Overview of the Impact of Ultrasonic Examination Performance Demonstration on the ASME Boiler and Pressure Vessel Code

2002 ◽  
Vol 124 (3) ◽  
pp. 254-260 ◽  
Author(s):  
Owen Hedden ◽  
Dave Cowfer ◽  
Jon Batey ◽  
Jack Spanner ◽  
Larry Becker
Keyword(s):  
Pressure Vessel ◽  
Subsequent Development ◽  
Pressure Vessels ◽  
New Information ◽  
Starting Point ◽  
Asme Code ◽  
Process Qualification ◽  
New Construction ◽  
The Impact ◽  
Performance Demonstration

This paper addresses implementation of ultrasonic (UT) process qualification by performance demonstration as imposed by the ASME Boiler and Pressure Vessel Code Section XI, Appendix VIII. The intended audience for the present paper is an engineer with a good knowledge of NDE, but a limited knowledge of the ASME Codes and Standards. The starting point for application of UT performance demonstration is described in a paper published in this journal just over a decade ago by Cowfer and Hedden. That paper addressed the application of ultrasonic performance demonstration to qualify an examination process for ASME Code Section XI inservice inspection. The present paper provides a brief summary of papers specifically selected to provide the reader with a concise update of progress in UT performance demonstration since the earlier paper. Given that qualification, the reader should not expect new information in this present paper. The papers selected have been mostly selected from those presented at ASME Pressure Vessels and Piping Conferences, from 1995 to 2002, addressing the subsequent development and application of the UT performance demonstration process. The emphasis is on work performed for nuclear utilities under the Performance Demonstration Initiative (PDI), for application to Section XI inservice inspection. However, material also is included describing parallel work in the European Community, and applications of UT performance demonstration in Sections I and VIII of the ASME Boiler and Pressure Vessel Code, for use of UT in place of RT for new construction, are included.

Analysis of Half-Pipe Heating Channels on Pressure Vessel Shells

1986 ◽  
Vol 108 (4) ◽  
pp. 526-529
Author(s):  
A. E. Blach
Keyword(s):  
Pressure Vessel ◽  
Analytical Method ◽  
External Pressure ◽  
Pressure Vessels ◽  
Numerical Examples ◽  
Asme Code

Half-pipe heating channels are used on the outside of pressure vessels such as agitators, mixers, reactors, etc., to avoid the high external pressure associated with heating jackets. No applicable method of analysis is contained in the ASME Code and proof tests are normally required for registration with governing authorities. An analytical method is presented which permits the evaluation of stresses in shell and half pipe; numerical examples are included.

Alternative RTNDT for Linde 80 Weld Materials

2002 ◽  
Author(s):  
K. K. Yoon ◽  
J. B. Hall
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Pressure Vessel ◽  
Nuclear Power ◽  
Power Plants ◽  
Pressure Vessels ◽  
Screening Criteria ◽  
Master Curve Method ◽  
Asme Code ◽  
Curve Method

The ASME Boiler and Pressure Vessel Code provides fracture toughness curves of ferritic pressure vessel steels that are indexed by a reference temperature for nil ductility transition (RTNDT). The ASME Code also prescribes how to determine RTNDT. The B&W Owners Group has reactor pressure vessels that were fabricated by Babcock & Wilcox using Linde 80 flux. These vessels have welds called Linde 80 welds. The RTNDT values of the Linde 80 welds are of great interest to the B&W Owners Group. These RTNDT values are used in compliance of the NRC regulations regarding the PTS screening criteria and plant pressure-temperature limits for operation of nuclear power plants. A generic RTNDT value for the Linde 80 welds as a group was established by the NRC, using an average of more than 70 RTNDT values. Emergence of the Master Curve method enabled the industry to revisit the validity issue surrounding RTNDT determination methods. T0 indicates that the dropweight test based TNDT is a better index than Charpy transition temperature based index, at least for the RTNDT of unirradiated Linde 80 welds. An alternative generic RTNDT is presented in this paper using the T0 data obtained by fracture toughness tests in the brittle-to-ductile transition temperature range, in accordance with the ASTM E1921 standard.

Accounting for the Effects of Inservice Inspection Flaw Depth Sizing Errors in Developing Flaw Size Distribution Tables

2009 ◽  
Author(s):  
S. R. Gosselin ◽  
F. A. Simonen
Keyword(s):  
Pressure Vessel ◽  
Pressure Vessels ◽  
Reactor Pressure Vessel ◽  
Expert Elicitation ◽  
Flaw Size ◽  
Physical Models ◽  
Asme Code ◽  
Valid Comparison ◽  
Vessel Material ◽  
Reactor Pressure

Probabilistic fracture mechanics studies have addressed reactor pressure vessels that have high levels of material embrittlement. These calculations have used flaw size and density distributions determined from precise and optimized laboratory measurements made and validated with destructive methods as well as from physical models and expert elicitation. The experimental data were obtained from reactor vessel material samples removed from cancelled plants (Shoreham and the Pressure Vessel Research Users Facility (PVRUF)). Consequently, utilities may need to compare the numbers and sizes of reactor pressure vessel flaws identified by the plant’s inservice inspection program to the numbers and sizes of flaws assumed in prior failure probability calculations. This paper describes a method to determine whether the flaws in a particular reactor pressure vessel are consistent with the assumptions regarding the number and sizes of flaws used in other analyses. The approach recognizes that ASME Code Section XI examinations suffer from limitations in terms of sizing errors for very small flaws. Direct comparisons of a vessel specific flaw distribution with other documented flaw distributions would lead to pessimistic conclusions. This paper provides a method for a valid comparison that accounts for flaw sizing errors present in ASME Code Section XI examinations.

