Answer / carl_ellis

The issue with corrosion of a bourdon tube is not accuracy,
it's safety.

Corrosion failure of a bourdon tube occurs when the elastic
element (Bourdon tube) has been weakened .

The potential corrosion hazard is leakage of the process
fluid, which may be hot, toxic or corrosive, from a
measuring instrument, process pipe or tank. The other
corrosion hazard is catastrophic failure of the bourdon
tube, and the release of energy that can approach that of a
shot from a firearm.

Those failures due to corrosion dwarf the effect of
corrosion on accuracy. A change in the bourdon tube
stiffness effects gauge accuracy whether that change comes
from temperature, corrosion, or overpressure. The
likelihood that corrosion will destroy the bourdon tube
result in the ultimate certainty of "uncertainty" - total
non-accuracy due to failure to operate.

Whoever wrote this question missed the point entirely about
corrosion effects on pressure elements in piping.

The question should be, "How can corrosion alter the safety
of bourdon tube pressure gauge?"

Carl Ellis
Measure First

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