Paulin Research Group has compared NozzlePRO saddle and nozzle results to more than five large, full-scale pressure vessel nozzle and saddle tests conducted either at the PRG lab in Houston or at fabrication facilities in the Houston, Texas area, and to numerous small-scale tests conducted at the PRG laboratories.
Verification Tests and Published Works
We conducted a series of validation tests regarding FEPipe for ASME Flat heads. The experiments were used to validate the new methods in the 2007 ASME Section VIII Division 2 code. You can view the full published report at https://thinkcei.atlassian.net/l/cp/KtEHAQZ4.
Additionally, we also tested fatigue testing of welded flat head pressure vessel joints and can be viewed at https://thinkcei.atlassian.net/l/cp/AF7E4A4w.
PRG and ASME Section VIII Div 1 Projects
In 2008, the ASME Standards Technology, LLC (ASME ST-LLC) awarded Paulin Research Group the projects ST-LLC-07-02 and ST-LLC-07-10. Project ST-LLC-07-02 is the ASME B31 project to align stress intensification and flexibility factors for the ASME B31 codes.
The PRGiK calculation spreadsheet computes i-factors and k-factors for branch connections using a selected set of equations to compare the results and more applicable data selected per B31.3 319.3.6. The tool also allows the i-factors to be used in stress and allowable calculations so that different stress equations and i-factor applications can be evaluated and different allowable and failure mechanisms can be compared.
To clarify, NozzlePRO does not generate Div. 1 calculations. The ASME Section VIII Division 1 employs a "Design by Rule" philosophy, where specific rules and procedures are provided in this code for the determination of minimum thickness under internal pressure, external pressure, the reinforcement of openings, and so on. These are calculations that are not performed or reported by NozzlePRO.
ASME Section VIII Division 1 does not provide rules to evaluate thermal stresses, stresses at attachments and supports, stresses in nozzles due to force and moment loading, fatigue (even just fluctuating pressure), and so on. In part, the reason is that the generalized treatment of these items cannot be easily reduced to a rule-based procedure. That is the purpose of the cited code paragraph below (paragraph U-2(g)): to instruct and enable the designer to seek design methodologies that can address these types of issues but that also provide design margins consistent with ASME Section VIII Division 1
“You can use the design by analysis methods of ASME Section VIII Division 2 ("VIII-2") part 5 for an ASME Section VIII Division 1 ("VIII-1") vessel pursuant to paragraph U-2(g) of VIII-1... so long as we use the same design margins as VIII-1. This "as safe as" clause of paragraph U-2(g) means we cannot use design by analysis to justify a minimum thickness less than the value arrived at by a paragraph in VIII-1. So the "in lieu of" phrase of VIII-2 4.1.1.5 has no effect.”
This is straightforward so long as elastic analysis techniques (VIII-2, para 5.2.2) are used, where the elastic stress classifications for primary stresses must use the allowable stresses from ASME Section II Part D Table 1A or Table 1B (secondary stresses have identical limits in VIII-1 and VIII-2).
The full research can be accessed from ASME’s digital collection site.