Boiler Blog | Nationwide Boiler Inc.

Let’s take a step back in time to a brisk day in October — a day that became a defining moment in Nationwide Boiler’s history. On October 17, 1989, at exactly 5:04 p.m. Pacific Daylight Time, a powerful 7.1 magnitude earthquake struck Northern California. For residents of the San Francisco Bay Area it was a moment frozen in time, one they would never forget.

It was a calm fall evening. More than 50,000 fans were settling into their seats at Candlestick Park for Game Three of the World Series, while millions more across the country tuned in to the live broadcast. As the stadium announcer provided pregame updates, no one could have anticipated what was about to unfold. Then, the ground began to shake. Screams erupted and the announcements stopped. ABC broadcaster Al Michaels, usually composed and articulate, was momentarily speechless. The energy of the stadium was replaced with an eerie silence. What followed was one of the most significant earthquakes in California’s history: a 7.1 magnitude event that would later be known simply as “the big one.”

In a matter of seconds, freeways collapsed, bridges broke apart, and buildings shifted from their foundations. The World Series was postponed. Fires erupted in multiple areas, including a major blaze in San Francisco’s Marina District, and millions of gallons of water were deployed by first responders to fight the flames. In the midst of widespread devastation, the city narrowly avoided a far worse outcome and utility services remained operational through the night, allowing emergency crews to respond effectively.

At Nationwide Boiler’s office in Fremont, Service Manager Neil McIntosh was still absorbing the shock of the quake. As he cleaned up broken glass and restacked books scattered across the office, he had an uneasy feeling that it would be a long night. And he was right — at 11pm that evening, the facility engineer from PG&E’s Potrero Power Plant, San Francisco’s primary power generation facility, called with a critical issue that could lead to the need for a rental boiler. And the standard question followed: “How fast can you respond?”

In the hours following the earthquake, PG&E engineers struggled to diagnose a serious problem: the plant’s electrically powered feedwater pumps, responsible for supplying water to the boilers that generated steam for turbine operation, had unexpectedly shut down. Under normal conditions, multiple backup systems would prevent any drop in water levels. But in this case, the boilers continued running without feedwater. When the pumps were eventually brought back online, it was already too late. The boilers were dangerously overheated, and it was no longer safe to reintroduce water. In a stopgap effort, a U.S. Navy ship docked next to the power plant was called in to provide emergency steam to cool the boilers. While helpful, this solution was temporary, and the city’s only other power plant was operating at full capacity to meet soaring demand. A failure at Potrero could have led to widespread outages. The only sustainable option was to deploy a high-capacity, fully equipped mobile steam plant that could deliver the right temperature, pressure, and controls to safely restart the system.

Within hours, a Nationwide Boiler 250 HP mobile boiler room was loaded and shipped to Potrero. With assistance from CalTrans and the California Highway Patrol, the unit navigated through a network of damaged freeways and arrived at the site. Shortly after arrival, the mobile boiler was brought online. The overheated boilers were cooled, the feedwater pumps were reactivated, and the turbines resumed power generation. Thanks to this rapid response, the city avoided losing a vital source of electricity at a time when it was needed most.

In the days that followed, the nation watched as rescue teams worked tirelessly to pull survivors from the rubble. The extent of the devastation was immense. But despite the tragedy, fires were brought under control, and emergency services maintained critical infrastructure under extraordinary pressure. Looking back, Neal McIntosh, a history enthusiast, often reflected on what could have happened. After the 1906 San Francisco earthquake, much of the city’s destruction was caused not by the quake itself, but by the fires that followed. Had Potrero’s boilers failed beyond recovery, the consequences in 1989 could have been similarly catastrophic.

Fortunately, Nationwide Boiler’s operations were largely unaffected, allowing our team to mobilize quickly and lend support when San Francisco needed it most. That day became more than a test of our equipment; it was a testament to the dedication of our people and the importance of being ready when every minute counts. What began as a moment of crisis became a defining chapter in Nationwide Boiler’s history — one that reminded us why readiness, reliability, and service are at the core of who we are.

Selecting the right boiler for your facility is more than just a design choice – it directly impacts efficiency, reliability, operating costs, and emissions compliance. Among the most common designs are firetube boilers and watertube boilers, each with unique advantages depending on the application. These boilers can also be classified by pressure (low or high), output (steam or hot water), and steam temperature (saturated or superheated), adding further considerations to the decision-making process.

The following overview outlines the key differences between firetube and watertube boilers to help facility managers, engineers, and plant operators choose the system that best fits their needs.

What is a Firetube Boiler?

