KR20100117546A - Plant pipe life evaluation method based on operation history including creep and fatigue - Google Patents

Abstract

PURPOSE: A method for evaluating and recovering the reliability of a high temperature and high pressure piping and a supporting system is provided to extend the service life and reliability of a pipe system. CONSTITUTION: A method for evaluating and recovering the reliability of a high temperature and high pressure piping is as follows. A pipe system detects the display load of the respective hanger and the display distance shift of the pipe system in a room temperature and high temperature. The data for grasping a confidence level about the pipe system is produced. The deformation ratio or the stress of the pipe system is within a safety range during the service life of the pipe system. A generator sends steam to a turbine(T) from a boiler.

Description

Reliability evaluation and recovery method of high temperature and high pressure piping and support system re-evaluated based on stress / strain based on operation conditions such as creep fatigue {Plant Pipe Life Evaluation Method Based On Operation History Including Creep and Fatigue}

This technology is about the life and reliability of high temperature and high pressure piping and support system.

The plant will start and stop repeatedly as the country's electricity usage changes. Piping material fatigues when the plant starts and stops. When this pipe material is fatigued, the allowable stress in the pipe is reduced. In addition, the power generation equipment is operated at a high temperature. If it is operated for a long time at this high temperature, the piping material is affected by creep and the piping is stretched. In addition, in the power plant used for a long time, the thickness of the pipe decreases due to the erosion inside the pipe, while the thickness of the pipe increases due to the corrosion. In addition, the weight per unit length of the pipe changes in accordance with the change in the moisture content of the insulation, and in order to improve the cycle efficiency or to solve the vibration problem during long-term use may change the equipment such as valves. Therefore, power generation piping is different from the time of construction as the following items have passed the operation period. For example, at the time of construction, 5 kg / cm ² of steam was flowed out after 5 years of operation, or 15 kg / cm ² of steam was flown at the time of construction. The following items are not artificially or undesirably, such as thick scales in the pipe, but the condition is different from the beginning of operation after the period of use as a result of operation, changing the integrity of the piping material. .

 Accordingly, the technology of adjusting and maintaining the changed soundness to enable safe and safe operation has been preceded (prior art document _patent document), and the technology has been created according to the idea of a better recovery strategy than that technology.

Patent No. 10-0290553 (March 03, 2001, Apparatus and method for measuring hanger load and soundness evaluation when installed in pipe

none

When the piping system environment changes, the supporting load of each row or support supporting the piping system changes from the time of commissioning, which is a condition immediately after construction. Some sections of the piping system are heavy due to corrosion, some sections are lightened by erosion, and some sections are lightened by changing equipment, and each section of piping where hangers and supports are installed due to changes in the piping system environment. The supporting load of the hanger or the support will be different from that of the trial run. Usually, the operators of high temperature and high pressure equipment inspect the pipe support device for a certain period of time and restore the condition of the high temperature and high pressure pipe when the display load of the pipe support device is different from the test run or if it is different from the design value. State, that is, the state immediately after construction of the facility. However, if the piping environment changes due to long-term operation of the high temperature and high pressure pipe, that is, when the weight of the pipe is light, the load supported by the pipe support device should be light. It will work. Therefore, in the present invention, the high-temperature and high-pressure pipe is used to restore the load state of the piping system to the state immediately after construction for the piping system where the piping system environment may change due to long-term operation. In order to extend the service life of the piping system, the stress generated inside the structural material of the piping system can be restored within the allowable value by applying the load suitable for the environment changed by the section of the piping system due to the change of the piping system environment.

Described in the detailed description for carrying out the invention.

The high temperature and high pressure pipe used for a long time changes the piping system itself due to changes in the piping system environment such as creep and fatigue, and the stress state of the pipe pipe changes as the load of the pipe support device changes, thereby reducing the reliability of the piping system, that is, the service life. At all points, calculate the exact load acting on each pipe support point of the piping system at high temperature and room temperature, and the exact distance movement of the piping system. By maintaining the strain or stress within the safe range for the service life of the piping system, we have laid the foundation for extending the service life of high-temperature, high-pressure piping and support systems such as power plants.

1 is an example of high temperature and high pressure piping of the power plant to which the present invention is applied
2 is a distance moving state and piping support device of the piping system according to the present invention
Figure 3 is a change in the reliability relationship of the piping system due to environmental changes in the piping system according to the present invention
Figure 4 is an example of a hanger of the pipe support apparatus to which the present invention is applied
5 is an embodiment of a support angle measurement of a rigid hanger according to the present invention
Figure 6 is an embodiment of the bolt / nut fastening sequence according to the present invention
Figure 7 is an embodiment of the relationship reliability recovery according to the present invention
* Description of the main parts of the drawings
g1-g4: support angle, delta: deflection

The thermal power plant sends steam generated from the boiler (B) to the turbine (T) to rotate the turbine blades to obtain power to drive the generator. Steam is sent from a boiler to a turbine, usually flowing inside a pipe mainly composed of alloy steel. FIG. 1 shows an example of a boiler B and a turbine T of a thermal power plant and piping connecting them. In general, thermal power plants collect steam generated from a boiler in a main steam header (MH) and send it to a turbine through a main steam engine (M), and steam introduced into the turbine rotates a turbine blade to improve power generation efficiency while working. The steam is sent back to the boiler through the reheat steam engine (RP) to send the steam back to the boiler and the steam heated once again in the boiler is returned to the turbine via the reheat steam header (RH).

