UDC 658.58
METHODOLOGY FOR ASSESSING THE QUALITY OF THE PROCESS OF MAINTENANCE AND REPAIR OF METAL-CUTTING MACHINES
A.V. Fedorov
A methodology for assessing process quality has been developed Maintenance and repair of metal-cutting machines and given practical example its use in production conditions industrial enterprise.
Key words: quality, service, process, machines, repair.
The modern concept of Total Quality Management (TQM) and international standards ISO 9000:2000 emphasize the process approach, according to which the production process is industrial enterprises is proposed to be considered as a network of interconnected and interacting processes, the management of which should be carried out according to the Deming-Shewhart cycle PDCA (Plan-Do-Check-Act) (Fig. 1), which includes the functions of planning, execution, quality control and regulation for each process .
Managing an organization as a network of processes necessitates quality control of each component process. According to , process quality control means taking measurements of monitored process parameters and comparing them with established requirements in order to determine compliance or non-conformity. Based this definition, we can conclude that to implement the process quality control function in PDCA cycle it is necessary to have measurable process parameters (its characteristics that are subject to measurement and control).
process indicators;
process product indicators;
indicators of customer satisfaction with the process.
Each of the listed groups of indicators can be expressed in cost, technical and time terms. Cost, time and technical indicators, in turn, can also be distributed among the levels of employee, site, workshop, subprocess, and function.
For the main business processes of an enterprise, the direct result of which is the release of products, carrying out activities to identify the characteristics of the processes that are subject to measurement and control in the PDCA cycle is usually not difficult. But when identifying measured parameters for auxiliary processes,
related to maintenance and repair of metal-cutting machines, providing basic production with equipment, fixtures, cutting and measuring tools, i.e. promoting the normal flow of the enterprise's main business processes, certain difficulties arise.
For example, in Fig. Figure 2 shows a matrix that takes into account the relationship between the measured parameters of one of the most important auxiliary processes in industrial enterprises - the process of maintenance and repair of metal-cutting machines and the requirements for its quality control.
As can be seen from Fig. 2, the quality of the maintenance and repair process cannot be comprehensively assessed by all elements of the matrix, since they are absolute indicators of the process and its product (functional equipment) and are expressed in quantitative form. Therefore, indicators for assessing process quality cannot be taken from operational data. They should be defined as relative values, i.e. as ratios. In this case, the conditions contained in the root columns of the matrix must be taken into account.
Based on the above, the following were selected as measured parameters for a comprehensive assessment of the quality of the maintenance and repair process:
efficiency and effectiveness indicators (PER) of the repair service;
material damage to the main production from equipment downtime and unscheduled repairs.
Registration of values of measured parameters with a certain pe-
frequency should be carried out in monitoring cards for the process of maintenance and repair of metal-cutting machines.
Measured parameters of the maintenance and repair process
ISO 9000 Cost indicators Time indicators Technical indicators
Process indicators Total cost of inventories cost of subcontracts, labor costs for RS personnel Total time spent on repair work Level of RS technical equipment, advanced equipment fleet
Process Product Indicators Cost repair work for a specific piece of equipment Time of subsequent operation of the equipment Technological accuracy
Indicators of consumer satisfaction with the process Total cost of repair work, share of repair costs in the cost of production Time to troubleshoot and troubleshoot Number of complaints, equipment failures
Maintenance and repair process monitoring map
STP for the maintenance and repair process
Requirements for the process owner to analyze deviations from the normal course of the process and document these deviations
Requirements for analyzing the effectiveness of corrective actions
Requirements for generating process reporting for a senior manager
Requirements for determining the planned values of process indicators for the next period
Rice. 2. Quality parameters of the maintenance and repair process
Obviously, the most important quality parameter for the maintenance and repair process is the PER, since they reflect the degree to which the actual results of the process correspond to the planned ones, as well as the relationship between the achieved result and the resources used. The advantage of PEDs is also that they can be used as a tool for continuous process monitoring.
A number of technical and economic performance indicators of the repair service were selected as the PER, which fully satisfy the conditions of the matrix (Fig. 2).
To obtain a visual representation of the level of quality of the maintenance and repair process, in monitoring maps it is advisable to use pie charts constructed according to the relative technical and economic indicators of the quality of the maintenance and repair process, and their weight coefficients (Fig. 3).
Each indicator is depicted on the diagram as a circular sector, the radius of which, μ, is equal to the value of the indicator relative to the selected analogue, and the central angle is the weight coefficient, expressed in a conventional value in degrees or radians. Basic values for all indicators are depicted by a circle with a radius equal to one. The central angle for the I-th indicator with the weight coefficient aI is defined as f = 2sh, rad, or f;- = 360°sh, deg.
