Wednesday, October 15, 2014

Comparison of ANSI and API Pump Designs

Comparison of ANSI and API Pump Designs

Type Pump and Specification
ANSI B73. 1 for horizontal end suction top discharge pump.
ANSI 873.2 for vertical In-line pumps.
All are single stage.
API 610 for horizontal single and multlstage
pumps. vertical in-line, vcrtical single, and multistage centrifugal pumps.
Maximum Allowable Working Pressure (MAWP)275 PSIG
Minimum 700 PSlG
Some API pumps are designed for pressure above 500 PSIG.
Hydrostatic Test Pressure415 PSIGMinimum 1050 PSIG
API pump hydrostatic test pressure will be 1.5 times the MAWP.
Flange Rating150# flat faced is standard. 150# raised face is available.300# raised face is standard.
600, 900, 1500 and higher ratings are available if required by the service.
Maximum Temperature2SO°F
Pump casing is foot mounted which limits allowable thermal growth
Pump casing is centerline mounted. No casing thermal growth limitations.
Materials of Constructions (Casing and Impeller)Ductile Iron
Alloy 20
A carbon steel casing or impeller is not commonly available
Carbon steel casing is standard.
Stainless steel is also available.
Impelller materials are cast iron, carbon steel, and stainless steel.
Maximum Head Differential550 to 600 feet
ANSI pumps are only single stage. Maximum impeller diameter is about 13 inches.
Practical limit is 10000 feet.
Horizontal API pumps can have as many as 14 stages.
Impeller Design and AttachmentOpen impellers are common. Some enclosed impellers are available.
No standard for attachment to the shaft. Most are threaded on the end of the shaft.
All are enclosed design. Some open designs are available for special coke crushing services.
Impellers must be key driven with a lock nut attachment.
Standard DimensionsANSI pumps are built for interchangeability between manufacturers.No standard dimensions apply.
Shaft SlevesNot required but are available. Fit to the shaft and extension past the gland are not ANSI specification requirements.Are required to prevent shaft damage in the scal or packing area.
Sleeve and stuffing box design is part of the API 610 specification.
LubricationCan be grease or oil lubricated.Oil lubrication is required. Usually ring oil system is provided.
Thrust bearing and LifeAntifriction bearings only.
B-10 bearing life of 17500 hours at design load is required.
Antifriction ball bearings must be duplex, single row, 40-degree angular-contact type, installed back to back.
L-10 bearing life must exceed 25,000 hours at rated condition, or 16,000 hours at maximum axial and radial loads at rated speed.
Wear RingsNot required and not available in most designs due to the use of open impellers.Case and impeller, front and back wear rings are required. Wear ring clearences, attachment and hardness differential are specified.

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