Page 346 - Centrifugal Pumps 2E

Chemical Pumps Metallic and Nonmetallic 311

Figure 15-18. Self-primer overhung single-stage (courtesy of Goulds Pumps,
Inc.),

• Quality was more difficult to obtain, and it was difficult and costly to
comply with NDE (nondestructive examination) requirements.
• Alloy 20 and Hastelloy-C pump case defects exposed during hydrotest
required excessive weld repair.
The extensive efforts made to overcome these problems included:

• Creation of new patterns to satisfy metal shrinkage.
• Development of Teflon-lined pumps.
• Development of other linings, such as polypropylene, epoxy, glass,
and Kynar.
Although lining the inside of pumps solved many of the earlier prob-
lems, new ones were created because linings:
• Were difficult to produce and apply to the complicated pump casing
areas.
• Would not properly adhere to metals.
• Would buckle, cold flow, or fail for other strength reasons.
Armored Pump

To overcome the difficulties experienced with pump linings, the ar-
mored pump was developed with complete pump casing and other wetted