Acceptance criteria for Visual Inspection of Weld defects

visual-of-weld-defect-in-pipeline
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Visual Examination


These Articles cover all visual Weld defects as per ASME Section VIII Div I.


(a) All these types of Parts, materials, finished joints, and completed vessels shall be visually examined by the manufacturer over the full surfaces to detect the defects. Surfaces that are accessible for the visual examinations and then after the vessel is completed do not need to be examined before completion of the vessel or vessel parts. However, such examinations shall occur before the final pressure test.


(b) The Manufacturer/Contractor shall prepare and qualify a written procedure that meets the requirements of Section V, Article 9 (Visual Examination). The procedure qualification (PQ) shall be subject to the demonstrated to the Authorized Inspector/Client.

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(c) The Manufacturer shall designate qualified personnel for the Visual Examination.


(d) All the cemented nozzles must be examined by an inspector to ensure that cement has flowed around the entire perimeter and that full penetration through the depth of the joint has been achieved.


Qualification of Visual Examination Personnel


(a) Personnel who perform the Visual Examinations shall be qualified and certified for this method in accordance with a program established by the employer of the person being certified, which shall be based on the following minimum requirements:


(1) instruction in the fundamentals of the visual examination method.


(2) on ‐ the ‐ job training to familiarize the personnel with the appearance and interpretation of indications of defects.


(3) An eye examination shall be performed per the requirements of ASME Section V, Article 9 to determine the near ‐ distance acuity of personnel to perform the required examination.


(4) Upon completion of the following requirement (1) and (2) above, the personnel shall be given an oral or written examination and performance examinations to determine, if the personnel are qualified to perform the required examination and interpret/review the results.


(5) Certified personnel whose work has not included a performance of visual examination for a period of 1 yr or more shall be re-certified by completing (1) through (4) above.


Acceptance Standards and Documentation


(a) The surface shall be free of any visible laminations, spalling, or cracks. Defects of cracks in tubes shall not be repaired and shall be considered the cause for rejections.


(b) For tubes, scratches shall not exceed 0.8 mm in-depth. For all other materials, the scratch depth shall not exceed 3 mm.


(c) After inspection Unacceptable discontinuities can be repaired by removing the discontinuities in their entirety, and the material repaired in accordance with the repair procedure written and qualified by the manufacturer with the concurrence or presence of the Authorized Inspector/client. The repair shall neither result in sharp edges and nor in the finished thickness is less than the minimum design thickness. The cracks and voids shall not be repaired by adding cement only.


(d) The examinations shall be documented in the accordance with ASME Section V, Article 9, T - 990, Documentations. UIG-81 provides the rules for Repair of the Material.


Finished Longitudinals and the Circumferential Joints


(a) Butt welded joints shall have complete penetration and full fusion. As-welded surfaces are permitted, However, the surface of the weld shall be sufficiently free from the coarse ripples, grooves overlaps, and abrupt ridges and valleys to permit proper interpretation/review of radiographic and other required non-destructive examinations (NDT). If there is a question/doubt regarding the surface condition of the weld, when interpreting/review a radiographic film, the film shall be compared to the actual weld surfaces for determination of the acceptability.


(b) A reduction in the thickness due to the weldings process are acceptable provided all of the following conditions are met below:


(i) The reduction in thickness shall not reduce the material of the adjoining surfaces below the minimum required thickness at any point.


(ii) The reduction in thickness shall not exceed 1 mm or 10% of the nominal thickness of the adjoining surface, whichever is less.


(c) When a single - welded butt joint is made by using the backing strip which is left in place [Type Number-2 of Table UW-12], the requirement for the reinforcement applies only to the side opposite to the backing strip.


(d) To assure that the grooves of the weld are completely filled, so that the surfaces of the weld metal at any point do not fall below the surface of the adjoining base materials, 73 weld metal may be added as reinforcement on each face of the weld. The thickness of the weld reinforcements on each face shall not exceed.


Nondestructive Examination of Welds on Pneumatically Tested Vessels


Radiographic Examination of Welded Joints


(a) All welded joints to be radiographed shall be examined in accordance with Article 2 of Section V except as specified below.