A firetube boiler, also known as Scotch Marine boiler, is one of the most traditional and widely used boiler designs. In this system, a large pressure vessel holds water, and tubes carrying hot combustion gases run through the vessel. As the gases pass through these tubes, heat is transferred to the surrounding water, gradually increasing its temperature until it produces either hot water or steam depending on the application. Because the “fire” or combustion gases are inside the tubes, the design is known as a firetube boiler.

Key Advantages:

• Lower upfront cost and simpler design
• Easier to operate and maintain
• Suitable for small to medium-sized facilities

Limitations:

• Slower to respond to load swings due to large water volume
• Design pressure capability is more compared to watertube designs

Firetube boilers are commonly utilized in industries and facilities such as small food processing plants, hospitals, schools, universities, and other heating applications where dependable steam or hot water is needed for steam systems operating at 150 psig and less.

What is a Watertube Boiler?

A watertube boiler operates differently than a firetube boiler. Instead of hot gases flowing through tubes surrounded by water, a watertube design allows water to circulate inside the tubes while the combustion gases pass around them. This configuration enables the system to handle much higher pressures and produce greater steam capacities than firetube units.

Key Advantages:

• Handles higher range of pressures, commonly up to 750 psig but pressures over 1000 psig are possible.
• Faster startup and load response
• More compact water content, reducing risk of catastrophic failure

Watertube boilers are commonly used in high-demand industries such as power plants, petrochemical plants, refineries, pulp and paper mills, large food processing, and large-scale manufacturing facilities, where high-pressure steam and higher capacities are required.

Limitations:

• Higher initial cost due to design and manufacturing differences
• Space requirements
• Typically, higher operation and maintenance costs

High Pressure vs. Low Pressure Boilers

Boilers are also defined by their maximum allowable working pressure (MAWP):

• Low Pressure Boilers: Operate at 15 psig or below. Commonly used for heating systems and hot water supply, they require less maintenance and are easier to manage.
• High Pressure Boilers: Designed for pressures above 15 psig. These units are essential for industrial steam production, power plants, and manufacturing processes where higher output is required.

Firetube boilers can be built for both pressure ranges, but watertube boilers are almost always high pressure due to their design.

Hot Water Boilers vs. Steam Boilers

While often confused, hot water boilers and steam boilers are separate classifications that can be applied to either firetube or watertube designs.

• Hot Water Boilers: Operate like large fuel-fired water heaters, producing hot water in the range of 120 - 220°F. These are primarily used for building heat, hydronic heating systems, and domestic hot water.
• Steam Boilers: Heat water beyond the boiling point to create steam. These systems are more powerful and used in industrial processing, sterilization, district energy systems, and power generation. Steam boilers may generate either saturated steam or superheated steam, depending on the application.

Saturated vs. Superheated Steam

When discussing steam boilers, it's important to understand the distinction between saturated steam and superheated steam, as each serves different industrial needs.

• Saturated steam is steam that is in equilibrium with water at the same temperature and pressure. It contains no additional heat beyond what's needed to convert water into steam. This type of steam is commonly used in heating applications and processes where direct contact with the product is required, such as food production or sterilization.
• Superheated steam, on the other hand, is produced by adding more heat to saturated steam without increasing its pressure. This results in steam at a higher temperature, which is ideal for driving turbines and other mechanical equipment. Because it doesn’t condense as easily, superheated steam is more efficient for energy transfer over long distances.

Understanding which type of steam your application requires can help you choose the right boiler and optimize performance.

Electric Boilers

Electric boilers are gaining popularity as a clean and efficient alternative to traditional fuel-fired systems. Instead of burning gas, oil, or coal, electric boilers use electrical resistance or induction to generate heat.

Key advantages include:

• Zero emissions at the point of use, making them ideal for facilities with strict environmental regulations.
• Compact design and quiet operation.
• High efficiency, often approaching 100%, since nearly all the electrical energy is converted into heat.

While electric boilers may have higher operating costs depending on electricity rates, they offer a low-maintenance, sustainable solution for many commercial and industrial applications—especially where fossil fuel infrastructure is limited or undesirable.

Making the Right Choice for Your Operation

Every boiler, whether firetube, watertube, steam, or hot water, has its unique strengths. The right choice depends on:

• Your unique operational needs; pressure requirements and steam capacity
• Facility size and available footprint
• Operator experience and maintenance resources
• Energy efficiency and emissions requirements

With modern advances such as ultra-low NOx burners, economizers, and Nationwide’s proven CataStak™ SCR System for near-zero NOx performance, today’s boilers are more efficient and environmentally friendly than ever before.

Whether you’re evaluating a firetube boiler for a commercial application or a watertube boiler for high-pressure steam production, understanding the differences between boiler types is essential for making the right investment.

