Your guideguide toto safersafer boilerboiler operation operation Your guide to safer boiler operation A 4 1

C 5 8 Supply main D 2 E

ASME Relief valve B Check valve City water 8 supply Fill valve 6 normally used

3 7 Hot water boiler

Pump

Return main

Steam boiler Hot-water boiler 1. Safety valve Steam boiler A. ExpansionHot-water tank boiler 1.2. SafetyLow-water valve cutoffSteam boiler B.A. Low-water ExpansionHot-water cutoff tank boiler 1.2.3. Safety Low-waterWater valvecolumn cutoff blow-down valve C.B.A. Combination Low-waterExpansion cutofftanktemperature/pressure 2.3.4. Low-water WaterPressuretrols column cutoff (one blow-down is high-limit valve safety) gaugeC.B. CombinationLow-water or altitude/temperature cutoff temperature/pressure gauge 3.4.5. Water PressuretrolsSteam column pressure-gauge (oneblow-down is high-limit valve safety) D.gaugeC. Operating Combination or altitude/temperature aquastat temperature/pressure gauge 4.5.6. Pressuretrols SteamWater columnpressure-gauge (one clean-out is high-limit (cross tee)safety) E.D.gauge High-limit Operating or altitude/temperature safety aquastat aquastat gauge 5.6.7. Steam WaterBottom pressure-gaugecolumn blow-off clean-out and drain (cross valve tee) E.D. High-limit Operating safetyaquastat aquastat 6.7.8. Water BottomLow-water column blow-off cutoff/blow-off clean-out and drain (cross valve tee) E. High-limit safety aquastat 7.8.Note: Bottom Low-water Second blow-off cutoff/blow-off low-water-cutoff and drain valvevalve not shown in diagram 8.Note: Low-water Second cutoff/blow-off low-water-cutoff valve not shown in diagram Boiler water-level – The fi rst duty when taking over a boiler-room shift is to make certain the pipe, fi ttings and valves Note: Second low-water-cutoff not shown in diagram Boilerbetween water-level the water glass – andThe boilerfirst dutyare freewhen and taking open overby blowing a boiler-room down theshift water is to columnmake certain and water the pipe,glass fittingsand noting and the valves promptness of the return of water to the glass. Boilerbetween water-level the water glass – Theand firstboiler dutyare freewhen and taking open over by blowinga boiler-room down shiftthe water is to columnmake certain and water the pipe, glass fittings and noting and thevalves promptness of the return of water to the glass. betweenThe most the water important glass and rule boiler – The are most free important and open rule by blowingfor the safe down operation the water of boilers column is toand maintain water glassthe proper and notingwater- the promptnesslevel at all oftimes, the returnand as ofconstant water toa level the glass. as conditions will permit. If water is not visible in the water glass, shut the boiler The most important rule – The most important rule for the safe operation of boilers is to maintain the proper water- off immediately until a safe water-level has been determined. Thelevel most at all times,important and as constantrule – Thea level most as importantconditions rule will for permit. the safe If water operation is not of visible boilers in isthe to water maintain glass, the shut proper the boiler water- leveloffLow-water immediately at all times, and untiland feedwater asa safe constant water-level acontrols level has as conditionsbeen – The determined. low-water will permit. cutoff If is water the most is not important visible electrical/mechanicalin the water glass, shut device the onboiler offyour immediately boiler for maintaining until a safe a water-level safe water-level. has been If a low-water determined. condition develops, it could very well result in an overheating and Low-water and feedwater controls explosion of your boiler. The low-water cutoff s–hould The low-waterbe tested at cutoff least weekly.is the most important electrical/mechanical device on Low-wateryour boiler for and maintaining feedwater a safe water-level. controls If– aThe low-water low-water condition cutoff develops, is the most it could important very well electrical/mechanical result in an overheating device and on yourexplosionLow-water boiler offor your maintaining cutoff, boiler. evaporation The a safe low-water water-level. cutofftest If (steamshould a low-water be boiler) tested condition at – least While develops, weekly. the boiler it could is in very operation, well result shut inoff an the overheating feedwater and explosionpump and of monitoryour boiler. the boilerThe low-water water-level. cutoff The should low-water be tested cutoff at should least weekly.shut down the burner before the water level goes Low-waterout of sight low; cutoff, if the burnerevaporation does not shut test off, (steam restart the boiler) feedwater – Whilepump beforethe boiler the wateris in operation, level goes shutout of off sight the lowfeedwater and pump and monitor the boiler water-level. The low-water cutoff should shut down the burner before the water level goes Low-waterimmediately troubleshootcutoff, evaporation the low-water cutofftest to(steam determine boiler) the cause – ofWhile failure. the The boiler boiler is mustin operation, be under shutconstant off attendancethe feedwater pumpoutby aof properlyand sight monitor low; licensed if the burnerengineerboiler water-level.does at all not times shut The duringoff, low-water restart this test.the cutofffeedwater should pump shut before down the the water burner level before goes outthe ofwater sight level low andgoes immediately troubleshoot the low-water cutoff to determine the cause of failure. The boiler must be under constant attendance out of sight low; if the burner does not shut off, restart the feedwater pump before the water level goes out of sight low and byLow-water a properly licensed cutoff, engineer slow drain at all test times (steam during this boiler) test. immediately troubleshoot the low-water cutoff to determine the – Whilecause ofthe failure. boiler is The in operation,boiler must shut be offunder the constantfeedwater attendance pump byand a properly slowly open licensed the bottom engineer blow at valve all times to drain during the waterthis test. from the boiler. The low-water cutoff should shut down the burner Low-waterbefore the water cutoff, level goes slow out drain of sight test low; (steam if the burner boiler) does not – While shut off, the restartboiler theis in feedwater operation, pump shut beforeoff the thefeedwater water leve pumpl andgoes slowly out of open sight the low bottom and immediately blow valve troubleshoot to drain the waterthe low-water from the cutoff boiler. to The determine low-water the cutoffcause shouldof failure. shut The down boiler the must burner Low-water cutoff, slow drain test (steam boiler) – While the boiler is in operation, shut off the feedwater pump beforebe under the constant water level attendance goes out by of a sight properly low; licensed if the burner engineer does at not all shut times off, during restart this the test. feedwater pump before the water level and slowly open the bottom blow valve to drain the water from the boiler. The low-water cutoff should shut down the burner goes out of sight low and immediately troubleshoot the low-water cutoff to determine the cause of failure. The boiler must before the water level goes out of sight low; if the burner does not shut off, restart the feedwater pump before the water level be under constant attendance by a properly licensed engineer at all times during this test. goes out of sight low and immediately troubleshoot the low-water cutoff to determine the cause of failure. The boiler must be under constant attendance by a properly licensed engineer at all times during this test. Firing – Aside from the standpoint of economy, maintain the fire as uniformly as possible to avoid an excessive rate of combustion, undesirable variations in temperature and possible explosions. The destructive force in a boiler explosion is caused by the instant release of energy stored in the water as heat.

