Boiler Maintenance – Courtesy of Rentech Boilers
Maintenance Requirements
A well-planned maintenance program avoids unnecessary down time or costly repairs. It also promotes safety and aids boiler code and local inspectors. An inspection schedule listing the procedures should be established. It is recommended that boiler room log or record be maintained, recording daily, weekly, monthly, and yearly maintenance activities. This provides a valuable guide and aids in obtaining boiler availability factor to determine shutdown frequency, economies, length of service, etc.
Even though the boiler has electrical and mechanical devices that make it automatic or semi-automatic in operation, these devices require systematic and periodic maintenance. Any "automatic" features do not relieve the operator from responsibility, but rather free him from certain repetitive chores, providing him with time to devote to upkeep and maintenance.
Good housekeeping helps to maintain a professional boiler room appearance. Only trained and authorized personnel should be permitted to operate, adjust, or repair the boiler and its related equipment. The boiler room should be kept free of all material and equipment not necessary for operation for the boiler.
Alertness in recognizing unusual noises, improper gauge readings, leaks, signs of overheating, etc., can make the operator aware of developing malfunction and initiate prompt corrective action that may prevent excessive repairs or unexpected down time. All piping connections to the system and its accessories must be maintained leak-proof because even a minor leak, if neglected, may soon become serious. This applies especially to the water gauge glass, water level control, piping, valve packing, and manway gaskets. If serious leaks occur shut down the boiler immediately and gradually reduce steam pressure. Do not attempt to make repairs while the boiler is under pressure.
Shift maintenance should include checking the boiler water level in the gauge glass and the boiler steam pressure on the gauge. Operate the intermittent blowdown valve to remove any accumulated solids in the mud drum. The valves on the water column and gauge glass should be operated to make sure these connections are clear. Monitor water chemistry to adjust the chemical feed treatment and continuous blowdown as required, to remain within water treatment guidelines established by the Owner's water treatment consultant.
Daily Maintenance should include a check of the burner operation, including fuel pressure, atomizing air or steam pressure, visual appearance, etc. Clean the observation ports during periods of low fire or shutdown. Test the boiler level alarms and low water cutoff. Maintain a daily schedule of sootblowing.
Check the condition of the refractory for significant damage or cracking. Patch and repair the refractory as required. Frequent wash coating of refractory surfaces is recommended. Use high temperature bonding, air-dry type mortar diluted with water, to the consistency of light cream, for this purpose. This will seal small cracks and prolong the life of the refractory. Any large cracks should be cleaned out and filled with mortar.
Follow the recommendations of you authorized inspector pertaining to safety valve inspection and testing. The frequency of testing, either by the use of the lifting lever or by raising the steam pressure, should be based on the recommendation of your authorized inspector. Test the boiler safety valves in accordance with the manufacturer's instructions to be absolutely sure that the valves have not corroded shut. Failure of the relief valves in an overpressure situation is DISASTROUS!
Have the unit inspected and checked by a service representative from the manufacturer, if possible.
Clean both the heating and heated sides of the boiler. Remove all manway and handhole covers. Open all bottom blowdown and drain valves. Hose the inside of the boiler with clean water under high pressure. Use a hand scraper to remove accumulated sludge and scale. Start near the top and work toward the bottom. After cleaning tube exteriors, inspect the tube surfaces for signs of overheating, such as bulging, blackened surfaces in the tubes, etc.
Specific local conditions determine the use of "wet" or "dry" storage during shutdown periods. If you are unsure of which procedure to follow, contact the Owner's water treatment consultant or your local insurance company.
Replacement of flange, manway, and handhole gaskets
1. Clean metal surfaces where cover plate bears against shell plate or ring.
2. Always use new gaskets. Apply graphite paste to gasket to prevent sticking and assure tightness.
3. Use care in centering cover plate and gasket in shell opening. Draw bolts up firmly. Yokes are designed for the positioning and holding of the covers only. Gasket sealing is accomplished by the application of internal pressure.
4. Spare gaskets should be maintained in your inventory to minimize your downtime.
Insurance regulations or local laws will require a periodic inspection of the pressure vessel by an Authorized Inspector. Sufficient notice is generally given to permit removal of the boiler from service and preparation for inspection. This major inspection can often be used to accomplish maintenance, replacements, or repairs that cannot easily be done at other times. This also serves as a good basis for establishing a schedule for annual, monthly, or periodic maintenance programs.
While this inspection pertains primarily to the waterside and fireside surfaces of the pressure vessel, it provides the operator an excellent opportunity for detailed inspection and check of all components of the boiler including piping, valves, pumps, gaskets , refractory, etc. Comprehensive cleaning, spot painting or re-painting and the replacement of expendable items should be planned for and taken care of during this time. Any major repairs or replacements that may be required should also, if possible, be coordinated with this period of boiler shutdown. Replacement spare parts, if not on hand, should be ordered sufficiently prior to this shutdown.
Have available information on the boiler design, dimensions, generating capacity, operating pressure, time in service, defects found previously, and any repairs or modifications. Also have available for reference records of previous inspections. Be prepared to perform any testing required by the inspector including hydrostatic testing of the equipment.