” that needs to be “squeezed”.

The JIT philosophy calls for the managers of both facilities to tighten up their operations such that T-100 is no longer needed and can be taken out of service. The removal of T-100 is a forcing function that compels the managers of Units A and B to tighten up their operations. The reduction in operating costs resulting from the removal of the tank and its associated pumps is merely a side benefit.

The company’s process safety professionals support this strategy for three reasons.

  1. If the tank is out of service we have one less item that can go wrong. (“If a tank’s not there, it can’t leak”.)
  2. The potential for process upsets such as tank overflow or pump seal leakage is removed.
  3. The absence of the tank and the pumps reduces the work of the operating and maintenance teams, thus reducing the chance of error in other parts of the facilities.

What I have just described is the world of the ‘Old Normal’. But the pandemic has taught us is that our single-source, lean supply chains are vulnerable. If the spare parts used in Units A or B are manufactured at a single location on the other side of the globe then any widespread disruption, such as a disease that shuts down whole sections of the country where those parts are made, can cause serious interruptions to our chemical plant. Maybe the ‘New Normal’ requires a new way of thinking.

In this new environment the managers at A and B need T-100 and the buffer capacity that it provides. Indeed, they request that an additional storage tank, T-101, be provided. But they are still vulnerable to single-source vulnerabilities at the identical pumps, P-101 A/B. So they call for the two pumps to be totally different. Maybe P-101A is an electrically-driven centrifugal pump from Asia, whereas P-101B is a steam-driven reciprocating pump from Europe.

This is what the new operation looks like.

Intermediate Storage Tank illustrates process safety reliability

From a process safety point of view the new operation appears at first to be less safe and more vulnerable. There are more equipment items that can leak, and activities such as procedure-writing, training and management of change all become more burdensome.

But the new arrangement does provide one important safety advantage. Shutting down and then restarting continuously operating facilities without proper planning is often hazardous; experience shows that these are often the times of greatest risk. Therefore the process safety professional has to balance the risks associated with events such as tank overflow from a second tank with the risks to do with unreliable operations.

There has always been a trade-off between efficiency and resilience. If someone wishes to make a facility more resilient, he or she can face pushback, often on the lines of, “We’ve run this way for the last 10 years and nothing has gone wrong, aren’t you being over-cautious?” In coming months and years it is likely that this tension will increase.

A further difficulty is that proposals to install additional equipment items will be made in an uncertain and challenging economic environment. If forecasts to do with deflation turn out to be correct, the additional capital and operating costs will be incurred at a time when revenues are reduced and/or unstable. None of this is easy. Nevertheless,  the new safety mantra becomes,

Do Less With More

Welcome to the ‘New Normal’.


Home-made masks

If you are making masks, we found the plan provided in the New York Times (and other newspapers) to be useful. We used old pillow cases for the fabric. Medical-quality masks have a metal strip at the top. The NYT design does not. But we found that a pipe cleaner inserted at the top does the job well. (If you don’t smoke a pipe but do have children you may find that they used pipe cleaners in some of their projects.)

Rumor has it that there was a Virginia law that prohibited anyone from wearing a mask when entering a bank, and that they had to change the law. It turns out that the rumor is not true; nevertheless it is still a good idea not to be masked like this when entering a bank.

Because masks such as these are not of surgical quality people wonder if they are worth the trouble. The cloth is not of a tight enough weave to trap the tiny virus germs. This is where the process safety way of thinking comes in. First, the masks protect other people more than the wearer. They trap droplets that the person emits when speaking or even just breathing normally. But the masks will also trap some of the incoming germs and therefore reduce the chance of infection. It’s the way of thinking that lies behind Layers of Protection Analysis (LOPA) or Fault Tree Analysis in which the mask is an AND Gate..

