ADVANCED MAINTENANCE SYSTEM OF LNG RECEIVING TERMINAL FOR LOW COST OPERATION AND HIGH RELIABILITY BY RBM AND RBQC

Transcription

1 23rd World Gas Conference, Amsterdam 2006 ADVANCED MAINTENANCE SYSTEM OF LNG RECEIVING TERMINAL FOR LOW COST OPERATION AND HIGH RELIABILITY BY RBM AND RBQC Main author Takafumi Aoki JAPAN

2 ABSTRUCT Tokyo Gas has three LNG receiving terminals around Tokyo Bay and two terminals of them, Negishi and Sodegaura Terminals, have been in operation more than 30 years. Some of LNG facilities in these terminals are subject to the occurrence of various phenomena associated with deterioration and maintenance cost of them is increasing due to aging. On the other hand, customers want less expensive city gas and continuous supply of that. In this situation, to obtain customer satisfaction and win the competition among LNG receiving terminals, reliability has to be prioritized, and significant reduction in maintenance cost for facilities is strongly needed at the same time. In order to solve this issue and to make cost reduction compatible with high reliability, we developed Logical Maintenance System (LMS) that can be applied to LNG receiving terminals, and it has been in operation since Outline of LMS and evaluation tools of that are introduced in section 1 and section 2. The applied results to LNG terminal and outcome of LMS are reported in section 3 and section 4.

3 TABLE OF CONTENTS 1. Outline of Logical Maintenance System 2. Evaluation Tools of Logical Maintenance System 3. Results 4. Conclusion 5. List of Tables 6. List of Figures

4 PAPER 1. OUTLINE OF LOGICAL MAINTENANCE SYSTEM Our LMS is designed to apply to maintenance of facilities in LNG receiving terminals. It is an epoch-making maintenance system because that can be used as a PDCA cyclic management system. LMS aims at minimization of life-cycle cost by analyzing quantitative data of usual maintenance and it also aims at optimization of capital investment by providing clear criteria of investment. LMS consists of five evaluation tools, i.e. RBM(Risk Based Maintenance), RBQC(Risk Based Quality Control), Long-term Maintenance Standard, KPI(Key Performance Index) and Asset Management System. By using the results of these evaluation tools, both of low cost maintenance and high level of reliability can be realized easily and efficiently. The system flow of LMS is shown in Figure1. Figure1: Flow of Logical Maintenance System

5 2. EVALUATION TOOLS OF LOGICAL MAINTENANCE SYSTEM 2.1. RBM(Risk Based Maintenance) RBM is well known as a maintenance method for optimizing maintenance based upon the risks, which are quantitatively evaluated by probability of breakdown and the influences of that. In LMS, we have arranged RBM to apply to LNG receiving terminals that can achieve more efficient maintenance. In advanced RBM, applicable to LNG receiving terminals, risk of each part of all facilities, for example main mechanical part, transmitter, control valve and so on, is evaluated by probability of breakdown and influence of that. If a certain equipment s probability of breakdown and influence of that is both great, the risk of that equipment would be greatest, if both is low, the risk of that would be lowest Probability of breakdown Probability of breakdown is defined as failure rate of each part by using our database of maintenance during the last decade. A Computer system that is designed especially for facility maintenance is in operation and database of usual maintenance, such as record of failure, result of periodic repair and so on is stored in it. Probability of breakdown is classified into four grades. When a certain equipment breaks down once a year or more, grade of probability of breakdown is 4. When it breaks down every 5 years or more, the grade is 3. If it breaks down every 30years or more, the grade is 2, and if it breaks down less than every 30 years, the grade is Influence of breakdown In advance RBM, influence when equipment breaks down is evaluated. Influence is evaluated from three aspects, that is supply reliability, safety and environment. Influence is classified into four grades that are shown in Table 1. That is, risk of breakdown is evaluated from these three aspects.

