Proceedings of the National Seminar & Exhibition on Non-Destructive Evaluation NDE 2011, December 8-10, 2011 STUDY AND COMPARISON OF DIFFERENT FABRICATION AND NDT REQUIREMENTS FOR PRESSURE VESSEL, BOILER, PIPING, STRUCTURE & NUCLEAR COMPONENT MANUFACTURING WITH RESPECT TO VARIOUS CODES & STANDARDS Kamal H.Dhandha 1, A.D.Bhathena 2, Manas Ghosh 3 and Dr.Sanjay Soman 4 1,2 Modular Fabrication Facility, E & C Division; 3 Heavy Engineering Division, Larsen & Toubro Limited, Hazira Manufacturing Complex, Surat, Gujarat, INDIA 4 Metallurgical & Materials Engineering Department, Faculty of Technology & Engineering, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, INDIA ABSTRACT Non-Destructive Testing (NDT) is the application of measurement techniques in order to identify damage and irregularities in materials. Different non-destructive examination methods are called for at various stages viz. In- Manufacture Inspection (IMI), Pre-Service Inspection (PSI) and In-Service Inspection (ISI). The presence of flaws in critical components may result in the integrity of such systems being compromised and increase the likelihood of failure. Correct selection and application of an NDT technique can provide confidence that a component or piece of plant does not contain defects of the type which the technique was capable of detecting. The capability of an NDT technique to detect and size specified defects can be assessed by the gathering of evidence based on physical reasoning, theoretical modelling, experimental work and previously published work. In this case NDT is just one of a number of quality control activities aimed at producing a component or piece of plant to a particular specification. The Non- Destructive Testing methods to be used and the maximum size of flaws which can be tolerated are given in the flaw acceptance clauses in various codes. In this liberalized and global market, it is necessary for an industry to manufacture product (viz. pressure vessels, boilers, piping, structure & nuclear components etc.) according to various national/ international codes & standards and hence, it is necessary to know, understand & interpret various acceptance criteria. Study of this acceptance standards & comparison between them is the need for today s Fabrication industries aspires to be globalized. Keywords : Integrity, Flaws, Interpretation, Reliability, Globalize INTRODUCTION In order to control the welding work and to have uniformity in the material selection, welding processes, testing and inspection, standards have been evolved based on long experience and critical experimentation. These codes are given for different categories of work such as Boiler, Pressure vessels, Pipe lines, Oil storage tanks, Structural works etc. Conformity to the particular norm or code laid down for each work is required for satisfactory functioning of the welded joints. A comprehensive knowledge about acceptance standards of various NDT methods according to various manufacturing codes & standards is mandatory for Welding/QA/QC Engineers today. THEORY Codes & Standards are the authentic documents, usage of which give a products / services of National / International standards with respect to quality, reliability etc. also this give uniformity of various manufacture to manufacture the product / service. Codes are mandatory, where as Standards are recommended and reference documents. Acceptance Criteria: Limit of shape, size and position of discontinuities acceptable within the context of the specific design requirements. Many codes are having common acceptance criteria. Therefore, it become unambiguous for inspector to identify the defects,
