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Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

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Chemical <strong>Pumps</strong> Metallic <strong>and</strong> Nonmetallic 311<br />

Figure 15-18. Self-primer overhung single-stage (courtesy of Goulds <strong>Pumps</strong>,<br />

Inc.),<br />

• Quality was more difficult to obtain, <strong>and</strong> it was difficult <strong>and</strong> costly to<br />

comply with NDE (nondestructive examination) requirements.<br />

• Alloy 20 <strong>and</strong> Hastelloy-C pump case defects expos<strong>ed</strong> during hydrotest<br />

requir<strong>ed</strong> excessive weld repair.<br />

The extensive efforts made to overcome these problems includ<strong>ed</strong>:<br />

• Creation of new patterns to satisfy metal shrinkage.<br />

• Development of Teflon-lin<strong>ed</strong> pumps.<br />

• Development of other linings, such as polypropylene, epoxy, glass,<br />

<strong>and</strong> Kynar.<br />

Although lining the inside of pumps solv<strong>ed</strong> many of the earlier problems,<br />

new ones were creat<strong>ed</strong> because linings:<br />

• Were difficult to produce <strong>and</strong> apply to the complicat<strong>ed</strong> pump casing<br />

areas.<br />

• Would not properly adhere to metals.<br />

• Would buckle, cold flow, or fail for other strength reasons.<br />

Armor<strong>ed</strong> Pump<br />

To overcome the difficulties experienc<strong>ed</strong> with pump linings, the armor<strong>ed</strong><br />

pump was develop<strong>ed</strong> with complete pump casing <strong>and</strong> other wett<strong>ed</strong>

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