scope:

SCOPE OF WORK

The thick-walled cylinder reference stress solutions were computed for four combinations of crack location and orientation: external axial, external circumferential, internal axial, and internal circumferential.

The thick-walled cylinder crack cases are described by three ratios: Y, a/l, and a/T. Y is the ratio of the cylinder outside diameter to the inside diameter, i.e., Y = OD/ID. The a/l ratio is the crack depth, a, to the surface crack length, l. The a/T ratio is the crack depth, a, to the cylinder thickness, T. The same set of a/l and a/T ratios were used as given in the ASME FFS/API 579-1 (2016) Annex 9C stress intensity K solutions, allowing the same interpolation of the tabular values to obtain K and reference stress.

The tables below show the ratio values used in this project. An extra column is included to relate the ASME Y and a/l ratios to their equivalent API 579 ratios: T/Ri (Ri is the cylinder inside radius) and a/c (c is the half crack length). The T/Ri ratio equals Y - 1, and the a/l ratio equals (a/c)/2. The labels "360-deg" and "full width" refer to partial depth surface crack shapes around the full circumference or along the full width of the cylinder length, i.e., "infinite" length crack shapes. These 360-deg and full width crack shapes provide an upper bound solution for the longer surface crack cases.

Some of the circumferential surface crack length cases are limited by the cylinder circumference. In the two tables below each a/l ratio crack length is compared to the cylinder circumference to identify the valid cases and the cases that are "too long" for the cylinder dimensions.

The total number of cases for each crack location are listed in the tables below for the combination of the single pressure load case, the a/T ratios, a/l ratios, and diameter ratios Y.

Using these sets of ratios, 523 crack cases were created and analyzed to compute the reference stress solution geometry factor values. The model "Run ID" numbers are used to uniquely identify each case.