Document: NRC Regulatory Guide
Document ID: 111e064c-2d28-4647-872a-806b29019408
Document Type: regulatory_guide
Title: Design Limit and Loading Combinations for Seismic Category I Fluid System Components
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1229/ML12298A124.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.48
CFR Part: 
CFR Title: 

Content:
s and valves under all design loadinig'combinations. However, Note 6 states that the design limits for non-active pumps and valves designed by analysis may be used if assurance is provided by detailed stress and deformation:analyses that operability is not impaired when designed to these limits. Active ASME Code Class 1 Valves (Designed by Standard or Alternative Design Rules) To provide greater assurance of operability, the primary pressure rating (Pr) for Code Class 1 active valves designed by standard or alternative rules should not be exceeded when the valve is subjected to the combination of loadings delineated in regulatory positions 5.a.(1), 5.a.(2), and 5.a.(3). This design limit is selected on the same basis as that designated for active pumps and valves that are designed by analysis and is analogous to design limits specified for the normal operating condition category of Section III of the ASME Code. Note 6 to the regulatory position also applies. However, in the case of pressure-related valves, Note 6 states that the primary-pressure ratings (Pr) for non-active valves designed by standard or alternative design rules may be used for the applicable loading combinations if appropriate testing demonstrates that operability is not impaired when the valve is so rated. Since detailed analytical techniques are not used to design pressure-temperature rated valves, demonstration of operability by test is'indicated. ASME Code Class 2 and 3 Components With one exception, no distinction is made between Code Class 2 and 3 components since the design requirements of Section III of the ASME Code are the same for both classes of components. The design rules for Code Class 2 and 3 components do not provide for design by analysis (except for Code Class 2 vessels designed in accordance with Section VIII, Division 2, of the ASME Code) and do not yet provide any design rules for pumps. Furthermore, no design limits for other than the normal plant condition are available (the