JPS5871427A - Pressure testing method for feed water heater system - Google Patents

Abstract

PURPOSE:To make working quick and to reduce working costs, by forming a shut off pressure resisting boundary in each valve port of pressure compensated flow control valves and a check valve around the heater by using a jig, and measuring the pressure variation in the pressure resisting boundary. CONSTITUTION:This system feeds only the required amount of heated steam generated in a turbine 1 to the feed water heater 4. The pressure compensated flow control valves 6, 9, and 10 and the check valve 5 are provided in the piping. At first individual valve is shut off by the on the spot working by using the jig. For example, with a double seat type pressure compensated flow control valve, even though the valve is fully closed, it is hard to shut off the steam perfectly. Therefore a valve body is pulled out of a valve seat, and a cylindrical jig is inserted and the valve seat is blocked by an O ring. After the check valve, the back surface of the valve body is pushed to the valve seat by the jig and it is blocked. Then a partitioned pressure resisting area is pressurized to a specified pressure by a booster pump 7. Thereafter a main valve 23 is fully closed, and the pressure is tested for 10min. In this way, a part of the piping is not required to be cut and blocked, and the quick measurement can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure-resistant test method for a pressure-resistant system comprising a 1% turbine-based feed water heater of a nuclear power plant and piping around the feed water heater.

FIG. 1 illustrates the system configuration of a conventional nuclear power plant extraction system. This system supplies the necessary amount of heated steam generated by the turbine 1 to the feed water heater 4, and safely processes the drain from which moisture has been separated in the stage of the turbine 1 into the condenser 2. It's poorly installed. In the piping 3 around the feed water heater, a flow control valve 6 (air-operated) for regulating the heating steam and a check valve 5 are installed. In the illustrated example, a gate valve for separating fluid is not installed because there is no space for installing it. In such a system, the feed water heater 4. When the drain piping has been modified, a pressure test conducted after the modification requires cutting off a portion of the piping, welding a flange to it, and closing the cut end of the piping with a closing plate.

These conventional methods have drawbacks such as extremely low work efficiency, long construction periods, and high costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple pressure test method that allows rapid pressure test work and requires a small amount of expense.

In order to achieve this object, in the present invention, the valve boats of the flow rate control valves and check valves on the piping of the feedwater heater system are closed off using a jig, and a pressure-resistant boundary is formed by these flow rate control valves and check valves. , employs a unique method of measuring pressure fluctuations within the pressure-resistant area surrounded by these pressure-resistant boundaries.

That is, the present invention creates a pressure-resistant area by cutting off a pressure-resistant system consisting of a turbine-type feedwater heater and piping around the feedwater heater of a nuclear power plant from the rest, and then pressurizes a part of this pressure-resistant area. In a pressure test method for a feed water heater system, which uses a pressure device to pressurize a pressure area and at the same time sets a pressure gauge in another part of the pressure area to measure the pressure resistance within the area. The valve boats of the flow rate control valves and check valves installed in advance in the piping around the feed water heater are tightened using a jig during field work, and a pressure-resistant boundary is formed with these flow rate control valves and check valves. The present invention aims to provide a pressure test method for a feed water heater system that measures pressure fluctuations within a pressure-resistant area surrounded by these pressure-resistant boundaries.

By employing the method described above, there is no need to cut the piping. By simply modifying a portion of the flow control valve and check valve, the boundary of the pressure-resistant area can be easily formed.

Therefore, the pre-steps for the pressure test can be greatly simplified, and an economical pressure test method that can be carried out with a small number of workers can be achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the pressure test method according to the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 2, the piping 3 around the feed water heater 4 is equipped with (air-operated) flow control valves 6, 9, and 10° check valves 5. The valve ports of each of these valves will be closed using a jig during field work. Various jigs are used depending on the valve type, pipe diameter, and pipe internal pressure. Using these jigs, the piping 3 is sectioned off at the positions of the flow control valve and check valve to form a pressure-resistant area. A pressurizing device is connected to a part of this pressure-resistant area. In the example shown in FIG. 2, a pressurizing pump 7 is used as a pressurizing device, and an operation is performed to pressurize the pressure-resistant area to a predetermined level via a one-way valve 23.

The pressure in the pressurized pressure zone is measured by a pressure gauge 8.

FIG. 3 is a structural example of a two-seat (air-operated) flow control valve. The steam coming out of the turbine 1 enters the left-hand inlet valve, passes through the valve bow (15, 16), and exits from the right-hand outlet. The flow of passing steam can be adjusted by moving the valve body 17 up and down. With this type of control valve, it is extremely difficult to completely shut off steam even when the valve is fully closed. Therefore, the jig 20 is used to repair it as follows. First, tighten bolt 1
Bonnet fixed with 4 11. Remove the blind head 13 from the valve port 12, and then remove the valve body 17. A portion of the jig 20 is then inserted into the valve port 15, 16, and the valve port is completely occluded with the surrounding O-rings 18, 19. The jig is fixed to the valve body 12 with bolts 14. Similarly, bolts 14 are used to secure the blind head 11 to the valve body 12. Thus, by closing off the valve port, a positive pressure-tight boundary is created.

