Washers · DIN 125
DIN 125 Plain Washer
The DIN 125 plain washer is a flat annular disc used to distribute bearing load and protect mating surfaces in bolted assemblies. Accurate Fastners manufactures and supplies these washers in stainless steel grades SS 202, SS 304 and SS 316 across a diameter range of M2 to M36.
- Standard
- DIN 125
- Grades
- 304 / 316 / 202
- Size
- M2 – M36
- Length
- —
Overview
What is the DIN 125 Plain Washer?
DIN 125 is a German industrial standard that defines the dimensional and geometric requirements for plain washers used beneath bolt heads and nuts. The standard specifies outer diameter, inner diameter and thickness relative to the nominal thread size, ensuring consistent load distribution across a broad range of bolted joint configurations. Washers produced to this standard are widely recognised and interchangeable with components sourced to the same specification from other manufacturers.
The DIN 125 plain washer takes the form of a flat annular disc — a simple ring with a precisely punched or machined central bore sized to accept a specific bolt diameter. Its flat bearing faces spread the clamping force of a tightened fastener over a larger surface area than the bolt head or nut alone would cover. This reduces surface pressure on the joint material, helping to prevent the fastener from pulling through or embedding into softer substrates over time.
What distinguishes the DIN 125 plain washer from heavier washer types is its defined, moderate thickness combined with closely controlled inner and outer diameters. The standard covers two form variants — Form A (finer tolerances) and Form B (larger outer diameter) — allowing engineers to select the appropriate geometry for the joint at hand. Accurate Fastners produces these washers in stainless steel, providing resistance to corrosion that makes them suitable for environments where carbon steel washers may degrade.
In Depth
Product description
Construction and Geometry
Each DIN 125 plain washer consists of a flat annular disc with a central bore, uniform thickness, and smooth parallel bearing faces. The inner bore is sized to provide clearance for the corresponding bolt shank, while the outer diameter is standardised to spread load predictably. Accurate Fastners produces these washers in SS 202, SS 304 and SS 316, covering nominal thread sizes from M2 through to M36.
The flat geometry requires consistent material thickness and flatness across the disc. In stainless steel production, the washer is typically formed by blanking or stamping from sheet or strip stock, followed by any required surface finishing. The annular form offers no sharp directional load path, distributing compressive stress radially and evenly beneath the seating face of the bolt head or nut.
Functional Behaviour in an Assembly
When a bolt is tightened, the washer sits between the bolt head or nut and the joint surface. It transmits the clamping force across its full bearing face rather than concentrating it on the smaller area of the fastener head. This load spreading may reduce localised indentation of the substrate, particularly in materials with moderate surface hardness, and helps maintain clamp load over the service life of the joint.
A plain washer also provides a consistent, smooth bearing surface for the rotating nut or bolt head during installation, which can reduce galling — a concern particularly relevant to stainless steel fasteners. In corrosive environments, using a stainless washer of a compatible grade alongside stainless bolts and nuts helps avoid galvanic incompatibility and ensures the joint remains serviceable without premature corrosion-related loosening.
Comparison with Similar Washer Types
The DIN 125 plain washer is distinguished from a spring washer, which is split and angled to provide axial spring force against loosening; from a locking washer, which incorporates serrations or teeth; and from a DIN 9021 large-series washer, which offers a significantly wider outer diameter for use against very soft or thin materials. The DIN 125 is a general-purpose flat washer suited to standard bolted joints.
Compared with an ISO 7089 washer — a comparable international specification — DIN 125 washers may differ slightly in outer diameter and hardness requirements depending on the size and form variant. Buyers familiar with ISO or BS washer specifications should confirm dimensional equivalence before substituting, particularly where close geometric tolerances are a consideration. Accurate Fastners' sales team can assist with dimensional cross-referencing on enquiry.
Material & Grade
Material and grade information
- SS 304
- SS 316
- SS 202
Accurate Fastners supplies DIN 125 plain washers in three stainless steel grades: SS 202, SS 304 and SS 316. SS 304 is an austenitic grade that generally offers good corrosion resistance in a wide range of non-aggressive environments and is commonly used in food and beverage processing, water treatment equipment and general industrial applications. SS 316 contains molybdenum, which typically provides enhanced resistance to chloride-containing environments compared with SS 304.
SS 202 is a lower-nickel austenitic grade that may be considered where cost is a primary factor and the operating environment is relatively mild. While it offers moderate corrosion resistance, it is generally regarded as less resistant than SS 304 in demanding conditions. Grade selection should take into account the specific chemical exposure, temperature range and service conditions of the application. Customers are encouraged to discuss grade suitability with Accurate Fastners' technical team before placing an order.
Grades shown are those documented for this product in the Accurate Fastners brochure. General material notes are guidance only; confirm grade selection for your environment.
Technical Data
Technical specifications
| Product type | Washer – DIN 125 Plain Washer |
|---|---|
| Material | Stainless steel |
| Material grade | SS 304, SS 316, SS 202 |
| Applicable standard | DIN 125 |
| Nominal diameter / size | M2 – M36 |
| Head / form | Flat annular disc |
Sizes
Available sizes
Documented size range
M2 – M36
Documented length range
Not applicable
Individual sizes within the documented range, thread pitches and lengths are confirmed at quotation stage.
