Plain Washers
Flat annular washers for load distribution, surface protection and hole bridging in bolted joints. Available in MS 4.6, SS 304, High Tensile 200HV, 300HV, Brass and Nylon. DIN 125 · IS 2016. M1.6 to M36 — ready stock Bengaluru.
Material
MS · SS 304 · HT 200HV · HT 300HV · Brass · Nylon
Standard
DIN 125 · IS 2016
Size Range
M1.6 – M36
Overview
What is a Plain Washer?
A plain washer — also called a flat washer — is a flat annular disc placed under a bolt head or nut to distribute the clamping force over a larger bearing area. Without a washer, the bolt head or nut contacts the joint surface over a small annular ring, generating very high local stresses that can crush, embed into, or damage softer materials. The washer spreads this load, protects the surface from rotational damage during tightening, and bridges oversized or irregular holes where the head would otherwise have insufficient bearing area.
RM Traders stocks plain washers to DIN 125 · IS 2016 in six materials — MS 4.6, SS 304, SS 316, High Tensile 200HV, High Tensile 300HV, Brass, and Nylon — covering metric bolt sizes M1.6 to M36.
MS 4.6 — Mild Steel
Standard carbon steel washer for general-purpose use. Suitable under Grade 4.6 bolts and for light-duty assemblies, timber connections, and general fabrication. Available plain or zinc plated (BZP) for basic corrosion protection.
SS 304 — Stainless Steel
Austenitic stainless steel for corrosion-critical, outdoor, and food-adjacent applications. Used in construction, electrical panels, and wherever zinc-plated MS would corrode prematurely. Passivated finish standard.
High Tensile 200HV
For Grade 8.8 Bolts
Hardened to minimum 200 Vickers (≈ 20 HRC). Required under Grade 8.8 bolts — at Grade 8.8 proof loads, a mild steel washer will embed under the bolt head causing loss of bolt preload. The 200HV hardness resists this. Stocked ex-stock for common sizes.
High Tensile 300HV
For Grade 10.9 / 12.9 · Made to Order
Hardened to minimum 300 Vickers (≈ 31 HRC). Mandatory under Grade 10.9 and 12.9 bolts where even a 200HV washer may embed at extreme clamping forces. Available at RM Traders on order with MOQ — contact us for lead time.
Brass
Copper-zinc alloy washers for electrical applications, plumbing, pneumatic fittings, and decorative assemblies. Excellent conductivity, low magnetic permeability, and a premium finish. Corrosion resistant in most mild environments.
Nylon
Plastic washers providing electrical insulation, vibration damping, and chemical resistance. Prevent galvanic corrosion between dissimilar metals. Protect delicate surfaces (aluminium, plastic panels, glass) from metal-to-metal contact marks.
Compliance
Standards & Specifications
Plain washers are manufactured and tested to the following standards covering dimensions, hardness, and surface finish:
- DIN 125 — German standard for plain flat washers. Specifies inner diameter (d1), outer diameter (d2), and thickness (h) for each metric bolt size M1.6 to M36. Form A (normal OD) for general use; Form B (large OD) for softer substrates such as timber, aluminium, and plastic.
- IS 2016 — Bureau of Indian Standards equivalent to DIN 125. Mandated for projects under BIS scope in India. Specifies identical dimensions to DIN 125 for corresponding metric sizes.
- Hardness grades — 200HV minimum recommended for use under Grade 8.8 bolts; 300HV minimum for Grade 10.9 and 12.9 bolts. Soft (MS 4.6) washers are suitable under Grade 4.6 and 5.6 bolts only.
- Product Grade A — Tight dimensional tolerances for sizes M1.6 to M20. Product Grade C (wider tolerances) for larger structural sizes — contact us for availability above M24.
