Boiler Blog | Nationwide Boiler Inc.

Boilers are important components in many industrial settings and ensuring their longevity and efficiency requires proper maintenance, even during out-of-service periods. To prevent corrosion and other forms of damage when a boiler is offline, it is important to protect both the fireside and waterside of the boiler. There are two methods in achieving this – the dry method and the wet method.

Dry Storage

When a boiler is expected to be out of operation for an extended period of time and needs to be ready for service quickly, dry storage is advised. The dry storage method for industrial boilers involves draining, thoroughly cleaning, drying, and sealing the boiler to prevent moisture and air entry during extended periods of inactivity.

NOTE: If you are placing your boiler in storage for less than one month, follow steps 1 and 2 only. Be sure to follow your company guidelines and, at a minimum, label it as an oxygen-free atmosphere.

The following general procedure is advised for placing a unit into dry storage:

1. Shut down and secure the boiler. Once the pressure decreases to 20 psig, drain the boiler and header valves under air. Once the pressure is reduced to 0, open the drums to allow air to circulate and facilitate the drying of all internal surfaces.

2. If the unit is cold and filled with water, drain it under air, blow out non-drainable tubes with compressed air, and use external heat sources to aid in drying internal surfaces. Install non-porous trays with moisture absorbent (preferably silica gel) into the drums, ensuring they don't touch the drum's metal surface. Use at least one pound of absorbent per 1,000 pounds per hour of steam capacity.

3. Attach nitrogen to the steam drum vent, close all other vents, and pressurize the boiler to reach 10-15 psig with nitrogen, adjusting the amount based on the unit's volume.

4. With the boiler and superheater pressurized, alternately open all drains to purge air until the pressure drops to zero, repeating as needed to minimize oxygen levels.

5. The unit should now be stored with a nitrogen pressure of 5-10 psig in the steam drum. To maintain this pressure, ensure all connections and valves are sealed or tightly closed, and check the gas pressure daily for proper protection.

6. Boiler inspections are recommended every 3 months to ensure no corrosion is occurring and to replenish the absorbent as needed. During these inspections, air will enter the unit so you will need to repeat steps 3 and 4 to expel the air.

Wet Method

Wet storage prevents corrosion by keeping the boiler fully submerged with the right chemicals. Volatile chemicals are recommended to avoid increasing dissolved solids in the water.

The following general procedure is advised for placing a unit into wet storage:

1. Fill the boiler with deaerated, demineralized water treated with 200 ppm hydrazine and enough ammonia to reach a pH of 10.

2. Pre-mixing chemicals with water is recommended, using the blend-fill method to ensure uniform distribution in the boiler. Simply adding chemicals through the drum manhead may not adequately disperse them unless the boiler is heated to induce circulation.

3. Fill the unit with treated, demineralized water up to the normal centerline of the steam drum, then stop the filling process.

4. Refill the superheater with treated demineralized water until the steam drum level rises. Keep filling until water starts to flow from the steam drum vents. Once the filling is complete, make sure all connections are securely sealed.

5. Attach a low-pressure nitrogen source to the steam drum to maintain 5 to 10 psig and prevent air from entering the unit during storage.

6. When the boiler is ready for use, drain the superheater and the boiler drum to the normal start-up water level and resume operation.

7. Analyze the treated demineralized water weekly and add chemicals as needed through the chemical feed line to maintain recommended levels. Water samples can be collected from the continuous blowdown line or a suitable drain.

8. A boiler should not be stored wet if there is any risk of temperatures dropping to freezing, unless adequate heating is provided. Adequate heating will prevent water from freezing and avoid damage to the pressure parts.

Protection of External Surfaces:

Protection of external surfaces is also necessary during periods of extended downtime. Fireside corrosion in idle boilers can cause damage to components due to sulfuric acid from flue dust and ash. To mitigate this, remove deposits using air blasting, washing, scraping, or brushing, and neutralize any residual acid with alkaline water until the water is fully neutralized. Once flushing is complete, fill the boiler with treated water and fire it with low sulfur fuel to ensure complete drying.

Auxiliary heaters and blowers may be needed during storage to keep the metal temperature above the dew point and prevent freezing, especially with wet storage in cold conditions. Additionally, protect machined surfaces with preservative coatings and ensure there are no fuel leaks by disconnecting all oil and gas connections.

