Safety and Protection in Electron Beam Welding: A Comprehensive Guide

When operating an electron beam welding machine, it’s essential to prevent hazards such as high-voltage electric shock, X-rays, visible light radiation, and smoke on the body.

Measures to Prevent High Voltage Electric Shock

Regardless of whether it’s a low-voltage or high-voltage electron beam welding machine, it carries a potentially lethal high voltage during operation. Therefore, all systems carrying high voltage in the welding machine must take effective insulation protection measures.

1) The high-voltage power supply and the electron gun should ensure sufficient insulation capacity, and the insulation test voltage should be 1.5 times the rated voltage.

2) The equipment should have a dedicated ground wire, and the shell should be grounded with a thick copper wire with a cross-sectional area greater than 12 mm2, ensuring good grounding, with a ground resistance less than 3Ω.

3) When replacing cathode components or undergoing maintenance, cut off the high-voltage power supply, and touch the parts to be replaced or areas needing repair with a well-grounded discharge stick to prevent electric shock.

4) An electron beam welding machine should install a voltage alarm or other electronic interlocking device to automatically shut off the power in case of failure.

5) Wear high-voltage resistant insulation gloves and shoes during operation, and use lead-glass windows for both high-voltage and low-voltage electron beam systems. The welding machine should be installed in an X-ray shielding room made of high-density concrete.

X-ray Protection

During electron beam welding, the high-speed electron beam colliding with the weldment produces X-rays; inside the gun body and workspace, electron beams colliding with gas molecules or metal vapor also generate a considerable amount of X-rays; during welding, about 1% of the ray energy is converted into X-ray radiation.

The allowed X-ray dose for workers in our country should not exceed 0.25mR/h. Therefore, protection measures against X-rays must be strengthened.

1) For electron beam welding machines with acceleration voltage equal to or lower than 60kV, a vacuum chamber made of steel plate of sufficient thickness can protect against X-rays.

2) For welding machines with an acceleration voltage higher than 60kV, the shell should be additionally protected with a lead plate of sufficient thickness.

3) When the electron beam welding machine operates under high voltage, the observation window should use lead glass.

4) The area of the workplace should generally not be less than 40m², and the height should not be less than 3.5m. For high-voltage electron beam welding equipment, the high-voltage power supply equipment and exhaust device can be separated from the operator’s workspace.

In addition, electron beam welding will produce harmful metal vapor, smoke, ozone, and nitrogen oxides, etc. The exhaust device should be used to timely discharge the waste gas and dust exhausted from the vacuum chamber, ensuring that the harmful gas content in the vacuum chamber and workplace is reduced to below safety standards, and the area around the equipment should be well ventilated.

Direct observation of the visible light emitted by molten metal is harmful to vision and skin, so it’s not allowed to directly observe the molten pool with the naked eye during the welding process. Protective glasses must be worn.

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