Water gauges – Keep all connections and valves clear. Test by blowing down the water glass and water column regularly. Gauge cocks or tri-cocks should also be blown regularly.

Safety valves – The safety valve is the most important valve on the boiler. Safety valves prevent dangerous over pressurization of the boiler. Safety valves are installed in case there is failure of pressure controls or other devices designed to control the firing rate. All safety valves should be kept free of debris by testing the safety valve regularly. This should be done when the steam pressure is at approximately 75 percent of the safety-valve set pressure. Safety and safety-relief valves on low-pressure boilers should be tested at least quarterly, this is in accordance with the National Board Inspection Code.

Blow-down valves – The concentration of solids in the boiler should be measured and the boiler blown-down at such intervals as necessary to maintain established limits. Blow-down valves are placed at the lowest point of the boiler for the purpose of blowing sediment or scale from the boiler. They should be maintained in good working order and are to be opened and closed carefully when used.

Starting fires in a boiler – Before starting fires in a cold boiler or restarting a fire that may have been accidentally extinguished, the entire fireside of the boiler must be thoroughly ventilated (purged) with the dampers open to remove unburned gases before attempting to relight the fire. Attempting to start a fire in a boiler with unburned gases is the most common cause of boiler furnace explosions.

Boiler-room requirement – A current proper engineer’s license and log shall be posted in the boiler room. It is the responsibility of the owner and the engineer to make sure the boiler is inspected annually.

Hot-water systems – These systems are equipped with expansion tanks for the expansion and contraction of the water as the temperature varies.

Firing cycle, power burners – The burner will start when the aquastat or pressuretrol calls for heat. The breeching damper will open and the draft fan will purge the combustion chamber. The main gas or oil valve will be energized when the pilot or ignition is proved.

Repairs – Any excessive overheating or burning, and any major repairs, must be reported to your boiler inspector.

Classification of boilers – High-pressure boilers are boilers operating at a steam or other vapor pressure in excess of 15 psig, or a water or other liquid boiler in which the pressure exceeds 160 psig, or has a temperature greater than 250 degrees Fahrenheit. Others are low-pressure boilers.

License requirement – Minnesota Statutes §183.501 states "No person shall be entrusted with the operation of or operate any boiler, steam engine or turbine who has not received a license of proper grade covering that boiler, steam engine or turbine.

Study material – The Division of Boiler Inspection has no study material available and suggests you contact your nearest technical college for classes or resource materials, or contact a library or bookstore for the appropriate book.

The following books may prove useful to boiler operators: • Special Engineer: Safe Boiler Operation Fundamentals by ATP and Low Pressure Boilers by Frederick M. Steingress • Grade "C" licenses: Low Pressure Boilers by Frederick M. Steingress • Grade "B" licenses: High Pressure Boilers by Frederick M. Steingress and H.J. Frost • Grade "A" licenses: Steam Plant Operation by Woodruff and Lammers • Grade "B" and "A" licenses: Stationary Engineering by Steingress, Frost and Walker

This document can be made available in alternative formats, such as large print, Braille or audio, by calling (651) 284-5031; TTY call 1-800-627-3529. Revised July 2013