(1) A complete set of radiographs and records, as described in Article 2 of Section V, for each vessel or vessel the part shall be retained by the manufacturer, as follows:


(i) films until the manufacturer's Data Report has been signed by the Inspector;


(ii) records as required by this Division (10-13).


(2) A written radiography examination procedures are not required. Demonstration of the density and penetrameters image requirements on production or technique radiography shall be considered satisfactory evidence of the compliance with Article 2 of ASME Section V.


(3) The requirements of T-274.2 of Article 2 of Section V are to be used only as a guide. The final acceptance of the radiography shall be based on the ability to see the prescribed penetrameters image and the specified hole or and the designated wire of the wire penetrameters.


(4) As an alternative to the radiographic examination requirements above, all welds in material 6 mm and greater in thickness may be examined using the ultrasonic test (UT) method per the requirements of 7.5.5 of Section VIII, Division 2.


(b) Indications have shown on the radiographs of welds and characteristic as imperfections are unacceptable under the following conditions and shall be repaired as provided in UW-38, and the repair radiographed to UW-51 or, at the option of the manufacturer, ultrasonically examined


In accordance with the method described in Mandatory Appendix 12 and the standards specified Appendix 12 and the standards specified in this paragraph, provided the defect has been confirmed by the ultrasonic examination to the satisfaction of the Authorized Inspector prior to making the repair. For material thicknesses in excess of 25 mm, the concurrence of the user shall be obtained. This ultrasonic examination shall be noted under Remarks on the Manufacturer's Data Report Form:


(1) Any indication characteristic as a crack or zone of incomplete fusion or penetration;


(2) Any other elongated indication on the radiograph which has a length greater than:


(i) 1/4 in. (6 mm) for the "t" up to 3/4 in. (19 mm).


(ii) 1 / 3t for t from 3/4 in. (19 mm) to 21/4 in. (57 mm).


(iii) 3/4 in. (19 mm) for t over 21/4 in. (57 mm).


where:-

"t" the thickness of the weld excluding any allowable reinforcements. For the butt weld joining the two members Having different thicknesses at the weld, "t" is the thinner of these two thicknesses. If a full penetration of the weld includes a fillet weld, the thickness of the throat of the fillet shall be included in "t".


(3) Any group of the aligned indications that have an aggregate length that greater than "t" in a length of 12t, except when the distance between the successive imperfection exceeds 6L.

Where L is the length of the longest imperfection in the group;


(4) rounded indications in excess of that specified by the acceptance standards are given in Mandatory Appendix 4.


Rounded Indications Chart Acceptance Standard for Radiographically Determined Rounded Indications in Welds


Applicability of These Standards


These standards are applicable to ferritic, austenitic, and nonferrous materials.


Acceptance-criteria-for-Visual-Inspection-of-Weld-defect, Visual-defect-of-all-welding-defect
Allowable limit of Weld Reinforcement


Terminology


(a) Rounded Indications:-

Indications with a maximum length of three times the width or less on the radiography are defined as rounded indications. These defect indications may be circular, ellipticals, conicals, or irregular in shape and may have tails. When evaluating the size of the indications, the tail shall be included. The indications may be from any imperfections in the welding, such as porosity, slag, and tungsten.


(b) Aligned Indications:-

The sequence of four or more rounded indications in the weld shall be considered to be aligned when they touch a line parallel to the length of the weld and drawn through the center of the two outer rounded indications.


(c) Thickness "t".

"t" is the thickness of the weld, excluding any allowable reinforcements. For the butt weld joining of two members of metals having different thicknesses at the weld, Where "t" is the thinner of these two thicknesses. If the full penetration weld including a fillet weld, the thicknesses of the throat of the fillet shall be included in "t".


4-3 Acceptance Criteria


(a) Image Density. The density image of the indication may vary and is not a criterion for acceptance or and rejection.


(b) Relevant Indications. (See Table 4-1 for examples.) Those rounded indications only which exceeded the following dimensions shall be considered relevant.


(1) 1 / 10t for t less than 3 mm.


(2) 1/64 in. for t from 1/8 in. to 1/4 in. (3 mm to 6 mm), incl.


(3) 1/32 in. for t greater than 1/4 in. to 2 in. (6 mm to 50 mm), incl.


