Machinery Component Maintenance and Repair Part 2 pdf

centralized organization of specialists within the operations department is charged with this responsibility for the network of facilities. Major engineering design and construction work related to new plants and plant expansions is handled by a separate corporate engineering department and will not be discussed in this section. The corporate engineering depart- ment is also available for special help to the operations department. As indicated previously, the interjection of technical specialists for the quick and efficient resolution of problems was one of the key points to a centralized system of engineering services, and the engineering staff at individual plants has, therefore, been kept minimal. In some plants, a certain need for minimum on-site staffing of chemical and mechanical engineers is required for day-to-day problems, but here special emphasis is placed on coordinating problem issues with the centralized staff. The normal day-to-day minor plant and equipment problems are handled by the plant manager with his staff sized on this minimum basis. The centralized engineering services then encompass these major responsibilities: 1. Aid in resolving specific equipment and process problems as they arise based on information gathered through monitoring techniques or through plant manager request. Suitable engineering or technician help is provided, including site visits when necessary. 2. Getting special services from the corporate engineering department to obtain maximum benefits from understanding the design concepts and to provide a valuable source of field problem feedback for future design considerations. This would also include obtaining recom- mendations from equipment manufacturers and outside consultants. 3. Monitoring process performance of all facilities including overall production, utility efficiency, and gathering sufficient data to gener- ally identify problem areas. Each facility requires a detailed analy- sis to determine the minimum key data required. Some monitoring is performed on a daily basis and is transmitted to the home office by e-mail. Other monitoring is performed on a weekly or monthly basis. The computer is used to perform routine calculations required for certain evaluations to determine minimum operating costs. Thus, the computer can be economically used and up-to-date process monitoring and reporting allows for prompt management attention to plant problems. 4. Monitoring of machinery and equipment performance. An example would be the periodic collection of data on all large compression equipment to determine stage efficiencies and intercooler perfor- 30 Machinery Component Maintenance and Repair mance since utility costs represent a significant portion of the total operating costs in most petrochemical or air separation plants. Where possible, the performance evaluations are translated into dollars so that business decisions can be made. Figure 2-3 shows a simplified computer program used for evaluating compressor efficiencies where the results are translated into cost inefficiencies in dollars/day. Of particular interest, also, is the increased use of field monitoring methods as a key element in evaluating equipment performance. In many cases, this represents the actual guidelines for determining frequency of inspections. 5. Monitoring of plant and equipment performance by regular visits of process and mechanical specialists to the facilities. This provides the necessary final tie of the centralized group with plant personnel. 6. Establishing safety, technical, and operating procedures to provide conformity to all plants. 7. The organization of corporate technical and training sessions for plant personnel based on the management evaluation of need. Summary The system of plant maintenance and engineering services outlined has been successful in achieving exceptionally low maintenance costs for a nationwide complex of plants. The overall maintenance system described herein has allowed a steady reduction in plant personnel with corresponding savings. Actual mainte- nance costs have steadily decreased as a percentage of original investment costs without any allowance for labor and material escalation. With these factors taken into account, the total maintenance cost reductions are indeed significant. The publishing of monitored data on plant performance and preventive maintenance compliance has allowed for prompt management attention to problems and has stimulated a noticeable spirit of competition among the plants. Needless to say, it also serves as a valuable method of evaluating plant manager performance. Although the system described herein may not be directly applicable to every large chemical complex for reasons of size or process type, the general trends toward computerization, sophisticated equipment monitor- ing methods and processes, cheaper transportation and communication costs, are indicative of increasing advantages obtainable in the future from centralized concepts in plant maintenance and engineering for multi-plant corporations. Maintenance Organization and Control for Multi-Plant Corporations 31 32 Machinery Component Maintenance and Repair Figure 2-3. Simplified computer program used to evaluate compressor efficiencies. Machinery Maintenance on the Plant Level With this overview behind us, let’s get back to the machinery engineer’s concerns on an individual plant level. As he of course knows, modern turbomachines can run reliably for many years if designed, applied, and operated correctly. As of 2004, the periods between inspection and over- haul, commonly called “turnaround,” on machines in clean, noncorrosive service can exceed eight years. It is easy to see how plant personnel may have trouble remembering just how much time and effort are required to successfully plan and execute an overhaul of a particular piece of equip- ment. A proper turnaround involves preplanning and teamwork among plant technical, warehouse, purchasing, safety, operations and mainte- nance forces, as well as with the original equipment manufacturer and other noncompany sources. In the case of sophisticated problems, con- sultants and laboratories may also come into play to restore machinery to a reliable, smooth-running, and efficient operation. Managing these resources and documenting the results presents a real challenge to those assigned the task of heading up the overhaul effort. This segment of our text deals with turnaround management principles that must be understood and considered by maintenance personnel on the plant level. Assignment of Qualified Personnel* Major