388 Kamal H.Dhandha et.al : Proceedings of the National Seminar & Exhibition on Non-Destructive Evaluation which exceeds acceptance criteria irrespective of availability of acceptance codes if abstract of it has been kept tip of the tongue. In some codes additional requirements are specified based on severity of application. ACCEPTANCE CRITERIA FOR MAJOR NDE METHODS Acceptance criteria for Ultrasonic Examination As per ASME Sec.VIII Div.1, Div.2, Sec.I, Sec.III NB, ASME B31.1, ASME B31.3 ((b) only), are (a) (b) Indications characterized as cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length. Other imperfections are unacceptable if the indications exceed the reference level amplitude and have lengths which exceed: (1) 1D 4 in. (6 mm) for t up to 3D4 in. (19 mm); (2) 1D3t for t from 3D4 in. to 2¼ in. (19 mm to 57 mm); (3) 3D4 in. (19 mm) for t over 2¼ in. (57 mm). Acceptance criteria for Radiographic Examination As per ASME Sec.VIII Div.1, Div.2, Sec.I, Sec.III NB, ASME B31.1, API620 & API650 are (a)&(b) Same as Ultrasonic Examination (c) (d) any group of aligned indications that have an aggregate length greater than t in a length of 12t, except when the distance between the successive imperfections exceeds 6L where L is the length of the longest imperfection in the group; rounded indications in excess of that specified by the acceptance standards given in as below. Rounded indications Relevant Indications Only those rounded indications which exceed the following dimensions shall be considered relevant. (1) 1D10t for t less than 1D8 in. (3 mm) (2) 1D64 in. for t from 1D8 in. to 1D4 in. (3 mm to 6 mm), incl. (3) 1D32 in. for t greater than 1D4 in. to 2 in. (6 mm to 50 mm), incl. (4) 1D16 in. for t greater than 2 in. (50 mm) Maximum Size of Rounded Indication. The maximum permissible size of any indication shall be 1D 4t, or 5D32 in. (4 mm), whichever is smaller; except that an COMPARISON BETWEEN ACCEPTANCE CRITERIA FOR VISUAL EXAMINATION OF WIDELY USED CODES Table 1 : Comparison between Acceptance standard for AWS D1.1, ASME Sec.VIII Div.1 & ASME B31.3
Table 2 : Comparison between Acceptance standard for ISO 5817, ASME Sec.VIII Div.1 & AWS D1.1 NDE 2011, December 8-10, 2011 389
390 Kamal H.Dhandha et.al : Proceedings of the National Seminar & Exhibition on Non-Destructive Evaluation COMPARISON BETWEEN ACCEPTANCE CRITERIA FOR RADIOGRAPHIC EXAMINATION OF WIDELY USED CODES
NDE 2011, December 8-10, 2011 391 isolated indication separated from an adjacent indication by 1 in. (25 mm) or more may be 1D3t, or 1D4 in. (6 mm), whichever is less. For t greater than 2 in. (50 mm) the maximum permissible size of an isolated indication shall be increased to 3D8 in. (10 mm). Aligned Rounded Indications. Aligned rounded indications are acceptable when the summation of the diameters of the indications is less than t in a length of 12t. Clustered Indications. The illustrations for clustered indications show up to four times as many indications in a local area, as that shown in the illustrations for random indications. The length of an acceptable cluster shall not exceed the lesser of 1 in. (25 mm) or 2t. Where more than one cluster is present, the sum of the lengths of the clusters shall not exceed 1 in. (25 mm) in a 6 in. (150 mm) length weld. Rounded Indication Charts relevant rounded indications characterized as imperfections shall not exceed those shown in Figures, which illustrate various types of assorted, randomly dispersed and clustered rounded indications for different weld thicknesses greater than 3 mm (1/8 in). Acceptance criteria for Liquid Penetrant Examination As per ASME Sec.VIII Div.1 (a) only), Div.2 (a) &b) only), Sec.I (a) only) API 620 & API 650 (a) only), Sec.III NB, ASME B31.1, are (a) Only indications with major dimensions greater than 1D16 in. (1.5 mm) (2 mm in ASME B31.1) shall be considered relevant. (b) All surfaces to be examined shall be free of: (1) relevant linear indications; (2) relevant rounded indications greater than 3D16 in.