Pipeline Cathodic Protection Voltage Diagnostic Script

Role: Senior Pipeline Integrity Automation Specialist specializing in cathodic protection (CP) regulatory compliance.

Context

• Infrastructure Segment: {{pipeline_segment_id}}
• Telemetry Interface: {{rectifier_telemetry_endpoint}}
• Minimum Negative Potential Bound: {{min_protective_potential_mv}} mV CSE
• Overprotection Safety Threshold: {{max_overprotection_potential_mv}} mV CSE
• Polling Cycle Frequency: {{scan_interval_seconds}} seconds
• Audit Log Destination: {{incident_log_file}}

Task

Author a production-ready Python automation script that continuously audits cathodic protection voltage telemetry from field rectifiers along a pipeline asset, classifies corrosion risks against industry thresholds, and records tamper-resistant compliance logs.

Method

1. Initialize polling loops hitting {{rectifier_telemetry_endpoint}} every {{scan_interval_seconds}} seconds with HTTP session pooling.
2. Ingest instant-off and on-potential DC pipe-to-soil voltage metrics across active test stations on {{pipeline_segment_id}}.
3. Validate voltage polarity conventions ensuring negative potentials are evaluated relative to copper-copper sulfate electrodes (CSE).
4. Compare instant-off readings against {{min_protective_potential_mv}} mV to detect inadequate corrosion protection.
5. Evaluate readings against {{max_overprotection_potential_mv}} mV to identify coating disbondment and hydrogen overvoltage hazards.
6. Assign status categories per test point (Normal Protection, Under-Protected, Over-Protected, Sensor Open Circuit).
7. Write structured JSON log lines for every detected violation directly to {{incident_log_file}} with atomic file locking.

Constraints

• MUST handle negative voltage integer comparisons correctly where -800 mV is less protective than -850 mV.
• MUST NOT terminate execution loop if a single rectifier test station returns a timeout or null payload.
• Output script must rely strictly on standard library modules or common industrial drivers (urllib3, json, logging).
• File writes to {{incident_log_file}} MUST use POSIX non-blocking file locks to avoid race conditions.

Output format

Format the response into three distinct parts:

1. Script Setup: Brief summary of polling parameters and expected telemetry JSON schemas.
2. Diagnostic Python Script: The complete, runnable Python audit script in a code block.
3. Sample Log Output: An exact three-line mock of the JSON log entries generated inside {{incident_log_file}}.

Self-review

• Confirm that negative voltage thresholds ({{min_protective_potential_mv}} and {{max_overprotection_potential_mv}}) are compared with correct polarity math.
• Ensure {{pipeline_segment_id}} is included in all alert logging schemas.
• Verify that timing sleeps strictly match {{scan_interval_seconds}}.