Boiler Blog Archive | 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.

Routine maintenance on your boiler is a critical component for proper and efficient boiler operation. One of the main factors to improper maintenance that can also lead to boiler failure is not understanding the concept of blowdown. In this month’s Boiler Basics 101, we will be going over what blowdown is and how it will help improve your boiler’s health.

When boiler water turns to steam, solids from the water are left behind. The blowdown process involves partially draining the boiler to remove the sludge those solids create. If these are not removed, boiler performance will be reduced and ultimately, it can lead to boiler failure.

Industrial boilers have three types of blowdown procedures:

• Low Water Cutoff
  This blowdown procedure should take place after every shift. The water column must be kept clean to ensure the water level in the gauge glass accurately represents the water level in the boiler. Regular checks on the boiler verifies that the low water cutoff is operating correctly and cleans it out.

• Bottom Blowdown
  Bottom blowdown is done by manually opening a set of two valves that drains water out of the bottom of the boiler. The purpose of the bottom blowdown activity is to clean out solids that accumulate at the bottom of a firetube boiler or in the mud drum of a watertube boiler. Solids are pushed through a blowdown separator designed to take water from the boiler during blowdown and reduce it to atmospheric pressure for disposal. During this process, steam is rapidly separated from blowdown water and vented out the top of the blowdown separator. From there, the cooled blowdown solids can be safely removed from the boiler.

• Continuous Blowdown
  The purpose of the continuous blowdown is to help control the water quality in the boiler; the more impurities and the more chemical treatment required, the greater the amount of blowdown required. It is a procedure facilitated by a pipe entering the upper section of the boiler, typically located in the steam drum of a watertube boiler or the upper steaming portion of a firetube boiler.

The continuous blowdown process is generally automated and does not require much manual interaction, like with bottom blowdown. When operating continuous blowdown, adjust the valve to maintain the recommended boiler water dissolved solids level. This helps control the dissolved solids in boilers that are operated at a steady load.

It is important to consider proper blowdown procedures to keep the water piping clean and the boiler in working condition. 

The rental boiler industry is unique and operates nowhere near the e-commerce business model; you may find it near impossible to find and compare pricing online. With that said, how can a user understand the potential cost of renting a boiler in the preliminary stages of their project, before they are ready to start reaching out and gathering information and pricing from vendors?

To get you started on the journey, these six major costs categories should be considered when looking at renting a boiler.

Ultimately, reaching out to your supplier of choice and obtaining a detailed proposal will be the best way to understand all costs involved with renting a temporary steam plant. Call or email your trusted Nationwide Boiler sales representative for a detailed cost proposal at 800-227-1966 or info@nationwideboiler.com.

Nationwide Boiler is known as being an innovative leader in the rental boiler industry. Over fifty years ago we pioneered the mounting of a 24,000 lb/hr package watertube boiler to a highway-legal trailer, and followed with many other firsts including the world’s largest trailer-mounted saturated and superheated steam boilers (125,000 lb/hr and 110,000 lb/hr, respectively).

In this age of digital technology and pandemic isolation requirements, Nationwide Boiler’s control division, Pacific Combustion Engineering, realized the need for virtual factory acceptance testing (FAT). An FAT is an essential element of the testing and acceptance of new critical control systems. The main goal of this test is to prove and certify performance built for a specific application and ensure all design requirements are attained.

Pacific Combustion’s new test gear consists of a 19” HMI that replaces toggle switches, indicating lights, potentiometers, and analog gauges. A PLC drives relays and consists of contacts that can be configured for the voltage that is required for input simulation. Outputs are displayed via selectable 120vac and 24vdc terminals. Analog 4-20ma inputs are selectable as either loop or self-powered.

During the virtual FAT, a web portal is accessible by the client through an audio/video link to the testing, and the client can actually operate the test rig HMI screen from their location. Links are also furnished to the burner management / combustion control system PLC and HMI.

This is a truly unique innovation at a time where travel can be difficult, providing an alternative to the traditional FAT and allowing business to continue even in heightened times like a global pandemic.