Pumps used in the oil and gas industry are usually made of expensive materials, so care must be taken to ensure that these materials do not wear out as much as possible. This is possible via wear ring.
The impeller, casing and pump shaft are the most important parts of the pump. Looseness between these three parts should be low because it should prevent fluid leakage, and on the other hand, low looseness leads to wear of these parts.
Hence an intermediate piece is placed on the shaft, impeller and casing. The shaft bush is located on the pump shaft, and rotating Wear Ring is put on the impeller (Impeller wear ring) and stationary wear ring will be placed on the casing (Casing wear ring).
The use of wear rings permits easy restoration of internal clearances by replacing rings in the event that clearances open during operation. These rings are called “case” and “impeller” wear rings.
Most pumps for refinery and heavy duty chemical plant applications are designed with close clearances between the impeller and pressure casing to separate the discharge pressure zone of the impeller from the inlet pressure zone and minimize back leakage or slip flow.
Wear rings are fitted at the close clearance location in the pump casing and usually at an opposing position on the impeller.
The most important factors in choosing the material of wear rims are as follows:
• Abrasion Resistance
• Corrosion resistance
• Casting and machining properties
• Production costs
The following should also be considered in the design and use of rings:
• It is necessary to select the distance between the wear rings to prevent the two rings from coming into contact during start-up.
• Selection of materials to prevent galvanic corrosion.
• It is possible to easily replace both rims.
• The surface on the wear ring should be serrated or honeycomb in order to improve its performance.
• The amount of wear in wear rings is highly dependent on their choice.
Hardness difference between two materials should be more than 50 HB.