Boiler and combustion safety: What you don't know can kill you!

John R. Puskar
Tags: workplace safety

An industrial explosion kills six in Michigan, another kills four in Virginia, and the list goes on. These are only two very tragic, national headlines. The National Fire Protection Journal (NFPA), reports annually that catastrophic fires and explosions cost industry hundreds of millions of dollars annually. These statistics say nothing of the thousands of small events that occur and go unrecorded such as boiler fires, process oven failures, and the burns and injuries from these events. Unfortunately, society and individual companies usually act on these issues only after some very large and tragic event occurs.

These statistics are dramatically better than 100 years ago when boiler explosions and the related carnage were an almost everyday occurrence. However, in my opinion, we have hit a plateau with fuel and combustion equipment safety. It doesn’t have to be this way, and your diligence and understanding after reading this paper might help to change this. This paper hopes to provide a means of encouraging combustion equipment safety action at your facility before it’s too late. I hope to raise your awareness about this area of safety that few people know about simply because it is complicated and misunderstood. Combustion equipment safety is critical to the daily operation of all facilities and the safety of every employee. This paper will help you understand how to protect your employees from combustion-related incidents involving fuel-fired equipment (boilers, ovens, furnaces) before you end up a headline.

For the non-combustion person, this paper reviews basic gas train safety controls and concepts and provides an understanding of the most common problems we have found through our inspections and safety testing of more than 9,000 gas trains, the training of thousands of skilled trades people, and the development of corporate combustion equipment safety programs for some of the world’s largest companies.

Most facilities do not have personnel properly trained in combustion equipment maintenance, start-up or shut-down procedures, and/or equipment operations. Most sites also do not follow proper interlock and safety testing guidelines even though they are mandated by law. Boiler safety laws passed by a number of states hoped to help this. Boiler inspections are mandated to be carried out in states and municipalities that have boiler safety laws. These are called jurisdictional inspections. In most states, these laws call for inspecting, but not testing, only the pressure vessel part of each boiler system. In 26 states, ASME CSD-1 (American Society for Mechanical Engineers, Controls and Safety Devices Code for Automatically Fired Boilers) is an adopted code. It mandates actual operational combustion safety systems testing for units up to 12.5 million BTUs per hour input (MMBTUH). Some states have also adopted NFPA 85 (National Fire Protection Association, Boiler and Combustion Systems Hazards Code) for units that are over 12.5MMBTUH. This code also requires safety systems testing. In these states, jurisdictional inspectors may ask to see evidence of the required gas train and safety interlock testing. However, it is beyond their work scope to do any of this testing.

‘But It Was Just Inspected!’
Interviews of people close to boiler explosions or fires will commonly contain the phrase, “But it was just inspected!”In their hearts, they believe thateverything humanly possible was done to avoid a catastrophe. People (i.e. owners or operators) think that a jurisdictional boiler inspection is the magic bullet or armor shield against problems, when in fact, in many cases it’s not. Very few realize what a typical mandated jurisdictional boiler inspection is and is not. Many large industrial clients are realizing that these mandated inspections are not enough to protect their most important assets – the lives of their employees. Some of these companies now have fuels and combustion equipment safety programs that go well beyond minimal legally mandated requirements. These “self audit” combustion system programs usually include an analysis for code compliance, installation deficiencies, interlock testing, screening for maintenance practices that can be impacting safety, and assessing technological advances that can improve safety.

Grandfathering Old Equipment
Jurisdictional inspectors often have their hands tied when it comes to what they can ask someone to do. What they are inspecting for is often limited by exactly the letter of the law. For example, in many cases, they can only evaluate equipment for its code compliance for when it was installed. Code compliance is usually not retroactive. Safety codes have committees and evolve for a reason. It’s because the technical world finds out how to do things better over time. It’s a shame that none of this has to ever get implemented.

There is typically no screening for how far away from the most recent codes the old “grandfathered” technology is. Passing a jurisdictional inspection sometimes means that you could be “technically” in compliance with archaic and antiquated equipment that is 50 or more years old. This could be equipment that requires many manual steps to operate safely and puts your site at serious risk of improper manual start-up or shutdown daily. You could walk away from this kind of inspection being technically “in compliance” but nowhere near the current codes level of safety.