The level of quality of the maintenance and repair process is determined on the basis of a complex average weighted indicator Uk, referred to here as the average weighted circular indicator. It is equal to the radius of a circle whose area is equal to the sum of the areas of the sectors of the diagram. It can be calculated using the formula
Rice. 3. Procedure for constructing a pie chart
where n is the number of relative indicators of the quality of the maintenance and repair process; w - weight coefficient; q is the value of the i-th indicator.
Experience shows that Uk is close to the weighted arithmetic average: deviations of Uk from this indicator in a wide range of changes in relative indicators and weighting coefficients do not exceed 10%.
The value of the average weighted circular indicator is graphically displayed by a circle in the form of a dotted line (Fig. 3). Uk< 1 означает, что уровень качества процесса ниже условного относительного аналога. Предлагаемый здесь средний взвешенный круговой показатель для широкого диапазона изменений относительных показателей и коэффициентов весомости имеет значения, близкие к значениям среднего взвешенного арифметического показателя. Более того, он обладает важным преимуществом по сравнению с арифметическим показателем. Оно заключается в том, что круговой показатель имеет геометрический смысл: он равен радиусу круга, площадь которого равна сумме площадей секторов диаграммы.
Weight factors for all indicators at each enterprise should be assigned using methods expert assessments and be adjusted when compared with past results. The PERs themselves are also selected by a specially created expert group, depending on the characteristics of the maintenance and repair process and the current balanced system indicators (BSC) at each enterprise, and after a certain period of recording indicators, the manager of the maintenance and repair process should determine standard and target values for each of them.
When determining material damage to main production processes from unscheduled repairs and equipment downtime, utilization indicators should be taken into account in the maintenance and repair process monitoring map work force and equipment. Then the amount of actual damage (My) can be determined with a sufficient degree of reliability by the amount of material losses due to downtime of equipment (Mo) and workers (Mr).
Mu = I Mr + £ Mo, (2)
where n is the number of workers taken into account; m is the amount of equipment taken into account.
To make claims for each specific case of violation of production conditions, a special act on economic claims is drawn up. If the costs of claims are recognized by the guilty service,
ba, then the claim signed by the parties is transferred by the interested party to the economic planning service of the enterprise. Next, the correctness of the calculations made is checked, and the amount of expenses is reflected in the reports of the relevant departments.
To automate the task of managing the process of maintenance and repair of metal-cutting machines according to the RBSL cycle, a computerized system for its dispatch and control was developed, which includes a process quality monitoring module. In Fig. Figure 4 shows a pie chart constructed by this automated system and characterizing the quality of the maintenance and repair process of metal-cutting machines at the Rudakovsky Mechanical Plant Branch of Tulatochmash OJSC.
No. Indicator Value
01.2013 02.2013 03.2013 04.2013
1. Failure rate 0.744 0.756 0.810 0.797
2. Share of repairmen’s salaries in maintenance and repair costs 0.925 0.894 0.914 0.873
3. Time lost due to breakdowns 0.870 0.886 0.895 0.871
4. Degree of development of subcontracts 0.801 0.843 0.900 0.850
5. Operational readiness coefficient 0.635 0.667 0.685 0.661
6. Available level of spare parts 0.691 0.689 0.751 0.720
7. Equipment utilization rate 0.740 0.762 0.792 0.753
UK 0.778 0.790 0.825 0.793
Rice. 4. Pie chart level of quality of the maintenance and repair process in March 2013 at the Rudakovsky Mechanical Plant Branch
OJSC "Tulatochmash"
The diagram shows those PER that most fully take into account the connection between equipment operation and the amount of labor and spare parts at the enterprise. Monitoring cards compiled by an automated system for dispatching and monitoring the process of maintenance and repair of metal-cutting machines allow the manager to monitor the quality of this process, i.e. receive a signal when various inconsistencies occur during maintenance, conduct systematic comparisons with past results and find out trends in changes in parameters, judge the results of the work of various departments of the repair service.
The application of the proposed methodology for assessing the quality of the maintenance and repair process of metal-cutting machines is successfully used at the Rudakovsky Mechanical Plant Branch of Tulatochmash OJSC and can contribute to the real implementation of the principles of the process approach and TQM at
other domestic industrial enterprises.
