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Hydrostatic test plan 0d& a' k: E, g5 1. Purpose of hydrostatic test The boiler hydrostatic test is a comprehensive inspection of the manufacturing and installation quality of the boiler’s pressure-bearing components, carried out after these components have been installed. 2. Scope of hydrostatic test: This hydrostatic test covers the boiler itself. ' A( |" E2 L& @;j; Y+ `! _ From the shut-off valve in front of the economizer inlet header to the high-temperature superheater outlet header. This includes the economizer, steam drum, water wall, superheaters (including low-temperature superheaters, high-temperature superheaters, and roof superheaters), as well as the systems within the boiler itself such as those for slag discharge, drain water release, sampling, air release, boiler chemical dosing, and feedwater temperature reduction – in other words, all the systems that are part of the primary piping. * x5 c1 ?&N1 i2 \ Where ^4 u! m/ z5 a"q3 N 1) The boiler level gauge is not involved in the overpressure test; when overpressure occurs, the gauge is disconnected and the drain valve is opened. 2) The safety door was subjected to a hydrostatic test, and it was pressed down by the water pressure. + o8 x6 l5 |8 N! x. c 3) Thermal measurement points, water level, and pressure sampling points within the hydraulic pressure range shall participate in the hydrostatic test prior to the valve opening. + \, H(Y0 c, f" N$ \# A6 R8 O+ H 4) participated in the hydrostatic test prior to the first drain during a drum vessel accident. 3. Hydrostatic test pressure and layout of pressure measurement points! M* K6 y' v' E! O/ b)`9 {5 N The hydrostatic test pressure shall comply with the requirements of the boiler manufacturer; if no such specifications are provided by the manufacturer, then the ‘Code for Inspection of Boilers in the Power Industry’ shall be followed. The test pressure is 1.25 times the maximum allowable operating pressure of the boiler (i.e., the calculated pressure of the steam drum): PS = 1.25P (where P is the calculated pressure of the steam drum). The selected specifications are a range of 0–10 MPa, an accuracy level of 0.5, and a diameter of 200–250 mm; it involves two pressure gauges that have been calibrated and approved by a **standard metrology authority. 7 c5 b6 Y6x- X# P; F Placement location: Drum 6 ?. t0 z; P! r( i u" g 3.1. For ease of monitoring during the pressure increase process, a pressure gauge with a range of 0–10 MPa, an accuracy of 0.5 grade, and a diameter of 200–250 mm should be installed on the outlet pipeline of the pressure increase pump, at the boiler’s zero-meter mark and near the pressure increase pump. This gauge must have been calibrated by a **standard metrology department. 4. Water and chemicals for hydrostatic testing + F% a5 s(g + z%). The water used for hydrostatic testing is chemically produced deionized water; to remove oxygen from this water, industrial hydrazine N2H4•H2O is added to bring its concentration to 200PPM, and the pH value is adjusted to achieve a concentration of 500PPM, with the pH range being between 10 and 5. 5. Hydrostatic test system 5.1. Main system: A Dg80 branch pipe is led from the demineralized water pipeline and connected to the economizer inlet header, allowing the fluid to flow into the economizer and throughout the entire primary steam system. The water supply utilizes a formal water replenishment system, and the water supply time must be strictly controlled: 2–3 hours in summer, and 4–6 hours in winter. Pressurization is achieved through the drain pipe on the economizer inlet header. The drainage system features a temporary drainage main with a diameter of Ф108X4.5mm that leads to a temporary waste liquid tank; the liquid is discharged after the specified requirements are met through the natural oxidation of hydrazine. + D/ _3 S& G. N8 t: p 5.2. Temporary dosing system: One metering pump is used as the dosing pump; the inlet of this pump is connected to the alkali tank, while its outlet is connected to the temporary water supply pipeline. When water is being filled into the boiler, the chemical dosing pump is started to inject chemicals into the temporary water supply pipeline. A sampling point is set about 10 m away from the dosing point; samples are taken from this point to test the concentration of the mixture, and the flow rate of the metering pump is adjusted based on the test results. Until the measured concentration meets the requirements. 3 G9 S7 h’@7 g; w, f’ w 6. Procedures and methods for hydrostatic testing$ |/ U: M: |7 { 6.1. Pneumatic testing: Once the conditions for hydrostatic testing are met, a pneumatic test is conducted on the boiler. The test pressure is 0.3 Mpa. The system is switched to the pneumatic testing mode, and all valves that are not related to air pressure, such as air release valves, sampling valves, and drain valves, are closed. An air compressor (6 m3/min) is started to supply oil-free compressed air into the system. Once the pressure reaches 0.3 MPa, the inlet valve is closed and the air compressor is stopped. A thorough inspection of the entire system is carried out; laundry detergent solution is applied to key components, or sound checks are performed to detect any leaks. If there is no significant change in pressure during the inspection and no leakage points are detected, the pressure should be maintained for 8 to 10 hours; if the pressure does not drop or only drops slightly, then the wind pressure test is considered successful. The wind pressure test uses the recirculation pipe at the outlet of the booster pump as the air inlet. 