--- title: "ISO 7089 Flat Plain Washer (GB/T 95) Specification" description: "ISO 7089 Flat Plain Washer (GB/T 95): full dimensional table with tolerances. DIN, ISO and ASME equivalents listed side by side." url: https://engineeringhardware.com/guide/standard/iso-7089-flat-washers/ source: Engineering Hardware & Fasteners --- # ISO 7089 Flat Plain Washer (GB/T 95) Specification Washers · GB/T 97.1 / ISO 7089 Dimensional table, tolerance classes and the DIN / ISO / ASME parts that supersede or match this standard. ISO 7089 specifies the dimensions and tolerances for flat plain washer (gb/t 95). The full dimensional table is reproduced below, followed by the DIN, ISO and ASME parts that match or supersede it. - **Standard:** ISO 7089 - **Product:** Flat Plain Washer (GB/T 95) — GB/T 97.1 / ISO 7089 (Series 086) - **Governing standards:** GB/T 97.1 / ISO 7089 Equivalence between national standards is dimensional, not always metallurgical. Check the property class separately when substituting. ![ISO 7089 Flat Plain Washer (GB/T 95) Specification reference image](https://engineeringhardware.com/wp-content/uploads/2026/06/Flat-Washers-—-ISO-7089-／-ISO-7093-Detail.webp) ISO 7089 is the standard cited for flat plain washer (gb/t 95). This page sets out what the standard controls for this part, reproduces the dimensional table supplied against it, and notes the related designations referenced on drawings. ## ISO 7089 — Scope ISO 7089 is "Plain washers — Normal series — Product grade A". ## Tolerance & Product Grades ISO 7089 is written to product grade A; a different grade of the same part is a different document in the family, not a variant of this one. ## Dimensions Specified by ISO 7089 | For bolt size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness t (mm) | Reference standard | | --- | --- | --- | --- | --- | | M3 | 3.2 | 7.0 | 0.5 | ISO 7089 / GB/T 97.1 | | M4 | 4.3 | 9.0 | 0.8 | ISO 7089 / GB/T 97.1 | | M5 | 5.3 | 10.0 | 1.0 | ISO 7089 / GB/T 97.1 | | M6 | 6.4 | 12.0 | 1.6 | ISO 7089 / GB/T 97.1 | | M8 | 8.4 | 16.0 | 1.6 | ISO 7089 / GB/T 97.1 | | M10 | 10.5 | 20.0 | 2.0 | ISO 7089 / GB/T 97.1 | | M12 | 13.0 | 24.0 | 2.5 | ISO 7089 / GB/T 97.1 | | M14 | 15.0 | 28.0 | 2.5 | ISO 7089 / GB/T 97.1 | | M16 | 17.0 | 30.0 | 3.0 | ISO 7089 / GB/T 97.1 | | M18 | 19.0 | 34.0 | 3.0 | ISO 7089 / GB/T 97.1 | | M20 | 21.0 | 37.0 | 3.0 | ISO 7089 / GB/T 97.1 | | M24 | 25.0 | 44.0 | 4.0 | ISO 7089 / GB/T 97.1 | | M30 | 31.0 | 56.0 | 4.0 | ISO 7089 / GB/T 97.1 | | M36 | 37.0 | 66.0 | 5.0 | ISO 7089 / GB/T 97.1 | ## Companion Standards ISO 7089 controls the geometry of flat plain washer (gb/t 95) — gb/t 97.1 / iso 7089 (series 086). Surface finish is governed by separate finish standards such as ISO 4042 for electroplating, and corrosion testing by ISO 9227 (neutral salt spray). Mechanical performance is set by the documents specific to this part family — ISO 898-1 and ISO 898-2 apply to bolts, screws, studs and nuts, and not here. ## When to Specify ISO 7089 Choose ISO 7089 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for flat plain washer (gb/t 95) — gb/t 97.1 / iso 7089 (series 086). Custom manufacturing · Made to drawing ## Need a washer to this standard in a non-standard size? Parts built to ISO 7089 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by stamping or punching. Minimum order from 2,000 pieces; samples within 7 days of drawing approval. [Custom washer manufacturing](https://engineeringhardware.com/custom/washers/)[Send a drawing](https://engineeringhardware.com/custom/washers/#rfq) ## Technical Drawing Dimensioned line drawing of M3 Flat Plain Washer (GB/T 95) — GB/T 97.1 / ISO 7089 (Series 086) to GB/T 97.1 / ISO 7089. