American Society of Mechanical Engineers Draft Criteria for Evaluation of Wrinkle Bends in Hazardous Liquid Pipelines
December 16, 2003
(8) Buckles, Ripples, Wrinkles
For small ripples (i.e., incipient buckles or wrinkles) which exhibit no cracks, no repair is required if the crest-to-trough height, h, meets one of the following criteria where the maximum operating hoop stress, S, is as shown. The absence of any cracks shall be confirmed using magnetic particle or dye penetrant inspection.
| Maximum Operating Hoop Stress, S | (h/D) x 100 cannot exceed |
| =20,000 psi (138 MPa) | 2 |
| >20,000 psi (138 MPa) but =30,000 psi (207 MPa) |
(((30,000-S)/10,000)+1) |
| >30,000 psi (207 MPa) but =47,000 psi (324 MPa) |
0.5 ((47,000-S)/17,000)+1) |
| >47,000 psi (324 MPa) | 0.5 |
[image describing pipe surfaces with labels corresponding to table above and items below - refer to PDF for image]
where
S is the maximum operating hoop stress, psi (i45 x S.MPa)
h is the crest-to trough height of the ripple, inch (mm)
D is the outside diameter of the pipe, inch (mm).
When a group of buckles, ripples, or wrinkles exist in proximity to one another, the limitation on h shall be applied to the largest crest-to-trough height.