Bibliography
1. Quality management: Textbook for universities / S.D. Ilyenkova, N.D. Ilyenkova, V.S. Mkhitaryan et al.; edited by S.D. Ilyenkova. 2nd ed., revised. and additional M.: UNITY-DANA, 2003. 334 p.
2. Antsev V.Yu., Fedorov A.V., Dolgov V.V. Management of the process of maintenance and repair of metalworking equipment // Directory. Engineering magazine. No. 8. 2004. pp. 55-58.
3. Zheleznov G.S. Graphic representation of the level of product quality // Methods of quality management. 2002. No. 12. P. 26 - 27.
4. Antsev V.Yu., Trushin N.N., Fedorov A.V. Resolving Uncertainties in Problems technological design based on the method of expert assessments // Technological systems engineering. Sat. Proceedings of the First International Electronic Scientific and Technical Conference. Tula: Grif and Co., 2002. pp. 229 - 233.
5. Litvak B.G. Expert assessments and decision making. M. "Patent", 1996. 56 p.
6. Statistical methods for analyzing expert assessments. M.: Nauka, 1977. 384 p.
7. Management and marketing. Volume 2. Textbook / ed. A. Zhichkina. M.: "European Center for Quality", 2002. 200 p.
Fedorov Alexey Valentinovich, Ph.D. tech. Sciences, Associate Professor, Russia, Tula, Tula State University
METHOD OF EVALUATION OF QUALITY OF SERVICE AND REPAIR MACHINE TOOL
Developed a method of assessing the quality of the process of maintenance and repair of machine tools and a practical example of its use in the production of an industrial enterprise.
Key words: quality, service, process, machine, repair.
Fedorov Alexey Valentinovich, candidate of technical science, docent, Russia, Tula, Tula State University
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Regulatory and technical documents; |
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PTE |
Rules of technical operation; |
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Technical specifications; |
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Operating organization. |
4 Basic provisions
4.1 The Federal Law "On Technical Regulation" defines the safety of products, production processes, operation, storage, transportation, sales and disposal as a state in which there is no unacceptable risk associated with causing harm to the life or health of citizens, property of individuals or legal entities, state or municipal property, environment, life or health of animals and plants.
In accordance with the Federal Law of July 21, 1997 N 116-FZ “On Industrial Safety of Hazardous Production Facilities”, individual workshops, areas and production sites of power plants are identified as hazardous production facilities posing a threat to the health and life of station personnel, the population and the environment. The Law includes maintenance and repair of equipment and technical devices used at hazardous production facilities identified in the types of activities in the field of industrial safety. in the prescribed manner as part of power plants.
4.2 During the operation of power plant equipment, a change in its technical condition occurs, which determines a decrease in reliability, efficiency of use and the likelihood of deterioration in industrial, environmental and other types of safety. Restoring the quality of equipment is carried out within the framework of the system of maintenance and repair of power plant equipment.
The main purpose of the functioning of the system of maintenance and repair of power plant equipment operating at power plants is to perform maintenance and repair and ensure the required level of quality of repaired equipment to ensure the safe operation of the power plant, the reliability of the repaired equipment, and maintain stable performance characteristics equipment and its efficiency during its service life within the limits of safety, reliability and efficiency established by regulatory and technical documentation.
4.3 Monitoring and assessing the quality of repairs are prerequisite ensuring the required level of quality of repaired power plant equipment.
The quality assessment of repairs of power plant equipment is carried out:
- in terms of quality indicators of repaired equipment;
- according to the degree of fulfillment of the requirements of regulatory and technical documentation for repairs to components, assemblies, parts and equipment as a whole during the repair process, which determines the quality of the repaired equipment.
4.4 This standard has developed a methodology for assessing the quality of repairs for various types power plant equipment, which is based on a unified methodology, according to which the methodology for assessing the quality of repairs of a specific type (type) of power plant equipment includes two components:
- methods for assessing compliance with the requirements of regulatory and technical documentation for repairs to components, assemblies, parts and equipment as a whole during the repair process to restore the physical and functional properties of the equipment.
4.5 The main regulatory documents establishing the quality indicators of repaired equipment and the requirements of regulatory and technical documentation for repairs to components, assemblies, parts and equipment as a whole during the repair process are the standards of the organization of the group “Technical conditions for major repairs. Norms and requirements” (hereinafter - technical conditions for major repairs) corresponding to the type and type of power plant equipment.
4.6 When accepting equipment from repair, an assessment of the quality of repair must be carried out, containing:
- assessment of the quality of repaired equipment;
- assessment of the quality of repair work performed.
