Boiler Blog | Nationwide Boiler Inc.

When offline, boilers can still be at risk of accumulating corrosion and deterioration that decreases the useful life of a boiler and increases maintenance and repair costs. With proper planning and preparation, a boiler can be taken offline safely with a procedure known as boiler lay up. There are two specific ways to properly shut down your boiler: dry lay up or wet lay up.

Dry lay up is a procedure that involves removing all water and moisture from the boiler. The main advantage of a dry lay up is that you can basically “set it and forget it”. There are no chemical, equipment, or fuel costs. Once completed, the boiler will just need to be checked occasionally to ensure moisture is not getting back into the boiler. A dry lay up is best for extended periods of shutdown. If the system will need to be put back online on short notice or remain in standby, this procedure would not be suitable.

A typical dry lay up procedure involves the following steps:

1.  Perform a lock-out and tag-out and isolate the boiler from the steam system.
2.  Perform column and bottom blowdowns and drain the boiler completely. 
3.  Open the fireside and remove any soot from the tubes. Look for rust or scale on the pressure boundary wall, and further evaluate any   leakage. Inspect refractory and insulation.
4.  Open the waterside and look for signs of gasket leakage and corrosion of the gasket seating surface. Inspect the entire waterside   and evaluate any scale and corrosion.
     - Any scale left on the waterside can trap moisture and oxygen and corrode the boiler further, so remove as much scale as possible.
5.  Dry all surfaces with a fan or electric air heater.
6.  Have a certified boiler inspector perform a thorough examination of all surfaces, internal and external.
7.  Determine if any repairs are required - this may be the ideal time to perform repairs without any incurring downtime, since you are   already preparing for an extended offline period.
8.  Coat the fireside with mineral oil, let it dry and close all openings including the stack. A moisture-absorbing material like silica gel or lime. 

A wet lay up is performed when the boiler is idle in standby; it is still full of water but isolated from the steam system while the burner remains offline. The procedure involves chemically treating the water to protect the metal surfaces of the boiler and is  the ideal lay up method when a boiler might need to be fired on short notice. It does, however, require additional monitoring and treatment costs that aren’t required for a dry lay up.

A typical wet lay up procedure is very similar to a dry lay up, however, the fireside should not be swabbed with mineral oil.

1.  Follow steps 1-7 above.
2.  Fill the boiler with the chemically treated hot water (greater than 180F) to its normal operating level. Allow air to continue to vent until  the boiler is full or until the steam boiler is at its normal operating level and warm.
3. Once complete, boiler water should be circulated periodically to prevent stratification of chemicals. Chemical concentrations should also be monitored routinely.

Before starting a steam boiler in wet lay-up, blow down the boiler to reduce alkalinity, ensure that all tags and locks are removed, and be sure to witness a minimum of three steam cycles before allowing the boiler to run in automatic. This will help ensure proper operation after bringing a system back online from a wet lay up.

If your facility falls under a temporary business closure mandate due to the current state of the COVID-19 pandemic, it is imperative that you follow one of the procedures outlined above to properly shut down your boiler system. View this technical article provided by the National Board for more detailed information on these two types of boiler lay up procedures.

Improper water treatment is the leading cause of tube damage and poor performance in a boiler system. In this month’s edition of Boiler Basics 101, we will discuss the consequences of introducing your boiler to hard water and the importance of utilizing a water softener.

If water is not treated properly before entering the boiler, scale will begin to form due to a chemical imbalance within the tubes. Scale is defined as concentrated minerals being precipitated when the water is evaporating in a boiler. The precipitated minerals consist of a mixture of calcium, magnesium, iron, aluminum, and silica, and are often referred to as “hard minerals”. Scale is detrimental in a boiler system because it acts as an insulator and prevents proper heat transfer. This can lead to decreased boiler efficiency, costly downtime, and even premature boiler failure. Eventually, scale build-up will cause boiler tubes to overheat and rupture.

To help prevent scale and deposit formation, make-up water should be circulated through a water softener before it is fed to the boiler. A water softener is an ion exchanger designed to remove positively charged ions from hard minerals (like magnesium, calcium, and iron) and replace them with negatively charged ions. The resin beads that are inside the resin tank are negatively charged by brine, which contains salt and potassium. As the water goes through the resin tank, the positively charged ions are chemically attracted to the negatively charged resin beads. The hard minerals then stick to the resin as the water runs through the tank, thus turning the water into “soft water”. This process frees the water from these minerals before entering the boiler and decreases the risk of tube scaling and irreversible damage.

