Changes in API 653, Tank Repair, Alteration, and Reconstruction
By Vincent A. Carucci
Two addenda have been issued for the Fourth Edition of API 653 since it
was published in April 2009. Addendum 1 was issued August 2010, and
Addendum 2 was issued January 2012. The following highlights several of
the changes that were made and is not all inclusive. Refer to API 653 for
Section 2: Referenced Publications
Several new references were added:
- API RP 580, “Risk Based Inspection”
- API RP 2009, “Safe Welding, Cutting, and Hot Work Practices in the
Petroleum and Petrochemical Industries”
- NACE RP 0205-2005, “Recommended Practice for the Design,
Fabrication, and Inspection of Tanks for the Storage of Petroleum
Refining Alkylation Unit Spent Sulfuric Acid at Ambient Temperature”
- ANSI/AWS Z49-1, “Safety in Welding and Cutting and Allied
Section 3: Definitions
A definition for “door sheet” has been added. It is a plate (or plates)
cut from the tank shell to create a temporary access opening. It is to be
reinstalled or replaced after work is complete.
Section 4: Suitability for Service
- Para. 22.214.171.124 has been changed to require that the effects of
partial vacuum be evaluated per API 650 Appendix V instead of API 620.
API 620 was previously used as the evaluation basis before Appendix V
was added to API 650.
- Para. 4.3.8 clarifies that the condition of tank shell welds shall
be evaluated using criteria contained in API 653, the as-built
standard, or by performing a fitness-for-service assessment.
- Paras. 126.96.36.199 and 188.8.131.52 clarifies that the required annular
plate thickness from the referenced table in API 650 may be determined
from interpolation using the calculated shell stress.
Section 6: Inspection
Significant changes were made to Para. 6.4.2 covering internal inspection
intervals in Addendum 1 and again in Addendum 2.
- For existing tanks, tank owner/operators shall review the internal
inspection interval and be in compliance with
this section within 5 years from the date of first publication
(Fourth Edition, Addendum 2, January 2012). This answers that commonly
- Initial and subsequent internal inspection intervals may be
determined considering any leak prevention, detection, corrosion
mitigation, or leak containment safeguards incorporated in the tank
design and installation. For example, the initial inspection interval
may be longer if an internal lining or cathodic protection system is
installed. An example contained in API 653 shows that the maximum
initial inspection interval for a 1/4 in. bottom with a fiberglass
lining and release prevention barrier is 25 years. Refer to API 653
- Para. 6.4.2 also permits initial and subsequent internal
inspection intervals to be determined using RBI procedures per API RP
580 and additional requirements contained in API 653 considering
likelihood and consequence factors. Refer to API 653 for details.
Section 9: Tank Repair and Alteration
- Para. 9.2.4, Door Sheet Installation. This is a new paragraph,
hence the need to define what a “door sheet” is in Section 3. It has
seven sub-paragraphs and four new figures associated with it. Details
are provided for door sheets made in riveted seam tanks, lap welded
seam tanks, and butt welded seam tanks (e.g., minimum spacing required
between new door sheet welds and existing shell seams). Before
Addendum 2, API 653 did not have any detail requirements specifically
for door sheets.
- Para. 184.108.40.206g is new. It defines minimum weld spacing
requirements for when a tombstone bottom patch plate is installed in
the critical zone if the tank shell plate is of unknown toughness.
This is also addressed in Figure 9.13.
Section 13: Marking and Recordkeeping
Para. 13.1.2 is new and provides nameplate requirements for tanks that
currently do not have nameplates. Two situations are covered:
- Replacement Nameplate. Information required by the as built
standard to complete the nameplate is available and traceable to the
- Assessment Nameplate. Information required by the as built
standard to complete the nameplate is not available. In this case,
information that was used in the assessment of the tank for its
suitability must be identified.
Refer to API 653 for details.
Annex F: NDE Requirements Summary
Para. F.2.3 has been modified to require the examiner’s employer to
determine and certify that each visual examiner meets API 650
Annex X: Duplex Stainless Steel Storage Tanks
Added to correspond to tanks constructed per API 650, Appendix X.