A process fluid lubricated pump for conveying a process fluid, having a common housing , a pump unit arranged in the common housing, and a drive unit arranged in the common housing , wherein the common housing comprises a low pressure inlet and a high pressure outlet for the process fluid, wherein the pump unit comprises a pump shaft extending from a drive end to a non-drive end of the pump shaft and configured for rotating about an axial direction (A), the pump unit further comprising a first pump section having a first set of impellers fixedly mounted on the pump shaft and configured for increasing the pressure of the process fluid, wherein the drive unit is configured to exert a torque on the drive end of the pump shaft for driving the rotation of the pump shaft , wherein a first balance drum is fixedly connected to the pump shaft between the pump unit and the drive end of the pump shaft , the first balance drum defining a first front side facing the pump unit and a first back side , wherein a first relief passage is provided between the first balance drum and a first stationary part configured to be stationary with respect to the common housing , the first relief passage extending from the first front side to the first back side , characterized in that a second balance drum is fixedly connected to the pump shaft between the pump unit and the non-drive end of the pump shaft , the second balance drum defining a second front side facing the pump unit and a second back side , wherein a second relief passage is provided between the second balance drum and a second stationary part configured to be stationary with respect to the common housing , the second relief passage extending from the second front side to the second back side , and wherein a balance line is provided connecting the first back side and the second back side . wherein the common housing comprises a low pressure inlet and a high pressure outlet for the process fluid, wherein the pump unit comprises a pump shaft extending from a drive end to a non-drive end of the pump shaft and configured for rotating about an axial direction (A), the pump unit further comprising a first pump section having a first set of impellers fixedly mounted on the pump shaft and configured for increasing the pressure of the process fluid, wherein the drive unit is configured to exert a torque on the drive end of the pump shaft for driving the rotation of the pump shaft , wherein a first balance drum is fixedly connected to the pump shaft between the pump unit and the drive end of the pump shaft , the first balance drum defining a first front side facing the pump unit and a first back side , wherein a first relief passage is provided between the first balance drum and a first stationary part configured to be stationary with respect to the common housing , the first relief passage extending from the first front side to the first back side , characterized in that a second balance drum is fixedly connected to the pump shaft between the pump unit and the non-drive end of the pump shaft , the second balance drum defining a second front side facing the pump unit and a second back side , wherein a second relief passage is provided between the second balance drum and a second stationary part configured to be stationary with respect to the common housing , the second relief passage extending from the second front side to the second back side , and wherein a balance line is provided connecting the first back side and the second back side . <EOS>