What Tank Owners Need to Know When Using SP031

What is SP031?

SP031 is the Standard for Repair of Shop-fabricated Aboveground Tanks for Storage of Flammable and Combustible Liquids. It provides a process for repairing or modifying certain atmospheric, shop-fabricated carbon and stainless steel tanks. The standard addresses work that may be needed after an inspection identifies corrosion, physical damage, or another condition affecting the tank.

SP031 can help return a tank to service when the proposed work falls within its scope and the repair is properly inspected, performed, tested, and documented. It does not provide a repair method for every type of tank or every form of damage.

How do SP001 and SP031 work together?

An inspection is often what brings the need for a repair to light. STI SP001 provides criteria for inspecting aboveground storage tanks and evaluating their suitability for continued service. When an inspection identifies a condition that requires repair, SP031 may provide the appropriate process for completing that work on a shop-fabricated tank.

The two standards serve different purposes: inspection establishes the tank’s condition and identifies what needs attention; the repair process addresses eligible damage or modifications. Owners should retain the inspection findings so the people planning and performing the repair can understand the full scope of the work.

When might SP031 be used?

SP031 may be appropriate for work such as repairing interior or exterior corrosion damage, addressing minor physical damage to a tank shell, replacing limited areas of material, or making certain modifications for a change in operation. The appropriate method depends on the tank’s original construction, its condition, the location and extent of damage, and the requirements of the current standard.

For example, a shell repair may involve welding, a patch, or material replacement. The repair must use suitable materials and qualified personnel, and the location and shape of a patch matter. Damage near a formed tank end, sometimes called the knuckle area, has particular repair limits because excessive cutting or welding there can affect the material. If damage exceeds those limits, replacing the tank end may be necessary.

An inspection finding does not, by itself, establish that a tank can be repaired under SP031. The owner should first determine the full extent of the work and confirm that the tank and proposed repair are within the standard’s scope.

What should a tank owner do before authorizing a repair?

Identify how the tank was built

Locate the tank’s nameplate or certification label, original construction information, and available records. The construction standard is a starting point for selecting an appropriate repair approach. Protect the certification label during the work and retain it with the tank’s records.

Have the entire tank assessed

Damage discovered during an inspection may be only part of the problem. A qualified inspector should assess the entire tank and identify all conditions requiring attention before the repair scope is set. This helps the owner evaluate the likely cost and decide whether repair or replacement is more practical.

Preparing a tank for repair can be a substantial part of the cost. Finding additional damage after work begins may change the scope, schedule, and cost of the project. A complete assessment gives the owner a better basis for making the repair decision.

Confirm that SP031 applies

SP031 has limits. Fire damage, damage from a natural disaster, excessive settlement, overpressure, cracking, and major changes to a tank may require an approach outside its ordinary repair provisions. A qualified tank builder or professional engineer may be able to address some conditions beyond that scope, in consultation with the authority having jurisdiction, or AHJ.

Some tank designs, including certain protected or insulated tanks, may require information or involvement from the original manufacturer. The owner should establish the appropriate path before work begins rather than assume that a repair method suitable for one shop-fabricated tank applies to another.

Agree on a repair and testing plan

The plan should identify the work to be performed, qualified personnel, compatible materials, inspections, and tests required after the repair. It should also account for any requirements of the tank’s original construction standard and the AHJ. Establishing the testing approach before work begins helps avoid uncertainty when the repair is complete.

Does repairing a listed tank preserve its original certification?

A repair or modification can affect the status of a tank’s original certification. The label identifies how the tank was constructed; it should not be treated as automatic approval of later work. Tank owners should understand the implications of a proposed repair, keep the supporting documentation, and address any approvals required by the AHJ.

What happens after the repair?

The repaired areas must be inspected and tested as applicable. The type and extent of testing depend on the work performed. Significant repairs may call for an integrity test of the entire tank based on its original construction standard. The results should be documented, including any test performed and its outcome.

The owner’s repair file should include the inspection findings or reason for modification, the original tank information, the SP031 repair or modification report, a description of the completed work, personnel qualifications, inspection and test results, and any required AHJ approvals. Depending on the circumstances, an updated inspection report should also determine whether the tank is suitable for service.

These records matter beyond the immediate repair. They give future inspectors and tank owners a history of what changed, how the work was evaluated, and the basis for returning the tank to service.

What is the most common mistake when using SP031?

Beginning work before understanding the whole tank, the full repair scope, and the applicable requirements. An incomplete assessment can leave damage unaddressed, lead to work outside the standard’s scope, or result in missing tests and documentation. Establishing those details at the outset also gives the owner a sound basis for comparing repair with replacement.