Document: NUREG-0800
Document ID: 26aca061-b0de-4983-bbca-3fccb00afc2f
Document Type: srp
Title: PRESSURE-TEMPERATURE LIMITS AND PRESSURIZED THERMAL SHOCK1
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070431.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.3.2
CFR Part: 
CFR Title: 

Content:
B provided in graphical form in Figure G-2214.1 of the Code. Refer to Figure 1 herein. The criterion recommended by MTEB EMCB can be expressed as 51 K < K for the shell region. I IRa 52 To get K , the stress level and wall thickness must be known. The pressure for I the hydrostatic test is 1.25 times the design pressure, so that the higher of two simple methods described below to approximate the membrane stress should be accurate enough for this purpose: stress = 1.25 times the Code allowable (S ) m stress = Pr t where P is the test pressure and r is the vessel radius. As an example, assume a vessel with a design pressure of 2500 psig, made of steel with an S of 26,700 m 5.3.2-11 DRAFT Rev. 2 - April 1996 psi, and a minimum yield strength of 50,000 psi. The stress for the preservice hydrotest is then 26,700 x 1.25 = 33,400 psi, or (1.25) (2500) (95) = 33,4000 psi, for a vessel 9 53 with a radius of 95 inches and a wall thickness of 9 inches. The next step is to determine the factor to apply to this stress to obtain K . Figure I G-2214.1 (reproduced here as Fig. 1) provides several curves, depending on the ratio of the stress level to the yield strength of the material. In this case, the conservative (i.e., higher of the above two approximations) stress level is 54 33,400; the yield strength is conservatively assumed to be 50,000 so the curve for a ratio of .7 should be used. (A ratio equal to or higher than the actual ratio must be used for conservatism.) For a 9-in. thick vessel ( t = 3), the value of M from m Figure G-2214.1 is 2.94. The K for this case is then: I K = (M )(Membrane Stress) I m K = (2.94)(33,400) = 98,3200 psi in. I 55 From Figure G-2210.1 (reproduced here as Fig. 2), a temperature of at least RT + 120 F is necessary for a K of this level. NDT I If, for example, an original RT of 40 F is assumed, the required temperature is NDT then 40 + 120, or 160 F. b. Inservice Leak and Hydrotest. The temperatures for the inservice leak and hydrotest, performed