Non-Destructive Testing
Meaning ~ Inspection techniques that evaluate the internal structure of manufactured materials without causing damage represent a formal verification category.
Astm E186
Meaning
Integrity checks for heavy-walled steel castings utilize reference radiographs to provide a standardized basis for evaluating internal discontinuities. These visual aids in astm e186 represent different types of flaws such as gas holes, sand inclusions, pipe voids, and shrinkage. Inspectors compare the production films against these master plates to assign a quality grade.
The standard applies specifically to metal sections with a thickness between two and four and a half inches.
Radiograph Set
Physical films or digital images provided with the standard serve as the benchmarks for evaluation. Within astm e186 the categories include gas porosity and various forms of shrinkage. Each category contains several levels of severity ranging from acceptable to rejectable.
Purchasing agents specify the required level in the contract based on the stress the casting will endure.
Casting Integrity
High-pressure applications require a higher grade of internal soundness to prevent leaks or structural cracks. The use of astm e186 ensures that the foundry and the buyer have a shared understanding of what constitutes a defect. Internal voids that are too large or too numerous lead to the scrapping of the component.
Comparative Basis
Interpretation of the results depends entirely on the subjective judgment of a trained technician. The astm e186 standard provides a way to quantify this judgment by providing a side by side comparison. Misidentifying a shrinkage type results in an incorrect classification and potentially allows a weak part into service.
Proper lighting and high-resolution screens are necessary to see the fine details in the reference films.