Dimensional Reference
Technical Drawing & Dimensional Tolerances
DIN 125 · IS 2016
Product Grade A
d1 = Inner (bore) diameter · d2 = Outer diameter · h = Thickness · All dimensions in mm per DIN 125.
| Size | For Thread | Inner dia d1 (mm) | Outer dia d2 (mm) | Thickness h (mm) | Weight kg/1000 pcs | |||
|---|---|---|---|---|---|---|---|---|
| min | max | min | max | min | max | |||
| 1.7 | M1.6 | 1.70 | 1.84 | 3.70 | 4.00 | 0.25 | 0.35 | 0.024 |
| 2.2 | M2 | 2.20 | 2.34 | 4.70 | 5.00 | 0.25 | 0.35 | 0.037 |
| 2.7 | M2.5 | 2.70 | 2.84 | 5.70 | 6.00 | 0.45 | 0.55 | 0.088 |
| 3.2 | M3 | 3.20 | 3.38 | 6.64 | 7.00 | 0.45 | 0.55 | 0.119 |
| 3.7 | M3.5 | 3.70 | 3.88 | 7.64 | 8.00 | 0.45 | 0.55 | 0.155 |
| 4.3 | M4 | 4.30 | 4.48 | 8.64 | 9.00 | 0.70 | 0.90 | 0.308 |
| 5.3 | M5 | 5.30 | 5.48 | 9.64 | 10.00 | 0.90 | 1.10 | 0.443 |
| 6.4 | M6 | 6.40 | 6.62 | 11.57 | 12.00 | 1.40 | 1.80 | 1.02 |
| 8.4 | M8 | 8.40 | 8.62 | 15.57 | 16.00 | 1.40 | 1.80 | 1.83 |
| 10.5 | M10 | 10.50 | 10.77 | 19.48 | 20.00 | 1.80 | 2.20 | 3.57 |
| 13.0 | M12 | 13.00 | 13.27 | 23.48 | 24.00 | 2.30 | 2.70 | 6.27 |
| 15.0 | M14 | 15.00 | 15.27 | 27.48 | 28.00 | 2.30 | 2.70 | 8.62 |
| 17.0 | M16 | 17.00 | 17.27 | 29.48 | 30.00 | 2.70 | 3.30 | 11.3 |
| 19.0 | M18 | 19.00 | 19.33 | 33.38 | 34.00 | 2.70 | 3.30 | 14.7 |
| 21.0 | M20 | 21.00 | 21.33 | 36.38 | 37.00 | 2.70 | 3.30 | 17.2 |
| 23.0 | M22 | 23.00 | 23.33 | 38.38 | 39.00 | 2.70 | 3.30 | 18.3 |
| 25.0 | M24 | 25.00 | 25.33 | 43.38 | 44.00 | 3.70 | 4.30 | 32.3 |
| 28.0 | M27 | 28.00 | 28.33 | 49.38 | 50.00 | 3.70 | 4.30 | 42.3 |
| 31.0 | M30 | 31.00 | 31.39 | 55.26 | 56.00 | 3.70 | 4.30 | 53.6 |
| 33.0 | M32 | 33.00 | 33.62 | 58.80 | 60.00 | 4.40 | 5.60 | 77.4 |
| 37.0 | M36 | 37.00 | 37.62 | 64.80 | 66.00 | 4.40 | 5.60 | 92.1 |
All dimensions in mm per DIN 125 / IS 2016 — Product Grade A. d1 = inner (bore) diameter · d2 = outer diameter · h = thickness. Sizes M7, M26, M28, M33, M35 also available — contact us for dimensions. Weight shown for mild steel (7.85 kg/dm³); SS weights approx. 2% higher, Brass approx. 11% higher.
Stock Range
Sizes & Material Availability
Standard stock range by material. All sizes metric coarse pitch per DIN 125 / IS 2016. HT 200HV ex-stock for common sizes; HT 300HV made to order with MOQ.