When determining these estimates, the results of meeting the requirements of technical specifications for equipment repairs must be taken into account.
5 General requirements for assessing the quality of repairs
5.1 Assessing the quality of repaired equipment
5.1.1 Assessment of the quality of repaired equipment characterizes the technical condition of the equipment after repair and its compliance with the requirements of regulatory and technical documentation.
Regulatory and technical documentation, in accordance with which the quality of repairs is assessed, includes: Rules for the technical operation of power plants and networks of the Russian Federation, standards "Technical conditions for major repairs", regulatory and design documentation of equipment manufacturing plants.
Repaired equipment may be assigned one of the following quality ratings:
- meets the requirements of NTD;
- meets the requirements of normative and technical documentation with restrictions;
- does not meet the requirements of NTD.
5.1.2 The rating “complies with the requirements of the normative and technical documentation” is established if all defects identified as a result of inspection of equipment components have been eliminated; NTD requirements defining the quality of equipment have been met; acceptance tests showed that the start-up, loading and operation of the equipment in different modes comply with the requirements of the operating standards (instructions); the quality indicators of the repaired equipment are at the standard level.
5.1.3 The rating “complies with the requirements of the normative and technical documentation with restrictions” is established if:
- some of the NTD requirements for repaired equipment are not met;
- individual defects with which the equipment can temporarily work have not been eliminated;
- there are comments on the operation of the equipment in various modes;
- the values of individual quality indicators do not correspond to the standard level, but further operation in accordance with the requirements of the NTD is possible, and the acceptance committee makes a decision on the temporary operation of the equipment.
5.1.4 Equipment repaired with the rating “complies with the requirements of the normative and technical documentation with restrictions” is allowed for operation with a limited period of further use, and an action plan must be developed to eliminate the identified deficiencies and a deadline for its implementation must be established.
5.1.5 If during the period of controlled operation it is determined that defects have arisen on the equipment that can lead to emergency consequences, or the operation of the equipment in any modes is characterized by a deviation from the permissible parameters and further operation is impossible, and the elimination of defects requires removal for repair five or more days, then the equipment must be taken out of service and a rating of “does not meet the requirements of the technical and technical documentation” is assigned to it. After repairs are carried out to eliminate defects, the equipment is re-accepted from repair, supervised operation is carried out, and a new quality assessment is established for the repaired equipment.
5.1.6 A quality rating is established for each type of repaired equipment.
The quality assessment of a repaired installation is usually established by assessing the quality of the main equipment, taking into account the quality assessments assigned to the auxiliary equipment included in the installation, which can limit the power, efficiency and reliability of the installation as a whole during subsequent operation.
5.2 Assessment of the quality of repair work performed
5.2.1 Assessment of the quality of repair work performed characterizes the organizational and technical activities of each of the organizations involved in the repair.
An organization may be assigned one of the following ratings for the quality of its repair work:
- Great;
- Fine;
- satisfactory;
- unsatisfactory.
5.2.2 An assessment of the quality of repair work performed is established for each organization within the scope of equipment repairs performed by it, taking into account the fulfillment by this organization of basic and additional requirements.
The main requirements include:
- implementation of the agreed statement of planned repair work, updated based on the results of defect detection;
- fulfillment of the requirements of the normative and technical documentation for the repair of equipment and its components;
- lack of assessment of the quality of the repaired equipment “does not meet the requirements of the normative and technical documentation” or “complies with the requirements of the normative and technical documentation with restrictions” due to the fault of the repair contractor;
- absence of equipment shutdowns during the period of controlled operation due to the fault of the repair contractor, with the exception of the need for one shutdown of the boiler or boiler body for a period of up to three days to eliminate defects in the welding of pipe joints that emerged during the period of controlled operation, and also with the exception of the need for shutdowns provided for during the period of controlled operation to monitor the condition of repaired critical components, to carry out adjustments and adjustments, including vibration, to balance the turbine unit shaft line in its own bearings.
Additional requirements include:
- availability of the necessary set of repair documentation;
- use of the necessary technological equipment, devices and tools provided for in the technological documentation, and compliance of their parameters with the passport data;
- compliance of the performed technological operations, including control ones, with the requirements of technological documentation;
- carrying out incoming inspection of materials and spare parts used during repairs;
- availability of a complete set of executive and reporting documentation for repairs.
5.2.3 An “excellent” rating is established when all basic and additional requirements are met.
A “good” rating is established when all basic and partial fulfillment (at least 50%) of additional requirements is met.