 In actual power plants, there are two pipes, a cold reheating engine flowing from a turbine to a boiler and a hot reheating engine flowing from a boiler to a turbine, so two reheating steam engines should appear. Since it is not important for the implementation of this patent, it is labeled as one reheating engine to help the practitioner understand.

The main steam generator for power generation is made of a thick alloy so that the temperature of the steam flowing in the pipe is 180kg / cm ² , 540 ℃ can operate for 20 to 60 years in a healthy state without rupturing the pipe even at high temperature and pressure. have. The present invention relates to a method of measuring the integrity of pipes for transporting fluids of high temperature and high pressure, such as the main engine for power generation, and recovering the integrity when there is a factor that inhibits the integrity. Therefore, from now on, only the present invention will be referred to as 'high temperature high pressure pipe' to transport the fluid of high temperature and high pressure in the pipe as described above. By setting a specific range for the high temperature and high pressure to the extent that the high temperature is the subject of the present invention, and will not be defined as not so far, but if the high temperature in the present invention usually refers to the normal temperature exceeds, high pressure is usually It means to exceed atmospheric pressure. However, since the piping of normal temperature and atmospheric pressure does not show a difference in application of this invention, this invention is not limited only to high temperature, high pressure, It can be said that it is applied to piping in the range of all temperature and pressure. However, in high temperature and high pressure piping, it is also required to apply the technology according to the present invention at a high temperature, high pressure, such as power plants, so the term 'high temperature and high pressure piping' will be used for a better understanding.

The high temperature and high pressure pipe is protected by a pipe support device such as a hanger and a support to support the weight of the piping system and to absorb deformation caused by external force of the piping system. The 'plumbing' is a pipe consisting of a pipe, a heat insulating material surrounding the pipe for insulation, a valve and a control device connected to the pipe, configured to transport the fluid, such as steam traps or strainers to equalize the characteristics of the fluid flowing in the pipe It refers to all the pipes and pipe fittings. The first design of the high-temperature, high-pressure pipes refers to the parts that are integrated into the pipes by welding or bolting devices, excluding large equipment such as pumps and heat exchangers. The piping system has a function of connecting a large apparatus and another large apparatus, and is expressed as a piping system connected from a pump to a heat exchanger, or a piping system from a heat exchanger to a boiler.

In this piping system, both ends of the piping system are connected to a large machine, and the joint connecting the large equipment and the end of the piping system is higher than the ground surface or the floor of the building, and the piping system is located in the air. In large plants, such as power plants, the distance between the large mechanical equipment often reaches a few meters, so when the piping system is left in the air, the piping system experiences a severe deflection due to the weight of the piping system. This deflection causes bending stress in the piping system, which significantly lowers the reliability of the facility. Therefore, a pipe support device is installed at an appropriate distance of the piping system so that the piping system is fixed at a constant position so that the piping system does not sag. have.

A device for fixing the piping system at a predetermined position is called a 'pipe support device', which is roughly classified into a hanger or a support. A hanger refers to the anchor point supporting the pipe at the top of the pipe, and a support point refers to the anchor point supporting the pipe at the bottom of the pipe. However, in the present invention, the spring hanger and the constant hanger having similar operating characteristics, such as the movement amount is directly displayed in the pipe support device according to the movement of the piping system, are 'hangers'. Rigid hangers that are not marked and supports that are normally classified as supports will be referred to collectively as 'supports'. In the present invention, the fixed point at which the pipe support device supports the piping pipe will be referred to as a 'pipe support point'. Therefore, the pipe support point means the pipe axial center point of the hanger or the support as the position where the hanger or the support is installed on the pipe. Such a hanger or a support also changes its spring characteristics due to deterioration of the material due to the deterioration of the driving period, or the damage of the operation link mechanism between parts, erosion and corrosion. In the case of a hanger using a spring, when the spring deteriorates or cracks, the load-length characteristic of the hanger is changed, so that the load and the moving distance indicated by the movement indicator P are different from the actual conditions. In this case, if the support is instructed to be different from the actual load and the actual moving amount, it is impossible to accurately evaluate the force and displacement of the pipe support system on the piping system. Therefore, the exact performance characteristics of the pipe support system must be confirmed. And displacement can be calculated accurately. Here, the position of the moving indicator (P) that appears after the pipe support has been used for a long time without the performance characteristics of the pipe support being re-checked is a value of a lack of reliability, so it is simply a 'display' value. Load, display distance movement amount, and when the performance of the pipe support device is re-checked and calculated with accurate load and distance movement amount, it will be expressed as 'exact load, accurate distance movement amount'. Other pipe support devices such as hangers or supports are general equipment that anyone skilled in the art can know, so the structure and the like will not be described herein any further.