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Inner diameter d1 (mm):** 3.2 - **Outer diameter d2 (mm):** 7.0 - **Thickness t (mm):** 0.5 ## Dimensions & Specifications (GB/T 97.1 / ISO 7089) | For bolt size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness t (mm) | Reference standard | | --- | --- | --- | --- | --- | | M3 | 3.2 | 7.0 | 0.5 | ISO 7089 / GB/T 97.1 | | M4 | 4.3 | 9.0 | 0.8 | ISO 7089 / GB/T 97.1 | | M5 | 5.3 | 10.0 | 1.0 | ISO 7089 / GB/T 97.1 | | M6 | 6.4 | 12.0 | 1.6 | ISO 7089 / GB/T 97.1 | | M8 | 8.4 | 16.0 | 1.6 | ISO 7089 / GB/T 97.1 | | M10 | 10.5 | 20.0 | 2.0 | ISO 7089 / GB/T 97.1 | | M12 | 13.0 | 24.0 | 2.5 | ISO 7089 / GB/T 97.1 | | M14 | 15.0 | 28.0 | 2.5 | ISO 7089 / GB/T 97.1 | | M16 | 17.0 | 30.0 | 3.0 | ISO 7089 / GB/T 97.1 | | M18 | 19.0 | 34.0 | 3.0 | ISO 7089 / GB/T 97.1 | | M20 | 21.0 | 37.0 | 3.0 | ISO 7089 / GB/T 97.1 | | M24 | 25.0 | 44.0 | 4.0 | ISO 7089 / GB/T 97.1 | | M30 | 31.0 | 56.0 | 4.0 | ISO 7089 / GB/T 97.1 | | M36 | 37.0 | 66.0 | 5.0 | ISO 7089 / GB/T 97.1 | ## Materials & Grades Select a material class to see the grades we supply it in. Each designation is listed with its ISO/EN, AISI/SAE, JIS and GB equivalents. Stainless Steel38 Carbon Steel66 Alloy Steel41 Bearing Steel5 Spring Steel25 Aluminum and Aluminum Alloys21 Brass17 Bronze11 Copper8 Titanium and Titanium Alloys18 Nickel and Nickel Alloys22 Iron-Nickel and High-Temperature Alloys10 Tool Steel and Specialty Hardened Steel9 Structural and Construction Steel9 ### Stainless Steel #### Austenitic Stainless Steel - A1 AISI 303 · SAE 303 · SUS303 · EN 1.4305 · X8CrNiS18-9 - A2 AISI 304 · SAE 304 · SUS304 · EN 1.4301 · X5CrNi18-10 · 06Cr19Ni10 - 304L AISI 304L · SUS304L · EN 1.4307 · X2CrNi18-9 · 022Cr19Ni10 - 302 AISI 302 · SUS302 · EN 1.4310 - 305 AISI 305 · SUS305 · EN 1.4303 - A4 AISI 316 · SAE 316 · SUS316 · EN 1.4401 · X5CrNiMo17-12-2 · 06Cr17Ni12Mo2 - 316L AISI 316L · SUS316L · EN 1.4404 · X2CrNiMo17-12-2 · 022Cr17Ni12Mo2 - 321 AISI 321 · SUS321 · EN 1.4541 · X6CrNiTi18-10 - 310 / 310S AISI 310 · AISI 310S · SUS310S · EN 1.4845 - 302HQ AISI 302HQ - A3 - A5 - 347 AISI 347 · SUS347 · EN 1.4550 · X6CrNiNb18-10 - 309 / 309S AISI 309 · AISI 309S · SUS309S #### Martensitic Stainless Steel - AISI 410 SUS410 · EN 1.4006 · X12Cr13 · 12Cr13 - AISI 420 SUS420J1 · SUS420J2 · EN 1.4021 · EN 1.4028 · 20Cr13 · 30Cr13 - AISI 431 SUS431 · EN 1.4057 · X17CrNi16-2 - C1 - C3 - C4 - AISI 440A - AISI 440B - AISI 440C SUS440C · EN 1.4125 #### Ferritic Stainless Steel - AISI 430 SUS430 · EN 1.4016 · X6Cr17 · 10Cr17 - F1 - AISI 434 - AISI 444 #### Precipitation-Hardening Stainless Steel - 17-4 PH AISI 630 · UNS S17400 · SUS630 · EN 1.4542 · X5CrNiCuNb16-4 - 15-5 PH UNS S15500 - 17-7 PH UNS S17700 #### Duplex and Super Duplex Stainless Steel - Duplex 2205 UNS S31803 · UNS S32205 · EN 1.4462 - Super Duplex 2507 UNS S32750 · EN 1.4410 - D2 - D4 - D6 - D8 - Lean Duplex 2101 UNS S32101 - Super Duplex S32760 UNS S32760 · EN 1.4501 ### Carbon Steel #### Low-Carbon Steel - SAE 1006 - SAE 1008 - SAE 1010 - SAE 1018 - SAE 1020 - Q195 - Q235 - SAE 1012 - SAE 