machinery overhauls require not only early planning input, but also early designation of qualified personnel to execute planning and related tasks. High quality machinery overhauls can be more consistently achieved if machinery expertise is directly applied. Process plants subscribing to this approach define, in specific outline form, the responsibilities of supervisory and staff personnel involved in turnaround (T/A) of major machinery. The outline explains the various job functions involved in T/A activities and identifies the timing and scheduling requirements which precede the actual shutdown. The assignment of qualified personnel starts with the designation of an overall T/A coordinator no later than nine months before the scheduled shutdown. As of this time, the plant’s senior machinery specialist is required to maintain formal communications with the T/A coordinator. Maintenance Organization and Control for Multi-Plant Corporations 33 * Based partly on material prepared by John D. Houghton and originally presented at the Seventh Turbomachinery Symposium, Texas A&M University, College Station, Texas (December 1978). Adapted by permission. Updated in 2004. Among other duties, the T/A coordinator screens and approves the planning and scheduling efforts of maintenance or contractor personnel involved in major machinery T/A’s after the senior machinery specialist has had an opportunity to review these efforts. Working hours and team composition are to be determined jointly by the T/A coordinator and senior machinery specialist. Experience shows that a spare parts and materials coordinator should also be designated no later than nine months before scheduled shutdown. This person will generally be responsible for implementing spare parts procurement requested by the senior machinery specialist and mechani- cal supervisors. He will be required to forward up-to-date listings of parts on hand to personnel requiring this information. The plant senior machinery specialist is generally charged with respon- sibility and authority to direct planning and execution of the machinery portion of the T/A. His background and experience should make him uniquely qualified for this job, and as senior resident expert he would be thoroughly familiar with all machinery affected by the planned T/A. A key job function is to be fulfilled by turbotrain T/A engineers. On major machinery T/As it was found essential to have one or more of these engineers assigned the responsibility of verifying the quality of execution of all machinery overhaul tasks. If a given plant does not have enough machinery engineers to man the job around the clock, affiliate loan or con- tractor engineering personnel should be brought in for the duration. The specific responsibilities of turbotrain T/A engineers have been described as those of a machinery advisor and quality control person who augments the mechanical supervisor and reports to the senior machinery specialist for work direction and guidance. His responsibility and authority extends from machine inlet nozzle to machine outlet nozzle and includes lube and seal oil systems. His work begins after all required blinds have been installed and ends after every item of machinery work is complete. He will then turn over the machinery to the mechanical supervisor for removal of blinds. A turbotrain T/A engineer typically has a degree in an engineering discipline (preferably mechanical engineering) and has had practical machinery engineering experience for a minimum of five years. His past assignments should have included active participation in major machin- ery erection, commissioning, testing, operation, troubleshooting, and repair. He normally performs work which involves conventional engi- neering practices but may include a variety of complex features such as resolution of conflicting design requirements, unsuitability of conven- tional materials, and difficult coordination requirements. His normal sphere of activity requires a broad knowledge of precedents in turbo- machinery design and a good knowledge of principles and practices of 34 Machinery Component Maintenance and Repair materials technology, metalworking procedures, instrument-electrical techniques, etc. This person should be a hands-on engineer whose past performance will have established his reputation as a resourceful, highly dependable contributor, a self-starter with sound judgement. Timing and Basic Definition of Critical Pre-Turnaround Tasks Senior Machinery Specialist Immediately following the designation of a T/A coordinator (approxi- mately nine months before T/A), the senior machinery specialist starts to interface with planners, designated turbotrain T/A engineers, maintenance or mechanical supervisors, and the T/A coordinator. From then on, the following action items and timing will be typical of this function: Nine Months Before T/A: • Work list items assembled by maintenance are forwarded to the senior machinery specialist for review purposes. A typical work list page is shown in Figure 2-4. • He receives the most probable work zone outline for review and comment. (For description of work zones, refer to Volume I of this series.) • The senior machinery specialist requests up-to-date tabulation of spare parts presently on hand for major machinery trains. The spare parts coordinator must provide this tabulation in a format similar to Figure 2-5. Eight Months Before T/A: • The senior machinery specialist determines which replacement parts are required for major machinery T/A • He issues written requests for the spare parts coordinator to place a “hold” on selected parts, locally stocked parts, or to obtain these from the corporate central storage location • He specifies inspection requirements for existing key spare parts and any additional key spares to be procured Six Months Before T/A, the senior machinery specialist must: • Commence refresher training for mechanical supervisors, craftsmen, and designated contract personnel • Arrange for vendor assistance • Review the machinery T/A schedule Maintenance Organization and Control for Multi-Plant Corporations 35 36 Machinery Component Maintenance and Repair Figure 2-4. Typical worklist page for major compressor turnaround. Maintenance Organization and Control for Multi-Plant Corporations 37 Figure 2-5. Typical spare parts tabulation. Three Months Before T/A: • He meets with designated turbotrain T/A engineers for detailed brief- ing and solicitation of additional input Two Months Before T/A, the senior machinery specialist should: • Review final (detailed) T/A plan for each train • Verify that work procedures are either