The piping system has its own weight for every component constituting the piping system, including the weight of the alloying components constituting the pipe, the weight of the fluid filled in the pipe. The weight of the whole components of the plumbing system will be referred to as 'plant weight.'

Therefore, the pipe support device is a facility that supports the piping system weight at regular intervals over the entire length of the piping system. In this piping system, sagging and bending of the pipe due to the weight of the piping system occur, Pipe diameter change and pipe length change due to thermal expansion, pressure in the pipe, wind pressure or snow outside the pipe, and pipe length change, and bending between adjacent pipe support points and pipe support points occur.

The spacing between pipe support devices is such that the amount of deflection of the supporting points between the two adjacent support devices such that the combined stress generated by the internal pressure, the weight and the external force is within the allowable stress for continuous operation within the life of the power plant. Alternatively, the amount of bending at the support point is limited. The amount of deflection or bending of the pipe means that the displacement of the structural material has occurred, which causes stress generation in the pipe material according to the material mechanic theory of mechanical engineering by the correlation of load, displacement and stress. This stress should be within the proper range, but if it exceeds one point, the material will eventually be destroyed. If this deflection exceeds a certain range, the pipe will be cracked or destroyed by swelling.

Considering the soundness of piping system only, if the distance between pipe support devices is set to zero, the bending stress does not occur in the pipe of piping system, so the bending stress becomes zero (0) to obtain the highest reliability. However, in this case, the cost of constructing the pipe support device is high and the economic efficiency is lost. Therefore, by increasing the distance between the pipe support devices and reducing the number of support devices, the bending stress acting on the pipe is determined to be an economical equipment that becomes the allowable stress range for operating the life of the piping system. This is to ensure that the spacing between pipe support devices is properly maintained so that the combined stress applied to each point at any point in the pipe does not exceed the range of failure within the service life of the facility.

Material breakdown occurs as the combined stress exceeds a certain range. Since stress is a function of displacement, in the case of power generation piping, the destruction of materials can be said to be destroyed when the displacement exceeds a certain range. Therefore, ANSI B31.1 (Power Piping), the technical standard for power generation piping, limits the bending strength within a certain range or sags the pipe within a certain range.

In general, a power plant sends hot steam, water, or hot gas into a pipe. As the power plant operates, the high temperature and high pressure pipe is continuously applied with high temperature and high pressure, or high temperature and high pressure are applied. In some cases, the temperature and pressure may change cycles, such as dropping to room temperature and atmospheric pressure, and in some cases, from high temperature and high pressure to normal temperature atmospheric pressure and then to high temperature and high pressure again.

The plant will start and stop repeatedly as the country's electricity usage changes. Piping material fatigues when the plant starts and stops. When this pipe material is fatigued, the allowable stress in the pipe is reduced. In addition, the power generation equipment is operated at a high temperature. If it is operated for a long time at this high temperature, the piping material is affected by creep and the piping is stretched. In addition, in the power plant used for a long time, the thickness of the pipe decreases due to the erosion inside the pipe, while the thickness of the pipe increases due to the corrosion. In addition, the weight per unit length of the pipe changes according to the change in the moisture content of the heat insulating material, and in order to improve cycle efficiency or solve vibration problems during long-term use, equipment such as valves may be changed. Therefore, power generation piping is different from the time of construction as the following items have passed the operation period. For example, after 5 years of operation in a pipe that was sending 5 kg / cm ² of steam at the time of construction, 15 kg / cm ² of steam would be flowed at the time of construction. The following items are not artificially or undesirably, such as thick scales in the pipe, but the condition is different from the beginning of operation after the period of use as a result of operation, changing the integrity of the piping material. .

 -The fluid itself

 -Internal pressure of the fluid

 -Temperature of the fluid

 -Erosion, corrosion, or attachment or dropping of scales

 - fatigue

 -Creep

 -Moisture content of insulation

 -Self-weight by changing the length, thickness and valve characteristics of the pipe through facility improvement

 -External force that collectively refers to the force exerted by the fluid inside the piping system and the force exerted by the fluid inside the piping system such as hammering and the external force such as snow or wind pressure.

-Hanger characteristic change or failure

As described above, the factors affecting the soundness of the pipes in relation to the operation of the equipment into and out of the pipes of the piping system will be referred to as the "piping environment" in the present invention. Therefore, in the piping system described above, sagging and bending of the pipe are caused by the weight of the pipe system, thermal expansion due to the fluid temperature in the pipe, pressure in the pipe, wind pressure or snow pressure outside the pipe, and change in the diameter of the pipe and pipe Change in length, bending between neighboring pipe support points and pipe support points, etc. ”means that the pipe system sags and bends due to the weight of the pipe system, thermal expansion due to the environment of the pipe system, and the pipe diameter change. , Pipe length change, bending between adjacent pipe support points and pipe support points, etc. ”.

