ASME B31.4-2016 pdf – Pipeline Transportation Systems for Liquids and Slurries
ASME B31.4-2016 pdf – Pipeline Transportation Systems for Liquids and Slurries.
(e) Grooving, Selective, or Preferential Corrosion of Welds.
Grooving, selective, or preferential corrosion of the iongitudinal seam of any pipe manufactured by the electric resistance welding (ERW) process, electric induction welding process, or electric flash welding process shall be removed or repaired.
4220.127.116.11 Gouges, Grooves, and Arc Burns.
Gouges and grooves shall be evaluated by nondestructive examination. Superficial grinding may be necessary to provide a smooth surface for nondestructive examination. The remaining wall thickness after grinding shall not be less than the minimum permitted by the component specification. Upon completion of superficial grinding, the absence of any cracking shall be confirmed by using dye-penetrant or magnetic-particle inspection. If no cracking is present, the net remaining wall thickness shall be determined by ultrasonic measurement. Gouges and grooves that leave less than the minimum wall thickness permitted by the component specification shall be removed or evaluated for repair in accordance with para. 418.104.22.168(b).
Arc burns shall be removed or repaired by grinding. Arc burns repaired by grinding shall be etched to confirm removal of all of the metallurgically altered material. Suitable etchants include 10% nital or 20% ammonium persulfate. All dark-etching material shall be removed, and the remaining wall thickness shall be determined by ultrasonic measurement.
422.214.171.124 Dents. Dents exposed for examination that have any of the following characteristics shall be removed or repaired unless an engineering evaluation can demonstrate that other mitigative action as defined in API 1160 will reduce the risk to an acceptable level:
(a) dents containing gouges, grooving, scratches, cracking, or other stress riser
(b) dents containing metal loss resulting from corrosion or grinding where less than the minimum wall thickness permitted by the component specification remains
(c) dents that affect pipe curvature at a girth weld or a longitudinal seam weld
(d) dents with a depth greater than 6% of the nominal pipe diameter [0.250 in. (6.4 mm) in depth for a pipe diameter NPS 4 and smaller]
The absence of any cracks shall be confirmed by inspection using magnetic-particle or dye-penetrant techniques. Prior to inspection, the surface of the dent shall be cleaned to bare metal. Dents that could restrict the passage of Iii tools should be removed.
4126.96.36.199 Cracks. Verified cracks except shallow crater cracks or star cracks in girth welds shall be considered defects and removed or repaired unless an engineering evaluation shows that they pose no risk to pipeline integrity. Shallow crater cracks or star cracks in girth welds, 32 in. (4.0 mm) or less in length, are not considered defects.
4188.8.131.52 Anomalies Created by Manufacturing Processes. An anomaly created during the manufachire of the steel or the pipe that exists in a pipeline that has been subjected to a hydrostatic test to a minimum level of 1.25 times its maximum operating pressure in accordance with para. 437.4.1 shall not be considered a defect unless the operator has reason to suspect that the anomaly has been enlarged by pressure-cycle-induced fatigue. If it is established that the anomaly has become or is likely to become enlarged by pressure-cycle- induced fatigue, the anomaly shall be removed or repaired.
Suspected hard spots or flat spots should he examined by means of a hardness tester. Areas having a hardness level corresponding to Rockwell C 35 or more shall he removed or repaired.
A lamination that lies on a plane parallel to the pipe surfaces shall not be considered a defect unless it intersects a seam or girth weld or it extends to the inside or outside surface of the pipe. A lamination that intersects a girth weld or seam weld, that lies on a plane inclined to the plane of the pipe surfaces, or that extends to the inside or outside surface of the pipe shall be removed or repaired. Prior to repair, the entire extent of the lamination should be defined by means of ultrasonic measurement of the wall thickness. Laminations discovered as a result of ILl activities should be cross-referenced, if possible, to deformation data to examine the possibility that a lamination is actually a blister.
4184.108.40.206 Blisters. Blisters shall be considered defects and shall be removed or repaired. Prior to repair, the entire extent of the blister should be defined by a nondestructive technique.
4220.127.116.11 Buckles, Ripples, Wrinkles. For small ripples (i.e., incipient buckles or wrinkles) that exhibit no cracks, no repair is required if the crest-to-trough height, Ii, 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.