Consider also that unless you are in an ASME CSD-1 or NFPA 85 state, inspections rarely address gas trains and/or fuel system issues. Interlock and gas train testing is usually assumed to be a responsibility of the owner in these non-code states. You can imagine that the level of compliance with these little-known testing requirements is much less in states where the issue of testing is not even on the table on a regular basis.

When it comes to process ovens, space-heating equipment, furnaces and other heat-based industrial processes, there are very specific guidelines for levels of fuel train protection, safety and testing. These are spelled out in NFPA 86 (Standard for Ovens and Furnaces). However, as in the case of boilers, very few people know about them. Often, these are custom pieces of equipment with safety controls that are assembled from components and not pre-engineered catalog systems. Unlike boiler systems, there are no jurisdictional programs in the United States to inspect or mandate safety testing for non-boiler fuel-fired equipment.

What is Interlock Testing? Why Does it Matter?
Burning fuels can be useful to mankind as long as it’s with a controlled process. Control means that combustion takes place where we want it, when we want it, and at the rate we want it. The complicated-looking series of valves, piping, wires and switches that comprise the “gas train” installed on gas-fired equipment is what attempts to do this.

Gas trains regulate the amount and the pressure of gas to burners. They also keep gas out of the combustion chamber whenever equipment is cycled or shut off. This is accomplished with a series of regulators, flow control valves and special shutoff valves. The shutoff valves are designed for very low leakage and are spring loaded to close. These are the safety shutoff valves. Larger gas trains require dual valves and some also have a vent between these for added safety. The vent and its piping are provided to allow automatic shutoff valve leakage a place to go outside the building when the equipment is cycled or shut off. It is only supposed to open when the equipment is off. The specific configuration that you have most likely depends on your insurer and local code requirements.

Gas trains also have a number of components that try and make sure that safe light-offs take place and that shutdowns occur immediately if anything goes wrong during the operation of the equipment. They do this with a series of special switches that look for conditions that could be dangerous. For example, too high or too low gas pressures being sent to the burner should trip gas pressure switches and cause the unit to shut down. These should also be switches to make sure that airflows are correct for purging residual combustibles prior to light-off and to make sure airflow is correct during operation.

Flame-sensing components also usually exist to make sure that flames are present when they are supposed to be present and not at a wrong time. Other components for sensing that the fuel valve is at low fire position prior to light-off may be present along with furnace pressure switches, high temperature limits, high steam pressure limits and/or water level cut-offs (depending on the type of equipment).

All of these components are logically linked or interlocked to a BMS (burner management system) controller. The BMS is the brain that supervises and sequences all of the light-off efforts, including the timing and adequacy of the purge prior to light-off and the time intervals allowed for getting pilots and main flames lit. The BMS then acts as your sentinel of safety and monitors all of the switch and safety conditions that are available waiting to direct the fuel valves to close if there’s a problem.

All of this equipment is supposed to be checked on a regular basis by law, but with maintenance budgets among the first be cut, proper checkouts and testing are seldom performed. Codes and manufacturers define what the testing frequencies should be for different types of components and safety systems. Frequencies of required inspection/testing range from daily for some items like observing flames (assuming you know what to look for), to annually for some block and bleed valve tightness testing requirements. It is in this frequency area that we find many problems in industry today.

Our typical circumstance is to find that no one at a site is aware of regular testing requirements specified by codes. In most cases, we find that sites do some level of testing, but it is rarely regular. The level of comprehensiveness varies depending on who is in charge and that person’s knowledge of the equipment or systems. If someone knowledgeable is doing the right thing, we often find that job rotations and turnover don’t guarantee that this diligence will be in place for many years at a particular site. Because of this, we have not found much consistency among sites under anyone’s corporate umbrella.

Where Did the Codes/Industry Protections Come From?
Before you can understand how to protect yourself and your facility, it is important to cover a little background. The early 1800s saw boilers and pressure vessels as being at the root of many catastrophes. This created a public uproar and a call for the technical community to provide new guidelines, laws and infrastructure to protect the public. Groups like the ASME and NFPA stepped up and changed the world with new pressure vessel and fuel train requirements. Pressure vessel and combustion-related incidents have dropped dramatically since that time. These groups have done a wonderful job through the years and have no doubt save thousands of lives in the process.

