Shop-Fabricated Tank Inspection

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Shop-Fabricated Tank Inspection

• Chris Bashor
• Minnesota Pollution Control Agency
• June, 2001

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Shop-Fabricated Tank Inspection

• History of States-EPA Workgroup Interest
• STI Standard SP001-00
• Comparison with API 653
• Relevance of SP001-00 to States and EPA
• Issues
• Conclusions

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History of States-EPA Workgroup Interest

• EPA identifies SPCC need no industry standard
  for inspection of small tanks
• Steel Tank Institute develops draft standard
• Workgroup reviews draft standard at May 2000
  meeting and submits comments
• Final STI standard September 2000

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STI Standard SP001-00

• Steel Tank Institute
• Applicability
• Periodic inspections
• Certified inspections

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Steel Tank Institute

• www.steeltank.com
• Contact Dana Schmidt 847-438-8265
• Paper copies available for 35
• Electronic version was emailed to states

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Applicability

• Shop-fabricated ASTs (up to 50,000 gal)
• Built to national standard (e.g. UL142)
• Storage of noncorrosive, stable, flammable, and
  combustible liquids having specific gravity not
  exceeding that of water
• Includes foundation and vents, but not piping

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Applicability (cont)

• Can be used for double-walled tanks
• Elevated or not, horizontal or vertical, manway
  or not
• MN believes standard is applicable for the most
  part to tanks of these types storing most other
  liquids, even if non-standard construction
• Corrosive liquids need special attention

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Periodic Inspections

• Qualifications owner or any employee (no
  training)
• Monthly water draw DW interstitial space pipe
  connections
• Quarterly walk-around for damage, external
  coating, cleaning, repairs, vents

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Periodic Inspections (cont)

• Annually proper drainage, foundation
• Other recordkeeping checklists, diagrams,
  maintenance info, references

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Certified Inspections

• Qualifications
• API 653 certified
• STI certified
• Frequency every 10 years, or more often based
  on calculated minimum remaining wall thickness

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Certified Inspections (cont.)

• Procedures
• All visual per periodic checklists
• Pressure test for tightness
• Shell inspection

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Certified Inspections (cont.)

• Shell inspection methods depend on whether tank
  is single or double-walled, elevated or not, has
  manway or not, has cathodic system or not
• Procedures include
• Ultrasonic thickness testing (criteria given)
• Visual inspection (minimal criteria given)
• ASTM G 158
• NACE RP-0285

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Comparison with API 653

• In general, SP001-00 is much less rigorous
• No standards for repairs or alterations
• No provisions for upgrading non-UL142 to
  acceptable condition
• All in all, however, generally appropriate to
  level of risk involved

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Relevance of SP001-00 to States and EPA

• Minnesota
• Other states
• EPA

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Minnesota

• SF tanks at small facilities
• Rules require equivalent of periodic but not
  certified
• Rule change would be needed for certified
• SF tanks at major facilities
• Permits do not now require inspection of SF tanks
• Re-permitting will require SP001-00 starting 2001

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Minnesota

• Enhancements to SP001-00 to be required
• Walk-around inspection monthly
• Periodic records kept for three years, certified
  report kept for life of tank
• Records and reports must document repairs needed
  and made
• Repairs recommended must be made unless waived
• Certified report must include UT and other data

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Minnesota

• So far, no facilities seem to be using SP001-00
• Owners waiting for state/federal requirement?
• Some consultants now use API 653 for SF tanks
• Consultants who are API 653 certified will be in
  a position to offer lower cost SP001-00 certified
  inspections

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Other States

• Wisconsin
• Working with STI to offer inspector certification
• Pennsylvania
• Has its own integrity inspection criteria
• Other states?

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EPA

• Current SPCC requires periodic integrity
  testing, gives examples of visual and N-D shell
  thickness (UT) testing (112.7(e)(2)(vi))
• SPCC revisions (when final) will be more specific
  about frequency and technique, and will
  specifically refer to SP001-00

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Issues

• Standard has weaknesses
• Availability of qualified inspectors
• How to get the owner into the program
• How to get that first certified inspection

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Conclusions

• On the whole, SP001-00 should prove valuable
• States and EPA can jointly have a positive
  influence on industry standards, e.g. STI, API
  (new RBI standard), Fertilizer Institute
• Would like to see more partnering with industry
  groups on AST standards, especially with API