Stress Analysis of Steam-Methane Reformer Tubes

Steam-methane reformer tubes operate at temperature exceeding 800°C and are
designed to last about 100,000 hours of service. However, the life achieved can be
significantly shorter due to creep failure of the reformer tube. In order to reliably predict
the performance of the tube, good estimation of the stresses acting at any point along the
tube length and thickness is required. Finite Element Method (FEM) will be used to
perform the stress analysis of the tube and the analysis will consider the variation in
stresses along the tube length and thickness due to temperature and pressure differences,
in addition to service life. The analysis was conducted by using ANYSY software. The
model is a two dimensional axisymmetric model. The main advantage to use a 2D
axisymmetric model compared to a full 3D model is the reduced calculation time and it is
easier to change subtle details to the geometry. Two different types of analyses were
conducted; stress analysis due to internal pressure and stress analysis due to difference in
temperature along the tube. For the first analysis, it was shown that the Von Misses Stress
is highest at the inner wall of the tube and lowest at the outer wall. For the second
analysis, it was shown that the Von Misses Stress is highest at the inner wall of the tube
and lowest at the middle of the tube. The Von Misses Stress is decreasing from inner wall
to the middle wall but then increasing to the outer wall.