(5 mm); (3) four or more relevant rounded indications in a line separated by 1D16 in. (1.5 mm) (2 mm in ASME B31.1) or less (edge to edge). Crack like indications detected, irrespective of surface conditions, are unacceptable. (c) ten or more rounded indications in any 6 sq. in. (3870 mm 2 ) of surface with the major dimension of this area not to exceed 6 in. (150 mm) with the area taken in the most unfavorable location relative to the indications being evaluated. Acceptance criteria for Magnetic Particle Examination As per ASME Sec.VIII Div.1(a) only, Div.2 (a) &b) only), Sec.I (a) only) API 620 & API 650 (a) only), Sec.III NB, ASME B31.1 (a) only), are same as for Liquid Penetrant Examination REFERENCES 1. ASME Sec. VIII Boiler & Pressure Vessel Code:2010 Div.1 Rules for Construction of Pressure Vessels, Div.2 Alternative Rules Rules For Construction Of Pressure Vessels 2. AWS D1.1/D1.1M:2010 Structural Welding Code Steel 3. ASME B31.1-2004 Power Piping 4. ASME B31.3-2006 Process Piping 5. ASME B31.4-2002 Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids 6. ASME B31.8-2007 Gas Transportation and Distribution Piping Systems 7. API 1104 Welding of Pipelines and Related Facilities, 20 th Edition, Nov 2005 8. ASME Sec.III Division 1 Subsection NB:2007 Rules for Construction of Nuclear Facility Components, Class 1 Components 9. ASME Sec.I:2010 Rules for Construction of Power Boilers 10. API Specification 2B Specification for the Fabrication of Structural Steel Pipe, 6th Edition, July 2001 11. API Specification 5L Specification for Line Pipe, 43rd Edition, March 2004 12. API Recommended Practice 2A-WSD Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms-Working Stress Design, 21st Edition, December 2000 13. API Recommended Practice 2X Recommended Practice for Ultrasonic and Magnetic Examination of Offshore Structural Fabrication and Guidelines for Qualification of Technicians, 2004 14. ASME Sec.II Part A:2010 Materials - Ferrous Material Specifications 15. NBIC National Board Inspection Code : 2007 16. API 650 Welded Steel Tanks for Oil Storage, Tenth Edition, November 1998 17. API 620 Design and Construction of Large, Welded, Low-pressure Storage Tanks, Tenth Edition, February 2002 18. ISO 3834:2005 Quality requirements for fusion welding of metallic materials, Benefits and Implementation Revision 1 1 August 2008, WTIA 19. ISO 5817-2003 Welding-fusion welded joints in Steel, Nickel, Titanium and their alloys (beam welding excluded) Quality Levels for Imperfections 20. ISO 6520-1:2007 Welding and allied processes - Classification of geometric imperfections in metallic materials - Part 1: Fusion welding 21. EN ISO 13920 General tolerances for welded constructions, Tolerances for lengths, angles, shape and position
392 Kamal H.Dhandha et.al : Proceedings of the National Seminar & Exhibition on Non-Destructive Evaluation 22. BS EN 12517-1:2006 Non-destructive testing of welds- Part 1: Evaluation of welded joints in steel, nickel, titanium and their alloys by radiography Acceptance levels 23. PD 5500:2009 Specification for Unfired fusion welded pressure vessels 24. AD 2000-Merkblatt HP 5/3 Manufacture and testing of joints, Non-destructive testing of welded joints, January 2002 edition 25. BS 5289:1976 (1983) Code of Practice. Visual inspection of fusion welded joints 26. BS 970:1997 Non-destructive examination of fusion welds Visual examination 27. BS 5950-2:2001 Structural use of steel work in building Part 2:Specification for materials, fabrication and erection Rolled and welded sections 28. IS 2825:1969 Code for Unfired Pressure vessels, BIS, New Delhi 29. IS 7215:1974 Tolerances for Fabrication of Steel Structures, BIS, New Delhi 30. IS 803-1976 Code of Practice for Design, Fabrication and Erection of Vertical Mild Steel Cylindrical Welded Oil Storage Tanks, BIS, New Delhi 31. NORSOK Standard M-101, Structural Steel Fabrication, Rev.4, Dec.2000 32. PFI Standard ES-3,2000 Fabricating Tolerances, Pipe Fabrication Institute