4.2　Centrifugal Pumps

4.2.1　For centrifugal pumps handling non-hazardous fluids in petrochemical industry，when the following operating conditions are met，centrifugal pumps for medium-and light-duty services should be selected and shall conform to the current industrial standard SH/T 3140 Technical Specification on Centrifugal Pumps for Medium-and Light-duty Services in Petrochemical Industry，otherwise，centrifugal pumps for heavy-duty services should be selected and shall conform to the current industrial standard SH/T 3139 Technical Specification on Centrifugal Pumps for Heavy-duty Services in Petrochemical Industry.

1　Rated discharge pressure:≤1.9 MPa（G）.

2　Pumping temperature（liquid temperature）:＜225℃.

3　Rated rotated speed for motor-driven pumps:≤3000r/min，the rated rotated speed may be increased by 5%for turbine-driven pumps.

4　Rated head:≤120m.

5　Maximum suction pressure:≤0.5MPa（G）.

6　Maximum impeller diameter for overhung pumps:≤330mm.

4.2.2　For centrifugal pumps handling hazardous fluids，centrifugal pumps with shaft seal for heavyduty services or seal less sealless centrifugal pumps should be selected.Centrifugal pumps with shaft seal for heavy-duty services shall conform to the current industrial standard SH/T 3139 Technical Specification on Centrifugal Pumps for Heavy-duty Services in Petrochemical Industry and sealless centrifugal pumps shall conform to the current industrial standard SH/T 3148 Technical Specification for Sealless Centrifugal Pumps in Petrochemical Industry.

4.2.3　If the fluid viscosity is larger than 20MPa·s，viscous fluid performance conversion shall be made for the centrifugal pumps.

4.2.4　Single volute casing may be used for the pump with discharge nozzle size of DN100（4in）or less.

4.2.5　Except for high speed pump，inducershould not used for centrifugal pump.

4.2.6　In addition to the requirements specified in Article 3.2.2 of this code，the allowable working pressure of pump casings shall also comply with the following requirements:

1　For medium-and light-duty centrifugal pumps with shaft seal and sealless pumps，the allowable working pressure of pump casings shall be at least equal to the maximum allowable working pressure of PN16 flanges at the handling temperature.

2　The allowable working pressure of casings shall be not less than the maximum allowable working pressure of PN20 flanges at the operating temperature for between bearings，axially split，single stage or double stage centrifugal pumps or vertically suspended single casing pumps in heavy-duty services.And for other types of pumps，the allowable working pressure of casings shall be not less than the maximum allowable working pressure of PN50 flanges at the operating temperature.

4.2.7　The total indicated runout（TIR）of the single piece of shaft measured at any point shall comply with the following requirements:

1　For centrifugal pumps with shaft seal and sealless centrifugal pumps for medium-and light-duty services，TIR shall be≤0.05mm；

2　For centrifugal pumps with shaft seal and sealless centrifugal pumps for heavy-duty services，TIR shall be≤0.025mm.

4.2.8　Each rotating part of centrifugal pump shall be dynamically balanced in accordance with the current national standard GB/T 9239.1 Mechanical Vibration-Balance Quality Requirements for Rotors in a Constant（Rigid）State-Part 1：Specification and Verification of Balance Tolerances，and balance accuracy shall comply with the following requirements:

1　For centrifugal pumps with shaft seal and sealless centrifugal pumps for medium-and light-duty services，the impellers shall be dynamically balanced to G2.5；

2　For centrifugal pumps with shaft seal and sealless centrifugal pumps for heavy-duty services，the impellers，balancing drums and main similar rotating parts shall be dynamically balanced to G2.5；

3　The impellers，drums and main similar rotating parts of high speed centrifugal pumps or pitot tube pumps shall be dynamically balanced to G1.0.