A “satisfactory” grade is assigned when all basic requirements and partial fulfillment (less than 50%) of additional requirements are met.
An “unsatisfactory” grade is assigned when one or more of the basic requirements are not met.
5.2.4 Repaired equipment may have a quality assessment - “complies with the requirements of NTD with limitation” according to the following reasons, not related to the quality of activities of repair organizations:
- reduction in power associated with the combustion of non-design types of fuel and fuel of degraded quality, restrictions on thrust and blast, restrictions on the circulating cooling water of turbine condensers;
- lack of necessary spare parts and materials;
- the presence of structural defects, consequences of accidents and the impossibility of performing the required volumes of work;
- other reasons not related to the quality of the repair organization’s activities.
In such cases, the assessment of the quality of the repaired equipment - “complies with the requirements of the normative and technical documentation with restrictions” does not affect the assessment of the quality of the repair work performed by the repair organization.
5.3 Procedure for assessing the quality of repairs
5.3.1 The quality of equipment repair is assessed during the repair process and upon acceptance of equipment from repair.
5.3.2 The order and procedure for monitoring and assessing the quality of repaired equipment and the quality of repair work performed is presented in Table 1.
Table 1 - Procedure and procedure for monitoring and assessing the quality of repairs
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Stage name |
List of work performed |
Executor |
Documentation to be completed |
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In the process of repairing the installation (power unit) |
Incoming inspection of materials and spare parts used in repairs. Defects of equipment components. Clarification based on the results of defect detection of the scope of repair. Quality control of repaired components, which consists of checking their compliance with the requirements of technical documentation, technological and design documentation. Quality control of repair work performed. Checking compliance with technological discipline. |
Work managers of enterprises and organizations involved in repairs, together with responsible representatives of the operating organization |
Results of incoming inspection, certificates for materials and spare parts used in the repair process. Executive documents for equipment defects. Statement additional work for repairs and work exclusion protocol. Act on the use of substitute materials. Protocol technical solution for identified but not eliminated defects. Test reports, measurement cards |
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Acceptance of repaired equipment, control, testing and testing before presentation to the acceptance committee |
Acceptance: responsible representatives of the operating organization. Testing, testing: under the guidance of a responsible representative of the operating organization with the participation of repair performers |
Testing protocols individual species equipment included in the installation, protocols for hydraulic tests, etc. Protocols for hidden work. List of completed repair work. Other documents as agreed upon by the operating organization and the repair contractors |
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Permission to start the installation (power unit) |
Monitoring the results of inspection of the installation (power unit), testing and testing of equipment, checking and analyzing documentation compiled during the repair process |
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Order from the technical manager of the power plant to start up the installation (power unit). The start-up is carried out after the repair contractors have submitted the work permit for repairs. |
Operating personnel in the presence of repair managers or persons appointed by them |
Before start-up, repair work managers submit written requirements to the authorized representative of the operating organization about the specifics of start-up and testing during acceptance tests that do not contradict the PTE |
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Acceptance tests |
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Start-up tests |
Monitoring the operation of the installation (power unit). Testing and testing of equipment in accordance with the acceptance testing program. Defect detection. |
Operational log, list of quality indicators. Note - Statements of quality indicators are compiled in accordance with the table given in 7.10 in Fig. 5 of this standard |
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Load test (48 hours) |
Checking equipment in operation under load at nominal parameters. Testing of equipment in accordance with the acceptance testing program. Determination of some quality indicators of repaired equipment. Defect detection. |
Operating personnel with the participation of repair performers |
Operational log, list of quality indicators |
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Completion of repairs |
The end of the repair is considered to be the time the generator is turned on to the network or the time the boiler is connected to the station live steam pipeline. If during acceptance tests defects were discovered that prevent the equipment from operating with the rated load, or the detected defects require immediate shutdown, then the repair is considered incomplete until these defects are eliminated |
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Acceptance of equipment included in the installation from repair |
The results of acceptance tests and documents drawn up by the repair contractor are considered. A decision is made on acceptance from repair. Monitoring compliance with the requirements and criteria that determine the assessment of the quality of repaired equipment and the quality of repair work performed. Preliminary assessments of the quality of the repaired equipment included in the installation are established. Preliminary assessments of the quality of the repair work performed are established. Warranties are accepted. The results of the commission’s work are documented in an act of acceptance from repair of equipment included in the installation, which is signed within 5 days after the end of acceptance tests |
Acceptance certificate for repair of installation equipment. The report is accompanied by protocols, certificates, statements and other documents drawn up by the operating organization and the repair contractor and reflecting: List of completed planned work; List of work performed in excess of the planned volume; List of uncompleted works and reasons for their non-fulfillment; List of directive documents, the requirements of which are met during repairs; Modernization works; List of works performed with deviation from established requirements, reasons for deviations. The report can be drawn up for a group of individual types of equipment included in the installation, or various components of the main equipment repaired by one enterprise |
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Preliminary quality assessment |
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Preliminary assessment of the quality of repaired equipment included in the installation |