Discussion

1965 ◽  
Vol 285 (1400) ◽  
pp. 141-174 ◽  
Keyword(s):  
Pressure Vessel ◽  
Crack Extension ◽  
Initial Crack ◽  
Pressure Vessels ◽  
Full Scale ◽  
Small Specimen ◽  
Starting Point ◽  
Specimen Test ◽  
Valid Test ◽  
The One

It is our purpose to review fracture characteristics of heavy-walled pressure vessels in relation to the plane-strain crack toughness known under the term, K Ic . As a starting point, suppose that direct measurement of the strength of a full-scale pressure vessel containing a specific crack is contemplated. An initial crack of approximately the desired size can be introduced in several ways, for example, by inserting a sharp groove and then vibrating that region until a fatigue crack develops. However, full-scale testing is often impractical either for reasons of expense or because the introduction of in-service damage, say by nuclear irradiation, is not feasible at the full-scale size. Furthermore, valid test results can usually be obtained at much smaller scale. Small specimen fracture tests Crack extension behaviour observed in a small specimen test can be regarded as representative of full-scale fracture behaviour so long as the stresses carried by the surrounding material into the region containing the crack receive adequate representation. Since the specimen size desired for irradiation purposes is quite limited, we consider next whether crack extension of a large part-through crack in a thick-walled pressure vessel can be modelled by testing just the slice of material indicated in figures 108 ( a ) and ( b ). The calibration and use of test specimens similar to the one shown in figure 108( b ) are described by Sullivan (1964).

Study on Design Approach for Tall Pressure Vessels With Intermediate Support in Consideration of Bottom Structure Flexibility

2020 ◽  
Author(s):  
Shunsuke Sasaki ◽  
Takanori Nanjo ◽  
Toshikazu Miyashita ◽  
Shunji Kataoka ◽  
Yoshiaki Uno
Keyword(s):  
Pressure Vessel ◽  
Reaction Force ◽  
Steel Structure ◽  
Pressure Vessels ◽  
Design Approach ◽  
Intermediate Support ◽  
Fixed Model ◽  
Structure Flexibility ◽  
Additional Support ◽  
The Impact

Abstract The skirt and shell thicknesses of vertical tall pressure vessels are sometimes much increased in FPSO (Floating Production, Storage and Offloading) due to ship motion acceleration. In that case, intermediate support is used as an additional support from steel structure surrounding the vessels. By theoretical calculation, Nanjo et.al. introduced dimensionless parameter N that can represent stiffness of pressure vessel and acceleration load with the assumption of structure drift at intermediate support [1]. The authors proposed N-chart to investigate the necessity and effective elevation of intermediate support by using the parameter N. The flexibility of steel structure on the bottom affects the function of intermediate support (e.g. increasing reaction force at intermediate support, effect on bottom skirt calculation); however, the flexibility is not included in the parameter N. In this paper, an additional factor for the flexibility was studied and introduced by structural analysis. A model with flexibility of structure supporting the bottom skirt was used for the analysis. The variable flexibility of steel structure was applied to the bottom of the model to study the impact of bottom structure flexibility on the pressure vessel design. The analysis result was compared with the bottom fixed model without structure flexibility to study an additional factor. Finally, appropriate design approach for tall pressure vessels with intermediate supports was proposed.

Influence of Head Thickness on Yield Pressure for Cylindrical Pressure Vessels

1974 ◽  
Vol 96 (2) ◽  
pp. 113-120 ◽  
Author(s):  
Andre´ Biron ◽  
Jean Veillon
Keyword(s):  
Limit Analysis ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Additional Material ◽  
Asme Code

Results are presented for the limit analysis of pressure vessel heads of torispherical and ellipsoidal shapes in order to evaluate the influence of different head thicknesses for a given cylinder thickness. Comparison is made with presently used configurations as recommended by the ASME Code. It is found in particular that increasing the knuckle thickness of a torispherical head would provide a significant increase in yield pressure without excessive additional material.

