What is a corrosion allowance and how is it assessed?
Corrosion allowance is an additional thickness of material
provided in a pressure vessel during its design to compensate for
expected material loss due to corrosion over its service life. It
acts as a safety margin to ensure the vessel remains structurally
sound even after gradual deterioration.
In India, corrosion allowance is an important consideration in
industries such as chemicals, oil & gas, power plants, and
manufacturing, and is evaluated as part of pressure equipment
safety under the Factories Act, 1948 and applicable state factory
rules.
Corrosion allowance is typically assessed based on:
- Type of fluid or chemical stored or processed
- Operating temperature and pressure conditions
- Material of construction of the vessel
- Historical corrosion rates and operating experience
- Industry standards and design codes (e.g., BIS standards)
- Environmental and atmospheric conditions
During inspection, the actual remaining wall thickness is measured
and compared with the original design thickness and corrosion
allowance to determine whether the vessel is still fit for safe
operation.
Uniquo evaluates corrosion levels using detailed inspection
techniques and, where required, NDT methods to measure thickness
loss. Our reports help organizations understand corrosion
progression, plan maintenance, and ensure safe continued operation
of pressure vessels.