Monitoring compliance with the requirements of regulatory and technical documentation that determines the quality of repaired equipment. Checking the elimination of identified defects. Analysis of the results of acceptance tests. Comparison of quality indicators with standard ones. Establishing an assessment of the quality of repaired equipment |
Acceptance committee headed by an authorized representative of the operating organization |
The assessment of the quality of the repaired equipment is entered into the acceptance certificate for the repair of the installation equipment. If the equipment is rated “complies with the requirements of the normative and technical documentation with restrictions,” then an action plan is developed to eliminate the identified deficiencies, indicating the time frame for its implementation. |
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Preliminary assessment of the quality of repair work performed |
Monitoring compliance with basic and additional requirements. Establishing an assessment of the quality of repair work performed: For each type of repaired installation equipment included in the acceptance certificate; To the repair company for the entire amount of work it performed on the installation |
Acceptance committee headed by an authorized representative of the operating organization |
An assessment of the quality of the repair work performed is entered into the acceptance certificate for repair of the installation equipment |
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Receipt from installation repair |
Review of the results of acceptance tests and documents compiled on the equipment included in the installation. Making a decision on acceptance of the installation from repair. The results of the commission’s work are documented in an acceptance certificate for the repair of the installation. The act is signed within 5 days after the end of the acceptance tests. The act includes preliminary assessments of the quality of the repaired equipment included in the installation, and preliminary assessments of the quality of the repair work performed by the enterprises performing the repairs. Preliminary quality assessments are accepted based on acceptance certificates for repair of installation equipment. The acceptance certificate for the installation from repair includes requirements for the need for shutdowns during the period of controlled operation to control critical components, to carry out adjustments and adjustments. These shutdowns do not affect the assessment of the quality of repair work performed. |
Acceptance committee headed by the technical manager of the power plant |
Acceptance certificate from installation repair |
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Controlled operation of repaired equipment. Start - after completion of acceptance tests. Completion - 30 calendar days from the moment the equipment is put under load |
Checking the operation of equipment in all modes, testing and adjustment, determining the quality indicators of repaired equipment. Carrying out shutdowns provided for in the acceptance certificate for installation repairs |
Operating personnel with the involvement of repair contractors if necessary |
Quality Indicator Sheets |
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Re-repair |
Detection of defects on equipment during controlled operation that could lead to emergency consequences or deviations from acceptable parameters characterizing the impossibility of further operation in accordance with the requirements of the PTE (repair duration to eliminate defects is at least 5 days). The equipment is taken out of service and subject to repair to eliminate defects. After repair, re-acceptance from repair is carried out, controlled operation |
Operating personnel, repair performers |
The equipment is rated “does not meet the requirements of the technical documentation.” After re-acceptance, a new quality rating is established for the repaired equipment. The repair company, through whose fault the repeated repair occurred, is given an assessment of the quality of the repair work performed - "unsatisfactory" |
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Final assessments of the quality of the repaired equipment included in the installation and the repair work performed |
Analysis of the results of controlled operation of equipment. If the owner or operating organization, on the basis of instructions from authorities state control based on the results of the inspection, gives a conclusion on a change in the quality assessment of the repaired equipment, the power plant is obliged to notify the repair contractor about this within three days after receiving the report indicating the reasons for the change and call his representative to make an agreed decision |
Acceptance committee headed by an authorized representative of the operating organization |
The preliminary quality assessment is considered final if the operating organization does not inform the repair contractor about its change. If, based on the results of controlled operation, the operating organization considers it necessary to change the preliminary quality assessments, then it is obliged to inform the repair contractor about this within 3 days after the end of controlled operation, indicating the reasons for the change, and call his representative to make an agreed decision. The final quality assessments are entered into the acceptance certificate for repair of plant equipment |
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Assessment of the quality of the repaired installation as a whole |
Analysis of the results of controlled operation of the installation as a whole and the installation equipment. Analysis of quality assessments of repaired equipment included in the installation |
Acceptance committee headed by the technical manager of the power plant |
An assessment of the quality of the repaired installation is entered into the acceptance certificate from the repair of the installation after the end of controlled operation |
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Preparation of reporting documentation for repairs performed |
By the end of the supervised operation, the reporting documentation for repairs is fully completed and provided to the operating organization. |
Repairers |
All documents drawn up during the repair process, acceptance tests and controlled operation by repair performers |
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Upon completion of controlled operation, within 10 days, the operating organization fully prepares the reporting documentation for repairs |
Operating organization personnel |
All documents drawn up during the repair process, acceptance tests and controlled operation |
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Note - In Table 1 and Figure 1, “technical manager of a power plant” is a person on the staff of the operating organization authorized to make decisions and give orders on all technical issues related to the equipment and structures of a given power plant |
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The table shows the stages of assessing the quality of repairs in their technological sequence, a list of work performed at each stage, performers and documentation drawn up during this process.
