Product Name: SST Backup Ring / Stainless Steel Backup Ring / Bearing Disk (Part No. 10187250)

Description:
This component is a stainless steel (SST) backup ring, also referenced as a bearing disk in some waterjet parts lists . It is a precision-machined, rigid ring installed within a pneumatic actuator or valve assembly alongside an elastomeric seal such as an O-ring .

Its primary function is to provide mechanical support to the primary seal under ultra-high pressure (up to 60,000+ PSI). By filling the extrusion gap between the seal and the metal components, it prevents the softer O-ring material from being forced (extruded) into the gap, which would otherwise cause rapid seal failure and high-pressure leaks .

In the pneumatic actuator assembly (Item 8/9 in the parts diagram), this backup ring works in conjunction with the piston, cylinder cap, wiper seal, compression springs, and O-rings to ensure the actuator converts air pressure into smooth, leak-free mechanical motion to control the waterjet valve .

Applications:

• Provides anti-extrusion support for O-rings in the pneumatic actuator (Normally Closed assembly) of waterjet on/off valves 

• Supports dynamic seals in high-pressure valves, intensifier pumps, and cylinder assemblies

• Suitable for ultra-high pressure waterjet systems operating at 60,000–90,000 PSI

• Compatible with KMT, AccuStream, H2O Jet, and standard waterjet systems

Features:

• Stainless Steel Construction: Provides excellent corrosion resistance, high strength, and anti-galling properties in high-moisture waterjet environments 

• Precision-Machined: Manufactured to exact tolerances for a perfect fit within the designated seal groove

• Anti-Extrusion Function: The rigid stainless steel material provides a non-deformable barrier, preventing the elastomeric seal from being forced into clearance gaps under extreme pressure 

• Critical Consumable Component: Designed to be replaced every time the primary seal is serviced to ensure system reliability

• Direct OEM Replacement: Cross-references with part numbers 10187250 (SST Backup Ring) and is listed as "Bearing Disk" in some documents 

Maintenance:

Failure Diagnosis:

• External Leakage: Visible water or air weeping from the actuator or valve body indicates primary seal failure, often related to a worn or missing backup ring

• Rolling or Twisting: If the primary seal shows signs of twisting or rolling in the groove, the backup ring may be undersized, damaged, or not properly seated 

• Extrusion Damage: During disassembly, inspect the primary seal; if it shows signs of "biting" or being forced into side gaps, the backup ring may have failed or been omitted 

• Visible Wear: Inspect the stainless steel ring for cracks, flattening, deformation, nicks, or corrosion

Replacement Guidelines:

• Always Replace with Seals: This is a single-use component. Always replace the backup ring with a new one whenever the adjacent O-ring or primary seal is replaced. Do not reuse old rings 

• Critical for High Pressure: At pressures above 5,000 PSI, a backup ring is mandatory to prevent extrusion. For waterjet pressures (60,000+ PSI), the backup ring is a required component, not optional 

• Clean Installation: Thoroughly clean the seal groove and mating surfaces before installation. Remove all debris, old seal residue, and mineral deposits

• Proper Seating: Ensure the backup ring is correctly seated at the bottom of the groove, typically on the low-pressure side of the O-ring

• Lubrication: Apply a thin film of high-pressure grease or O-ring lubricant to the ring and O-ring during installation to prevent dry start-up and pinching

• Full Depressurization: Always fully depressurize the waterjet system (high-pressure water, hydraulic system, and air supply) and follow lockout/tagout procedures before service

• Inspect Mating Surfaces: Check the groove and housing for burrs, nicks, or sharp edges that could cut or damage the new ring or seal