VISUAL EXAMINATION PROCEDURE
VISUAL EXAMINATION PROCEDURE
0 Rev
Date
First Issue
Santanu Saha
Revision Details
Prepared By NDT Level III
Approved( QCM )
VISUAL EXAMINATION PROCEDURE
Index 1.
Scope
2.
Reference documents
3.
Qualification of Visual Testing Personnel
4.
Equipment & Calibration
5.
Inspection method and lighting
6.
Sequence of inspection
7.
Surface finish and extent of inspection
8.
Application
9.
Reports and documentation
10.
Acceptance criteria
11.
Appendix – 1: measuring apparatus
12.
Attachments 1 & 2: Acceptance criteria.
1.0
Scope
1.1
This procedure gives minimum requirements to perform Direct Visual Inspection on all types of welds and components as required by
VISUAL EXAMINATION PROCEDURE the governing document whenever such type of inspection is applicable by contract Specification 1.2 2.0
Extent of visual inspection shall be as per governing document Reference Documents Current editions of the following references shall be applicable. 2.1 ASME B 31.1: Power Piping, 2007 edition, Addenda 2008. 2.2 ASME Sec VIII Div 2: 2007 Edition, Addenda 2009 2.3 ASME Sec I: Power Boilers: 2007 edition, Addenda 2009. 2.4 ASME Sec V: 2007 edition, Addenda 2009.
3.0
Qualification of Visual Testing Personnel
3.1
Personnel who perform Visual examination of welds shall be qualified and certified for the method in accordance with the following:
3.1.1
Instruction/training of at least 12 hours in the fundamentals of the Visual examination method.
3.1.2 On-the-job training to familiarize the VT personnel with the appearance and interpretation of indications of weld defects. The length of time for such training shall be at least 8 hours in addition to the training mentioned in 3.1.1, to assure adequate assimilation of the knowledge required. 3.1.3 An eye examination performed at least once each year to determine optical capability of NDE personnel to perform the required examinations. 3.1.4 Upon completion of 3.1.1 and 3.1.2 above, the NDE personnel shall be given a written examination and performance examination by QICL to determine if the NDE personnel are qualified to perform the required examinations and interpretation of results. The passing grade for the examination shall be at least 80%. The complete examination shall be divided in to three parts namely General, Specific and Practical (performance examination). The candidate must obtain at least 70% marks in each examination with no less than 80% in aggregate. 3.1.5 Certified NDE personnel whose work has not included performance of a specific examination method for a period of 1 year or more shall be recertified by successfully completing the examination of 3.1.4 above and also passing the visual examination of 3.1.3 above. Substantial changes in procedures or equipment shall require recertification of the NDE personnel.
VISUAL EXAMINATION PROCEDURE 3.2
Alternately, personnel Qualified to AWS QC 1; Standard for Qualification and Certification of Welding Inspection or ‘SNT-TC-1A’, Recommended Practice for qualification and certification of NDT personnel may be used for Visual examination of welds.
4.0
Equipment & Calibration
4.1
An array of devices are available for viewing measuring etc. whenever such a device is deemed necessary by contractual requirements or Specification, any device requiring calibration shall be calibrated accordingly and documented
5.0
Inspection Method & Lighting
5.1
Inspection Method Visual inspection shall be performed without magnification unless specifically required by the governing document. When magnification is required, evaluation and acceptance shall be based upon comparison with a reference standard where both magnified and unmagnified appearance can be determined
5.2
Direct Visual Examination Direct visual examination may usually be made when access is sufficient to place the eye within 24 in (600mm) of the surface to be examined and at an angle not less than 30 deg. to the surface to be examined. Mirrors may be used to improve the angle of vision, and aids such as a magnifying lens may be used to assist examinations. The specific part, component, vessel, or section thereof, under immediate examination, shall be illuminated, if necessary with flashlight or other auxiliary lighting, to attain a minimum of 100 foot candles (1000 lux) at the examination surface/site.
5.3
6.0
Remote Visual Examination In some cases, remote visual examination may have to be substituted for direct examination. Remote visual examination may use visual aids such as mirrors, telescopes, boroscopes, fiber optics, cameras or other suitable instruments. Such systems shall have a resolution capability at least equivalent to that obtainable by direct visual observation and prior approval by authorized inspector Records Weld inspection results shall be recorded when required, and maintained as required by the governing document or contract specifications Sequence of Inspection
VISUAL EXAMINATION PROCEDURE 6.1
Visual Inspection shall be performed prior, during and after the completion of weldment.
6.2 the
Visual Inspection should be performed prior to any other Inspection, if Inspector has reason to doubt the quality of the item as weldments. The inspector may require additional Inspection.
6.3
Visual inspection shall be done after PWHT (if any) and shall be done prior to any other NDE.
7.0
Surface Finish & Extent of Inspection
7.1
Surface Finish Unless otherwise specified, acceptance inspection shall be performed on an item in the final surface condition and final heat-treated condition. Surfaces to be inspected shall be free from, paint, scale, slag, and adhering or embedded sand or other extraneous materials. With the exception of undercuts, which are within specification allowances the contour of welds, shall blend smoothly and gradually into the base metal. Weld surface irregularities shall be removed to the extent that they do not interfere with the inspection. Penning shot, sand, grit, and vapor blasting shall not be performed on surfaces, which are to be liquid penetrant inspected unless specifically approved by the Authorized Inspector.
