Maintenance Practices

Greater emphasis on maintenance of materiel was a feature of the campaign to bring procurement and distribution into balance. In the period between the wars the quantity of chemical warfare supplies was extremely limited and consequently maintenance was not much of a problem. Most CW supplies were stored at the Edgewood Depot, which had access to the shops at the arsenal to do required maintenance. In the field the CW sections in division and company headquarters were responsible for first and second echelon maintenance while repair shops near the posts or at Ordnance Department depots carried on the higher echelon repairs. The CW sections normally consisted of one officer and several enlisted men. 

In the first two years of the war more than 75 percent of all maintenance activities were third, fourth, and fifth echelon. Third and fourth echelon work was accomplished at the principal shop located at Edgewood Arsenal or at the other shops at Camp Siben and Huntsville, Pine Bluff, and Rocky Mountain Arsenals. Fifth echelon maintenance or complete rebuild was generally done by contracting with the manufacturer of the item. In the case of the gas mask, the CWS awarded contracts to four industrial concerns who were not the original manufacturers. Because facilities were limited at the Chemical Warfare shops, it was also occasionally necessary to send equipment to commercial machine shops to expedite third 

Maintenance was defined as care taken and work done to keep any item of equipment in good working condition in TM 20-205, Dictionary of U.S. Army Terms, 18 Jan 44. 

First echelon maintenance was performed by the individual, while second echelon maintenance was carried Out by an organization using tools provided in the T/O E. 

Third echelon maintenance was performed by depot companies, and fourth echelon maintenance was accomplished in rear areas. Ltr, C Fid rv, CXI CWS, to CG AGF, et at., 15 Aug 42, sub Maintenance of CWS Materiel. CWS 470.72. As a result of an ASF directive of May 1943 two echelons were made out of the third, and the fourth echelon then became the fifth echelon. 

Depending on the size of a flame arrester, the cleaning of the flame arrester element may he done in place or in the maintenance shop. Removal of the flame arrester from its location and transport to the maintenance shop may reqnire heavy lifting eqnipment. 

Care is needed to ensnre that the cleaning method is compatible with the flame arrester in terms of the materials of constmction and the arresters overall rohnstness. Snitahle cleaning methods inclnde the nse of solvents, water, steam, compressed air, or nltrasonics. 

It is critical npon reassembly to check that all gaskets are properly installed and that the element is correctly aligned in the honsing to ensnre that there is no bypassing of the element. Failnre to do this may resnlt in complete loss of protection. 

If a flame arrester element is damaged, its effectiveness will be impaired, and a replacement shonld be considered. It is important to ensnre that the replacement meets all specifications and that it is installed correctly, per the mannfactnrer s recommendations. It is recommended 

All flame arrester mannfactnrers have written instmctions for installation, inspection, and maintenance, and these shonld be followed. Some flame arrester mannfactnrers reqnire that maintenance be done at their facility to avoid invalidating the flame arrester warranty. 

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In maintenance practice, we base our decisions on NDT that is performed during shutdowns. A significant amount of money could be saved if we would have NDT methods that minimise the time required for that shutdown, or, a step further, avoid it by performing inspections onstream. 

MaintainabiUty is a characteristic of design, installation, and operation, usually expressed as the probabiUty that a system can be restored to specified operable conditions within a specified interval of time when maintenance is performed in accordance with prescribed procedures. The ease of fault detection, isolation, and repair are all influenced by system design and are principal factors contributing to maintainabiUty. Also contributing is the supply of spare parts, the supporting repair organization, and preventative maintenance practices. MaintainabiUty must be designed into the equipment. Some factors to consider foUow. 

Guide fior Pressure Relieving and Depressuring Systems, RP 521, 2nd ed., 1982 Safie Maintenance Practices in Refineries, RP 2007, 2nd ed., 1983. 

Safety issues due to unknown or insufficient information on processing hazards by the client Safety issues due to unforeseen operating and maintenance practices by the toller... 

Existing maintenance procedures must be reviewed for several reasons. Typically, these are established based upon manufacturers recommended practices for stock equipment such as pumps, centrifuges and some reactors. However, a new toll can introduce special cleaning and preparation steps as well as possible material of construction incompatibilities. If the toller is using new equipment, special maintenance practices and tools may also be required. 