6 Table1: Classification of influences of breakdown in RBM Risk evaluation and maintenance review We evaluated risks of all facilities and all equipments in three LNG receiving Terminals of Tokyo Gas (for example, 4548 equipments and 47 facilities have been evaluated in Sodegaura Terminal). We made up a risk evaluation table that shows failure rate, influence and probability of breakdown at each part of facilities. If some equipment has high probability of breakdown and significant influence of that, the result would be extreme. In this case, we raise maintenance level. If the result is negligible, we reduce it Long-term Maintenance Standard Long-term Maintenance Standard is a maintenance standard set for facilities used for a long term and not to be replaceable, such as underground LNG tanks, LNG unloading berths. It provides the major points of defect diagnosis and premeditated inspection of these points by applying various technologies of deterioration diagnosis to enable life extension of facilities and to minimize life-cycle cost for maintenance RBQC(Risk Based Quality Control) RBQC is a method for optimization of quality control based upon the risk and cost. It aims at cost reduction and proper quality of specification.

7 Concretely, we reviewed our own maintenance standards and specifications of equipments to optimize quality control based on the risk that is provided from the result of RBM. A detailed procedure is as follows. We examine all custom-made equipments used in our LNG terminals at first, and then risks of these equipments failure are decided by the data of RBM. If risk is not great and the difference of cost between custom-made and standard equipment is great, custom-made equipment must be replaced with standard one. If risk is great or the difference of cost is small, custom-made equipment keeps being used. Outline of RBQC is introduced in figure 2. Figure2: Outline of RBQC 2.4. KPI(Key Performance Index) In Key Performance Index, indices that represent the quality of maintenance well, for example maintenance cost of facility, and the number of breakdown etc, are chosen for each facility. Various aspects of maintenance work are quantified by observing the transition of these indices continuously. KPI also provides other evaluation tools with various data of maintenance. For example, the number of breakdown is provided to RBM as failure rate, cost of maintenance to Asset management and so on. Indices of KPI that are chosen in our LMS are shown in table 2.

8 Table2: Indices of KPI 2.5. Asset Management System Introduction Asset Management System evaluates maintenance priority to optimize cost of facility maintenance and capital operation. In case of ceiling on budget, there is a possibility that all maintenance works scheduled can not be executed. This priority suggests which work should be done in this year and which work should be postponed next year. Priority is determined based on the maintenance data evaluated by the other tools of LMS. Maintenance priority is evaluated from two aspects. One is life-cycle cost, and the other is risk in operation. If life-cycle cost increases very much when a certain maintenance work is postponed and risk in operation is great, the priority of this maintenance work would be first. If life-cycle cost does not increase when postponed and risk in operation is not great, the priority would be lowest. Amount of increase of life-cycle cost is quantitatively evaluated by KPI, and risk in operation is provided from RBM. Figure 3 introduces concrete procedure to evaluate influence on life-cycle cost.

9 Figure3: Flow to evaluate influence on life-cycle(lcc) cost of a maintenance work Risk matrix to prioritize maintenance works To prioritize maintenance work, risk matrix that is shown in Table3 is used. If influence to life-cycle cost when a certain maintenance work is postponed is classified into Some and risk in operation is classified into B, priority of this maintenance work would be C1. We evaluate priority of all scheduled maintenance works of Sodegaura LNG receiving terminals in 2006, and some maintenance works scheduled has been postponed to the following year. Table3: Example of Risk Matrix on Asset management

10 3. RESULTS We applied RBM to LNG receiving terminals in advance of application of LMS in The entire system of LMS in Tokyo Gas has been in operation since Outcome of LMS is over 200,000,000 yen cost reduction of maintenance and over 150 efficiency improvement of maintenance by the result of comprehensive review of maintenance. 4. CONCLUSION Thus, LMS is achieving a great outcome. By establishing LMS as routine work flow, it can be realized to cope with both secure high reliability operation and cost reduction of maintenance, and this continuous approach increases competitiveness of LNG receiving terminals. 5. LIST OF TABLES Table1: Classification of influences of breakdown in RBM Table2: Indices of KPI Table3: Example of Risk Matrix on Asset management 6. LIST OF FIGURES Figure1: Flow of Logical Maintenance System Figure2: Outline of RBQC Figure3: Flow to evaluate influence on life-cycle (LCC) cost of a maintenance work