This brings us to today. While dramatically better than the 1800s, we have reached, in my opinion, a loss plateau. We still have dozens of deaths, hundreds of injuries, and billions of dollars in annual fuel and combustion equipment system losses worldwide. This is still happening today largely because of a lack of knowledge, enforcement of laws and codes already on the books, training and proper maintenance.

New Facility
I want to take you through a common combustion equipment scenario that many of us face or have faced. This will describe how and where you can get into trouble when it comes to combustion equipment safety even with all the existing laws, codes, and checks and balances. We’ll look at the case of a new facility being built and this same facility after it has been in operation for a number of years.

Consider a new facility being built to include gas-fired process equipment and a heating system that includes a boiler.

The project could have been conceived of and directed by someone in your corporate staff. It may give you an underlying sense of confidence to think that degreed professionals designed the facility. The plans were then most likely reviewed by a number of people including the city’s building department, the local fire department, an architect, and a licensed contractor probably did the equipment installation. You may expect to rest peacefully knowing that probably a dozen skilled professionals have, no doubt, reviewed and blessed everything about the installation.

But all may not be well. Here are some disturbing issues about this everyday scenario.

  1. City Building Departments

City building departments often farm out the review of plans to architects or engineers since they usually don’t maintain staff for large projects. Typically, they look for very significant and obvious local code related issues. The reviewer is likely to get paid $50 to $100 to spend less than an hour on your drawings. This is most likely not a detailed examination of how your system was selected or installed and it has nothing to do with how it’s operated.

They will most likely send an inspector out to see your equipment after it is installed. The inspector is probably a retired tradesman. He will certainly know about residential work since it’s probably 75 percent of what he sees. It’s very unlikely that this person would know much about boilers or industrial process equipment.

  1. Corporate Project Engineering Staffs

I was a corporate staff engineer for a major oil company. We managed projects. We relied on specialized consultants for giving us advice on equipment selections. In most cases, the firms we used relied on vendors to tell them what they needed. This information was translated to drawings and a conceptual specification was generated. Rarely did this level of design include detailed gas train piping drawings and wiring schematics. In most cases, this was not possible to develop until a specific equipment vendor was selected.

If the design process works correctly, the successful vendor provides detailed drawings for insurance approvals. This is then followed by a very detailed and thorough commissioning at the site to verify that all was installed and working properly. If these steps happen, then you are likely to be starting off with safe equipment. However, our experience is that many times something gets lost between the corporate specifications, the approved shop drawings, and what actually shows up on the job, let alone how it gets installed. Purchasing always looking for the low bidder never helps this situation.

  1. Project Architects

Architects receive little or no formal training in building mechanical or combustion systems. It is simply not usually in their scope. Most likely, they will rely on the city’s code officials, a hired consulting engineer, and/or a contractor or vendor to make this happen. The hired consulting engineer is many times no longer involved in the project after the project once the project is in the construction stage.

  1. Project Managers

These are (usually) general contractors hired to be schedule and budget people. Once again, it is not typically in their scope of work to spend much time or effort focused on meeting fuel, combustion or boiler safety codes. They usually assume others address these issues.

  1. Insurance or Mandated Jurisdictional Inspectors

When it comes to boilers and the insurance world, you first need to understand who’s covering what. A boiler is normally covered by two different insurance policies. One is the boiler/machinery (B/M) coverage which covers the pressure side and the second is the property coverage which covers the fire side. The pressure side means the tubes, drums and safety relief valves. The fire side means more the fuel train, firebox and refractory related issues. There are some companies who cover both the B/M and the property side, and others that handle only one or the other. This is a matter you should investigate and understand. Those that are on the property side may make recommendations to have safety controls and interlocks tested or have other fire side recommendations in their reports. These reports, and reports related to pressure side issues from B/M inspectors, can be seen by many other insurance companies and can lead to some companies not bidding on insurance coverages and/or coverages becoming more costly for sites where risk is perceived. In many cases, jurisdictional insurance B/M inspectors have their hands tied. They are only supposed to review pressure vessel and piping issues including air tanks, water tanks and boilers. They are not supposed to focus on issues like the gas piping at the site, the gas train component settings, control logic and/or the burner flame pattern. It has been our experience that many property insurance related inspectors spend more time looking at sprinkler and fire suppression issues than they do combustion equipment matters.

