Major repairs that involve welding of pressure parts of the boiler are done by Steelworkers in strict adherence to the procedures in section IX of the ASME (American Society of Mechanical Engineers), "Boiler and Pressure Vessel Code." This section is concerned with operator and preventive maintenance and major considerations for the maintenance and care of firesides and watersides. Procedures for laying up idle boilers are also discussed.
Operator maintenance is the necessary, routine, recurring maintenance work performed by the operators to keep the equipment in such condition that it may be used continuously, at its original or designed capacity and efficiency for its intended purpose. The operator is actually the most important member of the maintenance team. A well-informed and responsible operator can do the following:
1. Keep equipment in service for maximum periods of time.
2. Detect any flaws so equipment can be removed from service in time to prevent serious damages.
3. Perform minor repairs on equipment removed from service to minimize outage time.
It is sometimes difficult to determine where operator duties end and maintenance crew work begins. However, the operator must realize that he or she has the keenest interest in the condition of the equipment. A well-kept plant not only reflects the operator's interest (and the desire to better his or her position) but it also is vital to the safety of equipment and personnel. It is essential for every person in the operating aisle to perform the following duties:
1. Clean. Dirt is the principal cause of equipment failure. Whether it is fly ash in the switch gear, oil on the deck, cloth lint, or dust, it causes trouble. No matter the form in which dirt appears, it should be removed immediately by the operator. 12-38
2. Lubricate. Any two surfaces brought together develop friction. If not properly lubricated, these surfaces wear one another down, change clearances, and cause equipment breakdowns. A well-placed drop of oil or a thin layer of grease can go a long way toward keeping a much-used piece of equipment in good condition.
3. Cool. Every piece of equipment has an operating temperature range. The operator should be informed on this matter. An unusual change in temperature that the operator cannot correct should be reported immediately to the plant supervisor. When the temperature of a piece of equipment rises rapidly, an immediate shutdown is recommended,
4. Tighten. Vibration is another major source of equipment failure. A simple step taken in time, such as tightening of bolts, can prevent a serious failure. Equipment that is not secured properly, vibrates, causes an unbalance, vibrates further, and compounds a cycle that can only lead to further trouble. In making rounds, the operator should put his hand on the bearings, touch the fan housing, and feel the motor casing. When any unusual sound is heard, vibration felt, or motion seen, the proper steps should be taken by the operator to correct the condition.
Preventive maintenance inspection (PMI) is a system of routine inspections of equipment recorded for future reference on some type of inspection record. The purpose of PMI is to anticipate and prevent possible equipment failures by making periodic inspections and minor repairs in advance of major operating difficulties. Preventive maintenance directed specifically toward maintaining boiler efficiency is the exception, rather than the rule. Rising fuel costs have placed an increasing emphasis on conscientious maintenance because it results in higher boiler operating efficiency. Preventive maintenance practices are easily justified from an economical and safety standpoint. Tables 12-4 and 12-5 reflect NAVFACENGCOM recommendations for PMI.Continue Reading