The choice between dry and wet storage depends on different factors. Although wet storage is often preferred, factors such as water quality, weather conditions, storage duration, and heat availability may make dry storage a more practical option. Be sensible when considering the conditions and needs of your boiler and choose the best storage method to ensure your equipment remains in excellent condition and is ready for use when needed.

Learning and performing proper water treatment will protect your boiler system from tube damage and corrosion, and can also contribute to maximizing boiler efficiency. In this edition of Boiler Basics 101, we will discuss the consequences of improper water treatment and how to implement a proper water treatment plan.

If feedwater is not treated properly before entering the boiler, a chemical imbalance can initiate the formation of scale. Scale is the accumulation of mineral deposits, primarily calcium and magnesium, on the internal surfaces of the boiler.  These minerals have the potential to precipitate from the water and bond to surfaces, creating a layer that may result in harm to boiler tubes, reduced boiler efficiency, and potential for ruptures. Proper water treatment methods, such as the use of water softeners and deaerators, reverse osmosis, and chemical additives to condition the water, must be employed to prevent scale formation.

1. A water softener will remove the calcium and magnesium content in the boiler’s water supply. This effectively “softens” the water before it enters a boiler and removes the minerals that are often the cause of scale in a boiler.
2. A deaerator should be utilized to mechanically remove oxygen from the water before it enters the boiler. This will prevent boiler tube failure.
3. Reverse osmosis can also be used to aid your boiler. Reverse osmosis is a process that can be used in boiler water treatment to purify and condition the water by using pressure to filter out any hardness and impurities.
4. Chemical treatment is also necessary to ensure proper water conditioning alongside the mechanical treatments listed above. Typically, the chemicals used for treatment purposes are an oxygen scavenger, scale inhibitor, and an amine to treat the steam system piping.

It is important to note that from a rental perspective, it is the customer’s responsibility to maintain the water treatment conditions of their rental boiler to avoid equipment damage and additional repair charges that can result from improper water treatment procedures. It is recommended that the services of a reputable boiler chemical consultant are retained in order to supervise the water treatment conditions on a regular basis. Weekly tasks should include maintaining daily boiler logs, conducting chemical treatment tests, providing a report from the chemical treatment consultant, and sharing maintenance records with your rental boiler supplier.

All boilers are subject to damage if proper water treatment procedures are not followed. This is an important consideration both during operation and when the boiler is idle. Maintaining a water treatment plan will not just extend your boiler’s lifespan and the durability of its components, but it will also facilitate long-term cost savings. It is an investment that pays off in the form of lower energy costs, fewer repairs, reduction of costly down time, and compliance with regulations; all contributing to long-term cost savings.

Make sure to explore our earlier Boiler Basics 101 articles and keep an eye out for the upcoming edition!

The boiler rental business began over fifty years ago, solving multiple industries’ need for temporary and emergency steam. Nationwide Boiler was at the forefront of the boiler rental industry, starting off with one of the first mobile rental boilers; a 20,000 lb/hr, 300 psig design, O-type package watertube boiler. This boiler was designed for permanent use on a highway-legal open deck trailer, making it a true mobile boiler. This new idea allowed companies to cut capital costs, save time, and be more efficient in their operations. Now, rental boilers are available for small-scale projects to industrial sized applications.

In last month’s edition of Boiler Basics 101, we discussed why rental boilers are a great choice for boiler owners in a variety of industries. To continue the topic, we will now discuss the different types of rental boilers currently on the market.

Trailer-Mounted Boilers

• Permanently installed on highway-legal trailers for easy transport by truck
• Boilers of various sizes up to 125,000 lb/hr, both saturated and superheated steam
• Detachable goosenecks and booster extensions allow for easy removal when space is limited
• Not protected from the weather and precautions must be taken for freeze protection (heat tracing and insulation or temporary housing shelters)
• Separate feedwater and water treatment systems and other auxiliaries can be provided to support the boiler, as needed

Skid-Mounted Boilers

• Shop-assembled package boilers, without any true mobility
• Available in capacities up to 250,000 lb/hr
• Depending on the size of the boiler, skid-mounted boilers can be transported on a flat-bed trailer, step-deck trailer, or by rail
• Cranes and/or forklifts typically required for both loading and offloading
• Not protected from the weather and precautions must be taken for freeze protection (heat tracing and insulation or temporary housing shelters)
• Separate feedwater and water treatment systems and other auxiliaries can be provided to support the boiler, as needed

