Test Method For Leakage Of Vacuum Furnace

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The inside of the vacuum furnace atmosphere will directly affect the product’s surface treatment effect, the atmosphere in the furnace is determined by the tightness of vacuum furnace, so to ensure the quality of workpiece, the first thing to keep the vacuum furnace gas tightness is good, the vacuum furnace gas tightness check the difficulty lies in the furnace pipe area is large and complex, and easy to leak position is various, the check to the air tightness routinization and institutionalized.

Vacuum Furnace Leak Detection Method:

1. Decide the Key Parts of the Air Tightness Inspection

These areas of focus generally include:

1) Replace the parts of the equipment during maintenance.The furnace body and pipe parts that have been moved during maintenance should be regarded as the key parts of inspection.

2) Open the top cover and bottom cover, wear holes and access doors.

3) Entrance sealing roll gap.

4) Expansion joint on furnace shell and circulating pipe, furnace roller flange, heat exchanger flange, instrument flange and welding joint, etc.

5) Water-cooled pyrometer, camera, water-cooled heat exchanger, etc.

6) Analyzer sampling pipe joint, etc.

2. Check the Positive Pressure Part

In the normal production process, the annealing furnace should be kept at the micro positive pressure of 150-300Pa.

1) Judgment of leakage.Observe the online oxygen PPM analyzer measurement data, when a section of residual oxygen suddenly significantly increased, it may be the furnace shell or circulation pipe leakage.

2) Inspection methods and tools for leakage points.Tool room hydrogen detector.The method is to ensure that the hydrogen in the furnace is above 3%, and check the air tightness of the confirmed leakage furnace section with a portable hydrogen detector, and the key part is the top maintenance weld.When the leakage point is detected, the hydrogen detector will alarm.

3. Check the Negative Pressure Part

The suction end of the circulation fan is negative pressure. If the negative pressure part leaks, the air will be sucked into the furnace.

1) Judgment of leakage.By observing the changes in the data measured by the online analyzer, it can be determined whether the fan is leaking.

2) Inspection methods and tools for leakage points.The negative pressure leak point can be checked by changing the negative pressure to positive pressure and then using a hydrogen detector, or by using a helium leak detector, a device specially designed for negative pressure leak detection.

4. Treatment of Leakage Points

Annealing furnace is always in the working state, for some leakage points can be taken to use high temperature sealant and other methods to do temporary treatment, until there is a chance to stop the furnace to do a thorough treatment.

Repair welding of the cracking position;Old or damaged gaskets and rings should be replaced;Replace leaky parts such as expansion joints;Tighten loose bolts;Apply high temperature sealant.

Editor: Frank Lee

Copyright: SIMUWU Vacuum Furnace