  In general, the high temperature and high pressure pipe is expanded as the length of the pipe as shown in Figure 2 as the temperature of the piping system changes from room temperature to high temperature in accordance with the stop of the installation. The upper horizontal line in (1) and (2) of FIG. 2 means the same as the beam of an H-beam or a building in which the pipe support device is fixed, and the lower thick line indicates the pipe fixed to the left side. 2 shows that the pipe in the room temperature of the lower thick line in (1) is expanded to a high temperature state pipe in the lower thick line of (2) in FIG. This expansion amount EXT is a sum of thermal expansion amount according to short-term operating conditions between room temperature and high temperature, long-term expansion amount by creep, and carbonaceous expansion amount by external force. When the power plant is in operation and stopped, the power plant is at room temperature. In this case, the amount of thermal expansion disappears and becomes zero (0). The amount of expansion due to creep remains as it is, and the amount of carbonaceous expansion due to external force is the change before and after starting. Will remain. 2, (1) represents a room temperature state, (2) represents a high temperature state, 1,2,3,4 represents a pipe support device, and a, b, c, d represents the pipe support device 1 at room temperature. Lower portions of 2, 3, and 4 represent positions integrated with the plumbing system. a ', b', c ', d' indicates a position in which the lower part of the pipe support devices 1,2,3,4 is integrated with a piping system expanded by a high temperature at a high temperature (1) of FIG. Points a, b, c, and d move with expansion of the pipe.

As shown in FIG. 2, when the length of the piping system changes according to the change of the piping system environment, the support angle of the piping support device of the piping system (支持 角, a vertical line and a hanger rod (Hanger, generally lowered from the upper fixed point of the piping support device) Rod axis) also changes as g1, g2, g3, g4. If the support angle of the pipe support device is changed, the weight of the piping system does not change, and even though the support load of the pipe support device is the same, the support load of the hanger is changed by the combined force or decomposition of the vector whose angle changes. This indicates that even if there is no change in the weight of the piping system, if the length of the piping system is changed, the support load value of the pipe support device supporting the piping system is changed.

However, when the weight of the piping system changes due to the change in the piping system environment, the amount of deflection of the piping pipe changes as shown in FIG. 3. As a simple example, if the weight of WT is increased in the pipe between the pipe support devices 2 and 3 in the piping system of [Fig. 3], the pipe will sag as much as delta at the wp position, and the amount of deflection is at both ends of the pipe section where this deflection occurs. The bending stress is generated by causing the pipe to bend at the b 'and c' positions supporting the. In this case, if the self weight increases, the support load applied to the pipe support device (here 2 and 3) supporting the section in which the self weight increases is relatively increased. In this state, when the load display point, which is the status display point of the pipe support device, is more loaded than the design load, the conventional technique has been to reduce the increased load. However, if the load on the pipe support device 2, 3 of Figure 3 is reduced, it is immediately transferred to the pipe support device adjacent to the peripheral pipe support device 1,4 or 1,4. In this case, the piping pipe material with the supporting point of the pipe supporting device whose load is transferred increases the reaction force as the supporting load increases, which increases the bending deformation of the pipe, which increases the bending stress. This results in a change in the piping system environment, which causes additional stress on the piping system, resulting in similar reliability as before the load reduction in the second and third times, that is, the reliability of the piping system is lower due to the change in the piping system environment.

If the high-temperature and high-pressure pipes are operated for a long time, problems such as cracking, swelling, and swelling occur during the initial test operation due to corrosion, erosion, creep, and fatigue. This problem does not occur suddenly but gradually with the passage of time depending on the environment of the piping system. When evaluating the condition of the piping system in operation, it is possible to know how close the current condition is to the condition of the accident. In this way, access to the state of accidents is called the reliability of the pipe, and when the accident of material destruction due to changes in the pipe crab environment caused by long-term operation, the life of the pipe is said to be exhausted.

In high temperature and high pressure piping, the piping system environment changes as the operation period elapses, reducing the resistance of the pipe material due to creep and fatigue.In addition, by visually inspecting the outside of the piping system during operation, the internal condition of the piping system can be known. I can't. In the interior of the piping system, the strain is increased in the interior of the piping system according to all the piping system that is externally acted on, and this strain is generated by the change of the stress, which is generated by the application of the external stress. After all, it is the environment of the piping system that causes strain in the piping system. However, the piping system environment changes with the operation of the equipment, but this cannot be seen with the naked eye. Therefore, in order to know the influence of the material inside of the pipe system on the pipe of the pipe system, that is, the strain or stress state inside the material, the external force applied to the pipe system, that is, the degree of force, may be known.