  1. Local Fire Departments

Many local fire departments have fire prevention efforts including compliance inspections of local businesses. These usually address fire doors, sprinkler systems and general housekeeping issues. It would be rare for a fire department to have a boiler or gas equipment expert on its staff. Besides, boilers usually do not fall under any fire code.

So, where does this all leave us? It makes for a case where lots of people may have looked at or in some way have been involved in our new combustion equipment installation, yet no one may have specifically been focused on the combustion safety or fuel system related issues. We inspect and test many newly installed systems only to find things wired wrong, safeties that don’t work and/or things that don’t comply with applicable codes. This makes people very upset, delays starting facilities and costs someone a lot of money. It’s frustrating and embarrassing.

OK, So Now It’s Installed, But …?
Let’s assume that despite all that was just presented you ended up with a properly installed and commissioned system. Who is now qualified to operate and maintain the equipment? The staff, consultants and vendors have now all left your site. Operations, maintenance and people issues are now by far your biggest combustion equipment safety issue. The NBIC (National Board of Pressure Vessel Inspectors) statistics for boiler incidents show that nearly 40 percent of all deaths and accidents are caused by human error or poor maintenance.

The day after everyone has gone and you’re now alone with your officially blessed equipment, one poorly trained person with a well-placed screwdriver can reduce your building to rubble and kill everyone around in less than five minutes.

A lot of sites assume training is something that happens on-the-job in an informal sense. To them, it’s information that gets passed on from person to person over coffee or in between baseball scores. There may have been training years ago when the equipment was new. Now, maybe only half of those people are still around.

Codes offer very little specific direction regarding training other than to say that training is absolutely required and that it should be done either annually or regularly. The American Society of Mechanical Engineers (ASME) boiler code in Section VII, Subsection C2.110 says “safe and reliable operation [of boiler] is dependent … upon the skill and attentiveness of the operator and the maintenance personnel. Operating skill implies knowledge of fundamentals, and a suitable background of training and experience. Regularly scheduled auto-manual changeover, manual operation, and mock emergency drills to prevent loss of these skills are recommended” (ASME 2004). This kind of training, and especially the mock, upset troubleshooting, and emergency parts are especially ignored in most training programs we have encountered even though they are clearly among the most important things that operators and maintenance staffs should understand.

The National Fire Protection Association’s NFPA 85, Section 4.4.2 also identifies some requirements for boiler operator and maintenance training (NFPA 85, 2004). This information is helpful but again rarely ever finds its way into boiler operator training programs. Even more peculiar is that where boiler operator licensing is required, licensing exams have very little information, if any at all, related to fuel train safety or maintenance. Instead, these exams and the training for them focus almost exclusively on water and pressure vessel issues.

Preventive Maintenance
A comprehensive preventive maintenance program is your biggest defense and another vital part of staying safe.

Father Time and the deterioration and aging that he brings do nothing to help combustion equipment safety. Lots of things happen that make combustion equipment less safe with every minute of operation. Dirt accumulates in combustion air fans and burners. This changes fuel/air ratios. Gas valves get a little less tight every time equipment is cycled. Pressure switch diaphragms and contacts age. Water level controls accumulate sludge.

These are all examples of possible operational or maintenance issues that could spell trouble for you and your site. The problem is that very few sites maintain the specific expertise required for proper combustion systems maintenance. The skills and knowledge required to do this work safely are considerable. These people must do this work regularly to stay sharp, not once or twice a year. They also need frequent training and specialized tools like flue gas analyzers that require annual calibration and expensive maintenance. Most sites lack people with these skills and/or do not have them properly equipped. In many cases these people know enough to be dangerous. Don’t let your people try to do things like tune burners, change out firing rate control valves, and/or replace burner management systems unless they have been properly trained.

