BS M 36:1970

Foreword
Method
1. GENERAL
1.1 Scope
1.2 Definitions
1.3 Description of technique
2. OPERATIONAL REQUIREMENTS
2.1 Ultrasonic flaw detector and probe
2.1.1 Operating frequency range
2.1.2 Sensitivity
2.1.3 Linearity of amplification
2.1.4 Near surface resolution
2.1.5 Linearity of flaw detector time base
2.1.6 Flaw detector controls
2.1.7 Probe calibration
2.2 Immersion tank and probe manipulator
2.3 Ancillary equipment
2.3.1 Automatic flaw alarm
2.3.2 Automatic recording
2.3.3 Monitoring
2.4 Approvals
2.4.1 Equipment
2.4.2 Operator
3. REFERENCE STANDARDS
3.1 General
3.1.1 Master reference blocks
3.1.2 Standard reference blocks
3.1.3 Working reference blocks
3.1.4 Materials other than aluminium alloys
3.2 Use of reference blocks
4. INSPECTION PROCEDURE
4.1 General
4.1.1 Surface condition
4.1.2 Preliminary setting-up procedure
4.1.3 Probe adjustment
4.1.4 Scanning procedure
4.2 Determination of flaw parameters
4.2.1 General
4.2.2 Plan position of flaw
4.2.3 Depth of flaw
4.2.4 Equivalent flat-bottomed hole
4.3 Investigation of angle of maximum reflectivity
4.4 Precautions
4.5 Standard of acceptance
4.6 Reporting of flaws
4.6.1 Inspection report
4.6.2 Supporting diagrams
4.6.3 Marking the workpiece
APPENDICES
A. Inspection report
B. Supporting diagrams for inspection report
C. Test blocks
D. Determination of transmission factors and ultrasonic
     attenuation
E. Distance-amplitude curves and their derivation
TABLES
1. Dimensions of standard reference block
2. Dimensions of resolution test block
FIGURES
1. Typical inspection report
2. Basic method of stating flaw location by polar
     co-ordinates
3. Typical supporting diagram for a disc-shaped forging
     showing method of locating flaw
4. Basic method of stating flaw location by cartesian
     coordinates
5. Typical ultrasonic inspection chart for a 'Boomerang'
     shaped forging, showing method of locating flaws
6. Detail of recommended reference standard test block
7. Detail of resolution test block
8. Resolution criteria
9. Method for determining transmission and attenuation
     correction factors when using reference blocks non-
     representative of the material under test
10. Alignment of probe, normal to backplate (in far zone)
11. Alignment of probe, axial to ball
12. Typical distance - amplitude curve with water as
     couplant

Refers to the ultrasonic inspection by an immersion technique of special forgings used for rotating parts. Describes the method of testing by which the acceptability of such forgings can be assessed and specifies flat-bottomed hole reference standards, apparatus requirements, and control and test procedures. Confined to pulse echo techniques and the use of single crystal transceiver probes and limited to use on forgings having a thickness of not less than twice the near surface resolution of the probe. Intended for use on forgings when these are in the raw material state.

1.1.1 This British Standard applies to the ultrasonic inspection by an immersion technique of special forgings used primarily for rotating parts, e.g. turbine discs. It accordingly describes the method of testing by which the acceptability of such forgings can be assessed, and specifies flat-bottomed hole reference standards, apparatus requirements, and control and test procedures.

1.1.2 The method, which is confined to pulse echo techniques and the use of single crystal transceiver probes, is limited to use on forgings having a thickness of not less than twice the near surface resolution of the probe (as determined in 2.1.4) which lend themselves, by virtue of their form, to mechanical scanning in which the incident beam is approximately normal to the surface of the section being scanned.

1.1.3 The method is primarily intended and recommended for use on forgings when these are in the raw material state only. However, it can be used during manufacture on machined or part-machined components, provided that these components comply with the shape and thickness described in 1.1.2.

1.1.4 By agreement, the standard may also be used for tests on other types of forgings and wrought forms manufactured in all metallic materials, in which case due allowance has to be made for the differences in ultrasonic attenuation and transmission factors presented by each material. Factors affecting the apparent flaw size when estimated by comparison with the reference standards, and procedures which will enable due allowance to be made for them are described.