GB/T 37929-2019Non-destructive testing instruments—Testing methods for life of X-ray tubes (English PDF)

3.1 Life of X-ray Tubes

Test the life of X-ray tubes under the rated tube voltage, rated tube current and stipulated distance and orientation. Analytical instrument uses the spectral purity of X- ray tubes, namely, the impurity line, as the assessment parameter of the life of X-ray tubes. The assessment parameter of the life of other industrial X-ray tubes is the dose rate. When dose rate is less than 90%, it signifies the end of life.

4.1 Test Conditions

Test conditions shall comply with the requirements in Chapter 4 in GB/T 26594-2011.

4.2 Load Power

Load power shall be not lower than the rated power.

4.3 Qualification Requirements

tK---measurement time when it is found that the assessment parameter of life no longer complies with the stipulation in the detailed specification, expressed in (h); tK-1---the previous measurement time when it is found that the assessment parameter of life no longer complies with the stipulation in the detailed specification, expressed in (h).

At this moment, when the dose rate of X-ray tube is lower than 90%, the X-ray tube shall be determined as unqualified.

c) During the process of life test, if it is found on the testing instrument that X-ray tube is obviously invalid (for example, air leakage, or, rupture), then, ti shall be the time from the beginning of the test to the moment when such invalidation is found.

5.2 Method of Single Load Times

5.2.1 Use single load times N of X-ray tube to express the life of X-ray tube. N shall be stipulated in the detailed specification.

5.2.2 Single load power shall be not less than 90% of the maximum power under the stipulated load time. Repeated loads in a certain interval of time are allowed. The anode storage heat when each load begins and the interval time between two adjacent repeated loads shall be stipulated in the detailed specification.

5.2.3 Test procedure shall comply with the following steps:

a) In accordance with the stipulated load conditions, make the anode storage heat reach the value stipulated in the detailed specification;

b) In accordance with the single load conditions and interval time stipulated in the detailed specification, conduct repeated loads;

c) Comply with the assessment parameter of life stipulated in the detailed specification, however, after 0, (1-0.1 n) N, 0.9 N and N load, the measurement shall also be conducted.

5.2.4 Life test shall adopt average life for determination. When the average life rate A is not less than 90%, then, the X-ray tube is qualified in the life test. Average life rate A shall be calculated in accordance with Formula (3): Where, n---quantity of tubes being tested; […]