Let’s say, for sake of argument, that keeping a distance of two meters away from other people reduces the chance of infection by 95% over a given period of time. (The numbers in this example were created merely for illustrative purposes.) The probability of infection is (1.00 – 0.95), or 5%. Let’s make a second assumption that the masks catch 50% of the virus germs that enter them. So now the probability of infection drops to ((1.00 – 0.95) * (1.00 – 0.50)), or 2.5%. In other words, the mask does not offer complete protection — risk can never be zero. But it does offer useful protection and so it is worth wearing.


The New PSM Normal (1) — Deflation

Refinery distillation columns

The last few weeks have changed everything. How long the COVID-19 pandemic will last, how many people will fall ill and how many will die all remain a matter of speculation. Nor do we know the duration of this crisis, but it is probably going to be longer than most people expect. An article in The Atlantic magazine — Our Pandemic Summer — quotes Devi Sridhar, “Everyone wants to know when this will end. That’s not the right question. The right question is: How do we continue?”

We are equally uncertain as to what impact this disease is going to have on the world’s economies. It is possible that we will see a V-shaped recession followed by a return to prosperity, the “Old Normal” and vibrant economic activity. But I am dubious — too much has happened too quickly. Moreover, precedents from previous pandemics suggest that the second and third waves of an infectious disease can be the most deadly. So, even if we do open up the economy within the next few months, businesses and customers will remain reluctant to invest and spend because so much uncertainty remains. If this is the case then we face the possibility that we are not merely in a recession but at the start of a long-term depression.

In response to these health and economic crises I started a series of weekly posts at my New City of God site. The purpose of the series is to provide suggestions to people of faith as to how they can provide leadership in the new and rather scary world that we are entering. The first three posts are:

I am now starting a similar series of weekly posts here at the PSM Report to discuss how the process safety management (PSM) discipline may change in the coming months and years in response to the health and economic crises that are upon us.

Economic Background

The first step in the discussion is to consider how the overall economy is likely to change in coming years. Based on this evaluation we can then attempt to evaluate the impact on the energy and chemical process industries. Then we can consider how the PSM community can respond.

Anyone who has worked in the energy or process industries for more than a few years is all too familiar with ups and downs in business activity and employment prospects. So it is tempting to think that what is going on now is a repeat of what we have seen before. We just have to ride out this current downturn and wait for the good times to return. But I wonder if this is what will actually happen. There are two reasons for my concern. The first is that the current situation has merely exposed previously existing fault lines, particularly with regard to our use of debt. My second concern is to do with the massive and totally unprecedented spike in unemployment that has just taken place.


Our economies use debt to fuel growth. Or at least, that’s how it should be. But in recent years debt has not provided the growth that we had come to expect.

United States federal debt growth

The chart shows U.S. federal debt for the last 30 years. In 1990 it was $4 trillion. By 2019 it was up to $23 trillion. What it will be by the end of the year 2020 given all the stimulus programs that are being proposed is anyone’s guess. But it is bound to be a new record by a large margin. And it’s not just governments that have run up huge financial obligations. Individuals have bought into the same mind set: credit card debt, student loans, mortgages on expensive homes — the list goes on.

Even before the current crisis we were seeing problems with the effectiveness of all this debt. True economic growth comes from the development of resources and the efficiency with which those resources are used. In recent years real growth has slowed or even stopped. Therefore, nations all over the world have responded by increasing debt levels. They are using future debt to pay off today’s debt.

In a November 2018 Forbes article A Worldwide Debt Default Is A Real Possibility, John Maudlin talks about the failure of ‘debt productivity’.

. . . debt is losing its ability to stimulate growth. In 2017, one dollar of non-financial debt generated only 40 cents of GDP in the US. It’s even less elsewhere. This is down from more than four dollars of growth for each dollar of debt 50 years ago.

This has seriously worsened over the last decade. China’s debt productivity dropped 42.9% between 2007 and 2017. That was the worst among major economies, but others lost ground, too. All the developed world is pushing on the same string and hoping for results.

Now, if you are used to using debt to stimulate growth, and debt loses its capacity to do so, what happens next? You guessed it: The brilliant powers-that-be add even more debt. This is classic addiction behavior. You have to keep raising the dose to get the same high.

