Three new ultra low NOx (ULN) mobile boiler rooms have been added to Nationwide Boiler Inc’s growing fleet of rental boiler systems. The boilers have been specifically designed, manufactured and assembled to meet the increasing demand of steam for commercial and industrial boiler users located in California and other parts of the nation who must comply with strict air emission requirements. All three units have been pre-certified to comply with permitting agencies including the South Coast Air Quality Management District (SCAQMD) and the Bay Area Air Quality Management District (BAAQMD).
The three new units include a pair of 47.5 hp (200 psig) ULN boilers enclosed in 27’ single axle vans and one 650 hp (250 psig) ULN boiler enclosed in a 53’ van. All boilers include 9 ppm gas-fired burners (with the option to fire propane fuel), deaerators, feedwater pumps, chemical treatment systems, blowdown separators and sample cooler stations.
For more information about these boiler systems and other units in our rental fleet, visit our website at www.nationwideboiler.com.
Boiler Blog | Nationwide Boiler Inc.
Freeze Protection Guidelines
Freezing conditions pose a huge risk to boiler equipment if it is not properly protected from the harsh elements. In order to ensure that your unit continues to operate while facing freezing conditions, Nationwide Boiler recommends the following:
1. Enclose both the front and rear of the boiler area and use an external heat source to minimize freezing conditions.
2. Install heat tracing with insulation to protect exposed stagnant water lines.
3. Utilize an appropriate heat tracing method (electric or steam tracing) to all of your main lines and piping components.
This includes the following lines which should be heat traced regardless if the boiler is in operation or not
(in freezing conditions): sensing lines (steam drum to CMR, high steam and steam gauge), auxiliary
low-water-cut-off, water column and level control blowdown. Depending on the length of piping runs,
the main and continuous blowdown should also be heat traced.
4. In addition to heat tracing on stagnant sensing lines, drain the lines and fill them with a 50/50 (water/glycol) solution,
making sure to re-connect the line.
NOTE: The above lines are considered stagnant lines and should be heat traced regardless if the boiler is in operation or not (freezing conditions).
Nationwide has also done the following in addition to heat tracing on the stagnant sensing lines:
Drain line, fill with 50/50 (water/glycol) solution, re-connect line. Depending on the length of piping runs, the main and continuous blowdown should also be heat traced. For extended boiler down time, drain boiler and stagnant water lines completely.
- The above are recommendations; however, use sound engineering judgment calls when there are concerns of possible freeze damage to the equipment.
What is a non-return valve?
The main function of a non-return valve (NRV), otherwise known as stop or check valve, is to allow steam flow in one direction, and automatically prevent backflow. In other words, they prevent steam from flowing back to the main header of the boiler, or back to a boiler that has failed or is off-line.
An NRV can also be used to isolate a boiler during blowdown and shutdown, and to assist in returning a boiler to operation after any planned or unplanned maintenance.
Why are they needed?
The non-return valve is really just another safety device. Although the NRV should not be relied upon for primary shut-off, it does restrict the flow of steam back from the header into the boiler, which could be disastrous.
Per ASME standards, one NRV is required for one-boiler, high pressure applications (above 15 psig). For high-pressure applications involving multiple steam boilers with manholes that are connected to a common steam main, the steam connection from each boiler must be fitted with two stop valves. The first valve must be automatic and the second should be outside-screw-and-yoke (OS&Y).
How do they prevent backflow?
Non-return valves are flow sensitive, and rely on the steam flow to open and close. The internal disc opens and allows the flow of steam through the valve. The disc will begin to close as forward steam flow decreases or is reversed, depending on the design.
As you can see, non-return valves are critical for any steam boiler system, temporary or permanent. Be sure to check with your temporary equipment supplier to ensure that they include an NRV with their boiler rental package.
We are well into the winter season, which calls for a quick reminder on freeze protection for any boiler equipment installed outdoors, whether it is a temporary rental boiler or your facility equipment. Taking the proper preventative measures will avoid operational difficulties and major damage to your system. During freezing weather conditions, Nationwide Boiler recommends the following:
1. Enclose both the front and rear of the boiler area and use an external heat source to minimize freezing conditions.
2. Install heat tracing with insulation to protect exposed stagnant water lines.
3. Utilize an appropriate heat tracing method (electric or steam tracing) to all of your main lines and piping components. This includes the following lines, which should be heat traced regardless of whether the boiler is in operation or not (in freezing conditions):
a. Sensing lines (steam drum to CRM, high steam, and steam gauge)
b. Auxiliary low-water cut-off
c. Water column
d. Level control blowdown
e. Main and continuous blowdown (depending on length of piping runs)
4. In addition to heat tracing on stagnant sensing lines, drain the lines and fill them with a 50/50 (water/glycol) solution, making sure to re-connect the line.
5. When an extended boiler down time is expected, completely drain the boiler and stagnant water lines.
The above are recommendations, however, be sure to use sound engineering judgement calls when there are concerns of possible freeze damage to the equipment. And remember, with most rental companies, any freeze damage that requires repairs or replacement of boiler components will be the responsibility of the customer, so it is imperative that you take the correct steps to freeze protect your temporary equipment.
For further details on our freeze protection recommendations, feel free to give us a call at 1-800-227-1966.