CONTENTS
1.Scope
2. Qualification of NDE Personnel
3.Procedure
4.Materials
5. Surface Preparation
6. Examination
7.Interpretation
8.Reexamination for Repaired Area and Nonconformity Control
9.Post Cleaning
10. Report
LIQUID PENETRANT EXAMINATION INSTRUCTION LIQUID PENETRANT EXAMINATION REPORT.
1.Scope
1.1 This procedure is applied to a color contrast solvent removable penetrant examination technique between the temperature range of 60℉to 125℉(16℃to 52℃).
1.2 This procedure is applied to welds and nonporous materials of ASME Code pressure vessels fabricated according to ASME Code Section ⅧDivision 1
2. Qualification of NDE Personnel
Personnel performing liquid penetrant examination shall be qualified and certified in accordance with the requirements of HT’s Written Practice for NDE Personnel Training, Examination, Qualification and Certification based on the requirements of “SNT-TC-1A(Current Code accepted edition).
3.Procedure
The procedure shall be supplemented by the LIQUID PENETRANT EXAMINATION INSTRUCTION which shall be issued to every product to be examined and in which more detail parameters are specified. The Instruction shall be prepared by level Ⅱ, approved by level ⅢNDE examiner,
4. Materials
4.1 A group of penetrant materials shall include preplanning agent, penetrant, cleaning agent or remover, developer, It shall be selected from Table 1 (solvent removable type). Intermixing of penetrant materials from different families and different manufacturers is not permitted.
4.2 When examination nickel alloys, austenitic stainless steels and titanium, all liquid penetrant materials certifications shall be obtained. The certification shall include the penetrant manufacturer’s batch number, the test results and manufacture date. These records shall be kept in file in the NDE Room.
4.3 When examining nickel base alloys, all materials shall be analyzed individually for sulfur content. When examining austenitic stainless steel or titanium, all materials shall be analyzed individually for chlorine and fluorine content. The acceptance standard (for sulfur, chlorine and fluorine content) shall be in accordance with requirements of Article 6 Paragraph T-641 of ASME Code Section V.
4.4 All penetrant materials, which have been contaminated, deteriorated and ineffective shall not be used.
4.5 The cotton cloth, which shall be a clean and lint-free material, shall be used for excess penetrant removal.
4.6 When natural light is not enough for examination, adequate illumination is required to ensure adequate sensitivity during the examination and evaluation of indications.
5. Surface Preparation
5.1 Prior to each liquid penetrant examination, the surface to be examined and all adjacent areas within at least 1in.shall berry and free of all dirt, grease, lint, scale, welding flux, weld spatter, paint, oil, and other extraneous matter that could obscure surface openings or otherwise interfere with the examination.
5.2 In general, satisfactory results may be obtained when the surface of the part is in the as-welded, as-rolled, as-cast, or as-forged condition. Surface preparation by grinding, machining, or other methods may be necessary where surface irregularities could mask indications of unacceptable discontinuities. Sand blasting is prohibited as it may decrease the effectiveness of the penetrant examination.
6.Examination
Level ⅡNDE examiner shall perform liquid penetrant examination in accordance with following process and the requirements of the Instruction, and record examination data on the LIQUID PENETRANT EXAMINATION REPORT. If the area to be examined is too large, the examination can be performed in increment, the part temperature shall remains in the range of 60℉to
125℉(16℃to 52 ℃) during the examination.
6.1 Preplanning
Preplanning agents as defined in Table 1 shall be used for Removing extraneous matter that obstruct penetrant, such as dirt and dust etc. before penetrant application.
6.2 Drying after Preplanning
Drying of the surface to be examined shall be accomplished by normal evaporation. A period of time for normal evaporation shall not be less than 1min, so that the cleaning solution has evaporated prior to application of the penetrant (see Table 2).
6.3 Penetrant Application
6.3.1 The penetrant may be applied by spraying or brushing.
6.3.2 The penetrant time shall meet the requirement of Table 2.
6.4 Excess Penetrant Removal
6.4.1 After the specified penetrant time has elapsed, any excess penetrant remaining on the surface of the part shall be removed with dry cotton cloth, repeating the operation until most traces of penetrant have been removed.
6.4.2 The remaining penetrant traces shall be removed by lightly wiping the surface with cotton cloth moistened in solvent. To minimize removal of penetrant from discontinuities, care shall be taken to avoid the use of excess solvent. Flushing the surface with solvent, following the application of the penetrant and prior to developing, is prohibited.
6.5 Drying after Excess Penetrant Removal
After excess penetrant removal, the surface may be dried by normal evaporation. Before application of developer, the drying Time shall not be less than 1 min. nor more than 30 min. (see Table 2).
6.6 Developing
6.6.1Prior to applying developer, the developer must be thoroughly agitated
to ensure adequate dispersion of suspended particles.
6.6.2 The developer shall be applied as soon as possible after examination surface
has been dried. The time interval shall not exceed 30 min. If it is expected to exceed, the examination shall be performed in increments as. described in Para.6.
6.6.3 The developer shall be applied by spraying to form a thin coating over the entire surface being examined.
6.6.4 The developing time begins immediately as soon as the wet developer coating is dry, and shall conform to the requirements of Table 2.
7. Interpretation
LevelⅡorⅢNDE examiner shall observe and evaluate indications in accordance with the acceptance standards of ASME Code, and record evaluated result on the LIQUID PENETRANT EXAMINATION REROPT. Close observation of the formation of indications during application of the developer shall be accomplished to characterize and determine the extent of the indications.
7.1 The illumination during observation and evaluation shall satisfy requirement of paragraph 4.6.
7.2 Final interpretation shall be made after allowing the penetrant to bleed-out within 7 min to 30 min.
7.3 For those indications that are difficult to evaluate, recleaning and reexamination shall be performed according tolerant paragraph, broad areas of pigmentation are unacceptable, and such areas shall be cleaned and reexamined. 7.4 Only indication with major dimensions greater than 1.6mm shall be considered relevant
7.5 A rounded indication is one of circular or elliptical shape with the length equal to or less than three times the width
7.6 A linear indication is one having a length greater than three times the width 7.7 Acceptance Standards
All surfaces to be examined shall be free of:
(a) Relevant linear indication;
(b) Relevant rounded indication greater than 3/16in.;
(c) four or more relevant rounded indication in a line separated by 1/16in or
less (edge-to edge)
8. Reexamination for Repaired Area and Nonconformity Control
8.1Reexamination for Repaired Area
The reexamination for repaired area shall be the same as original and a record of repaired area shall be noted as well as the results of the reexamination for repaired area.
8.2 Nonconformity Control
Any nonconformity of examined item shall be reported to Level ⅢNDE examiner and handled according to Section 6 of QC Manual.
9. Post Cleaning
After completion of evaluation, post cleaning of the surface applied with penetrant and developer shall be performed immediately, Developer shall be removed by wipping with cotton cloth moistened In solvent (cleaning agents) with an assist of wire brushing.
10. Report
10.1 Thy report shall be satisfactory to the requirements of ASME Code for the report of NDE.
10.2.The report shall be prepared by the Level ⅡNDE examiner Who engaged in the liquid penetrant examination operation and interpretation, reviewed by the level ⅡorⅢNDE examiner and approved by the NDE Department Manager or his designated NDE Level Ⅲ Examiner prior to submission to the AI. 10.3.The report shall be kept in file in the NDE Room for at least 5 years.