The Last Barrier Before Startup

A pre-startup safety review confirms, before hazardous material or energy is introduced, that the facility is in the condition everybody assumes it is in. It is the last opportunity to find an error made during design, construction, maintenance or modification while the consequences are still zero.

What it typically catches

• Blinds and spades left in, or removed when they should be in.
• Valves in the wrong position; instruments left isolated or in bypass.
• Relief valves not installed, wrong set pressure, or with the inlet block valve shut.
• Trips and interlocks not function tested, or left inhibited from commissioning.
• Equipment installed contrary to drawings; missing supports on small-bore lines.
• Procedures not updated for the modification; operators not trained on the change.
• Fire and gas detection, fire water and emergency systems not returned to service.

Every item on that list has caused a serious incident somewhere. None of them is exotic; all of them are found by someone deliberately looking.