Changes in API 653, Tank Inspection, Repair, Alteration, and Reconstruction

By Stephen J. Gliebe, P.E.

The following highlights several changes to API 653 that are contained in the Third Edition, Addendum 3, dated February 2008. Note that there is a new, non-mandatory, Appendix H that provides guidance on performing a similar service assessment. Highlights of the similar service assessment methodology are also provided below.

Section 3: Definitions

New definitions have been added for candidate tank, control tank, hydrotest, product-side, similar service assessment, and soil-side.

Section 4: Suitability For Service

Section 6: Inspection

Reporting requirements have been greatly expanded (Para. 6.9). Refer to the sections covering report contents and recommendations for additional details.

Section 8: Reconstructed Tanks

All tanks that are reconstructed shall be checked for seismic stability based on the rules of the current applicable standard (Para. 8.8).

Section 9: Tank Alteration and Repair

Section 11: Welding

A new section covering preheat or controlled deposition welding methods as alternatives to post weld heat treatment has been added (Para. 11.3).

Section 12: Examination and Testing

Hydrotesting: A new section provides requirements for cases where a hydrostatic test is not required, such as repairs or alterations to a floating roof, and bottom repair or replacement outside the critical zone.

Appendix H: Similar Service Assessment

Appendix H, Similar Service Assessment, is new. The appendix provides a detailed approach for establishing internal inspection intervals for tanks for which corrosion rates have not been directly measured. Highlights of the methodology and a partial data sheet are noted below. Refer to Appendix H for complete details.

Methodology:

Partial Similar Service Assessment Data Sheet
(partial extract from API 653)