For more details and guidance, explore our resource: What Boiler Is Best for You.

This article has been updated to reflect its original publication date of April 2019, while incorporating current insights and clarifications to ensure continued relevance and accuracy.

When selecting an industrial steam boiler, it’s essential to understand the key differences between saturated steam and superheated steam boilers. These two steam classifications play distinct roles across industries, ranging from heating processes to power generation. In this guide, we’ll explore the science behind saturated and superheated steam, advantages and disadvantages of each, and how to determine which type of boiler is best suited for your application.

What Is the Difference Between Saturated Steam and Superheated Steam?

Saturated steam is steam that exists at the boiling point of water and is in equilibrium with liquid water at a given pressure and temperature. It contains moisture and is often referred to as “wet steam.” Saturated steam is produced when water is heated until it begins to vaporize.

Superheated steam, on the other hand, is created by heating saturated steam beyond the boiling point without increasing pressure. Also known as “dry steam,” superheated steam has no moisture content, a lower density, and higher energy content. It remains in a gaseous state even as it cools, which makes it highly effective in certain mechanical and thermodynamic applications.

Common Industries and Applications for Each Steam Type

Both saturated and superheated steam boilers serve important yet distinct roles across industries, which is why Nationwide’s fleet includes both saturated and superheated steam boilers for rent and for sale. Each type has advantages and limitations, making them better suited for specific applications.

Saturated Steam Boilers

Saturated steam boilers are commonly used for processes that require high-efficiency heat transfer. Industries that frequently rely on saturated steam include:

• Food and beverage processing
• Sterilization in healthcare and laboratories
• Pulp and paper manufacturing
• District heating systems
• Chemical processing

Advantages of saturated steam include:

• Efficient heat transfer: Excellent for processes requiring quick, even heating.
• Simple temperature control: Steam temperature adjusts with pressure for consistent results.
• Compact equipment: High heat transfer rate requires less surface area, reducing system footprint and initial equipment costs.
• Reliable for direct heating applications.

Superheated Steam Boilers

Superheated steam boilers are ideal for applications that involve turbines or steam-driven mechanical equipment. Since superheated steam doesn’t condense into water droplets, it prevents corrosion and erosion inside critical components. Industries that commonly utilize superheated steam:

• Oil refineries and petrochemical plants
• Power generation (steam turbines)
• Large-scale manufacturing facilities
• Enhanced oil recovery and gas processing

Advantages of superheated steam:

• Zero moisture content: Prevents damage to turbines and piping.
• Increased thermal efficiency: More energy per pound of steam, ideal for power generation.
• Higher work output: Superheated steam can do more work before condensing.
• Extended equipment life: Reduced risk of corrosion and scaling.

While certain industries tend to favor one type of steam over the other, it’s important to note that specific processes may require the opposite—for example, some applications in saturated steam-dominant industries may still call for superheated steam. Ultimately, steam type should be selected based on the specific process requirements, not just industry norms.

Saturated vs. Superheated Steam: Which Boiler Do You Need?

Choosing between a saturated steam boiler and a superheated steam boiler depends on your specific process needs. For direct heating, sterilization, or process steam, saturated steam is typically the better choice. For driving turbines or maximizing work output from steam energy, superheated steam offers significant advantages.

Here are some important factors to consider:

Nationwide Boiler: Your Source for Rental & Mobile Steam Boilers

Nationwide Boiler provides high-performance boiler solutions for both saturated and superheated steam applications. Our rental fleet includes mobile boiler systems available for temporary steam needs and our in-stock inventory offers boilers for permanent applications, with capacities suited for industrial facilities of all sizes.

We proudly own and maintain:

• The World’s Largest 150,000 lb/hr, 650 psig Mobile Saturated Steam Boiler
• The World’s Largest 110,000 lb/hr, 750 psig Mobile Superheated Steam Boiler

And we continually stock what we’ve coined as the “World Boiler”:

• 200,000 lb/hr, 750 psig B&W Skid-Mounted Superheat Steam Boiler

Whether you need short-term steam supply or a permanent solution, our team is here to help. Visit www.nationwideboiler.com to explore our steam boiler rentals, request a quote, or speak with a steam expert.

This article was originally published in April 2019 and has been thoroughly updated to reflect current industry standards, enhanced technical explanations, and expanded application insights for both saturated and superheated steam boilers.

Industrial facilities in Oregon and Washington now have a new edge in reliable steam supply. We are excited to share that Nationwide Boiler has expanded our exclusive territory and are now the sole representative for Babcock & Wilcox (B&W) package watertube boilers for customers in Oregon and Washington State. With decades of experience serving industrial customers and a reputation built on integrity and dependability, this expansion brings trusted B&W products, technical expertise, and rapid support to the Pacific Northwest.