5.3.3 The schematic diagram of quality assessment is shown in Figure 1.
Figure 1 - Schematic diagram for assessing the quality of repairs
Picture 1 - Schematic diagram repair quality assessment
6 General requirements for methods for assessing the quality of repairs of power plant equipment
6.1 The methodology for assessing the quality of repairs for various types (types) of power plant equipment is based on a unified methodology, according to which assessment of the quality of repairs of a specific type (type) of power plant equipment includes two components:
- methods for comparing quality indicators of repaired equipment;
- methods for assessing compliance with normative and technical documentation requirements when repairing equipment.
The block diagram of the methodology for assessing the quality of repairs is shown in Figure 2.
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Don State Technical University
Features of assessing the effectiveness of the activities of mobile auto repair shops when servicing automotive equipment
A.I. Naughty
A.A. Kotesova,
M.F. Detler,
A.V. Krivorotov,
A.Yu. Parubets
annotation
The features of the activities of mobile auto repair shops are considered. Mathematical models for determining indicators are proposed that take into account the randomness of receipt of service requests and the duration of the services themselves.
Currently, the maintenance and repair of automotive equipment is carried out at stationary services and mobile auto repair shops (PARM). PARMs are used for preventive, repair and emergency work on highways, in the army, in agriculture, at large mining and oil production enterprises. The effectiveness of PARM is determined by its strategy and territorial distribution of consumers. Comparative assessment the effectiveness of the PARM can be carried out using a generalized criterion
where Pki is a complex indicator for the i-th evaluated parameter, Kvi is the weight coefficient of the i-th complex indicator (determined by the Delphi method, the brainstorming method, etc.), i = 1,2,3,...,n - - number of parameters to be estimated. The complex indicator for the i-th assessed parameter of the enterprise is determined by the formula
workshop maintenance automobile mobile
where Kj is a single indicator characterizing the state of the j-th factor influencing the complex indicator of the estimated parameter (for all components of the estimated parameters Kj = 0...1); Квj -- weight coefficient of the jth factor; j --1,2,3...n -- number of factors influencing the estimated parameter.
Most researchers propose to include as mandatory evaluated parameters: Volume and range of services (works) provided; technical equipment of PARM and its staffing, equipment and the ability to carry out technical control, environmental safety, economic requirements. At the same time, the assessment of some single indicators for PRM has a number of features, which consist in the randomness of the moments of receipt of requests for service, the duration of the services themselves and the territorial location of service consumers. To estimate such indicators we use the apparatus of Markov random processes. Figure 1 shows the simplest labeled graph of the system state
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Rice. 1 System state graph
where S1 is the operating state (work execution); S2 - transport state (movement to the place of maintenance and repair, deployment point, etc.); S3-non-working state PARM (location point); -probability densities for the transition of PARM from the Si state to the Sj state; Pi is the probability of the PARM state at time ti. Having data on the probability density of transitions, we calculate the probabilities of all states of the system at different points in time. For a labeled state graph, A.N. Kolmogorov’s system of equations will take the form:
Let's find the final probabilities characterizing the average residence time of the PARM in the corresponding states, equating the left-hand sides of the equations to zero and using the relations Р1+Р2+Р3=1. We obtain:
Cyclic Markov processes can be used to analyze the operation of cars (Fig. 2). In this case, the car can be in good working order and working (S1), waiting for repairs (S2), being repaired (S3), waiting for work after repair (S4) and working again (S1). For limiting probabilities dP/dt=0
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Rice. 2 Scheme of a Markov cyclic process
Assuming the process to be Poisson, we will find the transition probability densities by relating them to the average residence time of the PARM in a certain state Si:
From or to general view, (5)
Taking into account (4) and (5)
Let us determine the average time the PARM remains in the corresponding states for several points of technical influences. For a constant speed of movement we have:
where Li is the distance between the points of technical influences and the location (PARM dislocation); n-number of territorial requirements for technical impact; n+1 is the number of transport states of the PARM, taking into account the return to the home base. The total operating time of the PARM during a shift is equal to:
where tPi is the time of technical influences on i-th section; tnv is the standard labor intensity of the j-th impact (TBj) equal to reciprocal hourly productivity of PARM, m-number of types of technical influences. The duration of technical impact for a specific requirement is a random variable, influenced by many factors. In a number of works, these factors are proposed to be taken into account using various coefficients
where?j is the complexity of the j-th technical impact; Kmj - coefficient taking into account the level of mechanization of work under the jth impact; CD coefficient, which takes into account the reliability of information during diagnosis; KPRj - coefficient taking into account the loss of working time for organizational reasons under the jth impact; Tsm - shift duration; C-number of shifts; Pj is the average number of simultaneously working at the post under the jth impact; Kptj is a coefficient that takes into account the complexity of the work and the qualifications of the workers.
