Boiler Blog | Nationwide Boiler Inc.

In industrial settings where boilers are vital to operations, safety and reliability are non-negotiable. One often overlooked component is the fuel train, or gas train, which plays a critical role in controlling fuel delivery. During budget cuts, maintenance of this system is frequently deferred—an oversight that can lead to gas leaks, combustion failures, and serious safety hazards. For facilities operating high-pressure steam systems, regular gas train maintenance is essential to prevent incidents and ensure safe, reliable performance.

Understanding the Role of the Gas Train

The gas train is a system of mechanical and electrical components that regulate fuel flow and pressure to the burner. It includes shut-off valves, regulators, pressure switches, solenoids, and piping—all working together to ensure safe fuel delivery and immediate shutdown in unsafe conditions.

Gas trains are designed to:

• Prevent unburned fuel from entering the combustion chamber
• Shut off fuel flow in the event of unsafe operating conditions
• Maintain consistent gas pressure for efficient burner operation
• Enable both manual and automatic control of fuel delivery

Even in systems equipped with modern burner management systems and interlocks, the effectiveness of these safety measures depends on proper maintenance and operator awareness.

Risks of Inadequate Maintenance

Neglecting gas train inspection and testing can lead to component failures that may not be immediately apparent but can compromise the entire combustion system. Common issues include:

• Leaking or sticking safety valves
• Inaccurate or failed pressure switches
• Improperly functioning regulators
• Worn or bypassed interlocks
• Electrical wiring faults

In many documented incidents, failures were not due to a lack of safety devices, but rather a lack of routine testing and operator training. Preventive maintenance is essential to avoid these scenarios.

Best Practices for Gas Train Safety

Implementing a structured maintenance and safety program can mitigate risks and improve system reliability. The following practices are strongly recommended:

1. Staff Training and Competency

Operators must be trained not only in basic boiler operation but also in combustion safety and hazard recognition. Training programs should include hands-on system reviews, mock upset drills, and instruction on emergency response procedures. Even when maintenance is outsourced, in-house personnel should have a fundamental understanding of the systems they oversee.

2. Written Startup and Shutdown Procedures

Many combustion incidents occur during equipment startup or shutdown. Standardized, clearly written procedures ensure consistency across shifts and personnel. These procedures should include purge verification, valve testing, and system readiness checks.

3. Routine Testing and Documentation

Facilities should establish a regular schedule for testing gas train components, including:

• Valve leak and tightness testing
• Functional testing of pressure switches and interlocks
• Flame safeguard system checks
• Compliance with applicable NFPA, ASME, and local code requirements

Documenting all tests and inspections ensures traceability and supports compliance efforts.

4. Third-Party Equipment Reviews

When acquiring new equipment or undergoing significant upgrades, a third-party review can help verify compliance, confirm correct installation, and identify design deficiencies. This is especially important when retrofitting legacy systems with modern controls or safety components.

5. Proactive Equipment Upgrades

Waiting for failure is not a viable safety strategy. Facilities should establish a timeline for replacing aging components and upgrading outdated systems. Modern PLC-based burner management systems and digital flame safeguards offer improved diagnostics, safety, and reliability.

Building a Culture of Safety

The safe operation of permanent boilers, rental boilers, and boiler combustion equipment depends not just on hardware, but on the culture and procedures that support it. Gas train maintenance should be treated as a critical operational task—not an afterthought. Investing in training, testing, and system upgrades enhances reliability, reduces unplanned downtime, and most importantly, protects personnel.

This blog post was originally published in September 2011 and has been updated to reflect current best practices, safety standards, and advancements in gas train maintenance.

Nationwide Boiler has achieved yet another safety milestone – 2,500 days without a loss time accident! This marks the longest length of time Nationwide has gone without an accident in our forty-four years of operation. The company maintains a shop facility of 26,000 sq.ft., used for the maintenance, repair and assembly of boiler systems and auxiliaries. Nationwide Boiler’s Experience Modification Rate (EMR), a benchmark measure used for insurance premium discounts that compares worker compensation claims to other employers of similar size operating in the same type of business, has greatly improved over the last seven years. To date, Nationwide Boiler has realized a cumulative cost savings of over three-hundred-thousand dollars as a result of the company's commitments to safety.

