Mechanical Stress Improvement ProcessIn considering the stress corrosion cracking problem in the heat affected zone of field welds in BWR primary pumping, Dr.’s Bill O’Donnell and Janek Porowski developed a reliable Mechanical Stress Improvement Process (MSIP) which applies compressive stresses and is easy to control and verify. MSIP was developed with supporting finite element analysis and tests which show that it provides compressive stress fields in both the axial and circumferential directions at the inner surface of weldments.

MSIP works by using a hydraulically driven clamp to squeeze the pipe on one side of the weldment. The permanent contraction produces a concave contour at the weld section and results in a corresponding reduction (typically <1%) in pipe circumference. Once the tool is removed, the weld area remains in hoop and axial compression through approximately half the wall thickness.

The Process was developed for pipe-to-pipe, pipe-to-discontinuity (such as valve body) and pipe-to-vessel nozzle configurations – and first applied in 1986 to mitigate Intergranular Stress Corrosion Cracking (IGSCC) in BWR recirculation piping.

The benefits of MSIP include:
  1. Early application can eliminate need for pipe replacement
  2. Reduces required inspection frequency
  3. Makes the welds in the system immune to corrosion damage
  4. Saves a utility money

A few related published articles include:
Advanced Methods of Improving Resistance to Stress Corrosion Cracking in BWR Piping Systems J. S. Abel, J. Titrington, R. Jordan, J. S. Porowski, W. J. O’Donnell, M. L. Badlani, and E. J. Hampton, presented at the American Society of Mechanical Engineers Pressure Vessels and Piping Conference, June 19 – 23, 1988, PVP Vol. 13, 1988. 

Use of Mechanical Stress Improvement Process to Mitigate Stress Corrosion Cracking in BWR Piping Systemsby J. S. Porowski, W. J. O’Donnell, M. L. Badlani, and E. J. Hampton. Nuclear Engineering and Design 124, pp. 91-100, Elsevier Science Publishers, February 1990.

Use of Mechanical Stress Improvement for Weldments with Cracks J. S. Porowski, W. J. O’Donnell, M. L. Badlani, and E. J. Hampton, Proceedings, SMIRT Post Conference Seminar No. 2, Assuring Structural Integrity of Steel Reactor Pressure Boundary Components Taipei, R. O. C., August 26-28, 1991.
Utility Plant Pipe & Fittings Nozzles & SE’s Total Notes
CeCo Dresden 3 50 2 52
CeCo LaSalle 2 25 29 54
CeCo Quad Cities 1 36 2 38
CP&L Brunswick 2 0 15 15 1
CeCo Quad Cities 2 43 4 47
Nuclenor Santa Maria de Garona 24 0 24
OKG Aktiebolag Oskarshamn 1 0 1 1
CP&L Brunswick 1 0 10 10
CeCo LaSalle 1 15 15 30
CeCo LaSalle 2 8 0 8
CeCo Dresden 2 82 22 104
PeCo Limerick 2 2 16 18
Northeast Millstone 1 0 22 22
Detroit Edison Fermi 2 6 21 27
CeCo Quad Cities 1 28 12 40
CP&L Brunswick 2 16 20 36 2
CeCo Quad Cities 2 30 14 44 2
Teollisouden Voima Oy TVO 5 0 5
Niagara Mohawk Nine Mile Pt 2 0 1 1
Taiwan Power Kuosheng 2 2 0 2 1
CP&L Brunswick 1 10 24 34 2
Northeast Millstone 1 34 9 43
Iberdrola Cofrentes 0 42 42
Boston Edison Pilgrim 1 16 0 16 2
PeCo Peachbottom 3 10 0 10
PeCo Limerick 1 0 7 7
Cleveland Elec. Perry 1 0 27 27 1
TVA Browns Ferry 3 71 29 100 2
GPU Oyster Creek 70 0 70 2
Georgia Power Hatch 1 18 11 29
TVA Browns Ferry 2 12 0 12 2
PP&L Susquehanna 2 8 6 14
PeCo Limerick 1 4 14 18
Georgia Power Hatch 2 0 18 18
PP&L Susquehanna 2 7 5 12
GSU River Bend 0 28 28
WPPS WNP-2 6 38 44
GPU Oyster Creek 39 16 55
678 479 1157

MSIP has been performed at 40 nuclear power plants worldwide:

(1) Some weldments with pre-existing cracks

(2) Weldments for replacement piping made of SCC immune materials

Learn from the experience of others. Especially when one such “other” is Dr. William O’Donnell, PhD, PE, Founder and President of O’Donnell Consulting Engineers, Inc., and ASME “Engineer of the Year” – his 50 years of experience in analysis of components including fatigue and fracture safety evaluations and failure analyses are now comprised in this volume.

If you are interested learning more in Engineering Design, Manufacturing and Construction, as well as Failure Analysis, then this book is a must have!

$49.95*

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Handbook of Lessons Learned

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