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Research Papers

Technical Basis of Material Toughness Requirements in the ASME Boiler and Pressure Vessel Code, Section VIII, Division 2

[+] Author and Article Information
David A. Osage

 The Equity Engineering Group, Inc. 20600 Chagrin Boulevard, Suite 1200 Shaker Heights, OH 44122daosage@equityeng.com

Martin Prager

 The Materials Properties Council, Inc. 20600 Chagrin Boulevard, Suite 1200 Shaker Heights, OH 44122mprager@forengineers.org

J. Pressure Vessel Technol 134(3), 031001 (Apr 13, 2012) (13 pages) doi:10.1115/1.4005854 History: Received December 16, 2010; Revised October 29, 2011; Online April 13, 2012; Published May 17, 2012

The development of new toughness requirements for carbon and low alloy steels was a major part of the effort to rewrite the ASME B&PV Code, Section VIII, Division 2. The new toughness rules in this code were established using the fracture mechanics assessment procedures in API 579-1/ASME FFS-1 (Fitness-For-Service), Part 9. The major change in the toughness rules when compared to older editions of Section VIII, Division 2 (2004 and prior) and the current edition of Section VIII, Division 1 are for carbon and low alloy steel materials excluding bolting. The new toughness rules in Section VIII, Division 2 are based on a Charpy V-Notch impact requirement of 20 ft-lb (27 J) consistent with European practice and the beneficial effects of post weld heat treatment are included consistent with the procedures in API 579-1/ASME FFS-1. This paper provides a technical background to the new toughness rules including the development of material toughness requirements and the development of impact test exemption rules.

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Copyright © 2012 by American Society of Mechanical Engineers
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Figures

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Figure 1

VIII-1, Paragraph UCS 66 exemption curves are shown. Indicated notes define the materials covered.

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Figure 2

(VIII-2 Figure 3.3)—Charpy V-Notch impact test requirements for full-size specimens for carbon and low alloy steels as a function of the specified minimum yield strength—Parts not subject to PWHT.Notes: (1) Interpolation between yield strength values is permitted. (2) The minimum impact energy for one specimen shall not be less than two-thirds of the average impact energy required for three specimens.(3) Materials produced and impact tested in accordance with SA-320, SA-333, SA-334, SA-350, SA-352, SA-420, SA-437, SA-508 Grade 5 Class 2, SA-540 (except for materials produced under Table 2, Note 4 in the specification), SA-723, and SA-765 do not have to satisfy these energy values. Materials produced to these specifications are acceptable for use at a minimum design metal temperature not colder than the test temperature when the energy values required by the applicable specification are satisfied.(4) If the material specified minimum tensile strength is greater than or equal to 655 MPa (95 ksi), then the material toughness requirements shall be in accordance with VIII-2, Part 3, paragraph 3.11.2.1.b.2.(5) Data of Fig. 8 are shown in VIII-2, Part 3, Table 3.12.(6) Data of Fig. 9 are shown in VIII-2, Part 3, Table 3.13.(7) See VIII-2, Part 3, paragraph 3.11.2.1.b.1 for Charpy V-notch specimen thicknesses less than 10 mm (0.394 in.)

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Figure 3

(VIII-2 Figure 3.4)—Charpy V-Notch impact test requirements for full-size specimens for carbon and low alloy steels for selected specified minimum yield strength—Parts subject to PWHT.Notes: (1) Interpolation between yield strength values is permitted. (2) The minimum impact energy for one specimen shall not be less than two-thirds of the average impact energy required for three specimens. (3) Materials produced and impact tested in accordance with SA-320, SA-333, SA-334, SA-350, SA-352, SA-420, SA-437, SA-508 Grade 5 Class 2, SA-540 (except for materials produced under Table 2, Note 4 in the specification), SA-723, and SA-765 do not have to satisfy these energy values. Materials produced to these specifications are acceptable for use at a minimum design metal temperature not colder than the test temperature when the energy values required by the applicable specification are satisfied. (4) If the material specified minimum tensile strength is greater than or equal to 655 MPa (95 ksi), then the material toughness requirements shall be in accordance with VIII-2, Part 3, paragraph 3.11.2.1.b.2. (5) Data of Fig. 8 are shown in VIII-2, Part 3, Table 3.12. (6) Data of Fig. 9 are shown in VIII-2, Part 3, Table 3.13. (7) See VIII-2, Part 3, paragraph 3.11.2.1.b.1 for Charpy V-notch specimen thicknesses less than 10 mm (0.394 in.)

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Figure 4

(VIII-2 Figure 3.7)—Impact test exemption curves—Parts not subject to PWHT

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Figure 5

(VIII-2 Figure 3.8)—Impact test exemption curves—Parts subject to PWHT and nonwelded part

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Figure 6

(VIII-2 Figure 3.12)—Reduction in the MDMT without impact testing—Parts not subject to PWHT

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Figure 7

(VIII-2 Figure 3.13)—Reduction in the MDMT without impact testing—Parts subject to PWHT and nonwelded parts

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Figure 8

Charpy V-Notch lateral expansion requirements (CVN LE) in old VIII-2 and the 2007 edition of VIII-2

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Figure 9

(VIII-2, Figure 3.6)— Charpy V-Notch lateral expansion requirements (CVN LE) in VIII-2, 2008 Addenda

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Figure 10

Required CVN LE for materials with a UTS > 95 ksi using approaches 1 and 2

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Figure 11

Final required CVN LE for materials with a UTS > 95 ksi

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