An Engineering Basis for Establishing Radiographic Acceptance Standards for Porosity in Steel Weldments

1965 ◽  
Vol 87 (4) ◽  
pp. 887-893 ◽  
Author(s):  
H. Greenberg
Keyword(s):  
Stress Concentration ◽  
Nondestructive Testing ◽  
Pressure Vessel ◽  
Maximum Size ◽  
Theoretical Studies ◽  
Concentration Effects ◽  
Close Proximity ◽  
Testing Techniques ◽  
Steel Welds ◽  
Made In

Radiographic acceptance standards, such as those found in the ASME Unfired Pressure Vessel Code are critically reviewed. Limits on the size and distribution of porosity in steel welds are analyzed from the viewpoint of susceptibility to failure in service. In large part, present standards for porosity appear to have been established on a “good workmanship” basis rather than on setting sound conservative limits for the maximum size, and distribution of flaws which can be tolerated without decreasing the reliability of the product. Radiographic acceptance standards in use today do not reflect the significant advances being made in (1) the fracture mechanics approach to designing for prevention of failure; (2) theoretical studies of the stress-concentration effects of holes in close proximity to one another; and (3) the possible use of complementary nondestructive testing techniques. Considerable emphasis is placed on the proposition that radiographic acceptance standards for weldments must be designed specifically for each particular application. Considerations applicable to welds in the 120-in-dia rocket motor case are cited as an example of how standards for acceptable porosity and inclusions can be established.

Is the Real Prevalence of Pancreatic Neuroendocrine Tumors Underestimated? A Retrospective Study on a Large Series of Pancreatic Specimens

2019 ◽  
Vol 109 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Stefano Partelli ◽  
Fabio Giannone ◽  
Marco Schiavo Lena ◽  
Francesca Muffatti ◽  
Valentina Andreasi ◽  
...  
Keyword(s):  
Neuroendocrine Tumors ◽  
Smoking Habit ◽  
Maximum Size ◽  
Histological Diagnosis ◽  
Main Diagnosis ◽  
Pancreatic Neuroendocrine Tumors ◽  
Intraductal Papillary Mucinous Neoplasms ◽  
Mucinous Neoplasms ◽  
Median Diameter ◽  
Made In

Background/Aims: The annual incidence of pancreatic neuroendocrine tumors (PanNET) has been estimated to be around 0.8/100,000 inhabitants. The aim of this study was to determine the frequency of incidental histological diagnosis of PanNET in pancreatic specimen evaluation for a purpose other other than PanNET diagnosis. Methods: One thousand seventy-four histopathological examinations of pancreatic specimens performed in 3 centers in Italy were retrospectively reviewed. All cases with a main pathological diagnosis of PanNET were excluded. Results: An incidental associated diagnosis of PanNET was made in 41 specimens (4%). Among those 41 cases, 29 (71%) had a largest diameter <5 mm (microadenoma), whereas the other 12 (29%) had a maximum size ≥5 mm (median diameter of the whole series = 3 mm, range 1–15). The association with a main diagnosis of intraductal papillary mucinous neoplasms (IPMN) was significantly higher for patients who had an incidental PanNET (p = 0.048). There was no association between incidental diagnosis of PanNET and age, gender, BMI, smoking habit, diabetes, and type of operation. Conclusions: The frequency of incidental histological diagnosis of PanNET is considerably high, suggesting that their real prevalence is probably underestimated. The present study suggests a possible correlation between the incidental occurrence of PanNET and IPMN.

Evolution of precipitation in reactor pressure vessel steel welds under neutron irradiation

2017 ◽  
Vol 488 ◽  
pp. 222-230 ◽  
Author(s):  
Kristina Lindgren ◽  
Magnus Boåsen ◽  
Krystyna Stiller ◽  
Pål Efsing ◽  
Mattias Thuvander
Keyword(s):  
Neutron Irradiation ◽  
Pressure Vessel ◽  
Reactor Pressure Vessel ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Reactor Pressure Vessel Steel ◽  
Steel Welds ◽  
Reactor Pressure

