Changes in Addendum 4 of API 570: Piping Inspection Code
By Stephen J. Gliebe, P.E.
Addendum 4 of API 570 was released in June 2006. This article
highlights several of the changes made since Addendum 3, dated August
- Para. 3.1. Changed the definition of an alteration. The addition
of any reinforced branch connection equal to or less than the size of
an existing reinforced branch connection is now considered an
- Para. 3.56 through 3.59. Added definitions for corrosion
specialist, pressure design thickness, required thickness, and
structural minimum thickness.
- Para. 7.3. Modified the process for determination of required
thickness as defined in paragraph 3.58. Pressure design thickness and
structural minimum thickness per paragraphs 3.57 and 3.59,
respectively, must now be considered.
- Para. 18.104.22.168. Added requirement to perform a fitness-for-service
analysis before installing a temporary repair by fillet welding a
split coupling or plate patch over a locally thinned area. Prohibits
installing a fillet-welded patch on top of an existing fillet-welded
patch. Added minimum spacing criteria for installing a fillet-welded
patch adjacent to an existing fillet-welded patch.
- Para. 8.1.4. Expanded the list of non-welded repairs to include
nonmetallic composite wraps, metallic and epoxy wraps, or other
non-welded applied temporary repairs. Added the requirement to
consider any resulting crushing forces when using procedures that
include pumping leak sealing fluids.
- Para. 8.2.6. Changed to require consultation with the inspector
and the piping engineer before substituting NDE for a pressure test
after a rerate. Added guidance for performing pressure tests on
insulated lines after repairs, alterations, or rerating, without
stripping the insulation.
- Appendix A, Para. A.3.1 through A.3.3. Added details on inspector