Single Turn Scarf Cut 55 Shore A AS568 Back Up Rings

AS568 O-Ring Backup Rings — Standard Size References and Custom Gland Dimensions

PTFE backup rings support an O-ring at the extrusion gap in a specified static or dynamic gland. Identify the AS568 O-ring dash number and the actual groove dimensions; the O-ring size reference alone does not define the backup ring geometry.

Choose the PTFE grade against fluid composition, temperature, pressure peaks and clearance under load. Review grade-specific compatibility and deformation data rather than assuming suitability for every hydraulic fluid or temperature.

PTFE Grade and Construction
Virgin PTFE hardness reference: 55 Shore D; confirm the grade, test method and acceptance range.

Specify solid (uncut), scarf-cut or spiral construction on the drawing. Check assembly access and groove fit before changing from one construction to another.

Material range:

Virgin PTFE: specify contact load, compression and dimensional stability requirements for the operating conditions.

Filled PTFE: glass, graphite, carbon or bronze are separate formulations; specify filler type and content and review mating-surface compatibility.

For a standard-size enquiry, send the AS568 O-ring dash number with backup ring ID, OD, axial thickness and the gland drawing. Custom dimensions require a drawing revision and tolerances.

The ring supports the seal adjacent to the clearance gap. Include the groove width occupied by both O-ring and backup ring so the complete assembly can be reviewed.

Extrusion damage can occur when the seal is forced into the clearance under pressure. Identify the maximum gap at operating temperature and load, together with O-ring material and hardness.

Review clearance reduction, seal compound and backup ring dimensions together. Specify surface finish, movement and installation constraints; a backup ring has no independent assembly pressure rating.

For one pressure direction, specify support on the low-pressure side of the O-ring. For reversing pressure, review support on both sides and the groove space required; confirm the arrangement on the assembly drawing.

NBR or FKM 90-durometer rubber backup rings are separate alternatives requiring compound and hardness-scale confirmation. They are not interchangeable with PTFE solely by nominal size.

Contoured profiles require their own section drawing and material designation.

Related Rubber and Oilfield Components

Rubber O rings:

1) Standard O-Rings

Sizes: AS568 dash sizes or metric dimensions with the specified tolerances.

Materials: NBR, silicone, FKM, HNBR or EPDM by specification; food-contact requirements need compound documentation.

Color: Black, Brown, or custom color.

2) Custom rubber o rings, X rings, or kinds of seals and washers&gaskets.

Custom parts are quoted against an approved drawing or sample with mating dimensions.

Specify shape, color and hardness requirements on the drawing.

Hammer union seals

Rubber seals with or without brass or stainless-steel backup rings; fit by union assembly specification.

Available Material: NBR, FKM, HNBR.

Nominal union sizes: 1, 1.5, 2, 3 and 4 inches; seal dimensions by assembly drawing.

Plug seals

Available Material: NBR, FKM, HNBR ect.

Nominal size references: 1, 2 or 3 inches; plug seal fit by assembly drawing.

Dust Seals or Swivel Dust Seals

Oil saver rubbers

Pipe wipers

Swivel Ball Plugs

Thread Protectors

Related product photographs for reference; identify the ordered ring by drawing:

Additional related product photographs:

For standard or custom backup rings, send the O-ring dash number, groove drawing and quantity. Define ring dimensions, construction, PTFE grade, pressure direction, fluid and temperature, and reference an approved sample for repeat orders.