Delivering Flexible, Reliable Boiler Solutions

As companies across Oregon and Washington face evolving capacity and compliance challenges, Nationwide Boiler is poised to deliver the same high-quality boiler equipment and service known throughout California, Nevada, and beyond.

With our expanded territory, industrial facilities in Oregon and Washington now gain direct

access to new, custom-engineered B&W boilers, supported by Nationwide Boiler’s technical expertise from initial design and project planning to installation and commissioning. This capability ensures facilities can secure tailored steam solutions that meet specific capacity, efficiency, and compliance requirements.

Comprehensive Product Offerings and Support

Custom-engineered boilers, especially large package watertube units, can carry manufacturing lead times of up to 54 weeks—posing risks for facilities that need immediate capacity. Through our exclusive representation of Babcock & Wilcox (B&W) in California, Washington, Oregon, and select Nevada counties, Nationwide Boiler provides customers with access to both built-to-spec boiler solutions and a robust in-stock boiler inventory to bridge the gap.

For urgent requirements, Nationwide Boiler maintains a wide range of in-stock B&W package watertube boilers, available for domestic and global shipment. This includes the 200,000 lb/hr, 750 psig / 750 °F superheated steam “World Boiler,” a B&W model FM120-124 package boiler,engineered for rapid deployment to minimize downtime and keep operations running.

Customers in the Pacific Northwest and beyond benefit from:

• Rapid access to new and used in-stock firetube and watertube boilers up to 270,000 lb/hr
• Expedited shipping worldwide, ideal for unexpected equipment failures or planned capital projects. In-stock package watertube boilers range from 50,000 lb/hr to 200,000 lb/hr
• Comprehensive support including engineering packages, technical documentation, and ongoing service.
• Application-specific consultation to match each facility's unique operational needs, such as fuel efficient economizers, SCR systems for ultra-low NOx and CO compliance, and advanced boiler control systems.

Meeting Urgent Steam Needs and Minimizing Downtime

In addition to permanent boiler sales, Nationwide Boiler provides one of the largest, most

reliable rental fleets in the industry, supporting customers when unexpected downtime, peak

demands, or planned outages occur.

With rental boilers ranging from 47.5 hp firetube boilers to 200,000 lb/hr watertube boilers, customers in Oregon, Washington, and across the globe gain flexible options for both short- and long-term needs.

Our rental solutions include:

• Trailer-mounted package watertube boilers, with an extensive inventory of B&W 75,000 lb/hr superheat steam boilers
• Complete mobile steam plant systems including boiler/burner package, feedwater system, water softener, chemical feeder, and blowdown separator
• Stand-alone auxiliary equipment options such as mobile feedwater vans and water softeners, blowdown separators, and gas regulators
• Add-on auxiliary equipment options such as economizers, CataStak™ SCR systems, and DataStak remote monitoring systems
• Expert guidance navigating regional code requirements, emissions regulations, and site- specific installation logistics.
• Hands-on local support from experienced sales engineers based in California, Washington, Texas, and various other locations across the globe.

Nationwide Boiler’s rental fleet ensures fast response, compliance-ready solutions, and minimized downtime for facilities worldwide.

Decades of Dependability: Tracing the Nationwide Boiler–B&W Partnership

For more than 150 years, Babcock & Wilcox (B&W) has set the standard in steam generation, pioneering safe, reliable watertube boiler technology used in industries worldwide. Nationwide Boiler has been a long-lasting B&W partner for decades, bringing proven technology and reliable boiler solutions to customers across the world.

By combining B&W’s engineering expertise with our own experience in system integration, rentals, and emissions solutions, we’ve been able to deliver dependable temporary and permanent boiler solutions backed by hands-on support. With this new territory expansion, businesses in Oregon and Washington now gain the same direct access to B&W boilers, along with the technical guidance and responsive service Nationwide Boiler is known for.

Industrial Boiler Solutions for the Pacific Northwest and Beyond

As an exclusive representative of Babcock & Wilcox in California, Washington, Oregon, and select counties of Nevada,  Nationwide Boiler continues to deliver industrial progress with proven technology, in-stock availability, and responsive support. Companies in Oregon and Washington now have direct access to custom-engineered boilers, immediate inventory, and expert engineering services – helping reduce lead times, control costs, and maintain operational continuity.

Whether you need a built-to-spec solution, an in-stock boiler for expedited shipment, or a rental unit to meet urgent steam demands, Nationwide Boiler is your trusted partner in the Pacific Northwest and beyond.

Contact our team today for fast quotes, emergency steam solutions, or to learn more about how this expansion can benefit your facility.