(4) 1/16 in. for "t" greater than 50 mm.


(c) The Maximum Size of the Rounded Indications. (See Table 4-1 for examples.) The maximum permissible sizes of any indications shall be 1 / 4t or 5/32 in. (4 mm), whichever are smaller, Except that the isolated indications separated from adjacent indications by 25 mm or more maybe 1 / 3t, or and 1/4 in. (6 mm), whichever is less.


For "t" greater than 50 mm, the maximum permissible size of an isolated indication shall be increased to 10 mm.


Ultrasonic Examination of Welds (UT)


Scope


(a) This Appendix describes methods which shall be employed when ultrasonic examination of welds is specified in this Division.


(b) Article 4 of Section V shall be applied for detailed requirements in methods and procedures unless otherwise specified in this Appendix.


(c) Ultrasonic examination shall be performed in accordance with a written procedure, certified by the manufacturer to be in accordance with the requirements of T − 150 of Section V.


Certification of Competence of Nondestructive Examiner


Personnel performing and evaluating ultrasonic examinations required by this Division shall meet the requirements of UW-54.


Acceptance and Rejection Standards


These standards shall apply unless other standards are specified for specific applications within this Division. Imperfections that produce a response greater than 20% of the reference level shall be investigated to the extent that the operator can determine the shape, identity, and location of all such imperfections and evaluate them in terms of the acceptance standards given in (a) and (b) Below


(a) The Indications characterized as the cracks, lack of fusion or incomplete penetration are unacceptable regardless of the length.


(b) Other imperfections are unacceptable if the indications exceed the reference level amplitude and have lengths that exceed:


(1) 6 mm for t up to 19 mm;


(2) 1 / 3t for t from 3/4 in. to 21/4 in. (19 mm to 57 mm);


(3) 3/4 in. (19 mm) for t over 21/4 in. (57 mm).


Where

"t" is the thicknesses of the weld which is excluding any allowable reinforcements. For the butt weld joining of two members which having different thicknesses at the weld, "t" is the thinner of these two thicknesses. If the full penetration weld includes a fillet welds, the thickness of the throats of the fillet shall be included in "t".


Report of Examination


The Manufacturers shall be prepared a report of the ultrasonic test (UT) examinations and a copy of this reports shall be retained by the Manufacturers as required by this Division (10-13). The report shall contain the information required by the ASME Section-V. In addition, the records of all repaired areas shall be noted as well as the result of the reexaminations of the repaired areas. The Manufacturer shall also maintain records of all reflections from uncorrected areas having responses that exceed 50% of the reference level. These records shall locate each area, the response level, the dimensions, the depth below the surfaces, and the classifications.


MANDATORY APPENDIX 8


Methods for Liquid Penetrant Examination (LPT)


NOTE: Satisfactory application of this method of examination requires special skills in the techniques involved and in interpreting the results. These requirements specified here presume applications by the suitably experienced personnel.


Scope


(a) This Appendix describes the methods, which shall be employed whenever liquids penetrants test examinations are specified in these Divisions.


(b) Article 6 of ASME Section V shall be applied for detailed requirements in methods and procedures unless otherwise specified within this Appendix.


(c) Liquid penetrant examination shall be performed in accordance with a written procedure, certified by the manufacturer to be in accordance with the requirements of T − 150 of Section V.


(d) Document showing that the required test examinations have been performed and that the results are acceptable shall be made available to the Inspectors.


Certifications of competency of Nondestructive Examination personnel.


The manufacturers shall certify that each liquid penetrant test or dye penetrant test (LPT/DPT) examiner meets the following requirements.


(a) He has vision, with corrections if necessary, to enable him to read a Jaeger Type No. 2. Standard Charts at a distance of not less than 300 mm, and is capable of distinguishing and differentiating contrast between colors used. These requirements shall be checked annually.


(b) He is capable in the techniques of the liquid penetrant examination method for which he is certified, including making the examination and interpreting and evaluating the results, except that, where the examination the method consists of more than one operation, he may be certified as being qualified only for one or more of these operations.


Evaluation of the Indications


An indication of imperfection may be larger than an imperfection that causes it; However, the size of the indication is the basis for acceptance evaluation. Only indications with the major dimensions greater than 1.5 mm shall be considered relevant.