This force is summed up by the load on the hanger or the support hanged on the pipe support, ie the amount of force hanged on the hanger or the support. Therefore, when the piping system environment is changed, the supporting load of each row or support supporting the piping system is different from the time of commissioning, which is a condition immediately after construction. Some sections of the piping system are heavy due to corrosion, some sections are lightened by erosion, and some sections are lightened by changing equipment, and each section of piping where hangers and supports are installed due to changes in the piping system environment. The supporting load of the hanger or the support will be different from that of the trial run. Usually, the operators of high temperature and high pressure equipment inspect the pipe support device for a certain period of time and restore the condition of the high temperature and high pressure pipe when the display load of the pipe support device is different from the test run or if it is different from the design value. State, that is, the state immediately after construction of the facility. However, when the high temperature and high pressure pipe is operated for a long time and the piping system environment is changed, that is, when the weight of the pipe is lightened at any part, the load supported by the pipe support device must be light. This will work. Therefore, in the present invention, the high-temperature and high-pressure pipe is to deteriorate the stress state inside the material of the piping system that is currently deformed by restoring the loading state of the piping system to the state immediately after construction for the piping system where the piping environment may change due to long-term operation. In order to extend the service life of the piping system, the stress generated inside the structural material of the piping system can be restored within the allowable value by applying the load suitable for the environment changed by the section of the piping system due to the change of the piping system environment.

  To this end, if the piping system environment is changed, the supporting load of each row or support supporting the piping system will be different from the time of commissioning, which is a condition immediately after construction. Some sections of the piping system are heavy due to corrosion, some sections are lightened by erosion, and some sections are lightened by changing equipment, and each section of piping where hangers and supports are installed due to changes in the piping system environment. The supporting load of the hanger or the support will be different from that of the trial run. Usually, the operators of high temperature and high pressure equipment inspect the pipe support device for a certain period of time and restore the condition of the high temperature and high pressure pipe when the display load of the pipe support device is different from the test run or if it is different from the design value. State, that is, the state immediately after construction of the facility. However, when the high temperature and high pressure pipe is operated for a long time and the piping system environment is changed, that is, when the weight of the pipe is lightened at any part, the load supported by the pipe support device must be light. This will work. Therefore, in the present invention, the high-temperature and high-pressure pipe is to deteriorate the stress state inside the material of the piping system that is currently deformed by restoring the loading state of the piping system to the state immediately after construction for the piping system where the piping environment may change due to long-term operation. It aims to extend the service life of the piping system by restoring the stress generated inside the structural material of the piping system within the allowable value by applying the load that is changed according to the section of the piping system due to the change of the piping system environment. .

In order to realize this specifically for high-temperature and high-pressure pipes, the display load and the distance travel of the pipe support device for two points of interest, such as the low temperature state before the operation of the facility or the high temperature state at which the facility reaches its normal power output. By visually reading and evaluating if the display load and distance travel of the pipe support system cannot be measured visually,

  To read the status values (position load and distance travel) of the instruments that can indicate the status related to the reliability of the high temperature and high pressure pipe currently in operation.

  In addition, the individual performance of the pipe support system is evaluated in order to evaluate whether the condition values indicated by the instruments that can indicate the state related to the reliability of the high temperature and high pressure pipe are correct.

  Accurately calculates the support load and distance movement amount for each pipe support device reflecting the results of individual performance evaluation. If the status values indicated by the instruments that can indicate the status related to the reliability of the pipe are not correct, correct them and correct them. Indicate,

  Instead of modifying the display load and distance travel amount of this pipe support device to be the state value or design value immediately after construction, allow the stress or strain in the piping material to cause the corrected display value and distance travel amount of the pipe support device. To lower below

  Accurate state value indicating the state related to the reliability of the high-temperature and high-pressure pipe by adjusting the load and the distance movement of the pipe support device corresponding to the difference between the stress or strain and the allowable stress or strain in the piping material based on the pipe support point. Based on this, the reliability of the entire area of interest of the high temperature and high pressure piping and supporting devices in the current state should be evaluated.

The reliability of the high temperature and high pressure pipe is high when the stress or strain acting on the material is within a predetermined value and there are many differences, and when it is close to the predetermined value, it means that the material will be destroyed soon.

Accordingly, the present invention is to increase the reliability of the piping system to extend the life of the piping system that the reliability of the piping system due to the change in the piping system reaction force caused by the support load of the pipe support device and the distance movement of the piping system according to the change of the piping system environment.

  Among all the pipe support devices supporting high temperature and high pressure pipes such as the power plant in operation, the load-related scale is measured at the position of the travel indicator (P) for the spring hanger, and the nameplate attached to the constant hanger for the constant hanger. Read the hanger capacity to understand the display load acting on the hanger, and at the same time, the spring hanger measures the distance-related scale at the position of the Travel Indicator (P), and in the case of the constant hanger, the distance-related scale of the nameplate attached to the constant hanger. A hanger operating point measuring step of checking the display distance movement amount of the hanger and the display distance movement amount of the hanger, respectively, at a normal temperature and a high temperature state, by determining the display distance movement amount of the piping system at the hanger position.

