Materials of Construction - Mesh Pads

The small wire diameter typically used in the construction of a mesh pad make corrosion resistance an important factor in selecting the matierla of construction for a mesh pad.  A corrosion rate of 0.005 inches per year is not serious where the material is quite thick such as in a vessel wall.  However, mesh pad wire diameters are typically 0.011 inches in diameter and a corrosion rate of 0.005 inches per year will destroy a mesh pad in 2 years or less. 

Materials with superior corrosion resistance generally come at a premium cost.  Thus the initial capital cost of a pad must be compared to the expected life and subsequent replacement costs.

Where a suitable metal is not available for the service, a non-metallic material may be suitable.  Non-metallics often offered superior resistance to metals but are limited by high operating or upset temperatures.

Non-metallic materials are limited by operating temperature.  One disadvantage of non-metallic materials is the risk of damage to the pad if hot gases were to backflow into the tower.