(a) The linear indications are one having a length that is greater than three times the width.


(b) The rounded indication is the one of circular and elliptical shape with the length equal to or less than the three times of the width.


(c) Any doubtful indications shall be reexamined to determine whether or not they are relevant.


Acceptance standards


These acceptance standards shall apply unless other more restrictive standards are specified for the specific materials or applications within this Division. All surfaces to be examined shall be free of:

(a) Relevant linear indications;


(b) Relevant rounded indications greater than 5 mm;


(c) Four or more relevant rounded indications in a line separated by 1.5 mm or less (edge ​​to edge).


The requirement of the Repair


The Unacceptable imperfections shall be repaired and re-examination made to assure removal or reduction to the acceptable size. Whenever imperfections are repaired by chipping or and grinding and subsequent repair by the weldings are not required, the excavated areas shall be blended into the surrounding surfaces so as to avoid sharp notches, crevices, or corners. Where welding is required after repair of imperfection, the area shall be cleaned and welding performed in accordance with a qualified welding procedure.


(a) Treatment of Indications Believed Nonrelevant. Any indications which are believed to be nonrelevant shall be regarded as an imperfection unless it is shown by reexamination by the same method or by the use of other non-destructive tests (NDT) methods and/or by surface conditioning that no unacceptable imperfection is presenting.


(b) The examinations of Areas from which defects have been removed. After the defects are thought to have been removed and prior to making weld repairs, the areas shall be examined by the suitable methods to ensure that it has been removed or reduced to acceptably sized imperfections.


(c) Reexaminations of Repair Areas. After repairs have been made, the repaired areas shall be blended into the surrounding surfaces so as to avoid sharp notches, crevices, or corners and reexamined by the liquid penetrants test or dye penetrants test (LPT/DPT) method and by all other methods of examinations that were originally required for the affected areas, except that, when the depth of repair is less than the radiography sensitivity required, radiography may be omitted.


Examination of Welds by Ultrasonic Test (UT)

Scope


(a) This Appendix describes that the methods which shall be employed when ultrasonic examination of welds is specified in this Division.


(b) Article 4 of Section V shall be applied for detailed requirements in methods and procedures unless otherwise specified in this Appendix.


(c) Ultrasonic examination shall be performed in accordance with a written procedure, certified by the manufacturer to be in accordance with the requirements of T − 150 of Section V.


Certification of Competence of Nondestructive Examiner


Personnel performing and evaluating ultrasonic examinations required by this Division shall meet the requirements of UW-54.


Acceptance and Rejection Standards


These Standards shall apply unless other standards are specified for specific applications within this Division. Imperfections that produce a response greater than 20% of the reference level shall be investigated to the extent that the operator can determine the shape, identity, and location of all such imperfections and evaluate them in terms of the acceptance standards given in (a) and (b) below.


(a) The defect indications characterized as cracks, incomplete penetration, or lack of fusion is unacceptable regardless of length.


(b) Other imperfections are unacceptable if the indications exceed the reference level amplitude and have lengths that exceed:


(1) 1 / 4 inch. (6 mm) for "t" up to the 3 / 4 inch. (19 mm).


(2) 1 / 3t for t from 3 / 4 inch. to 21 / 4 inch. (19 mm to 57 mm).


(3) 3 / 4 inch. (19 mm) for t over than 21 / 4 inch. (57 mm).


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Where,

"t" is the thicknesses of the weld excluding any allowable reinforcements. For a butt welds joining of the two members having different thicknesses at the weld, "t" is the thinner of these two thicknesses. If a full penetration of weld includes a fillet weld, the thickness of the throats of the fillet shall be included in "t".


Reports of Examination


The Manufacturer shall prepare a report of the ultrasonic examination and a copy of this report shall be retained by the Manufacturer as required by this Division (10-13). The reports shall contain the information required by the ASME Section V. In addition, a record of repaired areas shall be noted as well as the result of the reexamination of the repaired areas. The Manufacturers shall also maintain a record of all reflections from the uncorrected areas responses that exceed 50% of the reference level. These records shall locate each area, the response levels, the dimensions, the depth below the surfaces, and the classifications.


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