ISO 18279:2023 ろう付け | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 44, Welding and allied processes, Subcommittee SC 13, Brazing materials and processes, in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 121, Welding and allied processes, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This second edition cancels and replaces the first edition (ISO 18279:2003), which has been technically revised.

The main changes are as follows:

• An additional quality level for brazed joint imperfections has been added in Annex B in order to reflect the technical progress that has been achieved over the past decade as well as the need for increased requirements regarding reliability of brazed joints for critical applications. Quality levels have been revaluated.

Introduction

Brazed joints usually contain imperfections of various types, some of which are detrimental in almost every case while others can be detrimental or harmless, depending entirely on the service requirements of the joint in question. Therefore, it is often necessary to classify the imperfections in a brazed joint and then try to assess the significance of their effects on the behaviour of the joint in service. The classification is relatively easy and Table 1 describes the imperfections that most commonly occur. The assessment of significance is not easy (see also Annex A).

For welded joints, there has been extensive work carried out for many years on the significance of imperfections in service; however, such work has not been carried out on brazed joints. Moreover, the work on welded joints is only rarely relevant to brazed joints, mainly because of differences in geometry and stressing. Therefore, this document cannot give definitive quality levels for brazed joints. These can only be produced as experience is gained from industrial applications. However, Annex B gives some suggestions for quality levels for general applications, which can be of help where detailed information is not available. The use of quality levels can only be successful if the imperfections that are relevant to the application of the brazed joint are determined.

1 Scope

This document details a classification of imperfections that can occur in brazing joints. In addition, guidance is provided on quality levels and suggested limits for imperfections are detailed.

For requirements not covered by this document, reference can be made to other sources, such as statutory regulations, codes of practice and technical delivery conditions.

No information is given on how imperfections are to be assessed in individual cases because this depends on the requirements for the particular brazed joint. These imperfections are not always detectable by the use of non-destructive testing alone.

This document covers only imperfections that can occur in connection with brazing without the effect of any additional service loads. Only the type, shape and position of such imperfections are covered; no indication is given of the conditions of occurrence or causes.

For requirements for brazed joints which are relevant and essential to the particular function of the component, reference can be made to the relevant documentation, for example manufacturing documents or procedure sheets.

It is important that these requirements be precisely prescribed and that conformity with them be verifiable. Conformity can be established by testing either the brazed assembly itself or a test piece produced under comparable conditions.

This document does not specify requirements for acceptance levels for imperfections, since these will differ very markedly depending on the application, but it does suggest some quality levels which can be of value in the absence of more detailed information.

For the purposes of this document, the areas of a brazed assembly are designated as shown schematically in Figure 1.

Figure 1 — Schematic of brazed assembly

a)Simple brazed assembly

b)Section through assembly in a)

Key

	parent material
	parent material affected by brazing [heat-affected zone (HAZ)]
	diffusion-transition zone
	braze metal

NOTE Extent of HAZ will vary with materials and brazing process.

2 Normative references

There are no normative references in this document.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

Bibliography