Tame Your Transient Operations

Use a special method to identify and address potential hazards.

By Scott W. Ostrowski and Kelly K. Keim, ExxonMobil Chemical Company

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The operations representative(s) should go over with the entire team a summary of required operational activities (tasks) associated with the specific transient operation. The review should use unit MFDs, P&IDs and procedural sequence flow diagrams, as appropriate, to assist the team in its understanding. Typically a second member of the team (usually the process design/technology representative) will follow the operation under review on the MFDs or P&IDs. Discuss any potential procedural or equipment-related questions as they are identified.

The team should gain an understanding of required operator actions, hazards and potential higher-consequence loss-of-containment risks associated with the operation, and all preventing, alerting and mitigating controls in place. The team should test to ensure that procedures have been developed and are up-to-date for the transient operation under review, personnel responsible for conducting the operation have been adequately trained, and risks have been adequately controlled through application of hardware and procedural controls.

The team initially should scan the procedure as a whole, looking for items contrary to good format, e.g., use of warnings, cautions and notes, sequencing of activities, confirmation that steps begin with action verbs, etc. Group deficiencies, as applicable, and note them as finding(s) for the individual procedure.

Next, the team should break every procedure into a sequence of related steps. For each sequence, ask the question, "Will a deficiency in this sequence of actions potentially lead to a higher-consequence out¬come?"

If there is no potential, mark that set of steps in the right or left margin vertically with a highlighter to document the section has been reviewed.

If a risk exists, evaluate each step separately. Start by asking: "Will a deficiency in this step potentially lead to a higher consequence outcome?" If the answer is "no," move on to the next step. If the response is "yes," evaluate the step using the knowledge and experience of the team, aided, as necessary, by guide words. The evaluation should identify ways to improve the procedure to reduce the potential for an incident to a very low probability.

Determine if a procedural control is the most effective means to ensure activities are safely and reliably conducted. Improvements may be a change in wording, addition of a caution or warning box, or even additional facilities or controls to mitigate the risk. Document findings as a redlined change to the procedure or as a follow-up item on the HAZOP worksheet. It's best to use a computer projector to display the current procedure and the recommended change to the full team. Finally, highlight in the margin each line of the steps evaluated to indicate it was discussed in detail.

Subject any place in a procedure with an existing caution or a warning box to a more detailed evaluation. Confirm or add a caution or warning box, as appropriate, for the potential consequence. Check each precautionary statement to ensure it:

• alerts the operator to the hazard;
• includes a description of the necessary actions to avoid the hazard; and
• details the potential consequences of ignoring the warning.

Once the entire procedure is reviewed, repeat the review steps for the next procedure until all chosen for review are complete.

Documentation of findings. Capture follow-up items as redlined revisions to the procedure — if a change is simple, well understood and can be addressed by the team's suggested wording. Note on the master review copy of the procedure follow-up items that can't be addressed by a simple rewording with an item identifier, just as is done to drawings in redo HAZOPs (e.g., S-1, E-2, O-3).

Indicate on the HAZOP worksheet each finding identified for further consideration as a follow-up item. If the team can't achieve consensus on procedural controls or any improvements to those controls, it may consider enhanced training, process automation tools or facility changes to reduce the risk. Risk-assess any findings that call for facility changes and prioritize them for follow-up. Document recommended additional controls.

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