-SQA-SCOTTISH QUALIFICATIONS AUTHORITY HIGHER NATIONAL UNIT SPECIFICATION GENERAL INFORMATION INTERPRETING RADIOGRAPHS OF WELDMENTS

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1 -SQA-SCOTTISH QUALIFICATIONS AUTHORITY HIGHER NATIONAL UNIT SPECIFICATION GENERAL INFORMATION -Unit Number Superclass- -Title- WD INTERPRETING RADIOGRAPHS OF WELDMENTS DESCRIPTION- GENERAL COMPETENCE FOR UNIT: Applying principles of radiographic interpretation and welding to the practical interpretations of given radiographs for the identification of flaws. S 1. explain the basic principles and capabilities of radiographic inspection; 2. explain the factors affecting radiographic quality; 3. describe the application of the various radiographic techniques and principles of practical interpretation; 4. explain the technology of basic joining processes; 5. perform radiographic interpretation on given radiographs. CREDIT VALUE: 1 HN Credit ACCESS STATEMENT: Access to this unit is at the discretion of the Centre. However, it would be beneficial if the candidate had a knowledge of the basic NDT methods. This may be evidenced by possession of NC Module: Inspection: Principles of NDT Inspection: NDT Skills, or similar qualifications or experience

2 For further information contact: Committee and Administration Unit, SQA, Hanover House, 24 Douglas Street, Glasgow G2 7NQ. Additional copies of this unit may be purchased from SQA (Sales and Despatch section). At the time of publication, the cost is 1.50 (minimum order 5.00). 2

3 HIGHER NATIONAL UNIT SPECIFICATION STATEMENT OF STANDARDS UNIT NUMBER: UNIT TITLE: INTERPRETING RADIOGRAPHS OF WELDMENTS Acceptable performance in this unit will be the satisfactory achievement of the standards set out in this part of the specification. All sections of the statement of standards are mandatory and cannot be altered without reference to SQA. 1. EXPLAIN THE BASIC PRINCIPLES AND CAPABILITIES OF RADIOGRAPHIC INSPECTION Explanation of basic principles of capabilities of radiographic inspection is correct. Explanation of the theory of image formation with respect to exposure factors is correct. Description of radiographic films and processing is correct. Basic principles: sources and properties of x and gamma ray; absorption; scatter. Films and processing: film construction; latent images; developing. Written and/or oral evidence that the candidate has achieved the requirements of the performance criteria - and the range. 2. EXPLAIN THE FACTORS AFFECTING RADIOGRAPHIC QUALITY Explanation of factors affecting radiographic contrast is correct. Explanation of factors affecting radiographic definition is correct. Explanation of radiographic sensitivity is correct. 3

4 Radiographic contrast: radiation source type; density measurement; effect of changing source characteristics. Radiographic definition: film quality; types of unsharpness. Radiographic sensitivity: use of image quality indicators. Written and/or oral evidence that the candidate has achieved the requirements of the performance criteria - and the range. 3. DESCRIBE THE APPLICATION OF THE VARIOUS RADIOGRAPHIC TECHNIQUES AND PRINCIPLES OF PRACTICAL INTERPRETATION (d) Explanation of factors influencing radiographic technique is correct. Description of methods of assessment for radiographic quality with respect to image quality indicators (IQIs) is correct. Explanation of the cause of film faults and identification of spurious indications is correct. Explanation of requirements for viewing of radiographs is correct. Influencing factors: masking; types of screens and films. Techniques: SWSI; DWDI; DWSI Film faults and indications: processing faults; handling faults. Viewing: darkroom/area; viewers/intensifiers. Written and/or oral evidence that the candidate has achieved the requirements of the performance criteria -(d) and the range. 4

5 4. EXPLAIN THE TECHNOLOGY OF BASIC JOINING PROCESS Explanation of the basic joining processes in relation to specified welding processes is correct. Definition of the terminology applied to the processes is correct. Description of the types and origins of flaws associated with the specified processes is correct. Welding processes: MMA, MIG, TIG, SUB-ARC; ELECTRO-SLAG. Terminology: weld symbols; weld preps; weld prep annotation. Written and/or oral evidence that the candidate has achieved the requirements of the performance criteria - and the range. 5. PERFORM RADIOGRAPHIC INTERPRETATION ON GIVEN RADIOGRAPHS Selection of conditions for interpretation is correct. Appraisal of radiographic film to be interpreted is correct to the prescribed standard. Assessment of all radiographs and subsequent report is correct. Interpretation conditions: viewing facility; viewers; densitometer; high intensity viewer; sensitivity check strips. Written evidence that the candidate has achieved the requirements of PC to and the range. For PCs and appraisal and assessment should be carried out on a series of 6 radiographs covering the following defect types: 5

