PSI - Issue 60

Balaji Srinivasan et al. / Procedia Structural Integrity 60 (2024) 418–432 Balaji Srinivasan et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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FEA is a powerful tool but requires substantial computational resources and expertise to implement accurately. On the other hand, manual analytical methods like PD 5500 Appendix G and EN 13445-3 clauses 16.4 and 16.5 are relatively more accessible but may be overly conservative in some cases. Selecting and applying the most appropriate method is crucial for designing safe and reliable pressure vessel nozzles, safeguarding against potential failures, and ensuring compliance with relevant standards and regulations.

Table 1. Dimensional Limitations. WRC 368

WRC 497

WRC 107

WRC 297

EPRI 110996

19 < D/T < 999 4 < d/t < 999

For P, Mi, Mo,Fax: 0.333 <= d/D < 1.0 20 <= D/T < 250 d/D < t/T < 3.0 For Mt. 0.125 < d/D < 1.0

8.0 < R/T < 50 0.5 < r/t < 50 0.125 < r/R < 1.0 0.211 < t/T < 9 0.5 < r/rp < 1.0

20 <= D/T <= 2500 10 <= d o /t <= 100 d o /D <= 0.5 λ <=10 ; λ =(d o /D m )*(D m /T) 0.5 T/t <= 10

b = 0.875 d o /D or 0.875r o /R m for cylinders

0.039 < d/D < 0.515 0.388 < Dt/dT < 6.26 0.1 < t/T < 3.0 All diameters are mean diameters

d/D < 0.6 D/t < 600 t/T => 1 λ <= 2.8

7.5 < D/T < 99 7.5 < d/t < 198

2.2. Limitations of STP STP provides recommendations and supporting data for estimating local stresses induced by pressure and loads from outside the shells and formed heads. The study results from a Nozzle Design Rules-focused ASME ST-LLC Research Project (No. 07-10). STP is an extension of the work Paulin Research Group (PRG) completed for ASME ST-LLC under Research Project No. 07-02, "Stress Intensity Factor and K-Factor Alignment for Metallic Pipes" (2014). The primary objective of the work was to align the stress intensification and flexibility factors for metallic pipes used in the BPVC Section III-Rules for Construction of Nuclear Facility Components-Division 1-Subsection NC Class 2 Component and BPVC Section III-Rules for Construction of Nuclear Facility Components-Division 1 Subsection ND-Class 3 Component and ASME's Pressure Piping Codes (B31) with each other. The findings were presented in the STP-PT-073. Using the suggested modeling techniques from WRC 497, ASME VIII-Section 2 Annex 5. A and EPRI TR 110996 (1998), a thorough set of finite element runs were carried out to broaden the study's scope and assess alternative parameter ranges and geometries. The dimensional limitations are provided in Table 2. It shall be noted that the present study is limited to unpadded/un-reinforced nozzles configurations only.

Table 2. Limitations of STP 7 < D m /T < 2500

..Eq(1) ..Eq(2)

tp < 1.5T

..Eq(5)

0.1< t/T<10

.Eq(3) ..Eq(4)

d m /D m < 0.7

(d m /D m )(D m /T)

0.5 < 10 ..Eq(6)

7 < d m /t < 200 .

3. Methodology 3.1. Finite Element Analysis (FEA) Approach:

The ASME VIII-2 Part 5, the code provides the FEA guidelines for elastic stress. Using NozzlePro software (2018), 3-D shell components are used to create the nozzle (branch) and cylinder (header) for the nozzle shell junction evaluation and results are compared in line with ASME VIII-2 Part 5. A corroded model is utilized during the FEA with internal pressure and external forces applied. The approach relies on the involvement of the shell and nozzle (Wais et al. (2001), EPRI TR-110996 (1998), Wais et al. (1999), EPRI TR-110755 (1998), EPRI TR-106416