6.2. Hydrostatic test: Open all air valves, and close the drain valves for the water wall, encircling wall superheaters, etc., as well as the sampling valves, boiler chemical dosing valves, and the continuous blowdown valve on the drum. Isolate the level gauge, open the main valve for the feed of demineralized water, and supply water to the boiler. At the same time, start the chemical dosing pump to add chemicals. Adjust the flow rate of the chemicals injected by the dosing pump based on the concentration of the mixture measured at the sampling point, so that the concentration of chemicals in the mixture reaches the required levels: 200 PPM for hydrazine and 10 PPM for ammonia water. Conduct inspections while filling with water; report any issues found promptly, take necessary measures, and then continue with the filling process. When all the air valves discharge water, the tank is then filled with water. Switch the system to the pressurization mode, start the pressure-boosting pump, and control the pressurization rate at no more than 0.3 MPa/min. Stop pressurizing once the pressure reaches 50% of the test pressure, and conduct a preliminary inspection. If everything is normal, proceed to pressurize the boiler to its maximum allowable operating pressure for further inspection. If no leaks are detected, raise the pressure to the test pressure and maintain it for 20 minutes; thereafter, reduce the pressure back to the boiler’s maximum allowable operating pressure and carry out a thorough inspection of the boiler, making detailed records. If there are no leaks or deformations, the hydrostatic test is considered successful. 7 {6 n$ J! f a+ N: ~ 7. Technical quality requirements ( ]2 `9 Y5 p- H" y 7.1. In this approach, ammonia and hydrazine are added to the water supply pipeline via metering pumps while water is supplied to the furnace. During the water supply process, the concentrations of ammonia and hydrazine in the mixture are measured at sampling points, and the flow rate of the metering pumps is adjusted as needed so that the concentration of hydrazine in the mixture reaches 200 PPM and the concentration of fluorine-containing water reaches 500 PPM, thereby meeting the specified requirements. ! v" M: d! q" v: u3 P# q# k; a9 u 7.2. Based on the readings from the pressure gauges installed on the steam drum, there should be at least 2 pressure gauges per location, with an accuracy of 0.5 grade. 7.3. After the hydraulic test is successful, proceed with the approval procedures promptly; record any issues identified during the test and address them in a timely manner. 8 y- x: m: B" W 7.4. Before applying pressure to the boiler water, the system should be flushed with water. Once the boiler is filled with water, the drain valve should be opened, and flushing should be carried out using static pressure until the water discharged is clear and free of any impurities. , l0 a% V6 c0 b8 J5 | 8.Safety Precautions 8.1.Conduct a thorough and detailed technical safety briefing for all participants prior to starting work, and establish clear responsibilities for each position. 8.2. Establish a leading group for the hydraulic test; ensure that the construction workers have clear tasks and each assumes their own responsibilities, and that all actions are carried out under instructions to prevent errors or safety accidents. 0 S1 N; f+ Z' E$ z/ I& a 8.3. There must be at least 2 people in each group during the inspection to take care of one another; inspectors must carry flashlights, safety belts, and standard personal protective equipment. 8.4. When the suspension platform installed in the furnace chamber moves up and down, it must be operated under the supervision of a dedicated person. Scaffolding for inspection should be set up in all necessary areas as well as in any hazardous locations, and the platforms and lighting must be in good condition. During the overpressure test, the sling platform is strictly prohibited from moving up or down. When used as an isolation layer, the winch that suspends the platform must be locked, and a warning sign indicating that it is not to be used should be placed there. Wire ropes should be protected from damage caused by electric welding. 8.5. Under water pressure, no one shall stand in front of the welded joint or on the side of the flange; the equipment must not be struck, and welding or cutting operations must absolutely not be carried out on it. 9 B7 z' W/ r; b* S1 a'p( S 8.6. Fencing and signs should be installed in the areas under pressure; persons who are not authorized to work in such areas must stay away, especially near the pressure increase pumps and chemical dosing pumps. % u( |6 X9 p5 Q0 s2 E* U! a% P 8.7. The personnel responsible for adding chemicals should wear appropriate protective equipment and have emergency medications on hand. Medical staff and ambulances should be on duty at the site during the water pressure test. 6 {6 |7 u" K/ a0 t2 N! e' `% V 8.8. Communication must remain uninterrupted during high water pressure; in particular, the operators and commanders should have walkie-talkies available