QRA practitioners can use to satisfy some QRA objectives. Also, the American Institute of Chemical Engineers (AIChE) has sponsored a project to expand and improve the quality of component failure data for chemical industry use. And many process facilities have considerable equipment operating experience in maintenance files, operating logs, and the minds of operators and maintenance personnel. These data can be collected and combined with industrywide data to help achieve reasonable QRA objectives. However, care must be exercised to select data most representative of your specific system from the wide range available from various sources. Even data from your own plant may have to be modified (sometimes by a factor of 10 or more) to reflect your plant s current operating environment and maintenance practices. 

Adequate support from the facility staff is absolutely essential. The facility staff must help the analysis team gather pertinent documents (e.g., PSilDs, procedures, software descriptions, material inventories, meteorological data, population data) and must describe current operating and maintenance practices. The facility staff must then critique the logic model(s) and calculation(s) to ensure that the assumptions are correct and that the results seem reasonable. The facility staff should also be involved in developing any recommendations to reduce risk so they will fully understand the rationale behind all proposed improvements and can help ensure that the proposed improvements are feasible. Table 12 summarizes the types of facility resources and personnel needed for a typical QRA. 

The hazard identification step of the QRA typically requires the greatest involvement of plant personnel. For an existing process, only plant personnel know the status of process equipment and the current operating and maintenance practices. Excluding those personnel from the hazard identification step increases the chance of overlooking important potential hazards. For accurate results, the QRA team must have access to this information. 

If the pump is put into service with a bent or unbalanced shaft assembly, its premature tailure can be traced to inadequate maintenance practices. The evidence does not lie. However, if the premature failure leaves evidence of a deflected shaft, this would be an operations or design failure. All too often, the mechanic is blamed. The two pictures above show how a deflected shaft appears when rotated 180 degrees (Figure 9-11 and Figure 9-12). 

Maintenance practices are being combined more and more with operational practices to ensure that plants have the highest reliability with maximum efficiency. This has led to the importance of performance condition monitoring as a major tool in the operation and maintenance of a plant. Life cycle costs, rightly so, now drive the entire purchasing cycle and thus the... 

Modern day turbomachinery is built to last between 30-40 years. Thus, the keeping of basic maintenance records and critical data is imperative for a good maintenance program. Economic justification is always the controlling factor for any program, and maintenance practices are not different. 

KSC results from an environmental change that affects the probability of failure of the affected components. An obvious example is an increased failure rate due to a change in conditions such as fire, stresses from an earthquake, or improper maintenance practices affecting several components. NUREG/CR-2300 classifies this type of common cause as "Type 1."... 

Here are a few examples of faults in relief valves themselves. These are not the results of errors in design but of poor maintenance practice. The following have all been seen ... 

Snhseqnent chapters cover installation considerations (Chapter 6), inspection and maintenance practices (Chapter 7), regnlations, standards, and codes, inclnding certification test protocols (Chapter 8), and some illnstrative examples (Chapter 9). Chapter 10 provides a snmmary of the present state-of-the-art and what other information and research is needed, followed hy appendixes, a glossary, and snggested additional reading. 

This section discusses inspection and maintenance practices and procedures that affect the mechanical integrity of flame arrester installations. 

Based on the survey, the actual costs normally associated with the maintenance operation were reduced by more than 50 per cent. The comparison of maintenance costs included the actual labor and overhead of the maintenance department. It also included the actual materials cost of repair parts, tools and other equipment required to maintain plant equipment. The analysis did not include lost production time, variances in direct labor or other costs that should be directly attributed to inefficient maintenance practices. 

Poor maintenance practices lead to dirty and degraded coolant, which affects tool life, surface finish and perhaps the welfare of the operator. Proper filtration is vital, and care must be taken that contamination from other coolants or machine lubricants is kept to a minimum. 

Like any other type of equipment, clutches require regular inspection and maintenance. The sections to follow describe the general maintenance practices that are required to keep positive and friction clutches functioning properly. 

In addition to incorporating the preceding elements into any metrology program, periodic audits of the calibration and maintenance practices should occur. This is particularly important for systems generating data that are subject to review by... 

An H RA involves a review of the process design and its control, operation, and maintenance practices. The review is conducted by a multidisciplinary team with expertise in the design and operation of the process unit. The team uses a systematic screening process to determine how deviations from normal operation lead to process hazards. The H RA identifies areas where the process risk is too high, requiring the implementation of safety functions. The team s objective is to reduce the risk to below the owner/operator s risk criteria. 

FIG. 7—Radiator solder corrosion deposits at the tube to header joint, as viewed through the filler neck. This special form of corrosion can be minimized by radiator manufacturing techniques as well as recommended coolant maintenance practices. 

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