Full Content is available to subscribers

Subscribe/Learn More  >

Leak Before Break: Studies in Support of New R6 Guidance on Leak Rate Evaluation

[+] Author Affiliations
J. P. Taggart

Serco Assurance, Warrington, Cheshire, UK

P. J. Budden

British Energy Generation, Ltd., Barnwood, Gloucestershire, UK

Paper No. PVP2005-71377, pp. 353-359; 7 pages
  • ASME 2005 Pressure Vessels and Piping Conference
  • Volume 1: Codes and Standards
  • Denver, Colorado, USA, July 17–21, 2005
  • Conference Sponsors: Pressure Vessels and Piping Division
  • ISBN: 0-7918-4186-3 | eISBN: 0-7918-3763-7
  • Copyright © 2005 by ASME


The concept of leak-before-break (LBB) is often used in safety cases for pressure systems, particularly in the nuclear industry. An important factor in making a LBB case is in the prediction of the leak rate of fluid through a crack. This paper presents a summary of a programme of work, which had the aim of improving guidance on leak rate evaluation for the LBB procedures in the R6 defect assessment methodology. Methods of calculating leak rates have been reviewed, and this has led to a crack morphology model being proposed, which represents single-phase isothermal compressible flow through a crack. In the crack morphology model, the flow is assumed by default to be fully rough turbulent, and the effective roughness to vary between a local roughness value for narrow cracks, to a global value (i.e. the overall crack contours) for wide cracks. The effect of pressure drops due to changes in the flow direction at crack turns has also been included. Calculations using the model show that the friction factor relation due to Spence et al. gives better agreement with measured flow rates than that due to Button et al., which tends to overestimate the flow rate for the examples studied. The inclusion of an inertial pressure term arising from changes in overall flow direction appears to be justified.

Copyright © 2005 by ASME



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In