INSPECTION OFBRAZED JOINTS

ReviewersS. RangaswamyWall Colmonoy CorporationD. W. BucholzConforma Clad, IncorporatedD. L. McQuaidD. L. McQuaid & Associates, Incorporated

ContentsIntroduction 170Acceptance Criteria 170Discontinuities inBrazed Joints 170Inspection Methods 171Critical BrazedComponents 177Bibliography 178

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Photograph courtesy of Materials Resources International

AWS BRAZING HANDBOOK 169

INTRODUCTION

170 CHAPTER 8—INSPECTION OF BRAZED JOINTS AWS BRAZING HANDBOOK

The inspection of the brazement is the final step inthe brazing operation. Along with prior inspectionscarried out at various stages of the production pro-cess, final inspection is essential for assuring satis-factory and uniform brazed joint quality. Finalinspection also reveals how well the previous stepswere completed with respect to the overall integrityof the brazed joints.

Inspection procedures are important factors fromthe very beginning of the design stage. Care must betaken to ensure that the assembly can be manufac-tured to the required standard(s), but also that it canlater be properly inspected to assure that all qualityrequirements have actually been met and maintained.

The inspection method chosen to evaluate a braze-ment depends on the service requirements. In manycases, the inspection methods are specified by the enduser or by regulatory codes, standards, or both. Whenestablishing or interpreting these codes or qualitystandards for brazed joints, an approach similar tothat used in establishing standards for any other phaseof manufacturing should be used. These standardsshould be based upon requirements that have beenestablished by prior service tests, mechanical modelingand analysis validated by service tests, or mechanicaltesting that duplicates the service requirements.

The brazing procedure may be validated bydestructive testing to assure the ability to producebrazements that meet the service requirements andexhibit the desired level of reliability.

ACCEPTANCE CRITERIA

When defining the acceptance criteria for any typeof braze discontinuity, the following should be con-

sidered: (1) shape, (2) orientation, (3) location in thebrazement (i.e., surface or subsurface), and (4) rela-tionship to other discontinuities. Acceptance limitsshould always be stated with respect to the minimumrequirements for acceptability.

For example, it may be determined from history,analysis, or testing that a given amount (area) ofporosity is permitted to exist in a brazed joint with-out compromising overall integrity. The maximumamount of that porosity may be stated but the objec-tives are always to maximize the brazed area and beconscious of the fact that there is a minimum amountof brazed area below which the brazement cannotfunction or be considered reliable.

Judgments regarding the disposition of discrepantcomponents should be made by persons competentin the fields of brazing metallurgy and quality assur-ance. These persons should also understand the func-tion of the component. All such dispositions shouldbe documented.

DISCONTINUITIES IN BRAZED JOINTS

The limits of acceptability should be specificallydefined when nondestructive examination is used toidentify the following types of common discontinuities.

VOIDSVoids, the incomplete flow of the brazing filler

metal in a brazed joint, can be the result of one ormore of the following:

1. Improper cleaning,

INSPECTION OFBRAZED JOINTS

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