Document: NRC Regulatory Guide
Document ID: 7da9830f-b2a1-484a-82ce-5b0a588c4fce
Document Type: regulatory_guide
Title: Protection Against Pipe Whip Inside Containment
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1229/ML12298A123.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.46
CFR Part: 
CFR Title: 

Content:
sign, improperly controlled fabrication, installation errors, or unexpected modes of operation. Therefore; the above limits provide additional margin over significant design basis.stress cycles (for a 40-year plant life) which is available to account for these uncertainties. If less than two intermediate break locations are determined between terminal ends of the piping run or branch run by application of the stress intensity and cumulative usage factor limits discussed above, or if it appears that adequate pipe whip protection may not result from breaks postulated at these intermediate break locations, additional intermediate break locations selected on a reasonable basis should be postulated for each piping run or branch run. A reasonable basis for locating intermediate piping breaks should consider such factors as: (1) points of maximum stress intensity and/or cumulative usage factors (excluding terminal ends) in the piping run or branch run, (2) length of the piping run or branch run over which no protective measures against pipe whipping are provided, and (3) changes in coordinate plane (i.e., X-Y, Y-Z, and X-Z) of the piping run or branch run as determined by tracing the run in both directions starting at each terminal end. Based on a review of piping systems, a minimum of two intermediate break locations should be selected for each piping run or branch run. These break locations are postulated for design analysis purposes. There is not necessarily any correspondence between the number of postulated breaks and the number of pipe whip restraints needed to provide protection. However, the determination of the need for pipe whip restraints should consider the potential consequences of postulated breaks at these locations. ASME Code Class 2 and 3 Piping An approach comparable to that taken for Code Class 1 piping should be applied to define design basis break locations for ASME Code Class 2 and 3 piping of fluid systems in which piping breaks may be postulated.