1015 - Q215 - ML08 - ML08Al - ML10 - ML15 - ML20 - SWRCH6A - SWRCH8A - SWRCH10A - SWRCH12A - SWRCH15A - SWRCH18A #### Medium-Carbon Steel - SAE 1035 - SAE 1045 - S45C - C45 - SAE 1030 - SAE 1040 - SAE 1050 - 30 - 35 - 40 - 45 - 50 - S35C - S40C - S50C - C35 - C40 #### High-Carbon Steel - SAE 1060 - SAE 1070 - 65Mn - SAE 1065 - SAE 1075 - SAE 1080 - SAE 1085 - SAE 1090 - SAE 1095 - 60 - 65 - 70 - 75 - 80 - 85 #### Cold-Heading Steel - SWRCH22A - 10B21 - SWRCH22K - SWRCH25K - SWRCH30K - SWRCH35K - SWRCH40K - ML20Mn - ML25 - ML30 - ML35 - ML40 - 15B25 ### Alloy Steel #### Chromium Steel - 40Cr - 45Cr - AISI 5140 - SAE 5140 - AISI 5120 - SAE 5120 - SCr420 - SCr440 #### Chromium-Molybdenum Steel - 35CrMo - 42CrMo - AISI 4140 - SCM435 - SCM440 - 42CrMo4 - 30CrMo - AISI 4130 - SAE 4130 - SAE 4140 - AISI 4142 - AISI 4145 - SCM415 - SCM420 - SCM445 - EN 1.7220 - EN 1.7225 - 25CrMo4 - 34CrMo4 #### Nickel-Chromium-Molybdenum Steel - AISI 4340 - SAE 4340 - 40CrNiMo - SNCM439 - EN 1.6511 - 36CrNiMo4 #### Boron Alloy Steel - 10B22 - 10B21 - 15B21 - 15B25 - 20MnTiB - 20Mn2B - 35VB - 40MnB ### Bearing Steel #### Bearing Steel - GCr15 - AISI 52100 SAE 52100 · UNS G52986 - SUJ2 - 100Cr6 EN 1.3505 - GCr15SiMn ### Spring Steel #### Carbon Spring Steel - SAE 1065 - SAE 1070 - SAE 1075 - SAE 1080 - SAE 1095 - 65 - 70 - 75 - 80 - 65Mn #### Silicon-Manganese Spring Steel - 60Si2Mn - 60Si2MnA - SUP6 - SUP7 #### Chromium-Vanadium Spring Steel - 50CrVA - SAE 6150 - AISI 6150 - SUP10 #### Stainless Spring Steel - AISI 301 - SUS301 - EN 1.4310 - AISI 302 - AISI 304 - AISI 316 - 17-7 PH ### Aluminum and Aluminum Alloys #### Commercially Pure Aluminum - 1050 - 1060 - 1070 - 1100 #### 2xxx Series Aluminum - 2024 - 2011 - 2014 - 2017 #### 5xxx Series Aluminum - 5052 - 5083 - 5754 #### 6xxx Series Aluminum - 6061 - 6061-T6 - 6063 - 6082 - 6082-T6 #### 7xxx Series Aluminum - 7075 - 7075-T6 - 7005 - 7050 - 7075-T73 ### Brass #### Free-Cutting Brass - C36000 - H62 - HPb59-1 - C3601 - C3602 - C3604 - CuZn36Pb3 - CuZn39Pb3 - EN CW614N - EN CW617N - H65 #### Lead-Free Brass - C69300 - C27450 - CW510L - CW511L #### Naval Brass - C46400 - CuZn39Sn1 ### Bronze #### Silicon Bronze - C65500 - C65100 - C65600 #### Phosphor Bronze - C51000 - C52100 - CuSn6 - CuSn8 #### Aluminum Bronze - C95400 - C95500 - C63000 - CuAl10Ni5Fe4 ### Copper #### Copper - C11000 - T2 - C10100 - C10200 - C12200 - T1 - TU1 - TU2 ### Titanium and Titanium Alloys #### Commercially Pure Titanium - Grade 2 - Grade 1 - Grade 3 - Grade 4 - TA1 - TA2 - TA3 #### Alpha-Beta Titanium Alloys - Grade 5 - Ti-6Al-4V - TC4 - UNS R56400 #### Low-Interstitial Grade - Grade 23 - Ti-6Al-4V ELI - UNS R56407 #### Other Titanium Fastener Alloys - Ti-6Al-6V-2Sn - Ti-6Al-2Sn-4Zr-2Mo - Beta-C titanium - Ti-10V-2Fe-3Al ### Nickel and Nickel Alloys #### Commercially Pure Nickel - Nickel 200 - UNS N02200 - Nickel 201 - UNS N02201 #### Inconel Alloys - Inconel 625 UNS N06625 - Inconel 718 UNS N07718 - Inconel 600 UNS N06600 - Inconel 601 UNS N06601 - Inconel 686 UNS N06686 - Inconel X-750 UNS N07750 #### Monel Alloys - Monel 400 UNS N04400 - Monel K-500 UNS N05500 #### Hastelloy Alloys - Hastelloy C-276 UNS N10276 - Hastelloy C-22 UNS N06022 - Hastelloy B-2 UNS N10665 - Hastelloy B-3 UNS N10675 - Hastelloy X UNS N06002 #### Other Nickel Alloys - Alloy 20 UNS N08020 - Alloy 625 - Alloy 718 - Alloy 825 UNS N08825 - Alloy 925 UNS N09925 ### Iron-Nickel and High-Temperature Alloys #### A286 - A-286 - UNS S66286 - EN 1.4980 #### Invar - Invar 36 - Alloy 36 - UNS K93600 - FeNi36 #### Alloy 42 - Alloy 42 - UNS K94100 - FeNi42 ### Tool Steel and Specialty Hardened Steel #### Tool Steel and Specialty Hardened Steel - AISI D2 - AISI H13 - SKD11 - Cr12MoV - AISI O1 - AISI A2 - AISI S7 - SKD61 - 9CrSi ### Structural and Construction Steel #### Structural and Construction Steel - ASTM A36 - Q235B - Q355B - S355JR - Q235C - Q355C - S235JR - S275JR - S355J2 ## Applications & Industries The sectors that buy Flat Plain Washer to GB/T 97.1 / ISO 7089, and the duty each one buys them for. Stocked from M3 to M36 (nominal bolt size). ### Industries that specify Flat Plain Washer - **Machine building & OEM:** Setting bearing area on soft alloy, plastic and oversized holes. - **Timber & construction:** Large-diameter washers that stop pull-through in softer material. - **Rotating & vibrating plant:** Spring, tooth and wedge types that maintain or lock bolt tension. - **Steel fabrication:** Spreading load under a head or nut and protecting the surface finish. ### Typical applications - maintaining bolt tension in a joint that settles - spreading clamp load over a soft or oversized bearing face - protecting a painted or plated surface under a turned nut ### Service conditions to specify against - **Marine and coastal:** Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit. - **Hardness matters:** Under a high-strength bolt a soft washer embeds into the joint and preload is lost — specify a hardened washer for structural bolting. [Full application guide: where Flat Plain Washer are used, how to specify them, and the cases they are wrong for](https://engineeringhardware.com/applications/cad-svg-086-washer/) 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 ### What product grades does ISO 7089 define? ISO 7089 is written to product grade A; a different grade of the same part is a different document in the family, not a variant of this one. ### Does ISO 7089 specify the mechanical strength? No. ISO 7089 controls the dimensional requirements for flat plain washer (gb/t 95) — gb/t 97.1 / iso 7089 (series 086). Mechanical performance is set by the documents specific to this part family — ISO 898-1 and ISO 898-2 apply to bolts, screws, studs and nuts, and not to this product. ### Can I substitute ISO 7089 for the corresponding DIN standard on a drawing? On modern drawings the ISO standard is the master reference; the older DIN equivalent is a cross-reference. For most dimensional purposes the parts are interchangeable, but check tolerance grades and the head height — these are the most common points of divergence. ### Which edition of ISO 7089 does this table follow? The table reproduces the dimensions we supply flat plain washer (gb/t 95) — gb/t 97.1 / iso 7089 (series 086) to. We do not publish an edition year against it, so where the edition is contractually significant, cite the edition you require on the enquiry and we will confirm it against the table before quoting. ### How do I request a quotation? Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day. ## Related Pages [View the full Flat Plain Washer (GB/T 95) — GB/T 97.1 / ISO 7089 (Series 086) page](https://engineeringhardware.com/fastener/cad-svg-086-washer/) ### More Flat Plain Washer (GB/T 95) — GB/T 97.1 / ISO 7089 (Series 086) Guides