Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
API RP 1615-2011: Installation of Underground Petroleum Storage Systems – A Comprehensive Technical Overview
Key Requirements, Compliance Considerations, and Best Practices for UST Installation
Scope of API RP 1615-2011
API Recommended Practice 1615 (API RP 1615-2011) provides comprehensive guidance for the installation of underground petroleum storage systems (USTs). It covers new installations and the replacement of existing tanks, piping, and ancillary equipment used in the storage of flammable and combustible liquids at retail, commercial, and industrial facilities. The recommended practice addresses all critical phases from site preparation through final system commissioning, including handling of tank materials, corrosion protection, leak detection, spill containment, and overfill prevention.
Applicability
This document applies to underground storage systems storing Class I, II, or III petroleum liquids as defined by NFPA 30 and API RP 1604. It includes steel and fiberglass-reinforced plastic (FRP) tanks, metallic and flexible piping, cathodic protection systems, and secondary containment. While primarily focused on new installations, many of its provisions also serve as a benchmark for evaluating existing systems during upgrades.
Key Objectives
The primary goals of API RP 1615-2011 are to ensure long-term integrity of the storage system, prevent releases to the environment, and align with evolving regulatory expectations (e.g., U.S. EPA underground storage tank regulations). It emphasizes a risk-based approach that balances reliability, cost-effectiveness, and environmental stewardship.
Tip: API RP 1615 is frequently referenced by local and state authorities as a code of practice. Designers and installers should confirm whether it is adopted by reference in their jurisdiction and whether any amendments apply.
Technical Requirements and Recommendations
Below is a summary of critical technical elements covered in API RP 1615-2011.
| Component | Key Requirement | Reference Section |
|---|---|---|
| Tanks (steel) | Coatings, cathodic protection, and dielectric isolation; comply with API 650 or UL 58/1746 | Sections 5.1–5.3 |
| Tanks (FRP) | Provide structural integrity per manufacturer specs; UV protection during storage | Section 5.4 |
| Piping (metallic) | Corrosion protection (coating + cathodic protection) or replace with nonmetallic | Sections 6.1–6.2 |
| Piping (flexible) | Listed/tested for underground use; secondary containment where required | Section 6.3 |
| Cathodic protection | Impressed current or galvanic anodes; test stations installed; design life ≥ 30 years | Section 5.3.2 |
| Leak detection | Automatic tank gauging, interstitial monitoring, or continuous in-tank monitoring per EPA requirements | Section 9 |
| Spill containment | Spill buckets at each fill point; capacity ≥ 5 gallons (19 L) | Section 8.1 |
| Overfill prevention | Automatic shut-off or high-level alarm per API RP 2350 | Section 8.2 |
Corrosion Protection Systems
Metallic components require both coating and cathodic protection. API RP 1615-2011 specifies minimum coating resistivity and bond strength, and requires that the cathodic protection system be designed to maintain a protective potential at all coated surfaces. For impressed current systems, remote monitoring capabilities are recommended. The practice also stresses proper electrical isolation to prevent stray current interference.
Caution: Inadequate dielectric isolation between the tank and piping is one of the most common installation errors. Failure to install isolating unions or bushings can compromise cathodic protection and accelerate corrosion.
Leak Detection and Monitoring
The recommended practice outlines several leak detection methodologies for both tanks and piping. For pressurized piping, annual line leak tests (e.g., with a 3 gph/11.4 Lph detection threshold) are required unless the system is equipped with continuous electronic monitoring. For suction piping, periodic tightness testing (0.1 gph/0.38 Lph) is acceptable. Secondary containment piping (double-wall) must be monitored monthly for interstitial dryness.
Installation Procedures
Site preparation, backfill, bedding, and load distribution are addressed in detail. API RP 1615-2011 calls for a minimum of 6 inches of compacted sand or gravel below the tank bottom, and use of a structurally compatible backfill material. Excavation must be dewatered to prevent tank floatation, and all piping must be tested to 1.5 times design pressure before cover.
Implementation Highlights
Successful implementation of API RP 1615-2011 requires careful coordination between engineers, contractors, and regulators. The following areas deserve special attention.
Coordinating with Regulatory Requirements
In the United States, the EPA’s 2015 UST regulations align closely with API RP 1615-2011. Installers should verify that their installation plan meets or exceeds both the recommended practice and any state-specific requirements (e.g., California’s SWRCB provisions). For operations outside the U.S., local environmental agencies may reference API RP 1615 as a baseline for best available technology.
Quality Assurance and Testing
The standard emphasizes the installer’s responsibility for quality control. This includes visual inspections of tanks, coatings, and fittings prior to lowering; pressure testing of piping (both primary and secondary containment); and verification of cathodic protection potential at least 30 days after system energization.
Best Practice: Maintain a complete installation log that includes test results, as-built drawings, anode placement records, and manufacturer warranties. This documentation is invaluable for future maintenance and regulatory audits.
Compliance Notes
Regulatory Adoption and Enforcement
API RP 1615-2011 is not a law itself but is frequently adopted by reference in building codes, fire safety codes, and environmental regulations. For example, many U.S. states require UST installations to be performed “in accordance with API RP 1615.” In such jurisdictions, failure to follow its provisions can result in fines, corrective action orders, and liability for environmental releases.
Critical: An installation that does not meet the cathodic protection criteria of API RP 1615 may void tank manufacturer warranties and expose the owner to premature tank failure and costly cleanup.
Training and Competency
The recommended practice states that all personnel involved in UST installation should be trained and experienced in the specific tasks they perform. Operators should hold current certifications (e.g., PEI RP 200, API 653, or state-specific UST installer licenses). Periodic refresher training is recommended to stay current with evolving technology and regulatory changes.
Q: What is the scope of API RP 1615-2011?
A: It covers all technical aspects of installing underground storage systems for petroleum products, including site preparation, tank and piping materials, corrosion protection, leak detection, spill containment, overfill prevention, and testing.
A: It covers all technical aspects of installing underground storage systems for petroleum products, including site preparation, tank and piping materials, corrosion protection, leak detection, spill containment, overfill prevention, and testing.
Q: Does API RP 1615 require cathodic protection for fiberglass tanks?
A: No. The corrosion protection requirements in API RP 1615-2011 apply only to metallic components (steel tanks, metal piping, fittings). FRP tanks do not require cathodic protection, but must be installed per manufacturer instructions to avoid structural damage.
A: No. The corrosion protection requirements in API RP 1615-2011 apply only to metallic components (steel tanks, metal piping, fittings). FRP tanks do not require cathodic protection, but must be installed per manufacturer instructions to avoid structural damage.
Q: How does API RP 1615 relate to EPA UST regulations?
A: Many of the technical requirements in API RP 1615-2011 align with or are more stringent than the EPA’s 2015 UST standards. Following the recommended practice helps ensure compliance with the operator, equipment, and release detection requirements.
A: Many of the technical requirements in API RP 1615-2011 align with or are more stringent than the EPA’s 2015 UST standards. Following the recommended practice helps ensure compliance with the operator, equipment, and release detection requirements.
Q: Is API RP 1615-2011 still current?
A: As of 2026, API RP 1615-2011 is the latest edition. It was reaffirmed by API in 2021. Users should always check the API website for the most current version or any addenda. New editions are typically published every 10–15 years.
A: As of 2026, API RP 1615-2011 is the latest edition. It was reaffirmed by API in 2021. Users should always check the API website for the most current version or any addenda. New editions are typically published every 10–15 years.