available or being produced One Month Before T/A, his tasks include: • Review of detailed information package for each train. This package will have been assembled by the mechanical supervisors and plan- ners, as we will discuss later • Review of bar charts prepared by maintenance, and include these in package Finally, during the actual T/A, the senior machinery specialist must: • Participate in daily T/A meeting • Verify that work procedures are followed • Verify that data are taken and logged in as required • Address deviations from plan • Review test runs • Review updated start-up instructions Turbotrain Turnaround Engineers Approximately three months before the scheduled shutdown, desig- nated turbotrain T/A engineers meet with the senior machinery specialist for detailed briefings and reviews of machinery T/A organization, proce- dures, and preparations. Additional responsibilities are as follows: Three Months Before T/A: • Prepare detailed information package for each turbotrain. A typical table of contents for one such package is shown in Figure 2-6. Sample material making up the package is shown in later illustrations. Two Months Before T/A: • Review final (detailed) T/A plan for each train • Verify that work procedures are satisfactory One Month Before T/A: • Review detailed information package for each train • Review bar charts prepared by and forwarded by the senior machin- ery specialist 38 Machinery Component Maintenance and Repair During T/A: • Participate in daily T/A meeting • Verify that work procedures are followed • Review condition of used parts as they are removed from the machine • Verify that data are taken and logged in as required • Take photographs and dictate observations into tape recorder • Verify the installation is mechanically correct Maintenance Organization and Control for Multi-Plant Corporations 39 Figure 2-6. Table of contents for typical compressor turnaround package. [...].. .Machinery Component Maintenance and Repair 40 • • • • Resolve deviations from plan Verify machinery alignment Supervise test runs Restart per startup instructions Mechanical Supervisors/Planners Planners, and also mechanical and maintenance supervisors provide machinery related data and support to the senior machinery specialist and turbotrain T/A engineers involved in planning and execution... designs in the manufacturer’s shop Any parts that fail to stand up should not necessarily be replaced by standard parts There are many excellent 60 Machinery Component Maintenance and Repair aftermarket manufacturers of components and many specialized tools such as multiplane milling machines and overspeed spin pits for individual components Aerospace technology and materials are beginning to filter down... one should “exercise” the trip and throttle valve weekly by moving the stem in and out manually several turns on the hand wheel to preclude the buildup of deposits that would prevent the machine from tripping during a shutdown condition 44 Machinery Component Maintenance and Repair Figure 2- 7 Sample sheet of turbomachinery turnaround job plan Maintenance Organization and Control for Multi-Plant Corporations... drawn up and forwarded to the senior machinery specialist • The mechanical supervisors instruct the spare parts coordinator to assemble up-to-date tabulation of spare parts presently on hand for major machinery trains After review, they forward the tabulation to the senior machinery specialist Eight Months Before T/A: • The spare parts coordinator and maintenance personnel receive the senior machinery. .. regarding location, depth, and distribution of the rubs are the keys to a proper analysis Cleaning When cleaning fouled components—rotors and diaphragms, etc.— make sure the work is done in a remote location Sand or nut hulls used 56 Machinery Component Maintenance and Repair for this purpose will usually find a way of invading the wrong parts of the machine, such as bearings and seals The rotor should... accessible components, such as couplings, and also check items such as rotor float and shaft alignment, and all tripping devices and general instrumentation In the case of steam turbines, the overspeed trip bolt and the steam trip and throttle valve have proven to be the least reliable and yet most important—safety devices in the train A check of these two components is mandatory during major shutdowns, and. .. micrometers, and a knowledgeable pair of eyes can be invaluable in detecting a defective part Also, remember that just because the part came from the factory, doesn’t necessarily mean it is the right one for your machine While 46 Machinery Component Maintenance and Repair equipment manufacturers have various quality control procedures, they too rely on human beings, and errors do occur In addition, some parts... set and newly overhauled machine have been damaged by a few seconds of careless maintenance activity The instrumentation associated with the machinery train should also be checked and calibrated Again, a list and adequate record keeping prac- Maintenance Organization and Control for Multi-Plant Corporations 51 Figure 2- 12 Clearance tabulation tices are a must The list should include all set points and. .. boxes to major machinery spare parts storage The boxes have individual compartments for labyrinths, seals, bearings, etc A list on the lid details all parts inside, their location in the box, the manufacturer’s part number and the company’s stock number Once filled, the box is sealed and stored in the usual manner During an overhaul, the box is taken to the field and some or all of the parts consumed... oversee the job and believe that all decisions and compromises should be made by him He should be responsible for the engineering coverage, interface with the maintenance and operating departments, interface between user company and original equipment manufacturer, and for documenting the overhaul It is a responsible assignment, one that requires judgment, maturity, and initiative on the part of the engineer . engineering for multi-plant corporations. Maintenance Organization and Control for Multi-Plant Corporations 31 32 Machinery Component Maintenance and Repair Figure 2- 3. Simplified computer program used. assistance • Review the machinery T/A schedule Maintenance Organization and Control for Multi-Plant Corporations 35 36 Machinery Component Maintenance and Repair Figure 2- 4. Typical worklist page. Supervisors/Planners Planners, and also mechanical and maintenance supervisors provide machinery related data and support to the senior machinery specialist and turbotrain T/A engineers involved in planning and execution