His conclusion is that there will be what he calls a Great Reset.

. . . we will have to deal, one way or another, with the largest twin bubbles in the history of the world: global debt, especially government debt, and the even larger bubble of government promises. We are talking about debt and unfunded promises to the tune of multiple hundreds of trillions of dollars – vastly larger than global GDP.

Analyses such as these suggest that the savage economic downturn that we are currently enduring did not come out of the blue. In fact, all that the pandemic has done is merely speed up and highlight on-going trends.


The defining economic feature of the current pandemic is the startling and sudden increase in unemployment. The chart shows the data for the United States.  (In fact, due to delay in filing unemployment claims, the actual figures are probably much higher.) This situation is totally without precedent.

Unemployment in U.S.A. following COVID-19 pandemic

The economic impact of such high unemployment rates is to further slow down the economy. The unemployed no longer have a paycheck, so they do not purchase goods and services, so the providers of those goods and services have to cut back, which means that they have to release more of their workers, which means that even less is purchased, and so on and so on. It’s a vicious circle.


As I have already stressed, no one knows what the future holds and it is possible that we will bounce back from a short, V-shaped recession. But such a response seems less and less likely as this crisis drags on. Instead we seem to be entering a time of deflation where the driving economic force will be the lack of spending due to lack of wages.  This slowdown leads, in turn, to reduced investment.

Even people who remain employed or who have savings will cut back because they are uncertain about the future, so they save their money for a “rainy day”. Optional purchases are deferred, particularly on large capital expenditures such as automobiles. Moreover, the fact that we are told not to mingle with other people (social distancing) put a further damper on consumer activity.

In a deflationary economy people and businesses become very cautious about taking on new debt, even though interest rates are very low. The reason for this caution is that the payments on the debt will certainly have to be made, but there is much less certainty to do with the income that pays that debt.

Another worrisome feature of a deflationary economy is that commodity prices fall, as we are seeing with the oil industry. If the industry cannot make a profit then it is forced to cut investment, and so even more people are laid off or furloughed. Some businesses will be forced to close their doors permanently.

If deflation continues for long enough the economy moves from recession to depression, the defining feature of which is that there is a surplus of goods and services because people cannot afford to buy them.

Industrial Safety

Those who work in the energy and process industries rightly believe that safety is the top priority — it comes before everything else. We can see this mind set in representative statements such as the following, “Safety is a core value at ExxonMobil”.

Few of us ask why we have adopted this value. It wasn’t always this way. The following picture is taken from A Day in the Life of an Engineer made in the 1950s.

railway workshop 1950s

This fascinating video shows the day in the life of a professional engineer who works in a factory that manufactures railway engines. The engineer is clearly a highly skilled professional, proud of the work that he is doing. Yet what most of us first notice in the picture is the complete absence of safety equipment and Personal Protective Equipment. What changed over the course of the last 50 or 60 years? What took us from that picture to picture below, which is taken from the ExxonMobil page?

PPE offshore worker

Most of us would say that safety is ultimately a moral issue; it is our responsibility as a society to ensure that workers are not killed or injured. And this response is absolutely correct — safety is a moral issue. The ExxonMobil statement just quoted does not need to be backed up by any justification or rationale — safety is a core value and that’s that. If people who work for that company are asked to justify this view they will come up with phrases such as, “It’s right that people should not be injured or killed while at work”. They simply use different words to make the same moral statement.

Yet the principles of morality and ethics have not changed in the last few decades — there seems to be another factor that has led to the increased emphasis on safety programs over the course of the last 50 years. In that time society has become much wealthier, hence we can now afford to implement better safety standards, such as the use of advanced PPE. Therefore, it could be that the reason for the change in safety standards is simply that we can now afford to do the right thing in a way that they could not in the 1950s. We have more money to meet the moral imperative.

