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This technical report evaluates the load carrying capacity of API 6A integral flanges. The applied loading includes the end tension and bending moment in addition to the conventional rated pressure and makeup forces. The effect of a temperature difference corresponding to 250°F on the inside and 30°F on the outside is also evaluated. Three-dimensional finite element meshes are generated for each of the flanges. The computer program SESAM was used to obtain the stresses at selected critical flange and hub sections and to determine the gasket reaction due to the four unit load cases and the temperature difference load case. Leakage Criterion is defined as the load combination which reduces the initial makeup compressive forces in the gasket to zero. The stresses in each defined section are linearized in accordance with the ASME Section VIII, Division 2, procedure to determine the membrane and membrane-plus-bending stress intensities. These stress intensities are checked against the allowable conditions specified in API 6A, and the limiting loads are determined. A computer program LCCP was written to carry out this code check and a LOTUS 1-2-3 Release 3 worksheet was used to plot the load combination charts.

The three-dimensional model analysis of this study provide verification that exisymmetric finite elements results of flanges, as used in Bulletin 6AF, are conservative. Additinally, this study determined a few flanges to have lessloading capacity than originally defined in API Spec 6A for makeup loading., and thus have been reduced to meet design requirements.

Product Details

Edition:

4th

Published:

10/01/2010

Number of Pages:

118

File Size:

1 file , 7.4 MB

Redline File Size:

2 files , 15 MB

Product Code(s):

G, G6AF24, G6AF24, G, G, G6AF24

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The original design criteria and pressure ratings that form the basis of all present API flanges dimensions are based, developed in the late 1920s and 1930s, did not address external loading capabilities. The flange designs were based on surface stress calculations, which were appropriate for uniform-axis symmetric loading conditions as used for bolt loading and pressure.

Determining the limiting conditions of flanges beyond that of pressure rating, where external loading is considered, requires knowledge of stresses as they are distributed through the thickness. Methods of calculating these stresses have been developed through the use of finite element programs, and have been applied in this technical report.

Compliance with the API 6A criteria requires stress linearization calculations based on the methodology established by ASME Pressure Vessel Code, Section VIII, Division 2. These criteria are defined in terms of stress distributions through the thickness and necessitate a more accurate means of calculating component stresses as provided by finite element analysis. The present work establishes a better understanding of the stress distribution in these flanges under the effect of the combined actions of pressure, bending moment, tension, and the original bolt make up of the flange. The flange capacities which meet the design stress criteria of API 6A are determined.

Product Details

Edition:

3rd

Published:

09/01/2008

Number of Pages:

119

File Size:

1 file , 7.7 MB

Product Code(s):

G6AF23, G6AF23, G6AF23

Note:

This product is unavailable in Cuba, Iran, North Korea, Syria

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Indicates increased load carrying capacity for several flanges based on separate stress limiting criteria. These stress limiting charts were not provided separately in the original work in API Bulletin 6AF, which combined them with leakage criteria. The three-dimensional model analyses of this study provide verification that exisymmetric finite elements results of flanges, as used in Bulletin 6AF, are conservative. Additionally, this study determined a few flanges to have less loading capacity than originally defined in API Spec 6A for makeup loading, and thus have been reduced to meet design requirements.

Product Details

Edition:

2nd

Published:

04/01/1999

Number of Pages:

119

File Size:

1 file , 620 KB

Product Code(s):

G6AF22, G6AF22, G6AF22

Note:

This product is unavailable in Cuba, Iran, North Korea, Syria

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This technical report is the result of the evaluation of the load carrying capacity of API 6A integral flanges, including the end tension and bending moment in addition to the conventional rated pressure and makeup forces. The effect of a temperature difference corresponding to 250° F on the inside and 30° F on the outside is also evaluated. Three-dimensional finite element meshes are generated for the Type 6B, and Type 6BX flanges. The computer program SESAM is used to obtain the stresses at selected critical flange and hub sections and to determine the gasket reaction due to each of the four unit load cases and the temperature difference load case. The leakage criterion is defined as the load combination with reduces the initial makeup compressive forces in the gasket to zero. The stresses in each defined section are linearized in accordance with the ASME Section VIII, Division 2, procedure to determine the membrane and membrane-plus-bending stress intensities. The stress intensities are checked against the allowable conditions specified in Spec 6A.

Product Details

Edition:

5th

Published:

04/01/2013

Number of Pages:

128

File Size:

1 file , 49 MB

Product Code(s):

G6AF25, G6AF25, G6AF25

Note:

This product is unavailable in Cuba, Iran, North Korea, Syria