Water softening is one of the main ways to increase boiler longevity and maintain boiler performance. Nationwide Boiler’s fleet of mobile boiler rooms, steam plants, and feedwater system trailers include duplex water softening systems to ensure optimum boiler performance. We also have skid-mounted and trailer-enclosed, stand-alone water softeners available for rent or for purchase. It’s important to know that when Nationwide Boiler delivers a rental unit, it is the customer’s responsibility to maintain and supervise the water treatment and chemistry of the water entering their rental boiler.

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. To avoid damage and costly repairs, monitor water chemistry routinely and ensure that you are supplying your boiler with soft water at all times.

Winter is officially here! When cold weather settles in, it is important to make sure that your boiler is well-maintained. Like any other mechanical system, boilers will tend to wear down over time. Boilers can be dangerous if not properly inspected and not working properly. Full boiler efficiency will help avoid boiler downtime and unnecessary expenses. Here are 14 steps to follow to help you get on track with your winter maintenance:

1. Inspect the fuel source.

The fuel used needs to have the proper viscosity for atomization. Test and gauge the fuel viscosity to ensure full efficiency. 

2. Inspect the fireside.

Inspect the fireside and look for any indication of corrosion.  If no corrosion is found, continue to clean the fireside and the furnace area as necessary. 

3. Check the refractory.

Due to the cooler weather, be aware of thermal expansion. Boiler refractors are designed to expand and contract with temperature changes. But all boilers will incur some cracking due to those constant changes. If excessive cracks are found, repair as needed.

4. Inspect the waterside.

Inspect the waterside of the boiler for scale and remove as necessary. Scale prevents heat transfer inside the boiler and can significantly lower efficiency. All water-level controls need to be properly inspected, opened, and cleaned.

5. Inspect the burner.

While the boiler is open, inspect the burner components.  Visually check the boiler’s flames. If there are inconsistencies in the flame patterns or color, there may be an underlying issue. Make sure everything is in order before proceeding. Failure to maintain the fuel system in good working order could result in excessive fuel costs, loss of heat transfer or even a boiler explosion.

6. Inspect the controls.

Any controls used to monitor the water level of the boiler should be checked after reinstalling onto the boiler. Before starting the boiler, inspect all the operating controls and look out for any signs that show of overheating.

7. Close all openings.

Make sure all of the boiler’s openings which include all doors, manholes and handholes are properly closed.

8. Open the boiler’s valves.

This is inclusive of the boiler’s header valves, piping drains and vent valve. Make sure all are operating as required and that the vent is not clogged. All ventilation requirements for the boiler need to be checked and met. 

9. Test the pumps and valves.

You will need to test all of the boiler’s pumps and valves before fully operating to make sure everything is working properly. Once everything has been tested and approved for operation you can start warming up your boiler.

10. Warm up your boiler.

To account for the colder weather it is important to increase the boiler pressure slowly. This allows the joints and metals to heat up evenly and reduce expansion stress. 

11. Switch to automatic operation.

Once your boiler is up to operating pressure, switch to automatic operation.   

12. Analyze combustion.

When you perform a combustion analysis this helps increase performance, verify component operation, decreases maintenance and fuel requirements. This will save some potential expenses made in operation. 

13. Water treatment.

Water treatment is needed before feedwater can be pumped into a boiler. Test the boiler water and treat accordingly. Follow the guidelines provided in the Installation and Operations Manual.

14. Monitor your boiler. 

Within the first few days after start-up, monitor the boiler for any leaks or any additional maintenance items. If you discover water or steam leaks at this point, shut the boiler down and have the leaks repaired.

As we enter the heart of the winter season, it’s important to remember that cold weather conditions have the potential to cause freeze damage to any boiler installed outdoors. In particular, the protection of non-enclosed rental boilers and equipment installed outdoors is imperative to avoid damage. Rental boilers and equipment come in various designs and configurations, and each unique type will require different forms of freeze damage protection. Knowing the type of equipment will help determine the right steps on how to prevent damage.  

 Here are the most common types of rental boilers: 

  _{- Mobile Boiler Rooms
  - Mobile Steam Plants
  - Trailer-Mounted Boilers
  - Skid-Mounted Boilers
  - Mobile Feedwater Systems
  - Skid-Mounted Deaerators and Other Auxiliary Equipment}

Just remember that any lines without a constant flow of water will freeze and must be properly protected from the cold. Always make sound engineering judgment calls to avoid the repercussions of freeze damage. If you have a temporary boiler and want to learn more about the proper ways to avoid freeze damage, read the recent issue of Process Heating. Nationwide Boiler was featured and our Marketing Manager, Chelsey Ryker goes over the specifics of boiler protection for each model.