Fitness-For-Service Assessment of DEA Reboiler

Location
Structure Type
Software Used

Vancouver, British Colombia, Canada
H-100 DEA Reboiler
Abaqus

Objective

To perform a level 3 assessment using finite element analysis (FEA) as per API 579/ASME Fitness-For-Service (FFS). The goal was to determine if the vessel can continue to operate under required pressure and temperature loads, including cyclic effects caused by load fluctuation, and in the presence of detected dents on the vessel.

Grid lines around the nozzle to extract the displacement deviation as the result of dent

A detected dent on the vessel

Grid lines around the nozzle to replicate the displacement deviation as the result of dent in the simulation

Residual Stress the result pf denting which is used as the initial condition of next analysis

Challenges

Simulation of various dents with different shapes on the vessel to replicate the imposed displacement and residual stress/strain fields by the detected dents.

Solution

Various indentors with different shapes were modeled to simulate the foreign object impact on a pressure vessel resulting denting. In addition, an iterative procedure were developed to account for spring back in order to achieve the inspected displacement field around the affected area of dents.

Result

The stress field, as the result of FEA analysis, was compared with FFS criteria. It was verified that the vessel is able to continue to operate with the presence of detected dents and the remaining life of a vessel was determined under desired temperature and pressure and cyclic effects.

Key Results

Displacement field and subsequently stress/strain field as the result of dents were simulated in the vessel.
Stress field as the result of max internal pressure was compared with API579/FFS to show the component is allowed to continue to operate.