Shutdown and Start-up Frequency

Why it matters for underwriting

Machinery and thermal processes are statistically far more vulnerable during shutdown and start-up than during steady-state operation: thermal stress from rapid temperature changes, transient pressure surges, and the momentary bypassing of protective interlocks that can occur during cycling all elevate the probability of both mechanical breakdown and fire or explosion events. A site that cycles equipment frequently, whether due to shift patterns, seasonal demand or unstable production scheduling, accumulates far more of these high-risk transitions per year than one that runs continuously once started. Underwriters use cycling frequency to refine machinery breakdown and business interruption pricing beyond what steady-state hazard classification alone would suggest.

Capturing the attribute and evidence

Proposal forms ask how many planned shutdown and start-up cycles the critical machinery undergoes per month, whether these transitions follow a documented procedure or are managed ad hoc, and whether the insured’s loss history shows a concentration of past losses around shutdown or start-up events rather than steady-state running. Underwriters review the shutdown/start-up log, the standard operating procedure for cycling equipment, and the insured’s loss history report to corroborate the declared frequency and assess whether procedural discipline matches the operational tempo.

Effect on coverage, premium and conditions

Lower cycling frequency, or high frequency paired with a rigorous, well-documented shutdown/start-up procedure, generally supports more favourable machinery breakdown and business interruption terms. High, poorly controlled cycling frequency typically results in premium loading, higher deductibles applicable to breakdown losses, or conditions requiring the insured to formalise and follow a documented cycling procedure as a prerequisite for cover.

Mitigation measures

Insurers and risk engineers typically recommend documenting a standard shutdown and start-up procedure with defined checks at each stage, minimising unnecessary cycling through better production scheduling, and reviewing loss history specifically for shutdown/start-up-related events to target preventive measures where they are most needed.