What are the internal quality inspection procedures for large diameter flanges

The internal quality inspection of large diameter flange is to check the internal quality of the large diameter flange itself, which is a quality condition that cannot be found in the appearance quality inspection. It includes both the inspection of the internal defects of the large diameter flange and the inspection of the mechanical properties of the large diameter flange. Chemical composition analysis should also be carried out for important parts, key parts or large diameter flange.

After the large diameter flange is made into parts, its stress, importance and working conditions are different in the use process, and its materials and metallurgical processes are also different. Therefore, different parts classify the large diameter flange according to the above conditions and the requirements of the department. Different departments and standards classify the large diameter flange differently.

For internal defects, we will check whether there are defects such as internal cracks, shrinkage cavities, looseness, coarse crystals, white spots, dendritic crystals, streamline inconformity with the shape, streamline disorder, flow through, coarse crystal rings, oxide film, delamination, overheating, overburned structure, etc. in large diameter flanges by means of low magnification inspection, fracture inspection, and high magnification inspection. The mechanical properties mainly include tensile strength at room temperature, plasticity, toughness, hardness, fatigue strength, high temperature instantaneous breaking strength, high temperature endurance strength, endurance plasticity and high temperature creep strength.

Large diameter flange is produced by precision casting method. The structure of this kind of casting is much thinner than that of ordinary sand casting, and the quality is improved a lot. It is not easy to have problems such as loose structure, air hole, sand hole, etc.