AS568-242 Solid PTFE Back-Up Ring, for AS568-242 O-Ring Grooves - Anti-Extrusion Ring

FINAL SALE - NO RETURNS. THIS IS A STANDARD CATALOGUE SIZE; CONFIRM YOUR DIMENSIONS AND MATERIAL BEFORE ORDERING.

Because standard sizes are chosen by measurement rather than by machine model, they ship as final sale. If we send the wrong item, or it arrives damaged or defective, we replace it free of charge, and that never changes.

Are your o-rings extruding, nibbling or blowing out under high pressure? A back-up ring fills the clearance gap behind the o-ring so it cannot be forced into it, the standard fix for hydraulic joints above about 1,500 psi or with worn, oversized clearances.

This Beaver Island Parts Company back-up ring is a standard AS568-242 101.19mm ID x 3.53mm CS (3.984" x 0.139") size, molded in PTFE.

Specifications

What It Fits

This size is used across chemical pumps and valves, solvent and fuel handling, cryogenic service and static seals that must not swell. If your manual, parts list or old ring calls for AS568-242 101.19mm ID x 3.53mm CS (3.984" x 0.139"), this is the part.

Why PTFE

PTFE is chemically inert and will not swell, harden or degrade in fluids that attack rubber. Recommended for virtually all chemicals and solvents, cryogenic to high temperatures. Not recommended for applications that need elastic stretch or squeeze recovery; PTFE is rigid and does not rebound like rubber.

You Can Do This Repair

Place the back-up ring on the low-pressure side of the o-ring (the side away from the pressure). If pressure comes from both directions, use one on each side. Lubricate both parts and keep the back-up ring flat in the groove. PTFE does not stretch like rubber: warm it in hot water for a few minutes to soften it, ease it over the shoulder slowly, and let it cool in the groove.

Pro Tip: A thin coat of Aqua Flex silicone lubricant eases installation, protects the seal on first start-up and extends its life.

Shipping: This part is special-ordered and packed for you. It ships from our facility in about 10 business days, then transits by the carrier service you choose at checkout. The estimated delivery date shown on this page includes that lead time.

Why Buy From Beaver Island Parts Company

• Every dimension published. Size, material, hardness and temperature rating are listed up front so you can confirm fit before you buy, not after.
• Inspected, packed and labeled by us. Each order is checked and repacked in a bag labeled with the part's size and material, so it never gets lost in a parts bin.
• Real people who answer fitment questions. We are an American family-owned and operated small business. Send us your measurements or model number and we will help you confirm the right part.
• Replacement guarantee. If we ship the wrong item, or it arrives damaged or defective, we replace it free of charge.

Frequently Asked Questions

Q: Will this fit my equipment?
A: It fits any groove or fitting that calls for a AS568-242 101.19mm ID x 3.53mm CS (3.984" x 0.139") back-up ring. Size, not brand, determines fit for standard o-rings. Measure the old o-ring's inside diameter and cross-section with calipers, or better, measure the groove, because a used ring stretches and flattens. Match the material to the fluid: the right size in the wrong rubber will still fail.

Q: What is PTFE good for?
A: It is suited to virtually all chemicals and solvents, cryogenic to high temperatures. Avoid applications that need elastic stretch or squeeze recovery; PTFE is rigid and does not rebound like rubber.

Q: Can I install it myself?
A: Yes. Most o-ring replacements take only a pick tool, a clean rag and lubricant. Release pressure, drain the system if needed, remove the old ring, and follow the installation notes above. If it is your first time, take a photo before you take anything apart.

Q: When will it ship?
A: It ships from our facility in about 10 business days, then transits by the carrier service you choose.