Steel Tank Institute Inspection: The SP-001

Do you have a shop-manufactured storage tank under 30 feet in diameter? If so, your tank likely falls under the Steel Tank Institute inspection guidelines for storage tanks. The SPCC mandates that all tanks that contain petroleum and other hazardous liquids must be inspected, and the most commonly used code for these inspections is the SP-001. Today we’re discussing what you can expect from an SP-001 inspection, so that you can fully prepare yourself, your facility, and your employees for the evaluation.

Steel Tank Institute (STI) Inspection

The SP-001

The code for the SP-001 Steel Tank Institute inspection program is written and maintained by the STI, and it includes inspection intervals, requirements, and information regarding the acceptance of the results. The SP-001 code also includes sections regarding tank repairs, which you can use as necessary. Remember that all inspection reports and repair documents must be kept on file for the life of your storage tank.

There are two categories of inspections in accordance with the SP-001:

• Periodic Inspections:
  • Periodic inspections are performed by client-trained personnel.
  • They are usually performed daily, monthly, and yearly.
  • The monthly and yearly periodic inspections should be conducted in accordance with the code checklist and kept on file for the life of the tank.
• Formal Inspections:
  • Formal inspections are performed by STI-certified inspectors.
  • The intervals for these inspections depend on the size and type of the secondary containment.

Formal Baseline Inspection

A formal baseline inspection should be performed within the first five years that the tank is in service. This inspection is used to obtain the floor and shell plate thicknesses for future long-term, short-term, and remaining life calculations.

If the tank is in contact with the ground (i.e., a flat-bottom, vertical tank), it will need to be opened up and cleaned. It will also need to undergo an internal inspection. The floor plates cannot have any product, water, or rust on them, as this would interfere with the MFL and visual inspection of the floor plates.

• Internal & External Visual Inspection (VT) performed by an STI-certified inspector. The SPI-001 includes a visual checklist, and it is recommended that inspectors follow this checklist when performing a VT inspection. The inspection should include the following components:
  • Secondary containment (i.e. dikes)
  • Foundation
  • Shell (internal and external). This includes out-of-roundness and bulge inspection.
  • Floor plating (internal)
  • Nozzles (internal and external)
  • Roof (internal and external)
  • Sumps and internal piping
  • Ancillary equipment (i.e. gauge levels)
• Ultrasonic Thickness Testing (UTT) Inspection performed by trained personnel in accordance with SP-001 requirements. The following components are typically examined during this evaluation:
  • Internal floor
  • Shell (internal or external)
  • Nozzles

Additional roof inspections may be required depending on the results of the initial inspections (i.e. Magnetic Particle (MT) on the welds).

Finally, when all is said and done, a final report should be completed showing all of the inspection results and recommendations. This report should be reviewed by a client-approved engineer to determine if the tank is suitable for continued service.

2^nd Formal Baseline Inspection

A second formal inspection should be performed in accordance with the SP-001. Evaluations that are typically performed during this inspection include:

• Internal & External Visual Inspection (VT) performed by an STI-certified inspector. The SP-001 includes a visual checklist that inspectors are urged to follow when performing this inspection. The VT inspection includes all of the following components:
  • Secondary containment (i.e. dikes)
  • Foundation
  • Shell (internal and external). This includes out-of-roundness and bulge inspection.
  • Floor plating (internal)
  • Nozzles (internal and external)
  • Roof (internal and external)
  • Sumps and internal piping
  • Ancillary equipment (i.e. gauge levels)
• Ultrasonic Thickness Testing (UTT) Inspection performed by trained personnel in accordance with SP-001 requirements. The following components are typically examined during this evaluation:
  • Internal floor
  • Shell (internal or external)
  • Nozzles
  • Roof

Additional inspections may be required depending on the results of the initial inspections (i.e. Magnetic Particle (MT) on the welds).

When the evaluation has been completed, a final report must be composed showing all of the inspection results and recommendations. This report should communicate short- and long-term corrosion rates as well as a remaining life calculation. In addition, it must be reviewed by a client-approved engineer to determine if the tank is suitable for continued service.

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Is your storage tank due for a check-up? If so, contact Environmental Works, a full-service environmental consulting and contracting firm. With our many years of experience managing major environmental projects, you can feel comfortable trusting us with your storage tank needs. We can provide the Steel Tank Institute inspection (SP-001) and the API-653 inspection, as well as tank cleaning and confined space entry. To learn more about our services, please give us a call at 417-890-9500 or contact us online.