Boiler is an important heat source equipment that requires heat source production or heating users. Its installation is a complex and important project, and every link in it has an important impact on users. After all the boilers are installed, there is still a very important link - acceptance, which is very important for the boiler to be ignited and run normally.

Therefore, after the boiler is installed, the acceptance work after the boiler installation must be done well. According to the different uses of the product medium, boilers can be divided into: steam boilers and hot water boilers. The steam boilers and hot water boilers should pay attention to completely different places when they are accepted. Let's take a look.

Steam Boiler Acceptance

1. Steam Tghtness Test

After the boiler oven and boiling furnace are qualified, close all manholes, hand holes, valves, etc., after making preparations before ignition, start the ignition and increase the pressure to the working pressure for steam tightness test. When the boiler pressure rises to about 0.2MPa, the bolts of manholes, hand holes, flanges and other parts should be tightened, and then continue to increase the pressure to the working pressure, and check the following parts:

1) There should be no leakage in manholes, hand holes, flanges, etc.

2) All welds and bulges should be tight.

3) All instrument valves of the boiler should be tight.

4) The expansion of drums, headers, pipes, supports, etc. shall meet the design requirements.

5) The furnace wall should be intact and tight, without cracks and deformation.

2. Safety Valve Adjustment and Exhaust Steam Test

When the steam tightness test of the boiler is carried out, the safety valve adjustment and constant pressure work shall be carried out. This work shall be carried out jointly by the installation unit and the user unit, and shall be confirmed by the local supervisory inspection department.

(1) Adjustment of safety valve

1. Preparations before adjustment

(1) Do the calibration of the pressure gauge in advance to ensure the correctness.

(2) Control the water level and steam pressure to prevent water shortage, full water and overpressure accidents.

(3) A vent valve is set on the sub-cylinder, in case the steam exhaust capacity of the safety valve is insufficient and the overpressure of the boiler occurs, the steam is released and depressurized.

(4) Prepare protective equipment and clean up the debris on site.

2. Safety valve adjustment

The setting pressure of the safety valve shall be carried out as specified in the table below.

Note:

1. There must be a safety valve on the boiler, which is adjusted according to the lower set pressure in the table. For boilers with superheaters, the safety valve adjusted according to the lower pressure must be the safety valve on the superheater to ensure that the safety valve on the superheater is opened first.

2. The working pressure in the table refers to the working pressure at the place where the impulse is connected to the pulse type safety valve, and the working pressure at the place where the safety valve is installed for other types of safety valves.

3. The set pressure of the safety valve on the economizer is 1.1 times the working pressure of the installation site. After the safety valve is set, an automatic steam exhaust test should be done again, and the end of the constant pressure should be confirmed after passing the test. Records should be made of the test date, the personnel participating in the commissioning, and the opening pressure and seating pressure of each safety valve.

(2) Steam exhaust test of safety valve

The total steam discharge of the safety valve should be greater than the maximum continuous evaporation of the boiler. When all safety valves on the drum and superheater are opened, the increase in boiler steam pressure shall not exceed 1.1 times the design pressure. For a safety valve with sufficient steam exhaust, generally only the debugging of the opening pressure and the check of the return pressure are carried out.

The steam exhaust test of the safety valve should make the boiler pressurize to the opening pressure of the safety valve, and the safety valve will jump up automatically so that all the steam is discharged out of the furnace through the safety valve. If the steam pressure rise exceeds 1.1 times of the design pressure, the steam discharge of the safety valve is insufficient. At this time, pressure reduction measures should be taken to ensure the safety of the boiler, and the number of safety valves should be replaced in time or the diameter should be increased.

During the test, the person in charge must be present, and the test situation shall be recorded and archived.

3. Overall acceptance

After the debugging of the safety valve is completed and other preparations are completed, the pipes can be warmed and the main steam pipes can be flushed, and the boiler can be tested for 72 hours to complete the overall acceptance.

The boiler runs continuously for 72 hours under the rated load. During this period, if no abnormal phenomenon is found and the boiler can be guaranteed to work under normal parameters, the installation quality can be considered as qualified. And check that the following aspects work:

1) Installation records, acceptance technical documents and relevant test records provided by the installation unit at each stage.