Applications
Industrial applications
RO Water Purification Systems
Plain washers in SS 304 or SS 316 may be used in frame assemblies and pipe clamp joints within RO water purifier systems, where moisture exposure is continuous and corrosion resistance of the fastener assembly is a practical requirement.
Submersible Pump Assemblies
DIN 125 washers help distribute clamping loads at flanged joints and motor housing connections in submersible pump builds, where fasteners are typically exposed to water or damp underground environments over extended service periods.
Solar Energy Mounting Structures
In solar panel mounting systems, plain washers spread bolt loads across aluminium or steel structural members, helping to protect relatively soft profiles from indentation and maintaining clamp force in outdoor, weather-exposed installations.
Food and Beverage Processing Equipment
SS 316 DIN 125 washers may be specified in food and beverage machinery where contact with wash-down fluids or mild chemical sanitisers is anticipated, and where non-contaminating stainless surfaces are a general hygiene consideration.
Pharmaceutical Machinery
Pharmaceutical equipment assemblies may utilise stainless DIN 125 washers at panel, guard and frame joints where smooth, corrosion-resistant fastener components are preferred to support cleanroom and washdown environment requirements.
Featured for: RO Water Purifier, Solar Energy, Food & Beverage, Pharmaceutical Machinery
Features & Selection
Features and selection considerations
Design features
DIN 125 Standard Compliance
Washers are produced to the DIN 125 specification, providing standardised inner bore, outer diameter and thickness dimensions that are consistent and interchangeable with other DIN 125-compliant components in a bolted assembly.
Wide Diameter Range
Available from M2 to M36, the range covers fine instrument-scale joints through to heavy structural connections, allowing procurement of a consistent stainless product type across varied project requirements.
Flat Annular Disc Form
The flat disc geometry provides uniform bearing contact beneath bolt heads and nuts, distributing clamping force evenly and helping to reduce localised surface stress on the joint material during and after tightening.
Three Stainless Steel Grades
SS 202, SS 304 and SS 316 grades are offered, enabling grade selection based on corrosion environment, chemical exposure and budget, with guidance available from Accurate Fastners' sales team on request.
Quality Checks at Procurement and Delivery
Accurate Fastners' quality control team performs checks at both the procurement and delivery stages, providing a documented review of product consistency before washers are dispatched to customers.
Before you order
Nominal Thread Diameter
Select the washer by the nominal bolt diameter — for example, an M10 washer pairs with an M10 bolt. Confirm that the inner bore clearance suits the bolt shank tolerance used in your assembly, particularly for precision fits.
Grade Selection for Environment
Match the stainless grade to the service environment. SS 316 is typically preferred in chloride or marine-influenced conditions; SS 304 suits many general industrial uses; SS 202 may be considered for mild, dry or indoor environments.
Mating Fastener Compatibility
Ensure the washer grade is compatible with the bolt and nut grades being used. Using the same or closely matched stainless grades across the joint assembly helps reduce the risk of galvanic corrosion or differential surface degradation.
Quantity and Documentation
For large-volume orders, specify quantity, nominal size, grade and any required dimensional documentation at the time of enquiry. Accurate Fastners' quality control process supports supply with appropriate checks at procurement and delivery stages.
FAQs
Frequently asked questions
What is the DIN 125 standard and what does it specify for plain washers?
DIN 125 is a German industrial standard that defines the inner bore, outer diameter and thickness of plain washers relative to nominal bolt size. It covers two form variants and is widely used as a reference specification for general-purpose flat washers in industrial assemblies globally.
Which stainless steel grades does Accurate Fastners offer for DIN 125 plain washers?
Accurate Fastners supplies DIN 125 plain washers in SS 202, SS 304 and SS 316. Each grade offers a different level of corrosion resistance and price point. The sales team can advise on the most appropriate grade for your specific service conditions on enquiry.
What size range is available for these washers?
DIN 125 plain washers from Accurate Fastners are available in nominal thread sizes from M2 to M36. This range covers small instrument and electronics assemblies at the lower end through to larger structural and industrial bolted joints at the upper end.
Can DIN 125 washers be used with other DIN-series bolts and nuts?
Yes, DIN 125 plain washers are commonly used alongside DIN-series bolts, screws and nuts. The inner bore is sized to provide clearance for the corresponding bolt diameter. Accurate Fastners also supplies a range of complementary fasteners; contact the sales team for matched sets.
Are these washers suitable for outdoor or corrosive environments?
SS 304 and SS 316 stainless steel washers may offer meaningful corrosion resistance in many outdoor or humid environments. SS 316 is generally preferred where chloride exposure is present. Suitability for any specific environment should be confirmed with Accurate Fastners' team before procurement.
How can I request a quotation for DIN 125 plain washers?
Quotations can be requested by completing the enquiry form on the Accurate Fastners website, by emailing export@accuratefastners.com, or via WhatsApp. Please include the nominal size, grade, quantity and any dimensional or documentation requirements to receive an accurate response promptly.
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