Routine boiler maintenance is imperative not only for safety, but also to sustain efficiency and reliability of your system. Being proactive rather than reactive is likely to increase the longevity of your boiler as well as help prevent incidents that can result in injuries, damage, or worse. Incorporating routine maintenance into your facilities day-to-day operations will prove its worth with a great deal of short- and long-term benefits.

There are certain maintenance tasks that should be performed daily, and others that should be performed periodically. Below we have provided a list of best practices to follow when putting together your routine boiler maintenance plan.

On a daily basis, you should track and keep a log of the following items:

• Boiler pressure and temperature
• Stack temperature, to determine operational efficiency (a well-tuned boiler should have a stack temperature range of 50 – 100 degrees above the steam or water temperature)
• Gas pressure to the regulator, as well as downstream from it
• Water quality and pH levels, to ensure you are meeting the recommended levels

Blowdown of the boiler (bottom blow) and water column should also be performed on a daily basis. In addition, you should observe boiler and auxiliary equipment daily to ensure proper operation and that there is no damage, leaks, or unusual behavior. 

On a weekly to monthly basis, it’s important to conduct additional visual inspections and observe the operation of certain components for areas that may need to be addressed. This includes:

• Gauge glass
• Fuel supply valves
• Operating and modulating controls, water level controls
• Flame scanner & burner flame pattern
• High- and low-pressure switches, combustion air proving switch
• Indicating lights and alarms

When it comes to the burner, you should inspect the valves, pilot tube, and diffuser thoroughly for any signs of wear that might call for a repair. Also, be sure to observe the entirety of the boiler system for potential hot spots (an indicator of deteriorated refractory) and again, be sure to keep an eye out for any leaks of fuel, water, or flue gas.

Lastly, there are certain items that should be performed on a semi-annual to annual basis. Many of the tasks below can be checked off during the annual inspection, when the boiler is taken offline:

• Open access doors and inspect the fireside of the boiler
• Inspect boiler and tubes for evidence of corrosion; clean tubes and tube sheets thoroughly
• Examine the refractory for large cracks (greater than 1/8”) and patch as necessary
• Conduct safety tests on the gas valves
• Review all electrical connections for tightness, signs of wiring wear
• Check pump alignment on all base-mount pumps

This is also a good time to fully inspect the auxiliaries that provide fuel, air, water, and chemicals to the boiler. In addition, combustion should be reset periodically with the use of a combustion analyzer, for accurate readings of NOx, CO, and O2.

While the guidelines above provide a good baseline of tasks to perform when it comes to routine maintenance, be sure to consider the boiler manufacturer’s recommendations as well.  

With over 30 years of experience, our General Manager at Pacific Combustion Engineering, Jack Valentine, is an expert when it comes to the design of combustion control systems. In the Winter 2021 edition of Today’s Boiler, Jack discusses the features and options typical of Combustion Control Systems today. Let’s take a peek at what he had to say.

Combustion equipment safety is essential for the daily operation of facilities and safety of plant personnel. Safety protocols and mechanisms in industrial plants have improved drastically in the last century, but incidents still occur far too frequently. Because boiler systems are inherently dangerous, safety must be factored into the design of not just the boiler, but also the burner, combustion control, and the overall operation of the system.  

The Combustion Control System (CCS) on a boiler, also known as the Boiler Control System (BCS), refers to the set of instrumentation and controls that modulates the firing rate of the burner in response to load demand while maintaining the proper air/fuel ratio (AFR). It works in conjunction with the Burner Management System (BMS) that provides safeguards before, during the initial light-off of the burner, and at shutdown. The BMS also provides the flame safeties and interlocks required to keep the boiler safe during continuous operation. Depending upon the complexity of the boiler, the CCS can also provide other functions such as drum level control and draft control.  With Low NOx burners, it also controls the proper amount of flue gas recirculation (FGR) to the burner.

For the sake of simplicity, the various types of CCS described below will be for boilers firing a single fuel gas only; fuel oil and solid fuel systems add an entirely new level of complexity.