Boiler repaired

Safety and health audits/inspections can be done on or for the entire plant (e.g., manufacturing), a department (e.g., quality control), a specific worker unit (e.g., boiler repair), a job or task (e.g., diving), a certain work environment (e.g., confined spaces), a specific piece of equipment (e.g., forklift), a worker performing a task (e.g., power press operator), or prevention of an event (e.g., fire). It is important to ensure that inspections and audits be tailored to meet the needs of your company regarding auditing for safety and health concerns. 

The National Board Inspection Code, published by the National Board of Boiler and Pressure Vessel Inspectors, Columbus, Ohio, is helpful. Any repair, however, is acceptable if it is made in accordance with the rules of the Pressure Vessel Code. 

In the incident some of the "hot" tubes became overheated, and started to bulge. Eventually one of the tubes burst open and the contents of the boiler were discharged into the environment. No one was injured in the explosion, but it took several months to repair the boiler and the cost was heavy. In order to prevent another accident, a materials specialist was called in to examine the failed tube and comment on the reasons for the failure. 

Maintenance embraces regular inspection, periodic examination by competent persons , and repairs. Accidents may arise as a result of the lack of maintenance, during maintenance, and as a consequence of faulty maintenance. Preventive maintenance can be a legal requirement for, e.g., pressure vessels/boilers, lifting gear, power presses. A system is required for monitoring compliance witli scheduled preventive maintenance programmes, backed up by in-service inspection. Breakdown... 

The blowdown valves on the boilers were operated by a special key, which had a lug on it so that it could not be removed when the valve was open. It was therefore impossible, in theory, for two blowdown valves to be open at the same time. However, the boiler fitter kept and jealously guarded a private key w ithout a lug and had used this one to open the blowdown valve on the boiler that was under repair. He forgot to tell the process foreman what he had done or to close the valve. The presence of this key would appear to have been of little moment as long as the correct procedure of complete isolation was maintained, but as soon as it was departed from, the additional key became a menace, which eventually enabled the present tragedy to occur, the accident report said. 

A boiler had been shut down for the repair of a forced draft fan. A blind was not installed in the fuel gas line, nor apparently was a double block and bleed in the fuel line utilized. Gas leaked into the firebox during the repair period and was not removed. A severe explosion occurred during the attempt to light of. 

In 1854, the Manchester Steam Users Association was formed to help with the prevention of explosions in steam boilers and to find efficient methods in their use. To achieve this, the Association employed the first boiler inspectors, whose services were then made available to the Association s members. Within a short space of time, the members became convinced that insurance to cover the high cost of repair or replacement of damaged boilers was desirable, and this resulted in the first boiler insurance company (The Steam Boiler Assurance Company) being formed in 1858. The scope of the services for inspection and insurance later extended to include pressure vessels, steam engines, cranes, lifts and electrical plant, the insurance protection in each case being supported by an inspection service carried out by qualified engineer surveyors. 

While boiler explosions fortunately do not occur too often today because of the existence of extensive safety devices as well as the regular program of inspection, their effects can be catastrophic. Similarly, sudden and unforeseen damage caused by the overheating of multi-tubular steam boilers due to lack of water can lead to eventual furnace collapse, with very extensive repair costs as well as lost production. 

The thermal conductivity of an average boiler scale is 2.2 (W/m K) and that of complex silicate scales is 0.2-0.23 (W/m K). Since the furnace peak wall flux can be over 300,000 (W/m ) it may readily be seen that a small thickness of scale can raise the metal temperature into the creep region, resulting in very expensive repairs. 

Will adequate spare parts for the boiler be held in stock or be available within an acceptable time, and will labor be available to carry out the repair work ... 

Internal personnel will normally undertake boiler plant operation. Maintenance work may be by either internal personnel or outside contractors. Service contracts will be available from equipment suppliers covering all items of the boiler plant. Recently, companies have started offering contract energy-management schemes. These may be designed to suit individual applications and will be tailored to customer requirements. They may take over the operation of an existing plant or, if necessary, include for a new replacement plant. They will usually operate over a 3-10-year contract period. Dependent upon the terms of contract, all fuels, electricity, repairs and replacements may be covered. 

