Laboratory X-ray testing equipmentThe calibration method mainly involves a comprehensive inspection and adjustment of equipment performance to ensure its accuracy and reliability. The following is a universal calibration method:

1、 Preparation before calibration

1. Personnel requirements:

Calibration personnel should undergo professional training and hold the corresponding level of qualification certificate for radiographic inspection personnel issued by the State Administration for Quality and Technical Supervision.

Calibration personnel should be familiar with the basic structure, functions of each part, and operating procedures of the X-ray testing equipment used.

2. Equipment requirements:

Ensure that the X-ray inspection equipment is in good working condition, with no signs of damage, and that the installation screws are not loose.

Prepare the standard instruments required for calibration, such as standard test blocks (made of A3 steel, with a specification of 200mm × 100mm, surface roughness Ra ≤ 6.3, thickness meeting the corresponding requirements, with a tolerance of ± 4%), density meters, linear image quality meters, etc.

3. Environmental requirements:

Calibration should be carried out under specified environmental conditions, including appropriate temperature, humidity, and cleanliness.

If carried out in a calibration room, it should be ensured that the temperature and humidity in the laboratory meet the regulations; If the operation is carried out on site, it should meet the needs of the equipment for on-site use.

2、 Calibration steps

1. Penetration verification:

Cut the X-ray film into a specified size (such as 100mm × 225mm) and place it at a distance of 600mm from the focal point, with the long side of the film parallel to the axis of the X-ray tube.

Place a standard test block tightly in front of the film, use the specified thickness (such as 0.03mmPb) for the intensifying screen, and cover the area around the test block with the specified lead equivalent.

Exposure is carried out using rated tube voltage and rated tube current, with a typical exposure time of 5 minutes.

Process the exposed film in a darkroom, and prepare the developing and fixing solution, as well as the processing time and temperature according to the requirements specified for X-ray film.

After drying, measure the blackness value of the film with a blackness meter and calculate the arithmetic mean D. The background blackness of the film should not exceed 0.3, and the D value should not be less than the specified value (such as 1.5).

2. Radiation angle verification:

For orientationLaboratory X-ray testing equipmentPlace it on the support frame, align the window with the ground, and shield the ground with a specified thickness of lead plate. Adjust the X-ray machine to its rated value, perform radiography, and measure the distance from the center mark on the film to the boundary of the film with a higher density change zone. Calculate the radial and lateral radiation angles of the X-ray machine.

For the circumferential X-ray flaw detector, place it upright on the ground, measure the height of the center of the red band on the casing from the ground, and place a hidden bag filled with film at different positions 600mm away from the focal point (such as 0 °, 90 °, 180 °, 270 °) at this height. Other procedures and methods are the same as those for directional machine calibration and verification.

3. Timer error verification:

Set the machine timer to different positions (such as 0.5min, 1min, 5min, etc.), and start the stopwatch at the same time as turning on the machine. When the machine timer stops, stop the stopwatch at the same time, measure multiple times (such as 3 times) at each position, calculate the difference between the arithmetic mean and the set value, and take the maximum ratio between the two as the timer error.

4. Transparency sensitivity verification:

Measurement requirements are the same as penetration verification. Using the prescribed linear image quality indicator (such as the R'10 series in JB/T7902-1995), attach it to the edge area of the corresponding test block on one side of the X-ray machine, with the thin line of the image quality indicator facing outward.

Expose and process the film as required. When the background brightness is not lower than the specified value (such as 215cd/m? ）Observe the film with the naked eye under the viewing lamp, find the thinnest diameter that can be distinguished in the image quality indicator, and calculate the transparency sensitivity.

3、 Recording and identification

1. Record:

Calibration personnel should carefully record test data in the prescribed format and content, including calibration date, equipment model, calibration results, etc.

Auditors should verify the testing steps, methods, and all testing information data, and review any non conformities.

2. Identification:

After calibration, mark the instrument with information such as calibration date, validity period, and calibration personnel.

4、 Precautions

1. Safe operation:

When calibrating laboratory X-ray testing equipment, safety operating procedures should be strictly followed to prevent X-ray radiation from causing harm to the human body.

Calibration personnel should wear personal protective equipment such as protective clothing, goggles, etc.

2. Regular calibration:

X-ray testing equipment should be calibrated regularly to ensure its stability and accuracy in performance. The calibration cycle is usually one year or determined based on equipment usage.

3. Calibration report:

After calibration is completed, a calibration report should be prepared, detailing the calibration process, results, and conclusions. The calibration report should be signed and confirmed by the calibrator and auditor.

　　Laboratory X-ray testing equipmentThe calibration method includes preparation before calibration, calibration steps, recording and labeling, and precautions. Through a strict calibration process, the accuracy and reliability of X-ray testing equipment can be ensured, providing strong support for non-destructive testing work.