Materials Compatibility Beyond steam and water, it is good practice to refer to a materials compatibility table for all materials in contact with the fluid to determine proper matches. Further consideration should also be given to erosion resistance (hardness) with respect to the fluid, and/or the severity of the pressure drop on the trim. Therefore, we provide the compatibility matrix below for your review. A successful control valve application relies considerably on specifying the correct materials. Incompatible materials can lead to premature failure and incorrectly specified material may not meet performance specifications. For final selection, please refer to the Warren Controls Materials Compatibility Tables at www.WarrenControls.com.