Kimmel, A. L., Holingshand, W. R. and Shea, E. P., Effect of Dissolved Oxygen on Pitting of Boiler Tubes , Am. Soc. Mech. Engrs., Paper No. 61-WA-285 Colborne, G. F., Allen, A. R. and Thunaes, A., Crash Repair Program to Control Serious Pitting Corrosion on Process Tanks , Corrosion, 17, 20 (1961)... 

It is not the intention here to consider in detail the subject of boiler feed-water conditioning and treatment for nuclear plant, but the general principles may be noted. Essentially, the same objectives apply as in fossil-fuelled plant, embodied in the three aims to minimise corrosion, deposition and steam-carryover. Requirements are more stringent in nuclear plant because there is no possibility of repairing tubes which have failed, let alone those which have suffered either deposition or corrosion. Again, certain tubes in nuclear plant have very modest design corrosion allowances so that only minimal loss of thickness from any cause can be tolerated. 

Operators who balk at the cost of providing water treatment for resistance boilers are perhaps the very same people who fail to provide adequate maintenance from the beginning of their employment and end up complaining because of unplanned production shutdowns and considerable (and unnecessary) high-cost repairs. Water treatment does not have to be sophisticated or expensive for such relatively small and simple items of boiler equipment, but some form of treatment and control is required. 

Apart from daily routines, periodic boiler housekeeping, equipment lubrication, inspection, testing, maintenance, and cleaning, overhaul and repair work becomes necessary. 

Utilities plant contract labor Today these chemical water treatment-based full-service programs may be further enhanced by the supply of various boiler plant mechanical and electrical maintenance and repair work, plus energy management services, all from a single supplier source. In fact, many customers are now replacing their entire utilities staff with contract labor under a utilities service contract. The utilities plant contractor usually subcontracts the water treatment full-service component to a specialist water treatment and environmental services company. 

Steam Sampling Awareness. The very common problem of lack of any reliable sample points in the steam condensate system presumably exists on the premise that somehow the smaller the boiler, the less the risk of condensate-related problems or the lower the potential impact of contamination. Unfortunately, this premise is simply not true as some operators can testify when the repair bills arrive or... 

Steam traps cannot be inspected during boiler shutdowns. They must be inspected during actual operation and, if suspect, be repaired or replaced at some later stage. 

To obtain a clear picture of larger, more complex, offline WT boilers, in addition to visual inspections, it is common practice to trepan or cut sections out of some of the tubes. The deposits found are weighed, reported as a weight per unit surface area, and analyzed. Repairs are then made to the tubes. 

One of several codes written by the American Society of Mechanical Engineers. Some codes provide controls for the construction, repairs, and the operation of boilers and other types of PV and boiler appurtenances in the United States. 

Major Gen. tube Boiler was operated with a known tube leak until an orderly shutdown and repair could be arranged. Explosion occurred after small leak became a big one when wall of tube fell out... 

The sulfuric acid plant has boiler blowdown and cooling tower blowdown waste streams, which are uncontaminated. However, accidental spills of acid can and do occur, and when they do, the spills contaminate the blowdown streams. Therefore, neutralization facilities should be supplied for the blowdown waste streams (Table 15), which involves the installation of a reliable pH or conductivity continuous-monitoring unit on the plant effluent stream. The second part of the system is a retaining area through which non-contaminated effluent normally flows. The detection and alarm system, when activated, causes a plant shutdown that allows location of the failure and initiation of necessary repairs. Such a system, therefore, provides the continuous protection of natural drainage waters, as well as the means to correct a process disruption. 

Requirements for vessels fabricated by forging in Part UF include unique design requirements with particular concern for stress risers, fabrication, heat treatment, repair of defects, and inspection. Vessels fabricated by brazing are covered in Part UB. Brazed vessels cannot be used in leth service, for unfired steam boilers, or for direct firing. Permitted brazing processes as well as testing of brazed joints for strength are covered. Fabrication and inspection rules are also included. 

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