We make getting O-Rings easy. Below is a clean side-by-side so you can pick the right build for your application and get reliable sealing without surprises.
Quick answer
- If your seal is static and you need a custom size fast, choose Vulcanized Viton® FKM
- If your seal is dynamic, pressurized, or mission-critical, choose Continuously Molded
What each option means
Vulcanized Viton® Fluorocarbon (FKM) O-Rings
We cut precision FKM cord to length and vulcanize the ends together under heat and pressure. This delivers any inside diameter you need with Viton® chemical and temperature performance.
Continuously or Compression Step-Molded O-Rings
We mold the ring as a single piece in a controlled compression process using step tooling for large diameters. The result is a seamless O-Ring with uniform cross-section and tight tolerances.
Side-by-side comparison
| Attribute | Vulcanized Viton® FKM | Continuously Molded |
|---|---|---|
| Construction | Cut from FKM cord and vulcanized at the joint | One-piece molded, no joint |
| Seam | Single, visible vulcanized joint | Seamless all around |
| Size flexibility | Any ID and cross-section from stock cord sizes | Any ID within mold system capabilities |
| Tooling | No mold required | Custom molding setup required |
| Tolerances | Very good, minor variation at joint | Excellent, highly uniform |
| Strength under motion | Best for static applications | Best for dynamic or high-pressure systems |
| Lead time | Fast for one-offs and small runs | Longer due to molding cycle |
| Cost fit | Cost-effective for prototypes and large IDs in low qty | Cost-effective for critical or higher-qty needs |
When to choose each
Choose Vulcanized Viton® FKM if you need
- A large or uncommon diameter without waiting for a mold
- Quick turnaround for maintenance, MRO, or pilot builds
- A dependable static seal on flanges, lids, manways, or housings
Choose Continuously Molded if you need
- Seamless performance in dynamic motion or pulsing pressure
- The tightest roundness and cross-section uniformity for automation
- Premium integrity for critical service or regulated processes
Application guide
| Use case | Best choice | Why it benefits you |
|---|---|---|
| Tank lids, manways, inspection covers | Vulcanized Viton® | Any size fast, no tooling, great chemical resistance |
| Reciprocating or rotating motion | Continuously Molded | No joint, uniform compression, better durability |
| High pressure or frequent cycling | Continuously Molded | Premium integrity across the full circumference |
| Emergency replacement for a nonstandard ID | Vulcanized Viton® | Same-day or rapid build options to cut downtime |
Material performance
Both builds use Viton® FKM, so you get the same core benefits either way:
- Broad chemical resistance including many fuels, oils, and solvents
- Strong high-temperature performance
- Durable compression set characteristics for long service life
Lead times and ordering basics
- Vulcanized Viton® FKM
Typical lead times
• Up to 24 rings: :: Current Lead Time ~2-5 Days ARO
• 25 to 100 rings: :: Current Lead Time ~5-10 Days ARO
• 100+ rings: :: Current Lead Time ~10-15 Days ARO - Continuously Molded
Made to order. Lead time depends on diameter, cross-section, and quantity. We will quote realistic dates and options to keep your project moving. Typically :: Current Lead Time ~6-8 Weeks ARO
Quality and traceability you can count on
- Olypsys® measurement verification available, so you can document ID and cross-section from your phone or our vision systems
- Release Orders SOP-009.4 for customers who want scheduled releases that protect production lines and prevent stockouts
These are customer-first safeguards. You get the right seal, on time, with documentation that stands up to audits.
FAQs
Will I see the joint on a vulcanized ring
Yes, a small joint line is visible. In static service this does not affect performance when sized and compressed correctly.
Do both options use the same Viton® FKM compound choices
Yes. We will match compound, durometer, and cure requirements to your media and temperature. Certificates available on request.
What if I am unsure which way to go
Tell us your pressure, motion, media, temperature, and target ID and cross-section. We will recommend the safest, most economical path.
What you gain working with The O-Ring Store
- Faster, clearer sizing with Olypsys® measurement support
- Steady supply with Release Orders that lock in your schedule
- Confidence from ISO 9001:2015 systems and documented inspections
Ready to buy or quote
If you already know your size, you can order vulcanized Viton® FKM Online today. Vulcanized Viton® 75 Duro Custom O-Rings
For continuously molded rings or if you want us to validate the spec, send your requirements and we will quote fast.
- Phone Sales 208.413.6377
- Email sales@theoringstore.com
We are a small, responsive team that wins customers from the goliaths by being accurate, fast, and personal. Tell me what you are sealing and your deadline. We will get you the right O-Ring and keep your line running.