O-Ring Engineering Guides
Practical O-ring design guides covering squeeze, gland fill, stretch, extrusion, size measurement, material choice and failure analysis.
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Design fundamentals
10 guidesO-Ring Back-Up Rings Explained
When an O-ring needs an anti-extrusion back-up ring, how pressure direction controls placement, and what changes in groove width and assembly.
Read guideHow to Install an O-Ring Without Damage
A practical O-ring installation procedure covering inspection, lubrication, sharp-edge protection, stretch, twist prevention and post-assembly checks.
Read guideO-Ring Thermal Expansion in Groove Design
How elastomer and metal thermal expansion change O-ring squeeze, stretch and gland fill, with a workflow for hot and cold tolerance checks.
Read guideHow to calculate O-ring groove dimensions
Turn cord diameter and target squeeze into groove depth, width and corner radii, with typical ranges for static and dynamic seals and how fill sets the width.
Read guideO-ring stretch limits: how much is safe
How inner-diameter stretch reduces cross-section and squeeze, the ~5% installed limit for radial seals, and how to check stretch across the tolerance stack.
Read guideO-ring surface finish requirements
Recommended roughness (Ra) for O-ring grooves and sealing faces, why static and dynamic seals differ, and how too rough or too smooth both leak.
Read guideHow to select O-ring hardness (durometer)
How Shore A hardness trades off sealing, extrusion resistance and friction, why higher pressure needs a harder durometer, and typical 70A/80A/90A choices.
Read guide RecommendedWhat is gland fill?
Why an O-ring groove must never be completely filled, how thermal expansion and media swell consume free volume, and how to check gland fill across tolerances.
Read guide RecommendedWhat is O-ring squeeze?
How compression creates and maintains a seal, typical squeeze ranges for static and dynamic O-ring applications, and how to calculate it across tolerances.
Read guideStatic seal vs dynamic seal
Why relative motion changes almost every O-ring design limit: squeeze, surface finish, lubrication and clearance requirements for static versus dynamic service.
Read guideMeasurement and tolerances
2 guidesO-Ring Tolerance Stack-Up for Squeeze and Gland Fill
How O-ring and groove tolerances combine into minimum squeeze, maximum squeeze, stretch and gland fill, with a worked worst-case method.
Read guide RecommendedHow to Measure an O-Ring
Measure O-ring inner diameter, outer diameter and cross-section correctly, convert between them, and match your measurements to AS568 or ISO 3601 standard sizes.
Read guideFailure analysis
2 guidesO-ring compression set: causes and prevention
What compression set is, how it's measured, why heat and over-squeeze make O-rings lose sealing force over time, and how to prevent it by design and material.
Read guideO-ring extrusion failure
How pressure pushes an O-ring into the clearance gap, the three drivers of extrusion risk, and how to prevent nibbling with hardness, gap control and back-up rings.
Read guideMaterials and service
6 guidesO-Ring Color Guide and Material Identification
Why black, brown, green, blue and other O-ring colors cannot reliably prove material, hardness or compound, and how to identify a seal correctly.
Read guideO-Ring Lubrication Guide
How to select and apply an O-ring assembly lubricant without causing elastomer swell, process contamination, seal slip or dynamic wear.
Read guideO-Ring Shelf Life and Storage Guide
How packaging, temperature, ozone, light, deformation and traceability affect O-ring shelf life before installation.
Read guideEPDM chemical compatibility: where it excels and fails
Why EPDM suits water, steam and brake fluid but must never touch petroleum oil or fuel, plus its temperature and weathering strengths.
Read guideFKM vs FFKM: when perfluoroelastomer is worth it
How FFKM (Kalrez-type) differs from FKM on temperature, chemical resistance and cost, and how to decide when the perfluoroelastomer premium is justified.
Read guide RecommendedFKM vs NBR O-rings: how to choose
Compare FKM (Viton) and NBR (nitrile) O-rings by temperature range, chemical and fuel resistance, cost and typical applications, with a quick selection guide.
Read guideStandards and sizes
2 guidesAS568 O-Ring Size Chart Explained
How to read AS568 dash numbers, cross-section series, inside diameter, tolerances and metric conversions without confusing size with material.
Read guideISO 3601 vs AS568 O-Ring Sizes
A practical comparison of ISO 3601 metric O-ring sizes and AS568 inch dash sizes, including cross-sections, tolerances and interchangeability.
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