Brittle Fracture Prevention Model for Pressure Based on Master Curve Approach

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
QingFeng Cui ◽  
Hu Hui ◽  
PeiNing Li ◽  
Feng Wang
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Impact Toughness ◽  
Pressure Vessel ◽  
Master Curve ◽  
Fracture Prevention ◽  
Pressure Vessels ◽  
New Model ◽  
Prevention Model ◽  
The Impact

The brittle fracture prevention model is of great importance to the safety of pressure vessels. Compared to the semi-empirical approach adopted in various pressure vessel standards, a model based on Master Curve technique is developed in this paper. Referring to ASME nuclear code, the safety features including the lower bound fracture toughness and a margin factor equal to 2 for the stress intensity factor produced by primary stress are adopted in the new model. The technical background of the brittle fracture model in ASME VIII-2 has been analyzed and discussed, and then its inappropriate items have been modified in the new model. Minimum design temperature curves, impact toughness requirements, and temperature adjustment for low stress condition are established on the basis of new model. The comparison with the relevant curves in ASME VIII-2 is also made. The applicability of the new model is verified by the measured fracture toughness and impact toughness data of several kinds of pressure vessel steels. The results suggest that the minimum design temperature and the impact test requirements derived by the new model are compatible with each other. More testing data of different steels to check this model is necessary for further engineering application.

Surveillance Specimen Programs for WWER Type Reactors

2005 ◽  
Author(s):  
Milan Brumovsky
Keyword(s):  
Mechanical Properties ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Surveillance Program ◽  
Reactor Safety ◽  
Reactor Radiation ◽  
Critical Comparison ◽  
Asme Code ◽  
Surveillance Programs ◽  
Reactor Pressure

Reactor pressure vessels (RPV) are components with the highest importance for the reactor safety and operation as they contain practically whole inventory of fission material but they are damaged/aged during their operation by an intensive reactor radiation. Surveillance specimen programs are the best method for monitoring changes in mechanical properties of reactor pressure vessel materials if they are designed and operated in such a way that they are located in conditions close to those of the vessels. Reactor Codes and standards usually included requirements and conditions for such programs to assure proper vessel monitoring. WWER (Water-Water-Energetic Reactors) reactor pressure vessels are designed according to former Russian Codes and rules with somewhat different requirements using different materials comparing e.g. with ASME Code. Two principal types of WWER reactors were designed, manufactured and are operated in several European countries (and also in China, Iran): WWER-440 and WWER-1000. Their surveillance programs were designed in quite different way, with some modifications due to the time, country of manufacturing and experience gained from their operation. The paper gives a critical comparison of these programs in both types of reactors with requirements of both Russian and ASME/ASTM Codes and Standards. Finally, information about creation of the Integral Surveillance Program for WWER-1000 type reactor pressure vessels covering vessels from several countries is described.

Stress Analysis and Optimization Design of Pressure Vessel of Underwater Gamma Spectrometer

2014 ◽  
Vol 518 ◽  
pp. 275-278
Author(s):  
Feng Gao ◽  
Jian Guo Zhang ◽  
Fang Fang Yang
Keyword(s):  
Photon Energy ◽  
Pressure Vessel ◽  
Optimization Design ◽  
Detection Efficiency ◽  
Side Wall ◽  
Pressure Vessels ◽  
Monte Carlo Code ◽  
Gamma Spectrometer ◽  
Cylindrical Pressure Vessel ◽  
The Impact

Pressure vessel makes the underwater gamma spectrometer can operation in underwater environment. In this paper, a kind of cylindrical pressure vessel has been simulated and analyzed using CAD software named Solidworks. Analysis results show the end covers are much thicker than the side wall to satisfy the same design safety factor and the centers of the end covers are the stress concentration areas. Further more, a 2× 2 LaBr3: Ce scintillation detector and a series of pressure vessels with various design safety factors and same inner space have been simulated by Monte Carlo code MCNP. Calculation indicates that the thicker the shell, the lower the detection efficiency. Further more, calculation shows the impact of the pressure vessel on detection efficiency of underwater gamma spectrometer varies with the photon energy. The law is that the higher the photon energy, the lower the influence on the detection efficiency.

S-N Curves in Pressure Vessel Steels Using Theory of Critical Distances

2008 ◽  
Author(s):  
Somnath Chattopadhyay
Keyword(s):  
Crack Propagation ◽  
Surface Crack ◽  
Pressure Vessel ◽  
Process Zone ◽  
Critical Distance ◽  
Pressure Vessels ◽  
Carbon Steels ◽  
Medium Carbon Steels ◽  
Asme Code ◽  
Number Of Cycles

The S-N technology used in the ASME Code and similar design criteria includes both crack initiation and crack propagation phases of fatigue failure. Some of the pressure vessel construction codes have used the simplified fatigue initiation criterion based on stresses calculated at a distance of 0.05 mm from the surface crack. In this work such techniques have been assessed for pressure vessels in light of the theory of critical distances. This method has been used to generate S-N curves for typical materials such as medium carbon steels, nickel chrome steels and stainless steels. Separate techniques have been highlighted for obtaining the number of cycles to nucleate a crack from a free surface, and also the number of cycles to drive the nucleated surface crack to propagate to a length equal to the critical distance parameter related to the process zone. The two estimates on the number of cycles when combined constitute a reasonable estimate of the number of cycles to initiate a crack and form the basis of the S-N design curves. The method requires the material property information on elastic-plastic fracture toughness and short crack propagation characteristics including crack closure effects.

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