Oil, Gas & Energy Equipment Manufacturing worked example

Hazardous-Area Certification Burden at 7.2% review, hold, and rework allowance: a worked example

This worked example runs the hazardous-area certification burden numbers for a tougher week than the baseline: 7.2% review, hold, and rework allowance instead of the typical 10%. Estimate the labor hours to prepare hazardous-area certification for Ex-rated equipment, from the number of items to certify, the documentation rate, and an allowance for reviews, holds, and rework, so compliance and engineering teams can plan the effort before a quote goes out.

The inputs for this scenario

  • Ex-rated items to certify: 120 units (held at the documented default)
  • Certification documentation rate: 12 units / min (held at the documented default)
  • Review, hold, and rework allowance: 7.2 % (the input this scenario stresses; the baseline uses 10)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base certification time = Ex-rated items to certify รท certification documentation rate.
  • Required certification labor works out to 10.72 hr at these inputs, and this is the headline figure for the scenario.
  • Base certification time works out to 10 hr at these inputs.
  • Review and rework allowance applied works out to 7.2 % at these inputs.
  • Certification documentation rate works out to 12 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where review, hold, and rework allowance sits at 10% and the headline result is 11 hr, this scenario comes in 2.55% below the baseline at 10.72 hr.
  • Use it when scheduling certification staff for a production run of explosion-proof or intrinsically safe equipment, or when quoting the documentation cost of an Ex order. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Required certification labor: 10.72 hr (headline result)
  • Base certification time: 10 hr
  • Review and rework allowance applied: 7.2 %
  • Certification documentation rate: 12 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Hazardous-Area Certification Burden calculator, set review, hold, and rework allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.