2) Whether the layout of the boiler room is consistent with the design, and whether the thermal equipment and pipelines are in good condition.

3) Whether the installation of safety accessories is reasonable, sensitive and reliable, and whether the automatic control and instrument debugging are qualified.

4) Whether the installation quality of each telescopic part of the boiler and the installation of the expansion indicator are correct.

5) The operating conditions of each part of the boiler and the masonry and thermal insulation quality of the furnace wall.

6) The operating conditions of the combustion system and other auxiliary equipment, as well as the measures and effects of smoke and dust removal.

7) Whether the boiler water quality index conforms to the national regulations.

8) Whether the oven, boiling oven records, safety valve debugging records, as well as various thermal data and instrument operation conditions can meet the design requirements.

9) Sub-cylinder quality and documentation.

10) Boiler room safety measures such as platform escalators, lighting and exit passages, etc.

After the overall acceptance is passed, the installation unit shall transfer the technical documents and construction quality certification materials of the installed boiler to the user unit and store it in the boiler technical file.

Hot Water Boiler Acceptance

The installation quality of the hot water boiler shall be jointly responsible by the user and the installation unit. The water pressure test and overall acceptance shall be attended by the local supervisory inspection department.

1. Hydrostatic Test After Installation

First, open the air release valve at the top of the hot water boiler and slowly add water to the boiler. When the air release valve overflows, close the water supply valve, and then open the water supply valve after half an hour; when the air release pipe overflows again, close the water supply valve. Repeat this to exhaust the air in the boiler.

In addition to the general hydraulic test once every 6 years, the boiler pressure components also need to be hydraulically tested after major repairs or renovations.

1. Hydrostatic Test Pressure

Water pressure test pressure gauge

2. Hydrostatic Test

(1) When the water pressure test of the boiler is carried out, the water pressure should rise and fall slowly. When the water pressure rises to the working pressure, the pressure increase should be suspended to check whether there is water leakage or abnormal phenomenon, and then increase the pressure to the test pressure. The boiler should be kept under the test pressure for 20min, and then lowered to the working pressure for inspection. The pressure remains constant during the inspection.

(2) The hydrostatic test should be carried out when the ambient temperature is higher than 5°C, and antifreeze measures must be taken when the temperature is lower than 5°C. for hydrostatic testing

The temperature of the water should be kept higher than the surrounding dew point to prevent condensation on the surface of the boiler, but the temperature should not be too high to prevent vaporization and excessive temperature differential stress, generally 20~70℃.

3. Qualification Standard of Hydraulic Test

(1) There is no water droplets and moisture on the metal walls and welds of the pressure components.

(2) When the working pressure is reduced, there will be no water droplets on the expansion port,

(3) After the hydrostatic test, no residual deformation was found.

2. Overall Acceptance

The hot water boiler runs continuously for 72 hours under the rated load. During this period, if no abnormal phenomenon is found and the hot water boiler can be guaranteed to work continuously under normal parameters, the installation quality can be considered as qualified. The installation unit, the user unit and the local inspection department shall jointly conduct the acceptance inspection. In addition to the inspection of the same technical data and items as the overall acceptance of the steam boiler, the following two aspects shall also be inspected:

(1) Whether the installation of boiler foundation, steel frame, circulating water pump, gas collection tank, air release valve, decontamination device, etc. is qualified.

(2) Whether the protection measures for pump stop, sudden power failure and over-temperature alarm are complete, sensitive and reliable.

After the overall acceptance is passed, the installation unit shall transfer the technical documents and construction quality certification materials of the installed boiler to the user unit and store it in the boiler technical file.

Conclusion

No matter you have any questions in boiler purchase, selection, installation, transportation and commissioning, please contact EPCB, we have professional boiler engineers to answer your questions. After the boiler is installed, the acceptance steps are indispensable. If you carry out careful acceptance according to the methods mentioned above, then the boiler can operate in a safe state, and a safe and stable boiler system will not be caused by various problems. Downtime for maintenance will delay your production.

EPCB, your personal boiler system expert!

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