Internal Tank Lining Requirements – Revised July 1, 2006

Introduction:

Steel tanks that were internally lined (without the addition of cathodic protection systems) to meet the EPA December 1998 corrosion protection upgrade requirement have significantly higher percentages of failure, compared to steel tanks that used cathodic protection as the sole method of corrosion protection. Most of these lined tanks are “not still performing in accordance with original design specifications” (CFR 280.21) when the internal inspections are completed. Tank owners must ensure that repairs will prevent releases due to structural failure or corrosion. It should be noted that the EPA allowed internal lining as a temporary upgrade, to extend the life of a bare steel tank at least 10 years. If cathodic protection was added at the same time, or within 10 years of the lining date, then internal inspections were not required.

  1. Underground storage tanks that have not met the 1998 upgrade requirements may not use tank lining as a means of corrosion protection. Tank lining is not allowed as a method of repair on existing tanks previously protected from corrosion. According to EPA regulations, any tank installed after 12-22-88 cannot use internal tank lining (because any tank installed after that date must meet new tank requirements and lining is not an option for meeting the corrosion protection requirements under the new tank requirements).
  1. USTs upgraded by the addition of both internal lining and cathodic protection either at the same time, or by adding CP within 10 years of lining, do not require internal inspections if the cathodic protection system has been properly installed and maintained on the UST system.
  1. A lined steel tank that fails precision tightness testing may not be repaired and must be removed. The structure of the tank has failed due to corrosion; it must be taken out of service and permanently closed. Immediately remove the tank from service, pump out fuel to within 1” of the tank bottom, and report to the OCC within 24 hours.

4.Within 10 years after lining, and every five years thereafter, lined USTs must be internally inspected and found to be structurally sound with the lining still performing in accordance with original design specifications. The tank must first pass a precision tightness test of both the wetted and non-wetted portions of the tank.

→Notify OCC at least 48 hours prior to any lining activity.←

  • The tank must be prepared according to API 1631, Interior Lining and Periodic Inspection of Underground Storage Tanks (emptied, rendered vapor free) to ensure entry can be made safely. Provide the confined space entry form with OCC form following inspection.
  • The inspector visually inspects the tank lining for evidence of wrinkled surface or surface roughening. Only these minor imperfections in the lining can be repaired in accordance with the lining manufacturer specifications. Evidence of peeling, separation, blistering, or delamination indicate that the lining has lost adhesion. Obvious corrosion activity including perforations, rust, streaks, discolorations, pitting, scaling, weld deterioration, cracks near welds, general overall rust film or any sign of structural instability will fail a tank lining. While a tank is in its designated service, the lining must maintain bond to the tank for the period of the tank lining warranty (or at least 10 years).
  • Testing of the tank lining and tank metal thickness measurements shall be collected in accordance with API 1631 and NLPA 631, Chapter B. Criteria for pass and fail for average tank metal thickness are listed on the OCC form. Provide all measurements collected on the appropriate forms. If average metal thickness is 75% or less of the original thickness, the tank must be removed. Complete the certificate of performance (Internal Lining Inspection Form) and submit to the OCC within 30 days.

Internal Tank Lining Requirements

  • If the original tank metal thickness is at least 85%, and tank lining passes inspection without minor repairs, the tank will require another physical manned entry after five years.
  • If the tank lining requires minor repairs only and the steel is greater than 75% of original thickness, cathodic protection must be added to the tanks within 6 months.
  • Assess the suitability of a lined steel tank for upgrading with cathodic protection using a corrosion assessment test in accordance with accepted industry standard or practice. Complete the preliminary site survey, on-site field tests, laboratory testing, and data analysis according to ASTM G-158-98. Laboratory testing must also include hydrocarbon analysis specific to all past stored product (BTEX and TPH). If analyses exceed OCC action levels for BTEX constituents or TPH, results must be reported within 24 hours, and pre-approval for addition of cathodic protection must be requested.
  • Test the tanks after tank lining inspection and certify the CP system three to six months following installation.
  • Maintain all records for inspections, lining, repairs, suitability study, CP design and calculations, materials list, site drawing, system test results and certifications for the life of your tanks.

Please address any questions you may have concerning this guidance document to the OCC Petroleum Storage Tank Compliance and Inspection Department at (405) 521-2487.

Revised 07-2006