--- title: "Metric O-Rings (ISO 3601)" description: "Metric O-Rings (ISO 3601) to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections): full dimensional table." url: https://engineeringhardware.com/fastener/metric-o-rings/ source: Engineering Hardware & Fasteners --- # Metric O-Rings (ISO 3601) Seals · Metric O-Rings 11 catalogued sizes, dimensioned to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). Pick any row and the technical drawing redraws to it. Metric O-Rings (ISO 3601) to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections): the full dimensional table is reproduced below. 11 sizes are held in the table below, and the technical drawing redraws to whichever row you select. - **Standard:** ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections) - **Catalogued sizes:** 11 Dimensions are nominal values from the governing standard. Confirm the tolerance class for your application before ordering. ![Metric O-Rings (ISO 3601) technical product image](https://engineeringhardware.com/wp-content/uploads/2026/09/Metric-O-Rings.webp) Product catalog ## Related Metric O-Rings products [![Cute Bear Ultra Fine Soft Bristle Brush Baby Nail Seams Deep Cleaning Hands Washing Brush](https://img.engineeringhardware.com/Cute-Bear-Ultra-Fine-Soft-Bristle-Brush-Baby-Nail-Seams-Deep-Cleaning-Hands-Washing-Brush.webp)](https://engineeringhardware.com/product/cute-bear-ultra-fine-soft-bristle-brush-baby-nail-seams-deep-cleaning-hands-washing/) Common, Ring-Shank & Specialty Nails ### [Cute Bear Ultra Fine Soft Bristle Brush Baby Nail Seams Deep Cleaning Hands Washing Brush](https://engineeringhardware.com/product/cute-bear-ultra-fine-soft-bristle-brush-baby-nail-seams-deep-cleaning-hands-washing/) Soft Bristle Brush · ABS+Soft Bristle **US$0.84 – 1.86**MOQ 100 pieces [![Hot Sale U Type Nail with Different Size](https://img.engineeringhardware.com/Hot-Sale-U-Type-Nail-with-Different-Size.webp)](https://engineeringhardware.com/product/hot-sale-u-type-nail-with-different-size/) Common, Ring-Shank & Specialty Nails ### [Hot Sale U Type Nail with Different Size](https://engineeringhardware.com/product/hot-sale-u-type-nail-with-different-size/) U-Type Nail · ANSI, DIN, ISO **US$840.00**MOQ 1 ton [![N-4 12.5-23mm White Color Denim Buttons Engraved Letter Logo Durable Brass Jeans Buttons with Aluminum Arrow Tack](https://img.engineeringhardware.com/N-4-12-5-23mm-White-Color-Denim-Buttons-Engraved-Letter-Logo-Durable-Brass-Jeans-Buttons-with-Aluminum-Arrow-Tack.webp)](https://engineeringhardware.com/product/n-4-12-5-23mm-white-color-denim-buttons-engraved-letter-logo-durable-brass-jeans/) Common, Ring-Shank & Specialty Nails ### [N-4 12.5-23mm White Color Denim Buttons Engraved Letter Logo Durable Brass Jeans Buttons with Aluminum Arrow Tack](https://engineeringhardware.com/product/n-4-12-5-23mm-white-color-denim-buttons-engraved-letter-logo-durable-brass-jeans/) Jeans Button · Metal **US$0.036 – 0.16**MOQ 5,000 pieces [![19X30common Nails Carton Packing, 1″ 2″ 3″ 4″ 5″](https://img.engineeringhardware.com/19X30common-Nails-Carton-Packing-1-2-3-4-5.webp)](https://engineeringhardware.com/product/19x30common-nails-carton-packing-1-2-3-4-5/) Common, Ring-Shank & Specialty Nails ### [19X30common Nails Carton Packing, 1″ 2″ 3″ 4″ 5″](https://engineeringhardware.com/product/19x30common-nails-carton-packing-1-2-3-4-5/) Common Nail · ISO **US$780.00**MOQ 5 tons [![Ring Shank Annular Shank Nail HDG Hot DIP Galvanized Common Nails](https://img.engineeringhardware.com/Ring-Shank-Annular-Shank-Nail-HDG-Hot-DIP-Galvanized-Common-Nails.webp)](https://engineeringhardware.com/product/ring-shank-annular-shank-nail-hdg-hot-dip-galvanized-common-nails/) Common, Ring-Shank & Specialty Nails ### [Ring Shank Annular Shank Nail HDG Hot DIP Galvanized Common Nails](https://engineeringhardware.com/product/ring-shank-annular-shank-nail-hdg-hot-dip-galvanized-common-nails/) Common Nail · DIN, GB **US$720.00 – 780.00**MOQ 1 ton [![Polished Hardened Good Quality Common Nail 2.5 Inch](https://img.engineeringhardware.com/Polished-Hardened-Good-Quality-Common-Nail-2-5-Inch.webp)](https://engineeringhardware.com/product/polished-hardened-good-quality-common-nail-2-5-inch/) Common, Ring-Shank & Specialty Nails ### [Polished Hardened Good Quality Common Nail 2.5 Inch](https://engineeringhardware.com/product/polished-hardened-good-quality-common-nail-2-5-inch/) Common Nail · ANSI, DIN, GB, ISO, JIS **US$720.00 – 960.00**MOQ 20 tons [View all Common, Ring-Shank & Specialty Nails →](https://engineeringhardware.com/fastener-products/nails-staples-tacks/common-ring-shank-specialty-nails/) [Full product catalog](https://engineeringhardware.com/products/) ## Applications & Industries Where Metric O-Rings are used, and what decides the specification in each case. Stocked from 1.0 to 6.0 (inside diameter). ### Industries that specify Metric O-Rings - **Hydraulics:** Port, cover and piston seals. - **Pneumatics:** Cylinder and valve seals. - **Food and beverage:** EPDM and silicone compounds. - **Chemical plant:** FKM for aggressive media. - **Hydraulics & pneumatics:** Static and dynamic sealing in cylinders and valve bodies. - **Process & food equipment:** Sealing at joints that are cleaned and inspected. ### Typical applications - specifying inside diameter, cross-section and compound together - matching the compound to the fluid and the temperature - checking the groove dimensions give the right