ANSI Pump Materials
Why Pump Material is Important
ANSI pumps are used in a wide variety of applications and environments across many industries. For this reason, pump parts are available in a wide range of materials, each uniquely qualified to withstand a certain amount of corrosion, erosion, temperatures, and / or pressures.
Selecting the correct material for a particular application is critical to operate the pump safely and with minimal downtime between failures. When selecting part materials, consider not only the process fluid and temperature, but also the external factors such as the location of the pump (indoors or outdoors) and even the solution the pump will be cleaned with.
When manufacturers say that pumps are available in different materials, they are often referring to the material of the "wetted-end". The "wet-end parts" refers to the parts of the pump that come in contact with the process fluid, namely the casing, impeller, and the rear cover (stuffing box). The shaft comes in contact with the fluid, but it is not categorized as a wet-end part.
Common Materials and Cost
The most common wet-end materials that are available are:
- Ductile Iron (DI)
- 316 Stainless Steel (316 SS)
- Alloy 20
- Hastelloy B / C
The above list is ordered from lowest price (ductile iron) to highest price (Titanium). The price difference between materials may vary significantly, or not at all, so it is important to understand your budget and what material you need to safely accomplish the task.
If your application only requires ductile iron, there is no need to order parts in 316SS as long as the cheaper parts are in stock. On the other hand, the price difference between 316 SS and CD4MCuN may not be that significant, but the advantages of CD4MCuN (more durable, corrosive resistant) may outweigh the relatively small price difference.
CF8M vs CD4MCuN
In the industry, CF8M is simply referred to as "316 Stainless steel." CF8M is an ASTM (American Society for Testing and Materials) designation for a stainless steel casting material similar to machined 316 stainless steel. Technically, CF8M is a cast version of machined 316 Stainless that is not as corrosion resistant as the machined 316 SS.
Often referred to as "CD4," CD4MCuN is a duplex stainless steel with greater corrosive resistance and strength than 316 SS in most applications. Due to these benefits, ANSI pumps in CD4 can withstand more abrasive applications than parts in 316 SS, and may be more resistant to cracking and pitting than Alloy 20.