This article is based on damaged wear rings from centrifugal pump applications. Two types of wear ring materials are analyzed in this article. For each material, there are two wear rings: the stationary (inner) wear ring and the rotating (outer) wear ring. The surfaces of the two different wear rings' materials and their corresponding inner/outer ring will be scanned and evaluated to observe the type of wear that caused damage.
It is important that a specific form of wear called galling is not present in the wear ring scans, according to the ASTM G98 standard. Galling occurs when the contact pressure is larger than the desired threshold pressure for a material. The surface damage can be identified as galling when localized protrusions are present on the surface. However, when a material fails due to galling, there will be catastrophic damages, so the materials used in wear rings must have a large galling resistance.
The authors gathered two wear rings with completed lifecycles. These damaged wear rings will be evaluated by cutting the rings into adequate sample sizes and using a profilometer to scan and measure the surface profiles. The two materials that have been chosen are AISI 316L and 410 stainless steel (SS). The two samples will be tested to find their hardness values and to make sure their corresponding values verify the API 610 standard for galling.
Additionally, it was observed through the profilometer scans that the dominant source of wear was due to abrasive wear. In this report, the surface profiles will be discussed and quantified with their corresponding skewness and kurtosis values and graphs. Overall, the graphs were found to have a Gaussian distribution, and the specific quantities for kurtosis were found to be dependent on the material hardness.
Background: Wear rings. Pump wear rings are an essential component of most centrifugal pumps. The main functionality of pump wear rings is to reduce the amount of leakage to the atmosphere and to ensure that any damage that happens is due to process or mechanical errors that affect the wear rings, and not to the pump casing or the impellers. (1) Such errors could lead to catastrophic failure, such as galling, which
is carefully avoided during the design stages of most of the pumps by implementing applicable standards, such as ASTM G98 and API 610. FIG. 1 shows the location of a wear ring on a centrifugal pump impeller.
Two damaged wear rings taken from an 8,600-hp water injection pump are shown in FIG. 2. To avoid high...