Refinery valve fault repair and on-site maintenance management
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Keywords: refinery; valve failure; repair; maintenance management usually a refinery contains a large number of various valve parts and joints and other equipment, all kinds of heavy and light oil pipeline valves will inevitably in the long-term high-pressure operation Major accidents such as various faults and even leakage of resources such as oil and gas. According to the International Petroleum Industry Environmental Conservation Association (IPIECA) survey of many large refineries around the world, the annual oil and gas leakage caused by valve failures alone accounts for about 40% of total leakage. 50%, which not only brings huge economic resources waste, but also has a huge adverse impact on environmental damage. Therefore, it is of great guiding significance to accurately grasp the causes of various failures of refinery valves and propose on-site maintenance, repair and repair methods. .
1 Valve fault classification and its causes 1.1 External leakage The external leakage of the valve is usually caused by damage to key parts of the valve such as valve body, valve cover and flange. External leakage faults generally have the following causes: 1 filler does not meet the pipeline operation requirements; 2 flange bolts are incomplete, not tightened, uneven tightening force; 3 stem bending, damage, corrosion, sand holes on the valve body , air holes, cracks; 4 valve body flange or bonnet flange joint gasket does not meet the technical requirements, gasket cracks, etc., the valve body damage air tightness.
1.2 The internal leakage fault is different from the external leakage fault. The infiltration of the valve and the invisibility of the internal helium cannot be judged by an intuitive method. Therefore, the internal leakage fault of the valve is difficult to be discovered in time, and the damage is not serious. Sex is still building enough attention. Most of the internal leakage faults of the valve can be summarized as the following reasons: 1 The valve is not strictly enforced before installation, resulting in insufficient tightness and strength; 2 Impurities in the conveying medium damage the sealing surface; 3Using the gate valve section If the flow or pressure is too high, the ram is deformed and the closing is difficult to reach. 4 The daily pipeline valve maintenance system is not strictly implemented, and the faulty valve is not repaired or replaced in time.
1.3 The valve jamming refinery valve jamming fault can usually be summarized as follows: 1 trapezoidal thread is too dirty, poor lubrication is blocked or nut failure; 2 trapezoidal slot breaks stuck; 3 long-term non-operational use and rust; 4 After the valve is closed, the valve stem is heated to death; 5 the sealing surface is scratched and the closure is not strict;
2 Repair of valve failure 2.1 External leakage failure For external leakage type failure, the main repair methods are: 1 replace the pipe packing that meets the requirements and install it properly; 2 maintain, repair, straighten, grind or replace the valve stem, replace or repair 3) Add fixed support at both ends of the valve to withstand tensile, compressive and bending stresses, or take anti-accident protection; 4 Replace the frozen cracked valve with a frost-resistant steel valve and heat-treat the valve; Replace the gasket that meets the technical requirements; 6 fill and tighten the bolt, and the tightening force should be uniform; 7 Set the expansion device when the valve is inflated and contracted.
2.2 Internal leakage failure The internal leakage of the valve is repaired by: 1 setting the filter in the pipeline and cleaning the valve regularly; 2 adding the blind ring to the isolation valve for long-term closure; 3 periodically performing technical identification and maintenance on the valve Grinding to eliminate faults in time.
2.3 valve jamming fault valve jamming fault repair method is roughly as follows: 1 regularly wipe the valve thread and add lubricant to replace the failed nut in time; 2 timely replace or repair the rust or plating off the valve stem; 3 should close after closing the valve The hand wheel prevents the valve stem from being heated by the top; 4 when the valve is closed, the applied force is appropriate, and it is not allowed to operate with the method of lengthening the arm, and the operation is properly applied; 5 correctly select and install the wedge type double gate valve.
2.4 Valve component damage failure For the failure of the valve component, the usual treatment methods are: 1 repair the fastener at any time; 2 according to the specific replacement or reinforcement flange; 3 valve installation deviation, the valve should be re-installed to make the pipe and the valve concentric The flange is perpendicular to the pipe and the two flanges are parallel.
3 On-site maintenance management of valves 3.1 Strict implementation of relevant regulations 1 The corresponding provisions of the “Code for Design of Oil and Gas Pipelines†must be strictly implemented when installing valves at all levels of the refinery; 2 Wherever there is water, steel valves should be preferred. In the special time period where the temperature changes greatly, effective and reliable insulation measures must be taken for the refinery pipeline valves, and each valve should be inspected and registered regularly. 3 Before the pipeline valve is installed, the refinery should clean the impurities in the pipeline and avoid the valve. In the event of a blockage or other failure, the pipeline must be purged at a high pressure, and all valves must be inspected and checked and properly recorded when the pipeline is completed and accepted.
3.2 Standard valve operation procedure All the pipeline valves of the refinery are uniformly numbered, and a complete operation flow chart is drawn to clarify the switching operation sequence of the valves at all levels. Strengthen the management and education system for the work team, strictly implement the double-job work and the check valve system. Clarify the scope of responsibility for valve maintenance and repair at all levels, and clarify the responsibility system of each unit and individual.
3.3 Strengthen daily inspection and maintenance Regularly diagnose the damage of all valves in the refinery, and timely repair or replace the faulty valve according to the actual situation, and prohibit the valve from “working with diseaseâ€.
4 Conclusion The refinery contains a large number of various valves, and various failures are inevitable in daily production. Establishing and improving the daily management and maintenance of valves plays an active role in preventing valve failures. Accurate and quick repair according to the type of fault in time when the fault occurs can play a decisive role in reducing the accident.
references:
[1] Li Lingbo, Liu Zhongsheng, Xiang Chen, et al. VOC emission control strategy of refinery - equipment and pipe valve leakage [J]. Contemporary Petroleum and Petrochemical, 2013, 21 (9): 1-9.
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