The time spent at the deployment point can be determined by the dependence:
where it determines the form of work of the PARM (shift method, or with a daily return to the location after completion of work).
Taking into account expressions (3), (6)-(9), we determine the probability of finding the PARM in work at the first point
Probability of finding a PARM on the way:
Probability of finding the PARM at the deployment point:
Let's consider an example: requests for technical maintenance of equipment with a volume of impacts were received from three points: at the first - one TO-3 (18 hours), at the second and third, 2 TO-3 each. The points are located at distances of 30 and 50 km, respectively, the distance from the place PARM dislocations to the first point are 35 km, to the last 45 km. Shift duration is 16 hours. PARM works on a rotational basis 6 days. The average speed of a car is 60 km/h.
Using dependencies 7,8,10 we find: ,
Probability of PARM being in working condition at the first point
On the second and third points
The total probability of the PRM being in working condition; the performance indicators of the PRM depend on the size of the flow of requirements and its variation, and on the performance of its component maintenance tools. For the simplest failure flow, the probability of occurrence of a certain number of requirements can be calculated from the dependence
where is the average number of failures occurring during time t, is the failure flow parameter. IN real conditions work PARM is usually taken equal to 1 (1 hour, 1 shift, 1 week, etc.). The randomness of the flow of requirements and the duration of their execution lead to costs for the functioning of the entire system. These costs can be specified by the functionality:
where C1 is the cost of vehicle idle time in the queue, is the average length of the queue, C2 is the cost of idle PRM, n is the number of idle PARMs, is the demand flow parameter, is the service intensity. It is required to organize the work of the PARM in such a way that Нu =min.
Literature
Vishnevetsky Yu. T. Technical operation, car maintenance and repair. - M.: Dashkov and K, 2006. - 380 p.
Vlasov V.M. Car maintenance and repair. - M.: "Academy", 2003. - 480 p.
Vasiliev V.I., Zharov, S.P. Improving the methodology for adjusting standards for managing the operation of rolling stock at enterprises road transport regional transport systems. // Contemporary issues science and education. 2012. No. 6. With. 7-9.
Detler M.F., Krivorotov A.V., Nedoluzhko A.I., Parubets A.Yu. On the issue of applying the standards of the planned preventative maintenance and repair system to modern cars // Engineering Bulletin of the Don, 2017, No. 2 URL: ivdon.ru/ru/magazine/archive/N2y2017/4131
Kuznetsov E.S., Boldin A.P., Vlasov V.M. and others. Technical operation of automobiles. - M.: Nauka, 2001. - 535 p.
Bazanov A.V., Bauer V.I., Kozin E.S. Determination of the need for mobile equipment to ensure the operability of automotive equipment during the repair of main oil pipelines // Scientific and Technical Bulletin of the Volga Region (Kazan), 2012, No. 3. c. 50-53
Klyuchnikova, O. V., Tsybulskaya, A. A., Shapovalova A. G. Principles for choosing the type and number of construction machines for complex work // Engineering Bulletin of the Don, 2013, No. 4 URL: ivdon. ru/ru/magazine/archive/n4y2013/2064.
Louit, D., Pascual, R. and Banjevic, D. Optimal Interval for Major Maintenance Actions in Electricity Distribution Networks // Electrical Power and Energy Systems. 2009. No. 31. pp. 396-401.
Samuel Karlin. A First Course in Stochastic Processes, 1968, p. 557
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