Impact on Process Safety

The formal discipline of Process Safety Management (PSM) developed in the late 1980s. Many PSM activities, such as the writing of procedures, the management of change and execution of safety studies had been always been carried out. But about 40 years ago industry started to formalize these activities and to apply them universally, largely through the use of regulations from organizations such as OSHA and the UK HSE. PSM programs have, by and large, a built-in assumption that because something should be done, it can be done. For example, a Process Hazards Analysis team may recommend that a new instrument be installed or that additional training be provided to technicians. The team members have to justify their recommendation and it will have to compete with other project requests, many of which will themselves incorporate a safety ethic. Nevertheless, there is generally an assumption that safety recommendations will be implemented if the justification is strong enough.

If the economy is indeed entering a deflationary phase, possibly a long-term depression, then the energy and process industries will be confronted with reduced output and lower profits. Hence there will be less money to spend on all aspects of their businesses, including safety. There is always tension between safety and operations. We know that, over the long-haul, a safe operation is a profitable operation. But the short term reality is that safety is generally requires investments in items such as more reliable equipment, upgraded instrumentation or more training programs. Obtaining the necessary funding is likely to be a challenge in the coming months and years.


This post is somewhat downbeat, and I hope that my projections for the future of our industry are wrong. It would be great if we can return to the “Old Normal” after a quick V-shaped recession. But I am dubious. Moreover, if we have learned nothing else in the last few weeks, it is to be prepared for the worst (and hope for the best).

In future posts we will consider other aspects of the new economy, how the energy and process industries might be affected and how the PSM community can respond. It’s not all bad news. A time of crisis is also a time when we can adapt and learn.

Safety Moment #64: Equipment Spacing (Storage Tanks)

Tank Farm Spacing

The material in this safety moment is taken from the book Plant Design and Operations and from the ebook Siting and Layout. Further discussion to do with layout and spacing issues is provided in the article Siting and Layout of Process Facilities.

In Safety Moment #57: Equipment Spacing (Pumps/Fireproofed Pipe Racks) we started a discussion to do with the layout of equipment in a process or energy facility. In it we noted that there are many codes and standards that cover this topic. To supplement those codes we provided some guidance regarding the layout of pumps, given that they are a source of high pressure leaks.

Continuing the discussion in Safety Moment #64: Hydrocarbon Storage Tank Spacing, we look at hydrocarbon storage tanks, sometimes known as “API Tanks”. The following general guidance is provided.

  • Tanks should be located at a lower elevation than process areas so that if one of the tanks leaks and the secondary containment is not effective, flammable and toxic materials will not flow into the process areas. (The same argument holds if the spilled liquid could create a vapor that is denser than air and that could then flow downhill).
  • For the same reason tanks should not be located above populated areas.
  • Where it is not feasible to locate tank farms at elevations lower than process areas, increased protection measures may be required to offset the increased potential for ignition. These measures may include:
    • Diversion diking
    • High-capacity drainage systems
    • Vapor detection placed near potential release points
    • Increased fire protection
  • Spacing between tanks should be great enough to contain a fire, prevent spread of the fire to other tanks, and to allow sufficient access for firefighting crews.
  • Equipment other than associated piping should not be located within the diked area of storage vessels.
  • Flammable gas detection is not usually required for open tank areas unless a potential for gas accumulation has been identified.
  • Toxic gas detection should be installed if the potential exists for gas accumulation in a tank area. Alternatively entry into a bermed area must be treated as a confined space entry.
  • Fire detectors should be provided for tanks containing combustible or flammable liquids.

Secondary containment is frequently installed around tanks and tank farms. It generally consists of a containment or bund wall around equipment or tanks containing large volumes of liquid. If the equipment leaks or the tank is over-filled the liquid is contained and thus prevented from flowing into other parts of the facility, where it could create a safety and environmental problem.

Such a system, which is illustrated in Figure 2.3, is totally passive and therefore inherently safe. It requires neither instrumentation nor human intervention to be effective.

Figure 2.3
Secondary Containment

Tank with bund wall

The general rule is that the secondary containment should have a volume equal or greater to 110% of the volume of the largest tank being protected. If multiple tanks are enclosed, then only a spill from one tank need be considered.

