STI-SP001 Tank Inspection

STI-SP001 Tank Inspection Overview

STI-SP001 is a standard developed by the Steel Tank Institute (STI) for the inspection of aboveground storage tanks (ASTs). It provides guidelines for inspecting, maintaining, and ensuring the integrity of tanks used for storing hazardous and non-hazardous liquids.

Why is STI-SP001 Used?

Ensures compliance with industry regulations and environmental laws.
Helps detect corrosion, leaks, and structural issues before failure occurs.
Reduces the risk of spills and contamination.
Extends the lifespan of storage tanks.
Required for EPA Spill Prevention, Control, and Countermeasure (SPCC) plans.

Types of Tanks Inspected Under STI-SP001

Tank Types:

Shop-fabricated tanks (cylindrical, rectangular, horizontal, or vertical).
Field-erected small tanks (typically under 75,000 gallons).
Portable containers (55-gallon drums, totes, IBCs).
Double-walled tanks with interstitial monitoring.
Vaulted tanks and secondary containment units.

Components Inspected in STI-SP001 Tank Inspections

Tank Exterior Inspection:

Shell & walls: Check for corrosion, cracks, or deformations.
Tank bottom: Inspect for leaks or deterioration (if visible).
Roof & manways: Look for damage, corrosion, or loose fittings.
Supports & foundation: Ensure stability, no settling, or cracks.
Weld seams & joints: Check for signs of wear or leaks.
Appurtenances: Inspect the condition of electrical connections, vents, fittings, ladders, and fasteners. Look for and document any hazards.
Coatings & paint: Assess for deterioration or rust.

Tank Interior Inspection (if required):

Liner condition: Inspect for cracks, blisters, or leaks.
Internal corrosion: Evaluate metal surfaces and welds.
Sediment & sludge buildup: Determine if cleaning is necessary.

Piping & Fittings Inspection:

Valves & connections: Check for leaks, corrosion, and proper operation.
Vents & overfill prevention: Ensure proper function and no blockages.
Secondary containment: Verify effectiveness and integrity.
Leak detection systems: Confirm operation and sensor accuracy.

Safety & Compliance Checks:

Spill control measures: Ensure dikes, berms, or spill kits are in place.
Tank labels & markings: Verify correct labeling and signage.
Cathodic protection: Check sacrificial anodes or impressed current systems.
Testing records & documentation: Ensure logs are updated and available.

Detailed Breakdown of STI-SP001 Tank Inspection Procedures

STI-SP001 provides structured inspection procedures based on tank size, type, and risk factors. The inspections are categorized into Periodic, Formal External, and Formal Internal inspections.

1. Periodic Inspection (Monthly or As Required)

These inspections are visual and operational checks which are typically completed by the tank owner/operator. Contact us if you would like to schedule routine inspection service on your behalf.

Tank Exterior:

Check for visible corrosion, cracks, dents, or bulging.
Inspect for leaks or unusual stains on the tank surface or foundation.
Ensure paint and coatings are intact and free from peeling.
Confirm the tank is level (no tilting or settlement).

Piping & Valves:

Look for leaks at joints, valves, and connections.
Verify flexible hoses are in good condition (no cracks, bulges, or leaks).
Ensure supports and brackets are secure.

Secondary Containment:

Check for water accumulation or product leakage inside dikes or barriers.
Verify drain valves (if present) are properly closed.

Spill & Leak Prevention:

Brief review of overfill prevention devices.
Ensure vents are adequately sized, clear and not obstructed.
Assess leak detection systems (if present)

Documentation & Signage:

Review inspection records.
Inspect warning labels and signage are visible and compliant.

2. Formal External Inspection (Every 5-20 years or as Required)

A more detailed external inspection, typically performed by a certified inspector, includes visual and non-destructive testing (NDT) methods.
Tank Shell, Roof & Bottom (if visible):

Use ultrasonic thickness testing (UTT) to measure wall thickness.
Look for weld seam failures or cracks.
Examine roof integrity, including any domes or floating roofs.
Inspect bottom edge and chime area for corrosion.

Piping, Valves & Fittings:

Conduct pressure testing if required.
Verify secondary containment system functionality.
Inspect gaskets, flanges, and seals for deterioration.

Cathodic Protection & Coatings:

*May additionally require a Certified Cathodic Protection specialist

Check the function of sacrificial anodes or impressed current systems.
Assess coatings and reapply as needed to prevent corrosion.

Environmental & Safety Compliance:

Confirm the presence of a Spill Prevention, Control, and Countermeasure (SPCC) plan and review processes and procedures for monthly, annual inspections have been adhered to.

3. Formal Internal Inspection (As Required)

For tanks with higher risk factors (e.g., single-walled tanks in contact with the ground, high corrosion potential), an internal inspection may be needed. This requires draining the tank and conducting an in-depth evaluation.
Tank Interior (Shell, Roof, & Bottom):

Conduct testing to determine integrity.
Inspect for internal corrosion, pitting, or scaling.
Evaluate liner conditions (if present).

Structural & Mechanical Integrity:

Assess weld quality and check for stress fractures.
Measure steel thickness to determine material loss over time.
Verify any coatings or epoxy linings inside the tank are intact.

Leak Detection & Secondary Containment:

Test interstitial space monitoring for double-walled tanks.
Ensure leak detection sensors are functioning correctly.

Conclusion

The STI-SP001 protocol is essential for ensuring that aboveground storage tanks stay safe, compliant, and reliable. By following the inspection guidelines, tank operators can prevent failures, meet regulations, and extend the life of their tanks. Regular inspections of the tank’s shell, floor, roof, foundation, and other components are key to maintaining a secure and efficient storage facility. Whether the tank is large or small, made from steel or fiberglass, or used for hazardous or non-hazardous materials, regular checks are vital for ongoing safety and environmental protection.

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