  In the case of a support except for rigid hangers in a state in which the piping system is at room temperature or in a high temperature state, a straight line is drawn from the support pipe to the pipe of the piping system at a right angle from the axial direction of the piping system and at the time when the temperature state of the piping system is changed, In the case of rigid hangers, the support angle of the hanger rod is measured at each point before and after the temperature of the piping system changes, and the distance movement of the piping system is measured, or a commercial distance measuring means is installed between the support and the piping system. Calculate the distance movement of the support, and measure the load on the support through the support load measurement point to check the display load of the support and the display distance movement in the piping

  Calculate the display load and the display distance movement amount applied to each pipe support point of the piping system at high temperature and room temperature at all points with the pipe support device.

  Performance evaluation step of evaluating the performance of the pipe support device in the state where the pipe support device is installed in the field in order to grasp whether the performance of the pipe support device is changed due to material deterioration and breakdown, etc., as a result of long-term operation. through

  Calculate the exact load acting on each pipe support point of piping system at high temperature and room temperature, and the exact distance movement of piping system at all points with piping support device.

  Material and mechanical continuity based on physical constants such as thermal expansion coefficient and elastic modulus according to the material of piping system and pipe cross-sectional data, pipe section data, etc. By applying the beam analysis method, the reliability data calculation step evaluates the strain or the stress acting on the piping system in the section between all pipe supports and all pipe supports and pipe supports.

  Create data to understand the level of confidence in the whole relationship

  From the allowable strain or allowable stress according to the piping system and the piping material, the value obtained by subtracting the strain or stress value calculated for each pipe support point in the reliability data calculation step is negative (-). A pipe support device calibration value acquiring step of calculating and obtaining the load change amount at the pipe support point necessary to reduce the stress in the reverse order of the reliability data calculation step;

The pipe support system reliability recovery step of correcting the load change amount at the pipe support point according to the load calibration procedure for each pipe support device reflects the piping environment such as creep fatigue and the reliability is re-evaluated based on the stress / strain. The present invention relates to a method for evaluating and recovering reliability of high temperature and high pressure piping and support systems.

This will be described in detail as follows.

Among all the pipe support devices supporting high temperature and high pressure pipes such as the power plant in operation, the load-related scale is measured at the position of the travel indicator (P) for the spring hanger, and the nameplate attached to the constant hanger for the constant hanger. Read the hanger capacity to understand the display load acting on the hanger, and at the same time, the spring hanger measures the distance-related scale at the position of the Travel Indicator (P), and in the case of the constant hanger, the distance-related scale of the nameplate attached to the constant hanger. The hanger operating point measurement step of checking the display load of the hanger and the display distance of the hanger, respectively, is carried out at the high temperature and the high temperature of the hanger. As a first step in the evaluation, the high temperature and low temperature conditions are Each display load is calculated, and an investigation is made to calculate the amount of displacement of the piping system display distance between the high temperature state and the low temperature state. Movement indicators to be read during display load measurement are indicated by P in the representative pipe support device drawings in (1) to (3) of FIG. (1) of FIG. 4 shows a spring hanger, and (2) and (3) show a representative constant hanger.

  In the case of a support except for rigid hangers in a state in which the piping system is at room temperature or in a high temperature state, a straight line is drawn from the support pipe to the pipe of the piping system at a right angle from the axial direction of the piping system and at the time when the temperature state of the piping system is changed, In the case of rigid hangers, the support angle of the hanger rod is measured at each point before and after the temperature of the piping system changes, and the distance movement of the piping system is measured, or a commercial distance measuring means is installed between the support and the piping system. Calculate the distance movement of the support, and the load applied to the support is measured through the 'Pipe support performance evaluation step' described below. And the indication of the piping system It is carried out to measure the amount.

The method of measuring the support angle of the hanger rod is shown in FIG. As shown in [Fig. 5], the support angle of the pipe support device is brought into contact with a certain point of the hanger rod 21, and the vertical angle of the protractor 23 is brought into contact with the non-angular part. By reading the position where the axis center line of the hanger rod and the protractor meet, it can be known by measuring how much the hanger rod is bent from the vertical forming the horizontal plane, and the length (HRL) of the hanger rod is the upper hinge point 24 of the pipe support device. The distance between the portion indicated by HRL is measured by measuring the linear distance from the pipe center point 25. Non-spring hangers, constant hangers, and rigid hangers are provided by drawing a straight line in the direction normal to the axial direction of the pipe at the position of the support, and changing the length of the straight line after the piping system environment is changed. It is possible to know the relative distance travel of the piping system and the support.

