AF Form 1686: Cathodic Protection Operating Log – AF Form 1686 serves as the official Cathodic Protection Operating Log for Sacrificial Anode System (Not LRA) used by the U.S. Air Force. It documents routine monitoring and maintenance of galvanic (sacrificial anode) cathodic protection systems that safeguard buried or submerged metallic structures—such as underground storage tanks (USTs), pipelines, and related infrastructure—from corrosion.
This form ensures compliance with Air Force corrosion control programs, helps prevent environmental releases from fuel systems, and supports long-term asset integrity at U.S. military installations.
What Is Cathodic Protection and Why Use Sacrificial Anode Systems?
Cathodic protection (CP) is an electrochemical technique that prevents corrosion of metal structures by making them the cathode in a corrosion cell. In sacrificial anode (galvanic) systems, more active metals—like magnesium, zinc, or aluminum alloys—act as anodes. These “sacrifice” themselves by corroding preferentially, supplying protective current to the structure (cathode) through the surrounding electrolyte (soil or water).
Sacrificial anode systems suit low-current-demand applications, such as well-coated underground fuel tanks or short pipelines. They require no external power source (unlike impressed current systems), making them simple, reliable, and cost-effective for many Air Force facilities. Common anodes include high-potential magnesium for higher driving voltage in various soil resistivities.
Air Force policy mandates cathodic protection—combined with protective coatings—for all metallic fuel storage tanks (including USTs and associated piping) in contact with soil, as well as other structures containing flammable, combustible, or regulated products. This requirement helps comply with environmental regulations and reduces life-cycle costs by minimizing leaks and repairs.
Purpose of AF Form 1686
The form provides a standardized log for recording periodic checks on sacrificial anode CP systems. It captures key performance data to verify that the system delivers adequate protection, tracks anode consumption trends, and supports troubleshooting or replacement decisions.
Key benefits include:
- Demonstrating compliance with DAFI 32-1001 (Civil Engineer Operations) and AFI 32-1054 (Corrosion Control, or its current successor).
- Supporting annual galvanic anode checks and broader corrosion control programs.
- Providing historical data for infrastructure management, failure analysis, and budgeting for anode replacements.
- Aligning with Unified Facilities Criteria (UFC) 3-570-06, Operation and Maintenance: Cathodic Protection Systems, which includes sample completed versions of AF Form 1686.
Note: The form is marked “Not LRA” (Local Reproduction Authorized is not permitted). Always use the official version from Air Force e-Publishing.
How to Download the Official AF Form 1686?
You can download the current PDF directly from the official source:
AF Form 1686 PDF
This is the authoritative version for U.S. Air Force personnel. Use it for all official logging at installations.
Key Fields and How to Complete AF Form 1686
While exact block layouts appear in the PDF and UFC 3-570-06 (Appendix C provides item descriptions and sample completed forms), typical entries include:
- Header Information: Installation/base, structure or system identification (e.g., tank number, pipeline segment), location, date of installation, and anode type/material.
- Identification Blocks: Reference electrode type (usually copper/copper sulfate), test station details, and system specifics.
- Operating Record (Core Log Section): Date of reading, structure-to-soil potential (ON and/or instant-off if applicable), anode output or current measurements, remarks on conditions (e.g., soil moisture, any anomalies), and technician initials/signature.
- Additional Data: Notes on anode condition, any corrective actions, or references to related forms like AF Form 1687 (Leak/Failure Data Record) or AF Form 1688 (Annual Cathodic Protection Performance Survey).
Frequency: Perform galvanic anode checks annually (or as specified in local operating instructions) and document on AF Form 1686. More frequent monitoring may occur based on risk or historical performance.
Best Practices for Entries:
- Use calibrated equipment (e.g., voltmeter and copper/copper sulfate reference cell).
- Record “ON” potentials and, where possible, instant-off readings to assess true polarization (IR-drop free).
- Note any deviations from protection criteria (e.g., -850 mV CSE for steel structures per NACE standards referenced in UFC guidance).
- Maintain records on file for the specific CP system to support audits, troubleshooting, and life-cycle planning.
UFC 3-570-06 provides detailed tables describing each item on the form and sample entries for the operating record section.
Integration with Broader Air Force Corrosion Control
AF Form 1686 fits into the Air Force’s comprehensive corrosion prevention program:
- Pair it with impressed current logs (e.g., AF Form 491) where both system types exist.
- Use data for annual performance surveys and leak/failure tracking.
- Forward significant issues to the Base Civil Engineer (BCE) or corrosion control team.
- Reference DAFI 32-1001 for infrastructure corrosion control responsibilities and UFC 3-570-06 for detailed O&M procedures.
Proper use of this form helps protect critical infrastructure, reduce environmental risks from fuel leaks, and demonstrate due diligence in corrosion management.
Tips for USAF Personnel and Contractors
- Train technicians on proper CP testing techniques, including reference cell placement (e.g., directly over tanks every few feet).
- Integrate form data into digital maintenance systems where possible, while retaining the official paper or scanned record.
- Schedule checks during routine facility inspections to ensure consistency.
- Consult installation-specific operating instructions or the electrical Systems Asset Manager (SAM) for local requirements.
For full guidance, review the latest versions of:
- DAFI 32-1001
- UFC 3-570-06 (includes Air Force-specific appendices with form samples)
- AF e-Publishing for the most current form
Download AF Form 1686 here: Official PDF Link
Maintaining accurate cathodic protection logs protects assets, ensures regulatory compliance, and supports mission readiness across U.S. Air Force installations. If you manage CP systems, establish a clear process for completing and reviewing AF Form 1686 as part of your corrosion control program.
For questions specific to your installation, contact your local Civil Engineer squadron or corrosion control specialist.