| S.No. | Checkpoint | IS Requirement | Status |
|---|---|---|---|
| A. PRE-ENTRY ISOLATION | |||
| A1 | All inlet/outlet lines physically isolated by blanks, spades, or double-block-and-bleed Acceptance: Positive isolation verified; blind list signed; P&ID marked; no valve-only isolation | Cl. 7 — Isolation | OK NC NA HOLD |
| A2 | Electrical and mechanical equipment inside space locked out and tagged out (LOTO) Acceptance: LOTO lock by entrant; try-out tested at local isolator; tag signed and dated | Cl. 7 — Energy isolation | OK NC NA HOLD |
| A3 | Space drained, purged, and cleaned of previous contents; residues removed Acceptance: Drain fully; steam/water/N2 purge done; sludge removed; visual check done | Cl. 7 — Cleaning | OK NC NA HOLD |
| B. ATMOSPHERIC TESTING | |||
| B1 | Oxygen level tested: 19.5% to 23.5%; measured at top, middle, and bottom of space Acceptance: O2 = 19.5-23.5% at all levels; calibrated gas meter used; readings logged | Cl. 7 — O2 level | OK NC NA HOLD |
| B2 | Flammable gas / LEL tested: <10% LEL before entry and during work Acceptance: LEL <10%; continuous monitoring where gas may accumulate; alarm set 10% | Cl. 7 — Flammability | OK NC NA HOLD |
| B3 | Toxic gases tested (H2S <10 ppm, CO <25 ppm, and others per previous contents) Acceptance: H2S <10 ppm; CO <25 ppm; ammonia <25 ppm; other toxics below PEL | Cl. 7 — Toxicity | OK NC NA HOLD |
| B4 | Continuous gas monitor taken inside by entrant; alarm settings verified Acceptance: Personal 4-gas monitor on entrant; alarms active; calibration certificate current | Cl. 7 — Continuous monitoring | OK NC NA HOLD |
| C. VENTILATION | |||
| C1 | Mechanical ventilation (forced air) provided; minimum 20 air changes per hour Acceptance: Blower running; duct reaches bottom of space; fresh air intake clean | Cl. 7 — Ventilation rate | OK NC NA HOLD |
| C2 | Exhaust positioned to remove heavy / light gases as per gas characteristics Acceptance: H2S/LPG: exhaust low; ammonia/methane: exhaust high; cross-ventilation achieved | Cl. 7 — Air flow pattern | OK NC NA HOLD |