The method
Before using the result
- Constant positive corrosion rate and independently established minimum thickness. This is not an inspection interval, fitness-for-service assessment or certification.
Worked examples
These original training examples illustrate the method for API 510 Pressure Vessel Inspector (API 510). Use the matching “Load example” button above to explore a variation; example values are not equipment settings or prescribed criteria.
1. Worked example
Use an independently established minimum thickness and a representative corrosion rate. Keep arithmetic remaining life separate from the inspection interval and fitness-for-service decision.
- Current measured thickness
- 0.009 m
- Supplied minimum required thickness
- 0.006 m
- Supplied corrosion rate (mm/year)
- 0.2
- Source of minimum thickness
- Worked example: externally supplied assessment value
- Margin = 0.009 − 0.006 = 0.002999999999999999 m.
- Life = 2.999999999999999 mm / 0.2 mm/year.
- Thickness margin: 0.003 m
- Arithmetic remaining life: 15 years
- Minimum-thickness source: Worked example: externally supplied assessment value
2. Comparison example
Compare a different supplied condition using the same method. For Welding Exam, the important check is that the input meaning, units and method assumptions still match the problem.
- Current measured thickness
- 0.008 m
- Supplied minimum required thickness
- 0.006 m
- Supplied corrosion rate (mm/year)
- 0.2
- Source of minimum thickness
- Worked example: externally supplied assessment value
- Margin = 0.008 − 0.006 = 0.002 m.
- Life = 2 mm / 0.2 mm/year.
- Thickness margin: 0.002 m
- Arithmetic remaining life: 10 years
- Minimum-thickness source: Worked example: externally supplied assessment value
Check your understanding
1. Which relationship is used?
Arithmetic remaining life = (current thickness − supplied minimum thickness)/supplied positive corrosion rate.
2. Which assumption should you check first?
Constant positive corrosion rate and independently established minimum thickness. This is not an inspection interval, fitness-for-service assessment or certification.
3. How should you verify a different unit system?
Convert every input to the displayed calculation units first. Equivalent physical inputs must give equivalent results; a unit label alone does not convert a number.
Continue with the matching exam topic
This tool connects to API 510 Pressure Vessel Inspector (API 510) free practice. Work through a question independently, then use the calculation steps to identify where your method differs. The tool stays free whether or not you choose paid preparation.