Vessel Corrosion Assessment – FEM FFS Level 3

SERVICES LINES

• Mechanical Engineering

• Asset Integrity

• Project Management

INDUSTRY SECTOR

• Petrochemical/Chemical Processing

PROJECT SUMMARY
Significant corrosion was found both internally and externally on the cylindrical section of a vertical pressure vessel. While within the corrosion allowance, an extension of the remaining life of the pressure vessel was required.

SCOPE
A fitness for service assessment to API 579-1 Part 4 was conducted in order to determine a new future corrosion allowance for the cylindrical portion of the vessel.

This consisted of:

• Creating a representative geometry for the vessel, and a detailed model of the section under assessment.

• Conducting Finite Element Method elastic-plastic analysis and assessment to API 579-1 Part 4 Level 3 using ASME VIII Div. 2 Part 5 rules.

• Assessing protection against plastic collapse, local failure, and ratcheting in design, wind, and seismic load cases.

CHALLENGES'
The challenge was completing the fitness for service on an operational vessel with dynamic process and loading conditions.

OUTCOME
Based on the Level 3 FEM assessment conducted, the future corrosion allowance was able to be increased, extending the remaining life of the vessel, reducing operational outages and maintenance activities saving both time and money.