Process Safety: Walk The Line

Company-wide initiative eliminates operator line-up errors

By Jerry J. Forest, Celanese

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Additional design practices, to name a few, include formal plug and inspection programs, line labeling initiatives, spring loaded valves, and double blocks on some bleeders.

Operational Readiness. Experience has taught us that the frequency of incidents is higher during process transitions such as startups. These incidents often result from the physical process conditions not exactly matching those intended for safe operation. Thus, it is important that the process status be verified as safe to start. Operational readiness reviews ensure the process is safe to start by examining issues such as:

• equipment line-up;
• safeguard bypasses restored;
• bleed valves plugged;
• leak tightness;
• pre-startup safety reviews completed; and
• car seals in place.

Such reviews of simple startups may involve only one person walking through the process with a straightforward checklist to verify that nothing has changed and equipment is ready to resume operation. More complex reviews or higher risk startup situations may require different tools.

Operational readiness tools share some common elements such as defining equipment commissioning steps in standard operating procedures (SOPs). Commissioning tools include: process and instrumentation drawings (P&IDs) walk-downs, formal pre-startup safety reviews (regardless of whether a change was made), soap testing, checklist SOPs and similar maintenance/operations turnover, and verification after maintenance checks designed to ensure bleeders are closed and line-ups are correct.

A common tool used in industry is independent verification. It often targets some safety devices such as pressure relief devices but also makes sense for critical line-ups. Celanese uses a risk-based ranking criteria to determine if a task should be considered critical. These tasks are performed with a checklist in hand; the operator verifies each step when completed. After the task is finished, another person independently confirms the steps as complete and accurate.

Step Up Your Efforts

Adopt a belief that all process safety incidents are preventable and start with a goal of zero LOPCs caused by operator line-up errors. Of all LOPC incidents, those related to incorrect line-ups and open ends seem easiest to correct. When analyzing incidents, go beyond “operator left valve open” and answer “Why did the operator leave the valve open?”

Recognize which operating discipline and operational readiness tools operators require to understand the current operating state of the processing unit. Set the expectation that an operator must know with 100% certainty where energy will flow each time a change is made to the process. If that person doesn’t know with 100% certainty, then walk the line!

JERRY J. FOREST is global process safety manager for Celanese, Irving, Texas. E-mail him at

1. AFPM Safety Portal Event Sharing Database, (login credentials required), American Fuel & Petrochemical Manufacturers, Washington, D.C.
2. AIChE Center for Chemical Process Safety, “Conduct of Operations and Operational Discipline,” J. Wiley & Sons, Hoboken, N.J. (2011).

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