ISO 17635:2025

This document gives guidelines for the choice of non-destructive testing (NDT) methods for welds in metals and for the evaluation of the results for quality control purposes, based on quality requirements, material, weld thickness, welding process and extent of testing. This document also specifies general rules and standards to be applied to the different types of testing, for the selection of the method, the techniques and the acceptance levels. Acceptance levels cannot be a direct interpretation of the quality levels defined in ISO 5817 or ISO 10042. They are linked to the overall quality of the produced batch of welds. The requirements specified in this document for acceptance levels for NDT conform with quality levels stated in ISO 5817 or ISO 10042 (moderate, intermediate, stringent) only on a general basis and not in detail for each indication. Annex A gives correlations between quality levels, testing levels and acceptance levels for specific testing techniques. Annex B gives an overview on specific testing techniques of standards linked to quality levels, acceptance levels and testing methods.