Containerized Mobile Boilers

• Typically includes a package firetube boiler, installed inside a container and mounted on a chassis for mobility
• Ideal for users who need a boiler-only package that is weatherproofed for outdoor operation in the wintertime
• Separate feedwater and water treatment systems and other auxiliaries can be provided to support the boiler, as needed

Mobile Boiler Rooms

• Complete steam plants, self-contained within enclosed vans, with all equipment required to produce steam:
  • *Package firetube boiler
  • Atmospheric feedwater system
    • * Water softener
    • Chemical injection tank
    • * Blowdown separator
• Typically available in capacities up to 1,000 hp
• Weatherproofed and better suited than alternatives for outdoor operation in the wintertime

Mobile Steam Plants

• Similar to a mobile boiler room, with all equipment required to produce steam
• Equipment is installed on an open, step-deck trailer
• Not protected from the weather and precautions must be taken for freeze protection (heat tracing and insulation or temporary housing shelters)

Transportable Steam Plants

• Complete steam plant, normally built inside of a standard 20 or 40’ shipping container
• Available with either a vertical or a horizontal boiler arrangement depending on requirements
• Cranes typically required for both loading and offloading
• These systems accommodate less capacity than a mobile boiler room
• Popular for overseas and government projects, due to ease of transportation 

Each type of rental boiler system explained above has their own unique advantage and may be better fit for one user over another. The requirements of operation, however, are the same: end-users must supply a fuel source (natural gas, #2 oil, propane, or other fuel), electrical power supply, and make-up water. Which type of rental system is best fit for your unique operation?

Nationwide Boiler maintains an inventory inclusive of all types of boilers listed above, ranging in size from 47.5 hp to 200,000 lb/hr. Visit our website to find a complete listing of rental boilers available, and contact a Nationwide Boiler Sales Representative for additional details and pricing. 1-800-227-1966

Established in 1967 by late founder and pioneer Dick Bliss, Nationwide Boiler began with a mission to provide mobile, temporary boilers to steam users during planned and unplanned boiler outages. At the time, our rental fleet wasn’t much of a ‘fleet’ and consisted of just one 20,000 lb/hr trailer-mounted, O-type watertube boiler. Throughout the years, our inventory has grown to consist of over 100 rental boilers and related equipment, all with various specifications and capabilities. And with multiple storage locations throughout the country, we are capable of shipping our boilers to customers not just nationwide, but worldwide.

With a goal of being the #1 emergency boiler supplier, we understand the importance of educating steam users on emergency preparedness and the benefits of utilizing a rental boiler not just during emergencies, but also during planned outages and periods of high demand.

Reasons to Rent a Boiler

• Unforeseeable Situations
  •  A boiler shuts down unexpectedly, needing maintenance and/or repairs
  •  Disasters and natural causes that lead to a temporary steam need

Nationwide Boiler has come to the rescue in many emergency situations. One notable instance was the tragedy on September 11^th, 2001, where we responded quickly to assist ConEd with the supply of heat to New York city. 

• Increase in Demand
  • Companies face periods of increased demand due to varying factors, requiring additional steam capacity

Nationwide Boiler has a great deal of experience renting boilers when additional steam is needed. In fact, we have an annual rental with a tomato processing company to support their seasonal increase in demand.

• Planned Outages or Repairs
  • Annual boiler inspections or routine repairs that require a temporary steam source while a facility boiler is taken offline

Nationwide Boiler has over 50 years of experience in providing boilers and related equipment for companies that have planned outages and need temporary steam.

• Capital Resources
  • A company has budgetary restrictions and is unable to invest in a new boiler
  • Nationwide Boiler has a large inventory of 100+ rental boilers. We provide rental programs that are flexible to a company’s budget, and can assist with financing options.

 Whatever the reason for renting a boiler may be, make sure to rent from the best. Nationwide Boiler provides value with reliable equipment and top-notch customer service, and customer needs are always our priority.

Check out our recent article in Chemical Processing’s Steam System eHandbook for additional details on putting a contingency plan in place and forestalling your next steam system outage.