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George Antaki, Fellow ASME, has over 40 years of experience in nuclear power plants and process facilities, in the areas of design, safety analysis, startup, operation support, inspection, fitness for services and integrity analysis, retrofits and repairs. George has held engineering and management positions at Westinghouse and Washington Group Int...ernational, where he has performed work at power and process plants, and consulted for the Department of Energy (DOE), the Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI). More

Using NB-3200 FEA As An Option To Stress Equations In NB-3600

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  The ASME B&PV Section III Div.1 Code 2013 Edition is currently approved in 10CFR50.55(a). The 2013 edition, permits elastic FEA per NB-3200 in place of the stress equations of NB-3600, as follows: For pressure design -  “NB-3611.2 Acceptability When Stresses Exceed Stress Limits. When the stresses as determined by the methods given in NB-3630 exceed the limits thereof, the design can be accepted, provided it meets the requirements of NB-3200.” For shakedown check Eq. (10)(12)(13) - For the shakedown check, quoting from NB- NB-3653.1 Satisfaction ofFor shakedown check Eq. (10)(12)(13) - For the shakedown check, quoting from NB- NB-3653.1 Satisfaction ofPrimary Plus Secondary Stress Intensity Range. “(b) If for one or more pairs of load sets eq. (a)(10) is not met, thepiping product may still be satisfactory, provided that the conditions of NB-3653.6 are met or provided that therequirements of NB-3200 are satisfied.”   Equations (10), (12) and (13),...
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Five Keys to a Cost-Effective Repair/Modification Package for Tanks-Vessels-Piping

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: Process : Does the repair change the process chemistries, physics (fluid phase), and thermo-hydraulics (flow rates, pressures, temperatures)? Does the modification change the control room indications and the operating envelopes? Material : Are the selected metallic materials (base metal and welds) and non-metallic materials (gaskets, packings, etc.) compatible with the existing materials, with the environment, and with the service, for the design life of the repair? Is the material compliant with (a) the material specification (ASTM or ASME II), (b) the supplementary Code requirements, and (c) the supplementary plant-specific requirements? Will the material be procured from an approved supplier; does it require supplementary Quality Controls? ASME Code design : Does the modification alter the system layout? If yes, has the layout been checked for good practice and consistency with the process design (item 1 above)? Are the loads and load combinations well defined and categorized as Service Levels A,...
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12 Checks When Qualifying Piping Systems in Nuclear Applications

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The analysis and qualification of piping systems in nuclear power plants involves more than meeting Code stress limits. Generally, a piping system is qualified if the following criteria have been met. These various qualification criteria are typically specified in the plant FSAR, the plant design procedures, or the ASME Code. Pressure design in accordance with the design Code. This check will govern the schedule of pipes, the thickness of tubing, the schedule and pressure class of fittings, the reinforcement of openings and branch connections, the pressure rating of valves, the pressure class of flanges, and the pressure design of specialty fittings. ASME Code stress limits . This check will verify that the Code stress equations for the load combinations corresponding to Test, Design, and Service Levels A, B, C, and D loadings have been met. NRC Standard Review Plan (SRP) Section 3.6 stress limits for the postulation of high energy...
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Purpose of the Flange Bolt Rules in ASME VIII and ASME III

becht_nuclear_flange_pressur_20180103-202305_1
The partial objective of the ASME Appendices ASME VIII Div.1 Appendix 2, and ASME III Div.1 Appendix XI provide “Rules for Bolted Flange Connections” with ring-type gaskets. One of the rules provided applies to the calculation of the minimum required bolt area. In other words, what should be the minimum combined cross-section area of the flange bolts to (a) seal the gasket, while (b) not exceeding the bolt allowable stress? The two force components W m1 and W m2 The rules are intended to provide bolts with sufficient pre-tension to achieve two objectives: (1) Counter a pressure-induced force W m1 which tends to pry open the flange in operation, and (2) provide a compressive force W m2 which is needed to seat the gasket during initial assembly of the flange joint. The at-pressure force W m1 The W m1 force is in turn comprised of two contributions, illustrated in the...
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