This procedure stipulates the requirements for DP Testing of bottom plate & roof plate lap joint fillet welds of storage tanks, and other welded joints related to tank REFERENCE
API 650/653
Welding of Pipeline and related Facilities
ANSI B 31.3
Chemical Plant and Petroleum refinery Piping
ASNT-SNT-TC-1A
American Society for Non-destructive Testing and Recommended Practise.
ASME Sec. V
KOC Standards and Specifications 2
3
INPECTION PERSONEL: Qulaified DP technician shall be used for carrying out the DP test.Technician shall have Level-2 in D.P. DYE PENETRANT TEST PROCEDURE:
3.1
Materials/Tools:
Following three types of materials from same manufacturer shall be used in the examination. (Intermixing shall not be done). 1-Cleaner : Magnaflux-Spot check-SKL-SP is the proposed Chemical used as Cleaner. 2-Penetrant : Magnaflux-Spot check-SKD-S2 is the proposed Chemical to be used which is red in colour. 3-Developer: Magnaflux-Spot check-SKD-S is proposed chemical to be used which is a White chalk powder suspension in a quick evaporating liquid. 4-Sufficient lighting, wire brush, chipping hammer, grinding M/c etc., to be available at spot.
3.2
PROCEDURE : 3.2.1
SURFACE PREPARATION.
The surface to be examined (weld plus one inch both sides of the welds) shall be free of oil, grease, dirt, slag, spatters arc strikes etc., Surface irregularities and materials which could obstruct the entry of penetrant into a discontinuity shall be removed by grinding or brushing. Oily films grease, dirt etc., shall be removed by cleaner. Page 3 of 5
NDT PROCEDURE
3.2.2
PENETRANT APPLICATION.
The cleaned surface should be dry without any trace of moisture or cleaner prior to application of penetrant. Penetrant shall be applied by spraying to the surface. The penetrant dwell time shall be 5 to 10 minutes.Surface temperature shall be between 10 to 52 degree centigrade 3.2.3
DEVELOPING.
After the elapse of minimum developing time, the excess penetrant shall be removed from the surface by wiping it with a clean cloth. Any trace of remaining penetrant shall be removed by a cloth moistened with cleaner. Direct spraying of Cleaner for removing excess penetrant is not permitted. The surface shall be allowed to dry by evaporation of the cleaner. As soon as the surface is dry, developer shall be sprayed on to the cleaned surface after agitation, to form a thin and even layer of white developer. Application of developer shall not be delayed beyond 10 minutes after the removal of excess penetrant. The developer shall be allowed to dry by normal evaporation. 3.3
OBSERVATION AND EVALUATION:
The surface of examination shall be observed during the application of developer to detect the location and type of any indication, which would bleed excessively. However, final evaluation shall be made after the elapse of the minimum recommended time of product manufacturer, but not less than 15 minutes. All relevant indications shall be evaluated based on the acceptance criteria. Any indications resulting from mechanical discontinuities whose major dimension is over 1/16” shall be considered relevant. Linear indications are those in which the length is more than 3 times the width. Rounded indications are those, which are circular or elliptical with length equal to or less than three times the width. 3.4
ACCEPTANCE CRITERIA:
The following relevant indications shall be evaluated unacceptable. a) Any relevant linear indications. b) Rounded indications with dimensions greater than 3/16”. c) Four or more rounded indications in a line separated by 1/16” or less (edge to edge). d) Doubtful and detrimental.
3.5
REPAIRS:
The defects may be removed by grinding or chipping. If subsequent repair welding is not required the area shall be blended with the surrounding area to avoid sharp notches. If surface requires weld filling, the filled surface after welding shall be treated to achieve its regular status.
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NDT PROCEDURE
3.6
RE-EXAMINATION:
Repaired areas shall be re-examined with the liquid penetrant method. POST CLEANING:
After completing the examination, the surface shall be cleaned with clean rags. 4