Although a system such as that shown in Figure 2.3 is inherently safe, the drain valve in the wall has to be checked. It is needed because in order to drain accumulated rainwater from the contained area. But, if the valve is left open or if the drain line is broken, say by a passing vehicle or by someone treading on it, then any tank leak will bypass the secondary containment.

Copyright © Ian Sutton. 2018. All Rights Reserved.

Safety Moment #57: Equipment Spacing (Pumps/Fireproofed Pipe Racks)

Pump in process plant

One of the most difficult challenges faced by process safety professionals is that of equipment spacing. On most facilities, especially offshore, space is at a premium and there is a lot of economic pressure to place items close to one another. Doing so not only saves space but reduces the costs to do with long pipe runs.

On existing facilities where the equipment is already in place, a process safety analysis may recommend that additional safeguards, such as an automatic deluge system, be installed if it determined that items are too close to one another.

But, in general, keeping items well away from one another improves safety for the following reasons:

  • A fire is less likely to spread.
  • There is less likelihood of someone injuring themselves during routine operations or maintenance.
  • There is more access space for the emergency response team and their equipment.

There are many regulations, codes and standards to do with equipment spacing and layout. Examples are:

  • API Recommended Practice 752 —Management of Hazards Associated with Location of Process Plant Buildings
  • The National Electrical Code 70; and
  • API Recommended Practice 14J — Design and Hazards Analysis for Offshore Production Facilities.

In addition, many companies have their own standards and guidance.

The use of standards can also be supplemented by vapor dispersion analysis and other types of modeling.

Within this framework of regulations and engineering standards it is useful to have general guidance to do with acceptable spacing. We will be publishing the occasional safety moment on this topic. The first of these is Safety Moment #57: Equipment Spacing (Pumps/Fireproofed Pipe Racks).

Pumps are a frequent source of leaks, and they are often located close to piping, so their location is important.

Air coolers are also included in the Safety Moment because they can draw leaking vapors into their suction and disperse them over a wide area.

Safety Moment #62: From Complicated to Complex

Foggy window representing the uncertainty to do with complex, as distinct from complicated, systems

This Safety Moment has moved to


Safety Moment #59: In-Kind / Not In-Kind Change

Defining change in the context of Management of Change

Two recent Safety Moments have discussed the difficult, yet important, topic of defining “Change”. Change is a constant in all industrial facilities; so some means is needed for determining which of those changes need to be handled within the Management of Change system. The first two Safety Moments were:

In this Safety Moment — the third in the series — we review the distinction between “In-Kind” and “Not In-Kind” changes.

Safety Moment #58: From “change” to “Change”

Safety Moment #58: From “change” to “Change”

Conditions on process and energy facilities are constantly changing. Criteria are needed for deciding when a proposed should be handled through the Management of Change system. This Safety Moment discusses potential criteria. It also reviews the issue of critical and non-critical changes. 

Details are available at:

Safety Moment #56: Sinking Standards

Great Eastern / Titanic comparison

The Great Eastern

This month is the 30 year anniversary of the Piper Alpha disaster. And, as to be expected, there have been many articles, blogs and web pages to do with that event, and the lessons that it continues to teach us. But there is an earlier maritime event which probably had a greater impact in its day than did Piper Alpha in ours. And that event was the sinking of the Titanic.

That event has given rise to many stories, movies and even some proverbs.

  • Rearranging the deck chairs on the Titanic.
  • Until the moment she actually sinks, the Titanic is unsinkable. (Julia Hughes).
  • Seize the moment. Remember all those women on the ‘Titanic’ who waved off the dessert cart. (Erma Bombeck).

One of the most important lessons to do with this famous event concerns the gradual erosion of safety standards that took place from the time of the building of the Great Eastern in 1858 to the sinking of the Titanic, 54 years later (which is why the picture at the head of the post is of the Great Eastern, not the Titanic).

For more discussion to do with the Great Eastern / Titanic comparison, and what it can teach us today, please visit Safety Moment #56: Sinking Standards.