squeeze - using a back-up ring at high pressure - sealing a joint against fluid or air pressure - excluding dust and moisture from a housing ### Service conditions to specify against - **Sealed joints:** Used where the fixing has to keep water or air out as well as hold — the elastomer, not the fastener, decides service life. ### Where to use something else - Do not substitute an NBR ring for an FKM one because the dimensions match; the size fits and the compound fails, which looks like a leak with no cause. [Full application guide: where Metric O-Rings are used, how to specify them, and the cases they are wrong for](https://engineeringhardware.com/applications/metric-o-rings/) ## Technical Drawing Dimensioned line drawing of 1.0 Metric O-Rings (ISO 3601) to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Typical inside-diameter range (mm):** 1.0 – 20 - **Common compounds:** NBR, FKM, EPDM, silicone - **Notes:** miniature and pneumatic ## Dimensions & Specifications (ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections)) Every row below is a starting point for the customizer above — pick any size and the drawing will redraw to that row. | Cross-section (mm) | Typical inside-diameter range (mm) | Common compounds | Notes | | --- | --- | --- | --- | | 1.0 | 1.0 – 20 | NBR, FKM, EPDM, silicone | miniature and pneumatic | | 1.5 | 2.0 – 40 | NBR, FKM, EPDM, silicone | small pneumatic and instrument | | 1.78 | 1.78 – 50 | NBR, FKM, EPDM | nearest metric equivalent to the 1/16 in section | | 2.0 | 3.0 – 100 | NBR, FKM, EPDM, silicone | general hydraulic and pneumatic | | 2.5 | 5.0 – 150 | NBR, FKM, EPDM | general hydraulic | | 3.0 | 6.0 – 200 | NBR, FKM, EPDM | general hydraulic | | 3.5 | 10 – 250 | NBR, FKM | hydraulic | | 4.0 | 12 – 300 | NBR, FKM | hydraulic and larger flanges | | 5.0 | 20 – 400 | NBR, FKM | large flanges and covers | | 5.33 | 20 – 400 | NBR, FKM | nearest metric equivalent to the 3/16 in section | | 6.0 | 25 – 500 | NBR, FKM | large covers and housings | Metric O-Rings (ISO 3601) are seals manufactured to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). This page lists the full dimensional range with the key specifications engineers need to select and specify them. ## What Are Metric O-Rings (ISO 3601)? Metric O-Rings (ISO 3601) are seals defined by ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). They are selected by inside diameter and the dimensional characteristics shown below, and are available in a range of materials and finishes to suit the application and environment. ## Materials & Finishes O-rings and seals are specified by elastomer, not by steel grade: NBR (nitrile) for mineral oil and hydraulic service, FKM for higher temperature and aggressive chemistry, EPDM for water, steam and weathering, silicone for a wide temperature range in static duty, and PTFE where chemical resistance outweighs elastic recovery. Specify the compound, the hardness in Shore A and the temperature range alongside the dimensions. ## Specification Guides Each size, material and standard of Metric O-Rings (ISO 3601) has its own reference page with the figures for that one configuration. ## Goes With Hardware commonly specified alongside Metric O-Rings (ISO 3601). ## Pricing Metric O-Rings (ISO 3601) are supplied to order. Pricing starts from approximately US$0.050 per piece for standard sizes in standard nitrile (NBR) 70 Shore A; final pricing depends on size, material, finish and order quantity (MOQ applies). Submit your exact configuration with the quote form above. Custom manufacturing · Made to drawing ## Need a metric o-rings (iso 3601) outside the standard range? Inside diameter, cross-section and compound are the three that matter, and the compound is chosen against the fluid and the temperature rather than the dimensions. Minimum order from 2,000 pieces; samples within 7 days of drawing approval. [Custom seal manufacturing](https://engineeringhardware.com/custom/seals/)[Send a drawing](https://engineeringhardware.com/custom/seals/#rfq) Inside the plant ## Manufactured in our own plant This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided. 1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift. 2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g. 3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1. 4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227. ## Frequently Asked Questions ### Which standard governs Metric O-Rings (ISO 3601)? Metric O-Rings (ISO 3601) are manufactured to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). The dimensional values on this page follow that standard. ### Which sizes of Metric O-Rings (ISO 3601) does Engineering Hardware supply? The table on this page lists 11 sizes for Metric O-Rings (ISO 3601), ranging from 1.0 to 6.0. Sizes outside the table can be quoted on request. ### In which materials are Metric O-Rings (ISO 3601) supplied? Metric O-Rings (ISO 3601) are supplied in NBR (nitrile), FKM, EPDM, silicone and PTFE, selected by fluid and temperature, with finishes including zinc plating, hot-dip galvanizing and black oxide. Choose material and finish to suit the load and the service environment for Metric O-Rings (ISO 3601). ### How do I request a quotation? Use the parametric drawing on this page to set the exact configuration (size, material, finish) and click "Request this configuration" — a specialist from Engineering Hardware will respond within one business day.