Incomplete AVO near salt structures

Geophysics ◽  
1992 ◽  
Vol 57 (4) ◽  
pp. 543-553 ◽  
Author(s):  
Christopher P. Ross
Keyword(s):  
Seismic Profiles ◽  
Spectral Modeling ◽  
Signal Degradation ◽  
Amplitude Versus Offset ◽  
Bright Spots ◽  
Close Proximity ◽  
Pseudo Spectral ◽  
Amplitude Versus ◽  
Structure Class ◽  
Made In

Amplitude versus offset (AVO) measurements for deep hydrocarbon‐bearing sands can be compromised when made in close proximity to a shallow salt piercement structure. Anomalous responses are observed, particularly on low acoustic impedance bright spots. CMP data from key seismic profiles traversing the bright spots do not show the expected Class 3 offset responses. On these CMPs, significant decrease of far trace energy is observed. CMP data from other seismic profiles off‐structure do exhibit the Class 3 offset responses, implying that structural complications may be interfering with the offset response. A synthetic AVO gather was generated using well log data, which supports the off‐structure Class 3 responses, further reinforcing the concept of structurally‐biased AVO responses. Acoustic, pseudo‐spectral modeling of the structure substantiates the misleading AVO response. Pseudo‐spectral modeling results suggest that signal degradation observed on the far offsets is caused by wavefield refraction—a shadow zone, where the known hydrocarbon‐bearing sands are not completely illuminated. Such shadow zones obscure the correct AVO response, which may have bearing on exploration and development.

Study on a Large Opening in a Pressure Vessel

2011 ◽  
Vol 308-310 ◽  
pp. 58-61
Author(s):  
Wei Wang ◽  
Jing Bao Shi ◽  
Ming Fu Luo ◽  
Yu Fang Wang
Keyword(s):  
Numerical Calculation ◽  
Stress Concentration ◽  
Pressure Vessel ◽  
Mechanical Characteristics ◽  
Inside Surface ◽  
Reinforcing Effect ◽  
Area Method ◽  
Pressure Area ◽  
Opening Ratio ◽  
Large Opening

In this paper ,we ared study on the reinforcement of a large opening with which the opening ratio is (W)0.8 with numerical calculation. We analyzed the Mechanical characteristics of opened shell It shows the stress concentration is seen clearly on point A which is between Connecting Inside surface of pipe and shell ,and point B, which is between Connecting outside surface of pipe and shell. And the stress concentration on point A is more than on point A when the opening ration(W) is 0.8.And it is calculated reinforcing effect and analyze the limitation when the opening ration by pressure area method（Referred to PAM）.It is obtained the limitation of PAM by comparing numerical calculation to PAM.

Effect of stress relief temperature and cooling rate on pressure vessel steel welds

2002 ◽  
Vol 327 (1) ◽  
pp. 76-79 ◽  
Author(s):  
M.K Miller ◽  
S.S Babu ◽  
M.A Sokolov ◽  
R.K Nanstad ◽  
S.K Iskander
Keyword(s):  
Cooling Rate ◽  
Pressure Vessel ◽  
Stress Relief ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Steel Welds

scholarly journals A Series of Humanly-Fashioned Flints Found in the Cliffs and on the Shore at Mundesley, Norfolk

1920 ◽  
Vol 3 (2) ◽  
pp. 219-243
Author(s):  
J. Reid Moir
Keyword(s):  
Present Author ◽  
The South ◽  
North West ◽  
The North ◽  
Close Proximity ◽  
Made In

When visiting Mundesley, in Norfolk, in September, 1916, the present author found upon the shore, in close proximity to an exposure of clay which he now considers to be referable to the Cromer Forest Bed Series, a very finely-made and large flint flake, of human manufacture. This discovery induced him to again visit Mundesley, and during this year (1919) close upon three weeks have been spent in an examination of the stretch of cliffs and shore lying between Trimingham, to the north-west of Mundesley, and Bacton, which lies to the south-east.The author's researches have been greatly helped by the co-operation of three friends, Professor A. S. Barnes, Mr. Walter B. Nichols, and the Hon. Robert Gathorne-Hardy, who accompanied him to Mundesley, and to whom he offers his warmest thanks. He would, however, wish to make it clear that these gentlemen are in no way responsible for the statements made in this paper. For these the author is solely responsible.

Sign in / Sign up

Export Citation Format

Share Document