Wet Layup or Dry Layup: Which Is Best For My Boiler?

Wet Layup or Dry Layup: Which Is Best For My Boiler?

A boiler is the cornerstone of any commercial building and provides heating and hot water. When taken care of well, boilers can last many years, even under intense use. To maintain and lengthen the lifespan of these crucial pieces of equipment, boiler owners and operators need to perform regular maintenance, and even provide boilers periods of rest. This post will dive into the information you need to know about two different maintenance methods: wet layup and dry layup. Need help determining what is best for your situation? Read on to find out.

An Essential Guide To Boiler Layups

Both wet layups and dry layups are boiler maintenance procedures that have advantages for specific circumstances. A well-planned layup ensures that your steam boiler has been inspected, cleaned and repaired appropriately before taking it out of service. As we will discuss, the layup maintenance process involves shutting off the boiler and implementing water treatment chemicals or a drying agent. A proper layup procedure can help protect you from unnecessary breakdowns, resulting in lower costs for repairs and downtime.

The layup process should include: 

  • Inspection of the steam boiler and associated piping system to ensure that it is in safe operating condition. This can include visual inspection, pressure testing, ultrasonic testing or other forms of examination.
  • The boiler should be cleaned with water treatment chemicals. This will remove any deposits from the inside of the boiler and piping, but will not damage any components or leave behind any residue that could clog valves or cause other problems. 
  • Repair or replace damaged parts as necessary. Damaged components may need to be repaired in place by welding on new material or replacing them entirely if they are beyond repair.
  • Layups are a great opportunity for seasoned operators to train newer technicians. This may include going through the process to ensure a newer technician understands how their work impacts the safety and efficiency of the steam system. This could include training on how to properly inspect and clean components, as well as proper operation of valves and other equipment that may be used during this process.

Next, let’s overview the core differences between wet and dry layups.

What Is A Wet Layup?

What is a wet layup infographic

Sometimes, a boiler may need to be shut off for a short period of time such as a few days or weeks. In this scenario, it makes sense to perform a wet layup, because the entire boiler system does not have to be drained. A wet layup is a procedure that uses water and chemicals to clean the boiler. The water solution remains in the boiler for the duration of time that it is turned off, and then is partially drained prior to being fired up again.

During the wet layup, a technician will fill the boiler completely with hot water (typically above 180 degrees) and a chemical that brings the water pH level to at least 12.4. This component of the process is crucial because water with an elevated pH level helps prevent corrosion on the inside of the boiler. The chemicals also absorb any oxygen remaining inside the boiler which protects the metal lining of the boiler.  

Once the boiler is filled, the technician will close the header valves to the exterior of the machine, preventing any new oxygen from getting inside. 

A huge perk of this method is how easy it is to get the boiler back into operation. Once you are ready to turn it back on, you simply have to drain the excess water down to the typical boiler operating levels, and turn the machine back on.

What Is A Dry Boiler Layup?

What is a dry layup infographic

When you are planning to give your boiler a rest for multiple months, a dry layup is the best method. The process involves first conducting a blowdown. From there, a technician will open a vent and ensure the water inside the boiler is cooled to around 140 degrees before draining the boiler entirely. This is often referred to as a “full open and close” of the boiler. The fully drained boiler is crucial, because it will help prevent corrosion during the time it is inactive. 

This procedure also takes place if the boiler is being inspected. After the drainage, the float chamber and bottom of the boiler will also be rinsed. 

After the boiler has been cleared out, it is crucial that it’s dried entirely. Technicians will often use desiccant, which is a substance that helps completely dry out a space. Ensuring complete dryness will prevent corrosion entirely. 

Other occasions when a dry layup is ideal is when you need to replace or repair a part of the boiler. It is also an option if you have a leak in your system or when upgrading your boiler. 

As mentioned before, a dry layup is best when you plan to take your boiler out of commission for a longer period of time, simply because of the increased labor involved. For boilers in heavy commercial use, doing a dry layup if the boiler will be out of service several months is a good idea.


We hope this guide about wet and dry boiler layups has been useful for you. If you have any questions or concerns about boiler layups, please don’t hesitate to contact us. At W.C. Rouse, we’re always happy to help!

Jeff Lawley

After graduating from Florida State University with a B.S. in Mechanical Engineering, Jeff Lawley headed up the engineering department at Schaefer Interstate Railing. A few years later, he took an Engineering Sales position here at W.C. Rouse & Son, and over the next 8 years, he worked his way up to the position of President of the company.