AWS B1.10:1999 An American National Standard. Guide for the Nondestructive Examination of Welds

Transcription

1 AWS B1.10:1999 An American National Standard Guide for the Nondestructive Examination of Welds

2 Key Words Guide, eddy current examination, magnetic particle examination, nondestructive examination, penetrant examination, radiographic examination, ultrasonic examination, visual examination, leak examination, weld discontinuities AWS B1.10:1999 An American National Standard Approved by American National Standards Institute October 26, 1999 Guide for the Nondestructive Examination of Welds Supersedes ANSI/AWS B Prepared by AWS Committee on Methods of Inspection Under the Direction of AWS Technical Activities Committee Approved by AWS Board of Directors Abstract This guide acquaints the user with the nondestructive examination methods commonly used the examine weldments. The standard also addresses which method best detects various types of discontinuities The examination methods included are visual, penetrant, magnetic, radiographic, ultrasonic, electromagnetic (eddy current), and leak testing. 550 N.W. LeJeune Road, Miami, Florida 33126

3 Table of Contents Personnel... iii Foreword... v List of Tables...vi List of Figures...vi 1. General Scope Advantages and Limitations of the Inspection Method Acceptance Standards Cost Procedures References NDE Symbols Safety and Health Discontinuities Discussion of Discontinuities List of Discontinuities Porosity Inclusions Incomplete Fusion Incomplete Joint Penetration Undercut Underfill Overlap Lamination Delamination Seams or Laps Lamellar Tear Cracks Concavity Convexity Weld Reinforcement Nondestructive Examination Methods l Visual Examination (VT) Penetrant Examination (PT) Magnetic Particle Examination (MT) Radiographic Examination (RT) Ultrasonic Examination (UT) Electromagnetic Examination (ET) Leak Examination Interrelationships Among Welding Processes, Discontinuities, and Examination Methods Supplementary Reading Material...26 Annex A Examination Method Selection Guide...29 Annex B NDE Symbols and Abbreviations...31 Annex C Typical Industry Standards...37 Annex D Guidelines for Preparation of Technical Inquiries for AWS Technical Committees...39 AWS Document List...41 v

4 List of Tables Table 1 Common Types of Discontinuities Discontinuities Commonly Encountered with Welding Processes Common Weld Inspection Methods vs. Discontinuities Applicable Examination Methods Five Weld Joint Types...27 List of Figures Figure 1 Double-V-Groove Weld In Butt Joint Single-Bevel-Groove and Fillet Welds in Corner Joint Double-Bevel-Groove Weld in T-Joint Double Fillet Weld in Lap Joint Single Pass Double Fillet Weld in T-Joint Single-Bevel-Groove Weld in Butt Joint Fillet Weld Terminology Fillet Weld Discontinuities Groove Weld Terminology Groove Weld Discontinuities Steps in Penetrant Testing Magnetic Field Leakage Direct Magnetization Using dc Prods Indirect Magnetization Using a Yoke Making a Radiograph Typical Radiographs of Weld Discontinuities Detection of Planar Discontinuities at Various Orientations by Radiography Block Diagram, Pulse-Echo Flaw Detector Similarities Between Reflections of Light and Sound at Boundaries Refraction Diffraction Example of Longitudinal Testing No Discontinuities Discontinuity Incomplete Fusion of Backing Bar Eddy Current Weld Examination Encircling Coil for the Eddy Current Examination of Welded Pipe Typical Eddy Current Surface Prods for the Examination of Welds...25 B1 Standard Location of Elements Guide for the Nondestructive Examination of Welds...32 vi

5 AWD B1.10:1999 Guide for the Nondestructive Examination of Welds 1. General 1.1 Scope. This standard provides a reference guide for the kinds of nondestructive examination methods that are used to verify that welds meet the requirements of a code or specification. The nondestructive examination methods described are: (1) Visual (2) Penetrant (3) Magnetic Particle (4) Radiographic (5) Ultrasonic (6) Electromagnetic (7) Leak The types of discontinuities detected with each method are disclosed and their causes discussed. Acceptance criteria are not addressed in this standard. Such requirements may be in the application code. Requirements for nondestructive examination and acceptance criteria not provided in the application should be the specified in procurement documents prior the award of contracts. Nondestructive examination (NDE) is a general term used in this text to identify the common inspection methods for evaluation of welds and related materials without destroying their usefulness. The terminology used in this guide is that established in AWS A3.0, Standard Welding Terms and Definitions. That document defines a discontinuity as an interruption of the typical structure of a material, such as a lack of homogeneity in the mechanical, metallurgical, or physical characteristics. It defines discontinuity as a defect when it exceeds the sizes and types of discontinuities defined as rejectable by the applicable specification. For the purpose of this guide, reference will be made to detection of discontinuities without regard to the distinction between acceptance or rejection. Principal factors to consider when choosing an inspection method are the advantages and limitations of the method, anticipated type and size of discontinuity, acceptance standards, and cost. Annex A is a guide to process selection. 1.2 Advantages and Limitations of the Inspection Method. The advantages and limitations of the inspection method help to determine which method(s) are best for detecting discontinuities of a particular size, shape, and orientation. For example, radiography can detect discontinuities with major planes aligned parallel with the radiation beam, such as cracks oriented normal to plate surfaces. Radiography, however, usually cannot detect laminations in plate or cracks oriented parallel to the plate surface. Conversely, ultrasonic examination can detect cracks oriented in any direction provided the sound beam is oriented essentially perpendicular to the major axis of the crack. 1.3 Acceptance Standards. The statement the weld shall be radiographically examined is incomplete unless acceptance standards are specified. Acceptance standards define characteristics of discontinuities and state whether particular types of discontinuities are allowed. Certain discontinuities such as slag or porosity are acceptable providing their size and distribution are within specified limits. These criteria have to be incorporated in the acceptance standards. Most codes and specifications such as AWS D1.1, Structural Welding Code Steel, ASME Boiler and Pressure Code, and API 1104, Welding of Pipeline and Related Facilities contain acceptance standards. These and other construction standards are shown in Annex B. 1.4 Cost. Costs of the various inspection methods depend on the particular situation. Two factors that should be considered in selection of a nondestructive examination method are that of the equipment and of performing the inspection. Visual examination is usually the least 1