7.2
Area of Interest The area of inspection for welds shall include as a minimum, the area one inch on either side of the expected weld width. The area of inspection of other items shall be as specified in the governing document.
8.0
Application
a)
At fit-up for: 1. Joint clearances 2. Alignment
b)
Prior to welding for 1. Weld and preparation, dimensions and surface finish. 2. Clearance dimensions of backing strips, Backing rings, sockets consumable inserts. 3. Verification of correct type of material. 4. Verification of cleanliness requirements.
VISUAL EXAMINATION PROCEDURE 5. Placements of reference lines for socket welds. c)
Condition of tack welds, in accordance with requirements of the specific weld type.
d)
During welding 1. For compliance to proper Welding procedure.
e)
After 1. 2. 3. 4. 5.
9.0
Reports & Documentation
9.1
Visual Inspection Report shall include the following as minimum 1. Client Name / Symbol 2. Date 3. Job No 4. Item No. / Weld ID 5. Drawing No 6. Status e.g.:- As received, before welding, after welding, before painting etc. 7. Name and Signature 8. Observation 9. Disposition – Accept / Reject 10. Remarks - e.g. Subjected to NDE, PWHT, Blasting, painting etc.
welding for Contour and finish of outside surface. Contour and finish of inside surface when accessible. Size of legs and throat thickness of fillet welds. Degree of undercutting. Evidence of mishandling, from center punch or other impression marking or excessive grinding.
10.0 Acceptance Criteria 10.1
Acceptance Acceptance standards shall be as required by the governing documents. Discontinuities shall be classified in accordance with applicable acceptance standards. Refer attachment 1 acceptance criteria as per ASME B 31.1 and attachment 2 as per ASME Sec VIII Div 2.
VISUAL EXAMINATION PROCEDURE APPENDIX I MEASURING APPARATUS & PRACTICAL APPLICATIONS ATTRIBUTE Wall thickness Bevel Angles Outside Diameter Inside Diameter Reinforcement Undercut Fillet Legs or Throat Thickness
TOOLS Vernier Calliper, Micrometer Bevel Protractor, Bridge Cam Gauge Vernier Calliper, Tape Vernier Calliper, Tape Bridge Cam Gauge Bridge Cam Gauge Bridge Cam Gauge, Weld Fillet Gauge
ATTACHMENT 1 ACCEPTANCE CRITERIA – VISUAL EXAMINATION ASME B31.1: 2007, Addenda 2008 Acceptance Standards. The following indications are unacceptable:
VISUAL EXAMINATION PROCEDURE a. b. c. d. e.
Cracks – external surface Undercut on surface which is greater than 1/32 in. deep Weld reinforcement greater than specified in Table I Lack of fusion on surface Incomplete penetration (applies only when inside surface is readily accessible) f. Any other linear indications greater than 3/16 in long g. Surface porosity with rounded indications having dimensions greater than 3/16 in. or four or more rounded indications separated by 1/16 in. or less edge to edge in any direction. Rounded indications which, are circular or elliptical with their length less than three times their width. TABLE I REINFORCEMENT OF GIRTH & LONGITUDINAL BUTT WELDS Thickness of Base Metal, in. (mm)
Maximum Thickness of Reinforcement for Design Temperature > 750º F 350ºF – < 350º F (400º C) 750ºF (175º C) (175ºC – 400ºC) in. mm in. mm in. mm Upto 1/8 (3.0), incl 1/16 2.0 3/32 2.5 3/16 5.0 Over 1/8 to 3/16 (3.0 to 5.0), incl 1/16 2.0 1/8 3.0 3/16 5.0 Over 3/16 to 1/2 (5.0 to 13.0), 1/16 2.0 5/32 4.0 3/16 5.0 incl Over 1/2 to 1 (13.0 to 25.0), incl 3/32 2.5 3/16 5.0 3/16 5.0 Over 1 to 2 (25.0 to 50.0), incle 1/8 3.0 1/4 6.0 1/4 6.0 Over 2 (50.0) 5/32 4.0 The greater of 1/4 (6mm) or 1/8 times the width of the weld in inches (mm) General notes: a. For double welded butt joints, this limitation on reinforcement given above shall apply separately to both inside & outside surfaces of the joint. b. For single welded butt joints, the reinforcement limits given above shall apply to the outside surface of the joint only. c. The thickness of weld reinforcement shall be based on the thickness of the thinner of the materials being joined. d. The weld reinforcement thickness shall be determined from the higher of the abutting surfaces involved. e. Weld reinforcement may be removed if so desired. ATTACHMENT 2
VISUAL EXAMINATION PROCEDURE ACCEPTANCE CRITERIA – VISUAL EXAMINATION ASME SEC VIII DIV 2: 2007; ADDENDA 2009 Acceptance Criteria: Welds that are observed to have indications exceeding the criteria given in Table 7.6 are unacceptable. Unacceptable indications shall be removed or reduced to an indication of acceptable size. Whenever an indication is removed by chipping or grinding and subsequent repair by welding is not required, the area shall be blended into the surrounding surface so as to avoid notches, crevices, or corners. Weld seams that will be hidden in the final vessel configuration shall be visually examined for workmanship prior to final assembly.
VISUAL EXAMINATION PROCEDURE
