Published February 2025 • Maintenance Programs • 5 min read

Hazardous Location Maintenance Checklist

No hazardous location certification stays valid without routine inspections. This field checklist keeps inspection teams focused on what auditors ask for: proof that equipment is intact, wiring is secure, and documents match the nameplate. Use it for IEC 60079-17 visual or detailed inspections, NFPA 70 Article 500 reviews, and plant shutdown walkdowns.

Plan the Inspection

Before anyone walks the line, confirm the basics. Missing documents trigger repeat work orders and erode confidence fast.

  • Latest hazardous area classification drawings and zone maps.
  • Equipment register with certificate numbers, EPLs, and temperature codes.
  • Maintenance history including last inspection type and findings.
  • Calibrated test equipment for insulation resistance or thermography (if required).

Visual Checks That Matter

During Routine Walkdowns

  • Confirm flameproof and increased safety enclosures are closed and bolting is complete.
  • Check Ex d flamepaths for corrosion, paint overspray, or damaged joints.
  • Inspect cable glands for thread engagement, sealing rings, and correct type.
  • Look for unauthorized equipment, portable heaters, or lighting.
  • Verify warning labels and emergency shutdown markings remain legible.

Detailed Tasks by Protection Method

Ex d Flameproof Measure bolt torque where specified, record flamepath gap checks, inspect breather drains, verify space heaters do not exceed T-code. Ex e Increased Safety Pull sample terminations, confirm creepage distances are clear, check insulation for discoloration, tighten terminal screws. Ex i Intrinsic Safety Review barrier certificates, confirm loop calculations are within entity limits, check grounding resistance, verify cable segregation. Ex p Pressurization Validate purge timers, alarm interlocks, leak test results, and that protective gas supply is dry and sufficient.

Documentation Tips

Short, consistent records beat complex templates. Auditors look for traceability and closure.

  • Log every enclosure with pass/fail status, actions taken, and responsible technician.
  • Attach photos for nonconformities—especially for flamepath damage or wiring issues.
  • Use unique finding IDs that tie back to work orders and completion dates.
  • Update equipment register immediately when components are replaced or upgraded.
Inspection Frequency: Follow IEC 60079-17 clauses 4.3 and 4.4. Start with detailed inspections on new builds, then move to visual or close inspections if equipment history supports it. Dust atmospheres often need shorter intervals due to buildup risk.

When to Escalate

Escalate findings when:

  • Enclosure integrity is compromised (missing bolts, damaged threads, cracked windows).
  • Intrinsic safety circuits are undocumented or wiring changes are untested.
  • Pressurization alarms are bypassed or interlocks defeated.
  • Dust layers exceed 1/8 inch (3 mm) on hot surfaces.
  • Combustible gas detectors routinely alarm during normal operations.

Close the Loop

Maintenance is only complete once corrective actions are verified. Track each remedial action with completion date, responsible person, and follow-up evidence. Share trends monthly so operations understands which areas generate repeat findings.

Need help standing up a formal inspection program? HazloLabs builds tailored checklists, trains inspection crews, and audits documentation so you can show compliance without a scramble.