6 Cracks, lack of fusion, porosity, slag, lack of penetration, herring bone porosity, inclusions, excess penetration, root concavity, undercut. MERIT To gain a pass in this unit, a candidate must meet the standards set out in the outcomes, performance criteria, range statements and evidence requirements. To achieve a merit in this unit, a candidate must demonstrate a superior or more sophisticated level of performance. This may be demonstrated by: (i) (ii) (iii) solving problems with particular efficiency and simplicity; drawing diagrams with clarity; expressing and presenting answers to descriptive questions ASSESSMENT In order to achieve this unit, candidates are required to present sufficient evidence that they have met all the performance criteria for each outcome within the range specified. Details of these requirements are given for each outcome. The assessment instruments used should follow the general guidance offered by the SQA assessment model and an integrative approach to assessment is encouraged. (See references at the end of support notes). Accurate records should be made of the assessment instruments used showing how evidence is generated for each outcome and giving marking schemes and/or checklists, etc. Records of candidates achievements should be kept. These records will be available for external verification. SPECIAL NEEDS Proposals to modify outcomes, range statements or agreed assessment arrangements should be discussed in the first place with the external verifier. Copyright SQA 1997 Please note that this publication may be reproduced in whole or in part for educational purposes provided that: (i) (ii) no profit is derived from the reproduction; if reproduced in part, the source is acknowledged. 6

7 HIGHER NATIONAL UNIT SPECIFICATION SUPPORT NOTES UNIT NUMBER: UNIT TITLE: INTERPRETING RADIOGRAPHS OF WELDMENTS SUPPORT NOTES: This part of the unit specification is offered as guidance. None of the sections of the support notes is mandatory. NOTIONAL DESIGN LENGTH: SQA allocates a notional design length to a unit on the basis of time estimated for achievement of the stated standards by a candidate whose starting point is as described in the access statement. The notional design length for this unit is 40 hours. The use of notional design length for programme design and timetabling is advisory only. PURPOSE The purpose of this unit is to give candidates a basic knowledge of radiographic inspection and enable them to demonstrate competence on interpretation and acceptance of radiographs. CONTENT/CONTEXT Corresponding to Outcomes Outcome 1 Explain the basic principles of radiographic inspection. Sources of x and gamma rays. Properties of x and gamma rays, absorption and scatter. Penumbra, inverse square law, film types. Radiographic source (x or gamma ray). Energy values used. Photographic emulsions, exposure and processing. Outcome 2 - Explain the factors affecting radiographic quality. Density and its measurement. Causes, effect and control of scatter, contrast, quality of radiation, effect of changing kv and source types, (e.g. x-ray/gamma) screens. Geometric unsharpness, film unsharpness, film graininess. Factors affecting sensitivity and its assessment, using IQIs. Outcome 3 - Describe the application of the various radiographic techniques and principles of practical interpretation. Radiographic techniques (SWSI, DWSI, DWDI), masking, blocking, media, choice of screens, filters, choice of film, identification of weldments, marking out etc. 7

8 Types of IQIs. Causes and effects of film and processing faults. Viewing conditions. Outcome 4 Explain the technology of the basic joining processes. Welding processes, technique and procedures covering MMA, MIG, TIG, SUB- ARC, electro-slag, but only those applicable to the candidates environment or experience. Welding terminology and symbols. Origin of weld defects and their appearance on the radiograph. Outcome 5 Perform radiographic interpretation on given radiographs. Viewing requirements. Practical interpretation of radiographs. Reporting. APPROACHES TO GENERATING EVIDENCE This unit should be carried out in a classroom with blackout facilities or classroom and separate radiograph viewing room. Access to relevant specification, radiographs and radiograph master reports must be readily available or where the candidate can be easily directed to the information. Delivery of the unit should be in order of the outcomes as stated. Where appropriate, the outcomes should be related to the candidate s own workplace or experience. ASSESSMENT PROCEDURES Centres may use the Instruments of Assessment that are considered by tutors/trainers to be most appropriate. Examples of Instruments of Assessment that can be used are as follows: Outcome 1 - Multi-choice question paper containing 20 questions divided proportionally across the content of the three PCs. Outcome 2 - Multi-choice question paper containing 20 questions divided proportionally across the content of the three PCs. Outcome 3 - Multi-choice question paper containing 20 questions divided proportionally across the content of the four PCs. Outcome 4 - Multi-choice question paper containing 20 questions divided proportionally across the content of the three PCs. Outcome 5 - Practical and proforma written reports on 6 radiographs. 8

9 An example of alternative instrument of assessments that may be used are as follows: Outcome 1 - Short answer question paper containing not less that 10 questions covering the content of the three PCs. Outcome 2 - Short answer question paper containing not less that 10 questions covering the content of the three PCs. Outcome 3 - Short answer question paper containing not less that 10 questions covering the content of the four PCs. Outcome 4 - Short answer question paper containing not less that 10 questions covering the content of the three PCs. Outcome 5 - Practical and proforma written reports on six radiographs. It is strongly recommended that the multi-choice answer questions and the short written answer questions for Outcomes 1,2 and 3 are combined to provide a balanced assessment process for the candidate. PROGRESSION This is a specialised unit and has no progression. REFERENCES 1. Guide to unit writing. 2. For a fuller discussion on assessment issues, please refer to SQA s Guide to Assessment. 3. Information for centres on SQA s operating procedures is contained in SQA s Guide to Procedures. 4. For details of other SQA publications, please consult SQA s publications list. Copyright SQA 1997 Please note that this publication may be reproduced in whole or in part for educational purposes provided that: (i) (ii) no profit is derived from the reproduction; if reproduced in part, the source is acknowledged. 9