  The performance evaluation step of evaluating the performance of the support device in the state in which the pipe support device is installed in the field in order to grasp whether the performance of the pipe support device is changed due to deterioration and failure of materials, which is essential as a result of long-term operation, What is necessary is just to implement patent 10-0290553 (The March 03, 2001, hanger load measurement and soundness evaluation apparatus and method in the state installed in piping).

  Evaluating the load that the pipe support device supports the high temperature and high pressure pipe (load evaluation step) Also Patent No. 10-0290553 (03/03/2001, hanger load measurement and soundness evaluation device and method when installed in the pipe ).

Patent No. 10-0290553 discloses an accurate load-correct length by applying an additional load to the pipe support device while the pipe support device supports the weight of the piping system and measuring the change in the length of the elastic body such as a spring of the pipe support device. By recording the change, the exact load currently acting on the measured pipe support and the exact load-to-length change characteristics of the measured pipe support are obtained, resulting in a performance table of the measured pipe support. Even if the operation characteristics are changed due to deterioration or other factors as a result of long-term operation such as 10 years or 20 years after the operation, it shows the exact load acting on the pipe support device and the load-length change characteristic that will occur in the future. In the present invention, the above patent is not necessarily limited to the method for evaluating the performance of the present pipe support apparatus, but the reason mentioned in the embodiment of the present invention is that the method is the only commercialized method to implement the present invention. Because. Whichever method is used in the future, if the method can show the current correct working load and the correct load-precise displacement characteristics of the pipe support device installed and supporting the piping system in operation, the method of evaluating the performance of the pipe support device will be described. Can be used.

After performing the performance evaluation step of the pipe support device, the load displayed by the movement indicator of the pipe support device is corrected to be misunderstood by deterioration, etc., so that the correct load is displayed, and the load can be displayed like a rigid hanger or a support. The load acting on the pipe support without the moving indicator is known so that the load acting on all the pipe support points installed in the piping system of interest is known. In addition, the load on the pipe support points at two points of interest (starting at normal temperature operation and at a high temperature operating state or when the power plant is commissioned and after 5 years of power plant operation) and the relative movement amount of the pipe support points (pipes) And the amount of movement between the pipe support device) can be known accurately. The exact load and exact distance travel of the pipe supports at these two points of interest are input data for the next piping reliability data calculation step.

  Material and mechanical continuity based on physical constants such as thermal expansion coefficient and elastic modulus according to the material of piping system and pipe cross-sectional data, pipe section data, etc. By applying the beam analysis method, the reliability data calculation step for evaluating the strain or stress acting on the piping system in all pipe supports and between the pipe supports and the pipe supports is carried out. This is to determine which point of piping system is located, where the pipe support device is located, so that the risk of damage or accident is highest, and how much the average reliability of the piping system is.

The method of analyzing the material dynamic continuous beam is based on the exact working load and the exact distance movement of each pipe support point obtained in the performance evaluation step of the pipe support device, and the shape of the piping system is input from the 3D isometric drawing. By inputting additional pipe material, inner diameter, outer diameter, modulus of elasticity and thermal strain, the reaction system is divided into finite elements based on the correlation between material movement and load. And the amount of deflection, that is, stress and strain.

  Detailed calculation of reaction force and deflection can be performed as follows. When analyzing any two adjacent spans supported by a pipe support to calculate the reaction force on the pipe material when the weight and external force act on the pipe, the lengths of the two spans are called, and each of the three excess bending moments at three points The angle of rotation of the tangent at the point of the left pipe is called the angle of rotation of the tangent at the point of the right pipe. If you ask

Is expressed as the term of external load acting on each span and the moment at both ends and summarized using the moment area method as follows.

 In addition, the deformation amount in the piping system n can be obtained as follows.

The reaction force applied to each support point can be obtained by superimposing the reaction force at the support point obtained by the above-mentioned self-weight and external force and the reaction force at the support point considering the thermal effect for each constraint in the future. It can be found through the structural analysis using the system.

From the allowable strain or allowable stress according to the piping system and the piping material, the value obtained by subtracting the strain or stress value calculated for each pipe support point in the reliability data calculation step is negative (-). In the pipe support device calibration value acquisition step, which calculates the load change at the pipe support point necessary to reduce the stress in the reverse order of the calculation step of the reliability data, finds the pipe support point having low reliability, but the strain or stress, the reliability index, is the pipe support device. It is not an item that shows the effect on the pipe support device. Therefore, the stress and strain were based on the load or distance travel applied to the pipe support device in order to mark it as an item that can be repaired or calibrated. Stress or strain to calculate Since it is possible to calculate how much the corresponding load is, what is the mathematical analysis.

Evaluating the reliability of a pipe is a quantification of how far the pipe is from the point of failure. Calculate the combined stress or deflection / bend amount at all pipe support points where the pipe support device is located and compare it with the combined stress or deflection / bend amount at the time when the piping system breaks down. The smaller the difference, the more the relationship loses its soundness. Allowable stress or allowable strain is the value that the stress or strain at the time of breakdown of the material is set to allow for some degree of safety.

