Every year as warmer weather approaches, water treatment account managers begin receiving the same important question from customers:
“How should we properly lay up our boiler for the summer?”
It’s a simple question, but the answer is critical. A proper boiler layup procedure protects internal metal surfaces, prevents corrosion, and ensures the boiler returns to service efficiently and reliably. Skipping or rushing this process can lead to costly repairs, reduced efficiency, and shortened equipment life.
The appropriate layup method depends primarily on:
- The length of the shutdown
- How quickly the boiler may need to be restarted
- The size and type of boiler (fire-tube vs. water-tube)
There are two primary layup methods:
wet layup and
dry layup. Selecting the correct method and following proper procedures will help extend the life of your boiler and protect your investment. Our
Boiler Layup Procedure* sheet can help with more detailed steps for the following layup methods.
Wet Layup
Wet layup is typically used for short-term shutdowns, generally less than 30 days. The key to a successful wet layup is maintaining proper water chemistry to prevent corrosion.
Critical Chemical Parameters
To protect the boiler’s internal surfaces:
- Alkalinity should be maintained at greater than 400 ppm.
- Oxygen scavenger residuals should be kept above 200 ppm to prevent oxygen pitting.
Wet Layup Procedure
- Fill the boiler with hot, treated water to help drive off dissolved gases.
- Vent the boiler thoroughly to remove air and non-condensable gases.
- Add the required chemicals to achieve proper residual levels.
- Fill the boiler completely to the vent line and seal it.
To maintain consistent chemistry and prevent stratification, a chemical pot feeder installed with a circulating pump is highly recommended. Drawing from the bottom and supplying to the top of the boiler ensures uniform chemical distribution and simplifies ongoing treatment adjustments.
Routine testing during wet layup is essential to confirm that chemical residuals remain within the proper range. With a pot feeder system in place, maintaining levels becomes straightforward.
Restarting from Wet Layup
Before startup:
- Perform a bottom blowdown to reduce alkalinity and conductivity.
- Lower the water level to normal operating level.
- Proceed with a standard boiler startup procedure.
Reducing alkalinity before startup helps prevent carryover conditions and operational issues.
Cascade Blowdown System (For Larger Systems)
For larger boiler systems, a cascade blowdown system can be an effective wet layup method.
In this configuration:
- The surface blowdown from the online boiler supplies treated water to offline boilers.
- Heated, chemically treated water flows from the surface blowdown line into the bottom of the offline boiler.
- A return line at the top or opposite side provides circulation.
This setup maintains proper alkalinity and oxygen scavenger levels in idle boilers without requiring separate chemical feed systems.
Dry Layup
Dry layup is recommended for extended shutdowns when the boiler will be offline for a prolonged period.
Dry Layup Procedure
- Allow boiler pressure to drop to zero.
- Open the vent and bottom drain.
- Completely drain the boiler.
- Thoroughly dry the water side using large fans, electric heaters, or other drying methods.
Moisture must be eliminated to prevent corrosion during extended downtime.
Once dry, install a
Vapor Phase Corrosion Inhibitor (VPCI). A product that we often rely on is
Cortec's Boiler Lizard. This product contains VPCI in a polyvinyl alcohol (PVA) water soluble bag, making it easy to use.
- Insert the inhibitor tube inside the boiler.
- Slit it open.
- Seal the boiler tightly as if preparing to operate it.
The VPCI vaporizes and forms a protective molecular layer on all internal metal surfaces, preventing corrosion during the shutdown period.
Cortec offers a suite of products to assist with boiler layup for a variety of sizes and situation
Restarting from Dry Layup
When the boiler is refilled:
- The inhibitor dissolves into the water.
- No special removal procedure is required.
- Standard startup procedures can then be followed.
Final Thoughts
Proper boiler layup is not just a seasonal task, it is a preventive maintenance strategy that directly impacts equipment longevity, reliability, and operating efficiency.
Choosing between wet and dry layup depends on shutdown duration and system configuration, but in all cases, maintaining proper chemistry and preventing oxygen exposure are the primary goals.
Working closely with your water treatment provider ensures that your boiler remains protected during downtime and is ready to return to service without costly surprises.
A well-executed layup today means fewer problems tomorrow and a boiler that continues running at peak efficiency for years to come.
| * The instructions above outline boiler shutdown and startup procedures from a water treatment perspective. For the safety and protection of your equipment, please refer to the boiler manufacturer’s recommendations for proper mechanical shutdown and startup procedures. |
Dennis Kwasny
Territory Manager – Northern WI
Dennis has worked in the water treatment industry for over 30 years and has experience in boiler, cooling and wastewater chemical treatment programs. Dennis leads educational training events and seminars to promote better water management and improve safety. He is a Certified Water Technologist (CWT). Contact him directly at 715-409-0129, dennis@watertechusa.com or follow him on LinkedIn.
https://www.linkedin.com/in/dennis-kwasny-cwt-5482b453/