Instead, FIG. 5 shows the structure of a known check valve.

This check valve is modified as shown in FIG. The jig 20 in this example takes the reaction force in a part of the valve body, and
It has the function of pressing to the left. The valve body 17 is in contact with the jig 20 through the cap 21, and by turning the rotary lever 22, the cap is pushed out to the left, and the valve body 17 is fixedly pressed against the valve seat. In this way, the valve body 17 closes the valve port, and the valve body is held by the jig and exhibits sufficient pressure resistance.

After the above operations are completed, the pressure pump 7 is used to pressurize the partitioned pressure-resistant area. The pressure in the pressure-resistant area is increased to 1.5 times the maximum working pressure P, and the main valve 23 is fully closed. next,
The pressure gauge 8 measures the change in pressure in the pressure-resistant area over time.

Figure 7 is a model graph explaining the time-lapse measurement method for pressure resistance tests. The pressure test takes about 10 minutes. If the measured pressure change decreases as shown in Figure 8, and the degree of decrease (rate of decrease) is within the decrease curve calculated from the allowable leakage of the 6 valves, it means that there is no leakage from the pressure-resistant area. The pressure test was passed.

This embodiment is not limited to what has been specifically described.

For example, instead of the configuration shown in FIG. 4, a configuration as shown in FIG. 10 may be adopted. In this example, valve boat 15.
The valve seat rings 27 and 28 are removed from the valve port 16, the closing plates 24 and 25 as jigs are respectively attached thereto, and the valve ports are returned to their original positions.

Further, the pressure-resistant area can of course be pressurized from a position other than that shown in FIG.

- For example, as shown in FIG. 9, a pressurizing guide 26 may be provided in the jig 20, and the pressure-resistant area may be pressurized via this pressurizing conduit.

As mentioned above, according to the present invention, the pressure-resistant system to be tested can be partitioned very easily to form a pressure-resistant test area, and the present invention is far superior to conventional methods in terms of speeding up and simplifying the construction work. . Therefore, the testing period can be significantly shortened, and the cost-restricting effect is also extremely noticeable. The economic effects are noteworthy.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing a piping system of a conventional feed water heater system, Fig. 2 is a flowchart showing an example of a piping system to which the pressure test method according to the present invention is applied, and Fig. 3 is a flowchart showing a conventional (air-operated) piping system. A longitudinal cross-sectional view showing an example of the structure of a two-seat type flow rate control valve, Fig. 4 is a longitudinal cross-sectional view showing an example of the structure in which a jig is incorporated into the control valve of Fig. 3, and Fig. 5 is a view of a conventional check valve. FIG. 6 is a vertical cross-sectional view showing an example of a structure in which a jig is incorporated into the check valve of FIG. 5, and FIGS. 7 and 8 are measurements of a pressure test method according to the present invention. Figure 9 is a vertical sectional view showing a modification of Figure 4, and Figure 10 is another configuration example in which a jig is incorporated into the control valve in Figure 3. FIG. 1... Turbine, 3... Piping, 4... Feed water heater, 5... Check valve, 7... Pressure pump (pressurizing device),
6,9゜101...Flow control valve, 15.16...Valve boat, 20mm f trouble 3 mouth yrJ4I2] Fraud trouble No. 60 '1! ! Jq Prisoner Yu, Figure 6, 7■

Claims (1)

[Claims] 1. A pressure-resistant system consisting of a turbine-type feedwater heater of a nuclear power plant and piping around the feedwater heater is isolated from the rest to form a pressure-resistant area, and a part of this pressure-resistant area is pressurized. Using a device to pressurize a pressure-resistant area, and at the same time placing a pressure gauge in another part of the pressure-resistant area to measure the pressure-resistant performance within the area;
In the pressure test method for the feed water heater system, the valve boats of the flow control valves and check valves that are pre-installed in the piping around the feed water heater are closed off using a jig on site. A pressure test method for water heater systems that forms pressure-resistant boundaries and measures pressure fluctuations within the pressure-resistant area surrounded by these pressure-resistant boundaries. 2. In the pressure resistance test method according to claim 1, the pressure resistance test in the pressure resistance area is performed based on the pressure drop rate in the pressure resistance area and the closed valves of the flow control valve and the check valve. A pressure test method for water heater systems that compares allowable pressure leaks from boats. 3. In the pressure test method according to claim 1 or 2, the flow rate control valve is a two-seat type flow rate control valve, and the jig for closing the valve boat is A pressure test method for a feed water heater system that is newly installed on a valve boat in place of the valve body after the valve body is removed. 4. In the pressure test method according to claim 1 or 2, the jig used for the check valve acts to press and fix the valve body of the check valve to the valve seat. Pressure test method for feed water heater system. 5. In the pressure test method according to claim 3, the jig is provided with a pressurizing conduit that communicates with the pressure-resistant area, and the feed water heater is pressurized in the pressure-resistant area through the pressurizing conduit. System pressure test method.