Sites that don’t want to have these problems with in-house staff sometimes blindly rely on contractors thinking that surely since they have a van with graphics they must know everything. Certainly there are many fine contractors out there. However, you’ll want to be very careful before letting someone touch your equipment. If you own and operate combustion equipment, you and your staff must have some core level of knowledge regarding safe practices before you can even hire the right contractor. Ask lots of questions about the specific level of training and experience that the person coming to the job has had. Make sure this person is not going to learn on your equipment.

Regardless of who does your equipments maintenance, another issue that you will have to be diligent about is maintaining your documentation. This means panel drawings, switch set points, purge times and even component model numbers and operational manuals. Many incidents have occurred from improper troubleshooting of problems because information was not readily available.

We Can Again Meaningfully Decrease Fuel/Combustion Incidents, Here’s How:
Natural gas and combustion equipment safety continues to be a black art among many users. Most sites have personnel that are not adequately trained in either the safe start-up/shutdown of equipment, daily operations, or proper testing and maintenance. Our firms’ survey of industrial users found that less than 10 percent actually perform manufacturer or code required preventive maintenance including testing of critically important safety interlocks. The combination of these two circumstances (poor training and improper maintenance) can spell disaster, and it has in numerous facilities. When assessing your site’s level of combustion equipment risk, remember the following:

  1. Most of the explosions and fire incidents, by far, have historically been due to human error. All of the safeties and interlock equipment in the world won’t help if you attempt to bypass or jumper-out safety controls. There is no possible substitute for proper training. Training has to include mock upset and hazard recognition drills. Your site needs training even if you will have contractors doing preventive maintenance work.

  2. Start-up and shutdown are your biggest risks. You need clearly written procedures that everyone understands and agrees with so that consistent safe practices are in place with every shift and every employee.

  3. Make sure that you do regular and complete interlock and fuel train valve tightness testing. Jurisdictional inspectors, even where they are mandated to be around, cannot be at your facility every day. Combustion equipment safety testing needs to be part of your organization’s culture regardless of what it costs and what the perceived hurdles are. You should comply with code requirements for testing even if they are not enforceable in your area.

  4. Create corporate guidelines for third party combustion equipment reviews and commissioning for newly acquired equipment or for major upgrades. Now that you see how little review and attention combustion equipment may receive from the time it’s specified to when its really operating, you may want a dedicated professional review of the process.

5.   Upgrade equipment for safety's sake. Do not wait for a problem and let attorneys dictate when this happens.

It takes a lot of effort to change culture and practices that have evolved over decades. In the beginning, you will probably get a lot of the same old, “Gee, we have been doing it this way for years” stories. Our clients have found the first year of having a comprehensive combustion equipment testing and training program to be painful. It takes a lot of effort and faith to fix things that “ain’t broke” to some people. Certainly the financial wizards will need lots of hand-holding when it comes to upgrading equipment just for the sake of safety, even though the upgrade may not increase throughput – although, in many cases, it will.

Once an incident occurs, it means years of court cases, job losses and changes, higher insurance rates, and maybe even criminal litigation. It also takes years to overcome the stigma of possible safety credibility to employees and the community. Start with a review of your equipments state of protection relative to current codes. We call this a “gap analysis”. Prioritize your needs and address them at a comfortable pace. Conduct a human “gap analysis” to identify the state of knowledge and skills regarding your operations and maintenance staff. Make training a regular and serious effort. The bottom line is that implementing comprehensive combustion equipment safety programs saves lives. The right thing to do is to be proactive. This is not the thing to do under the duress of catastrophes and death.

About the author:
John R. Puskar, P.E., is the principal and owner of Combustion Safety Inc., located in Cleveland. For more information, e-mail, visit or call 216-749-2992.

National Fire Protection Association. NFPA 85 Boiler and Combustion Systems Hazards Code (2004 Edition).

American Society of Mechanical Engineers, ASME Boiler and Pressure Vessel Code, Section VII, Recommended Guidelines for the Care of Power (2004 Edition) Boilers.

National Board of Boiler and Pressure vessel Inspectors.

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