Page 18 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Chapter 1
Installation, Malntenance, and

Repair of Horizontal Pumps

The most common centrifugal pump in the petrochemical industry is
the horizontal single stage process pump. This pump has many different
external designs. Perhaps the most common is the end suction top dis-
charge design shown in Figure 1-1.
There are many features about this pump that make it adaptable for
most applications. Designs can be small and inexpensive, or they can
be designs that meet API 601" standards as well as with ANSI**
specifications. The top centerline discharge provides excellent stability
when subjected to piping stresses and high temperatures. Larger pump
models incorporate a double volute internal passageway that helps to bal-
ance radial loading on the impeller. This pump design has a vertical ra-
dial split casing with centerline supports and an overhung impeller
mounted on a shaft supported by bearings. By changing impeller designs.
this pump can be adapted to all kinds of product applications from light
hydrocarbons to slurries.
ANSI pumps differ from API* designs as follows: They are chemical
process pumps designed in accordance with ANSYASME B73.1M-199 1
(horizontal end suction) and ANSYASME B73.2M-1991 (vertical inline).
ANSI pumps (Figure 1-2) are generally supplied with open impellers.
Temperatures are usually limited to 300°F and pressures to 300 psi
maximum, depending on the material and flange type. Capacity ranges
from 0-5,000 gpm, and materials are mostly ductile iron cases and im-
pellers. Often stainless steel is used together with 316 stainless steel shaft

* API = American Petroleum Institute
** ANSI = American National Standards Institute

3