The allowable stress or allowable strain is already well known in the industry in consideration of the material conditions, and the object to be analyzed for the allowable stress of the piping material or the breakdown stress of the material, Von-Mises stress, etc. Decisions should be made with appropriate margins, taking into account operation or life conditions that take into account creep and fatigue characteristics. In this way, the allowable stress or allowable strain is compared with the calculated stress and strain at each pipe support point on the finite element so that the difference between the allowable stress and the calculated stress is high, the sound is high. The same logic applies to strain.

  Since the distance between the allowable value such as allowable stress or allowable strain and the calculated value of stress or strain calculated for each pipe point is equalized for the whole piping system, it is good for the reliability of piping system. Should be raised. From the very low reliability to the numerical evaluation to increase the reliability, the degree to which the low reliability can be increased can determine how much the entire pipe support system bears the weight or load of the entire piping system.

  In terms of the reliability of the whole piping system, if the stress level acting on the entire piping support point can be the stress level that divides the entire piping load into the entire piping support point, the reliability of the entire piping system, i.e., the service life can be extended. In this way, the load adjustment amount is determined to increase or decrease the load so that the load corresponding to the stress at each pipe support point is determined so as to minimize the dispersion of the stress level so as to extend the overall life of the pipe.

Reliability recovery step of pipe support device that corrects the load change at the pipe support point according to the load calibration procedure for each pipe support device is to change the state of the pipe support device by the unloaded weight. In the case of constant hanger, the link mechanism is adjusted. In case of rigid hanger, the length of hanger rod is adjusted. This should be followed by the user instructions made by the manufacturer of the pipe support.

After adjusting the load acting on the piping support device of the piping system as above, if the piping system becomes the operating condition again, measure the operating point of the piping support device once again to investigate the display load and the display distance movement, and Check for normal operation.

  In this way, as the pipes are bent and sag as shown in (1) of FIG. 6, the pipes are bent and drooped as shown in (2) of FIG. 6, so that the load or stress applied to the entire piping system can be spread evenly, thereby improving the reliability of the piping system. .

Described in the detailed description for carrying out the invention.

Claims (1)

To increase the reliability of long-term high temperature and high pressure piping
In the case of the spring hanger among all pipe support devices, read the load related scale at the position of the travel indicator (P), and in the case of the constant hanger, read the hanger capacity of the nameplate attached to the constant hanger to understand the display load acting on the hanger. At the same time, the spring hanger reads the distance-related scale at the position of the travel indicator (P), and in the case of the constant hanger, it reads the distance-related scale of the nameplate attached to the constant hanger. A hanger operating point measuring step of checking the display load of the hanger and the movement distance of the display distance of the hanger, respectively, in a state where the piping system is at room temperature and a high temperature;
In the case of a support except for rigid hangers in a state in which the piping system is at room temperature or in a high temperature state, a straight line is drawn from the support pipe to the pipe of the piping system at a right angle from the axial direction of the piping system and at the time when the temperature state of the piping system is changed, In the case of rigid hangers, the support angle of the hanger rod is measured at each point before and after the temperature of the piping system changes, and the distance movement of the piping system is measured, or a commercial distance measuring means is installed between the support and the piping system. Calculate the distance movement of the support, and measure the load on the support through the support load measurement point to check the display load of the support and the display distance movement in the piping
Calculate the display load and the display distance movement amount applied to each pipe support point of the piping system at high temperature and room temperature at all points with the pipe support device.
Performance evaluation step of evaluating the performance of the pipe support device in the state where the pipe support device is installed in the field in order to grasp whether the performance of the pipe support device is changed due to material deterioration and breakdown, etc., as a result of long-term operation. through
Calculate the exact load acting on each pipe support point of piping system at high temperature and room temperature, and the exact distance movement of piping system at all points with piping support device.
Material and mechanical continuity based on physical constants such as thermal expansion coefficient and elastic modulus according to the material of piping system and pipe cross-sectional data, pipe section data, etc. By applying the beam analysis method, the reliability data calculation step evaluates the strain or the stress acting on the piping system in the section between all pipe supports and all pipe supports and pipe supports.
Create data to understand the level of confidence in the whole relationship
From the allowable strain or allowable stress according to the piping system and the piping material, the value obtained by subtracting the strain or stress value calculated for each pipe support point in the reliability data calculation step is negative (-). A pipe support device calibration value acquiring step of calculating and obtaining the load change amount at the pipe support point necessary to reduce the stress in the reverse order of the reliability data calculation step;
Through the pipe support device reliability recovery step of correcting the load change at the pipe support point according to the load calibration procedure for each pipe support device
Reliability evaluation and recovery method of high temperature and high pressure piping and supporting system that is re-evaluated based on stress / strain rate by reflecting operation conditions such as creep fatigue, so that the strain or stress of the entire piping system is within a safe range for the service life of the piping system.

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