Aleksandar,
API 610, the refinery pump standard, calls for the pressure containment case of a pump to be designed according to the rules of ASME Section VIII, the unfired pressure vessel code. This implies that the corrosive and abrasive properties of the pumped fluid as well as the temperature and pressure be considered when establishing a corrosion allowance. They then go further to recommend a minimum of 3mm corrosion allowance.
Regards,
Gunnar Hole