Mechanical Stress Improvement Process (MSIP®) is a patented process that was invented, developed and first used in 1986 by NuVision Engineering, Inc. for mitigating Stress Corrosion Cracking (SCC) in Nuclear Plant piping weldments. MSIP® is accepted by the United States Nuclear Regulatory Commission as a Stress Improvement (SI) process for mitigation of stress corrosion cracking in both BWR and PWR plants. In addition, MSIP® has and continues to be applied to prevent SCC in RBMK piping welds in Russia and Lithuania.
- Permanent Stress Corrosion Crack Mitigation by compressing the pipe 1 – 2% close to the weld
- Over 6000 welds squeezed worldwide
- Over 25 Years of Successful Operating Experience
- Qualified and verified by EPRI, ANL, Battelle, and PNNL (for USNRC).
- Redistributes ‘as-welded’ tensile residual stresses generating axial and hoop compression ~ 50% through wall in inner weld region.
- Physically Verifiable by Circumference Measurement
MSIP® works by using a simple hydraulically operated clamp which contracts the pipe on one side of the weldment. The clamps have been designed and built for pipe diameter applications from 2” through 34”. The photographs below show a typical tool design that uses a specially designed hydraulic box press for bringing the clamp halves together. A portable hydraulic pump is used to activate the box presses. Plant air is used for pump operation.
All of the equipment necessary is shown below.