Journal of Failure Analysis and Prevention

, Volume 7, Issue 5, pp 352–359 | Cite as

An Inadequate Weld Repair and a Consequent Rupture of a Pressure Vessel

Peer Reviewed

Abstract

The incident of concern involved a steam accumulator that was a component part of a steam generating facility. The accumulator ruptured during normal operating conditions that included an internal pressure of 120 psi (0.83 MPa). The rupture involved the complete fracture of a circumferential weld joining the bottom head to the accumulator cylindrical shell. An analysis of the fracture revealed the presence of a subsurface crack at the weld. This crack encompassed the entire weld line around the vessel and extended radially across nearly the full thickness of the weld. Using metallurgical analysis, this crack was determined to have been in place since the time when the accumulator was first manufactured. Eventually, a leak occurred at the weld line. The process to repair the leak failed to detect the condition of defect. The work of investigation also determined that the repair preceding the fracture was not conducted in accordance with the requirements of the National Boiler Inspection Code (NBIC). The condition of defect, which would have been detected if NBIC procedures had been used, was instead left in place and the accumulator, as a pressure vessel, ruptured as a result.

Keywords

Failure analysis Weld repair Pressure vessel 

References

  1. 1.
    American Society of Mechanical Engineers: ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, 1998 EditionGoogle Scholar
  2. 2.
    ASM International: ASM Handbook, 10th edn. Volume 1—Properties and Selection Irons, Steels and High-Performance Alloys (1990)Google Scholar
  3. 3.
    ASM International: ASM Handbook, 8th edn. Volume 7—Atlas of Microstructures of Industrial Alloys (1972)Google Scholar
  4. 4.
    The National Board of Boiler and Pressure Vessel Inspectors: National Boiler Inspection Code, 1995 Edition, 1997 AddendaGoogle Scholar

Copyright information

© ASM International 2007

Authors and Affiliations

  1. 1.Engineering Design and Testing Corp., Columbia District OfficeColumbiaUSA
  2. 2.Engineering Design and Testing Corp., Kansas City District OfficeOverland ParkUSA

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