Why the inspection regime is a legal obligation

A hazardous area installation that was correctly designed and installed at year 0 will, over years, degrade :

• Bolts loosen from thermal cycling
• Gaskets harden and crack
• Cable glands age, lose sealing performance
• Paint chips, corrosion starts
• Modifications happen in the field (someone removes a stopping plug for “temporary” work and forgets to replace it)
• New equipment added without proper certification check

Without a disciplined inspection regime, the certified installation drifts toward non-compliance silently. IEC 60079-17 + ATEX 99/92/EC make this regime a legal obligation for the operator.

A failure to maintain inspection records is among the easiest non-compliances for a competent authority to find (the inspection register is the first thing they ask for).

The three inspection grades

A typical year for a refinery section might look like :

• Quarterly visual by operations on every device
• Annual close inspection on critical devices, alternating with non-critical
• Detailed inspection every 3 years for offshore / corrosive environments, every 6 years for benign indoor

Inspection tables — what to check for each protection method

Each protection method has its own inspection checklist in the standard. Some highlights :

Ex d (Flameproof)

• All bolts present and torqued (loose bolt = flame can escape)
• No paint or contamination on flange faces (would prevent flame quenching)
• Cable glands certified type, correctly installed
• Stopping plugs in unused entries
• Flame gap dimensions within tolerance (detailed inspection only)

Ex e (Increased safety)

• IP rating preserved (no openings, no damaged seals)
• Terminal screw torque (loose connection = heating risk)
• Insulation distances respected
• Cable entry seals intact

Ex i (Intrinsic safety)

• IS loop documentation current and matches installation
• Barriers / isolators correct and functioning
• IS cables segregated (no mixing with non-IS in same tray)
• Earthing of IS barriers (if zener type) low resistance to PE
• No unauthorized modifications

Ex p (Pressurization)

• Purge cycle works (pressure reached and held)
• Loss-of-pressure alarm functions
• Cooling air supply clean and uncontaminated

The inspection record format

A typical record entry :

Item :  PT-101 pressure transmitter
Zone :  1 (gas, IIB, T3)
Type :  Ex ia IIC T4 Ga
Inspection grade :  Close (annual)
Date / Inspector :  2026-05-12  /  J. Müller (TÜV-certified Ex inspector)

Findings :
- Marking visible : YES
- Cable gland tightness : OK
- IS loop document : current, matches install
- Bonding test : 0.2 ohm to local PE ✓
- Visual damage : minor scratching, no functional impact
- IS barrier in cabinet C-101 : OK, no alarm history

Non-conformities : NONE
Actions : NONE
Next inspection due : 2027-05

A facility with 5000 Ex devices generates thousands of these records per year. Without a CMMS-supported workflow, the documentation burden becomes unmanageable.

Competence requirements

The standard explicitly addresses who can perform each inspection grade. Modern best practice :

• Operations technicians : trained on Ex awareness (1-day course) → can perform visual inspections
• Maintenance technicians : 3-day Ex foundation course → can perform close inspections under supervision
• Ex-competent persons : 5-day comprehensive Ex training + exam → can perform close inspections independently
• Ex specialists : detailed training + certified by recognized body (TÜV, IECEx CoPC scheme) → required for detailed inspections, modification design, area classification review

Without documented competence, inspection records are not credible. Modern audits scrutinize the training certificates of named inspectors.