Mould pressing head is an indispensable and important part of pressure vessel equipment in petrochemical, atomic energy and food and pharmaceutical industries. The head is a dished end of the pressure vessel, and is a main pressure-bearing component of the pressure vessel. The quality of the head is directly related to the long-term reliable running of the pressure vessel.

　　At present, the quality control methods of integrally mold pressing head mainly adopt x-ray detection technology. The advantage is that there are no special requirements for the tested products, and the test results are displayed intuitively. The disadvantage is that two-dimensional imaging of three-dimensional objects, hidden defects cannot be displayed. The solution to this disadvantage is usually to perform secondary radiography in two directions that are perpendicular to each other. The hidden defects can be directly determined from the two negatives. Or using tomography to accurately locate hidden defects.

　　However, because the overall mold pressing head is limited by the geometry and size of its structure, the above two methods cannot be used to confirm where are the defects hidden. The internal defect status of the head will have different impacts on its reliability. Accurate judgment and measurement are an inevitable requirement for its quality control.

　　Therefore, in order to solve this problem, the technique of the secondary radiographic positioning measurement method for the embedded defects of the integral molded head was developed. It is easy to guide the repair and elimination of defects. Strengthen the quality inspection and production process control of the whole mold pressing head.