Page 90 - Failure Analysis Case Studies II
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Fig. 3. View of buckled column.
3. STRESS ANALYSIS AND ASSESSMENT
The approach in this section is to compare stresses at critical points in the structure with allowable
and failure stresses, inferred from BS 5500 [l], the design code for pressure vessels, which has high
temperature materials data.
Figure 4 is a summary of design and failure data for Grade 43 steel, based on a service life of
150,000 hours or 17 years. Failure data for creep rupture is inferred from design data using the
quoted safety factor of 1.3.
Further, extrapolation for temperatures > 480°C is necessary. There is a justification for using
100
h 80
m
5 60
v
v)
v) 40
2
tj 20
0
400 420 440 460 480 500 520
Temperature (C)
-A- Design - Failure
Rg. 4. BS 5500 stress-rupture data for Grade 430 steel.