Plain Washers — Material Availability (DIN 125 / IS 2016)
| Size (For Thread) | MS 4.6 | SS 304 | HT 200HV | HT 300HV | Brass | Nylon |
|---|---|---|---|---|---|---|
| M3 – M5 | ✓ | ✓ | ✓ | On order | ✓ | ✓ |
| M6 | ✓ | ✓ | ✓ | On order | ✓ | ✓ |
| M8 | ✓ | ✓ | ✓ | On order | ✓ | ✓ |
| M10 | ✓ | ✓ | ✓ | On order | ✓ | ✓ |
| M12 | ✓ | ✓ | ✓ | On order | ✓ | ✓ |
| M14 | ✓ | ✓ | ✓ | On order | ✓ | ✓ |
| M16 | ✓ | ✓ | ✓ | On order | ✓ | ✓ |
| M18 – M20 | ✓ | ✓ | ✓ | On order | On order | On order |
| M22 – M24 | ✓ | ✓ | ✓ | On order | On order | On order |
| M27 – M36 | ✓ | ✓ | On order | On order | On order | On order |
Form B (Large OD) also available — DIN 125 large-diameter washers for timber, aluminium and soft-substrate applications. Sizes M4 to M24 in MS; M4 to M16 in SS 304. Enquire for availability and pricing.
Note on 300HV: High Tensile 300HV washers are manufactured to order with MOQ — contact us with bolt grade, size, and quantity for a quotation.
Note on 300HV: High Tensile 300HV washers are manufactured to order with MOQ — contact us with bolt grade, size, and quantity for a quotation.
Use Cases
Applications
Structural Steel & ConstructionUnder bolt heads and nuts in steel frame connections, purlin fixings, base plates, and PEB structures — MS 4.6 or HT 200HV depending on bolt grade.
Precision MachineryHT 200HV or 300HV under Grade 8.8/10.9/12.9 bolts in machine tools, presses, and gearboxes where joint preload must be maintained without washer embedment.
Timber & Civil ConnectionsMS Form B (large OD) washers to distribute load across wood grain in timber framing, roofing purlins, and civil anchor bolt connections.
Marine & CoastalSS 316 plain washers for marine superstructure, pontoon fixings, coastal structural connections, and environments with salt spray or chloride exposure.
Electrical & PlumbingBrass washers on electrical conduit fittings, plumbing connectors, and pneumatic assemblies — good conductivity, corrosion resistance, and premium appearance.
Surface Protection & InsulationNylon washers to protect painted panels, aluminium profiles, and plastic enclosures from contact marks — and to electrically isolate fasteners in sensitive assemblies.
Frequently Asked
Questions
What is a plain washer and what does it do?
A plain washer (also called a flat washer) is a flat annular disc placed under a bolt head or nut before tightening. It serves three functions: (1) Load distribution — spreads the bolt's clamping force over a larger bearing area, preventing the head from sinking into or damaging softer base materials; (2) Gap bridging — covers oversized or irregular holes where the bolt head would have insufficient bearing area; (3) Surface protection — protects painted or finished surfaces from rotational damage during tightening. Manufactured to DIN 125 / IS 2016, stocked in MS, SS 304, HT 200HV, HT 300HV, Brass and Nylon, M1.6 to M36.
What is the difference between DIN 125 and IS 2016?
DIN 125 is the German standard and IS 2016 is the Bureau of Indian Standards equivalent — both specify identical dimensions (d1, d2, h) for each metric bolt size. They are fully interchangeable. IS 2016 is mandated for BIS-regulated projects in India. RM Traders supplies to both standards simultaneously — one product satisfies both.
What is a High Tensile 200HV washer and when should I use it?
A 200HV washer is hardened to a minimum of 200 Vickers (≈ 20 HRC). It is specified for use under Grade 8.8 bolts. At Grade 8.8 proof load (580 MPa), a mild steel washer will plastically deform and embed under the bolt head, causing loss of preload and joint loosening over time. The 200HV hardness prevents this. Using a soft MS washer under an 8.8 bolt is technically incorrect in precision or load-critical assemblies.
What is a High Tensile 300HV washer and when is it required?
A 300HV washer is hardened to a minimum 300 Vickers (≈ 31 HRC). It is mandatory under Grade 10.9 and Grade 12.9 bolts. At these grades, bolt proof loads reach 830–970 MPa — forces high enough to embed even a 200HV washer. At RM Traders, 300HV washers are made to order with MOQ — contact us with your size and quantity requirements.
When should I use Brass or Nylon plain washers?
Brass washers are specified for electrical conduit fittings, plumbing connectors, pneumatic assemblies, and decorative applications where good electrical conductivity, low magnetism, and a premium finish are required. They resist corrosion in mild environments and pair well with brass or copper fittings. Nylon washers provide full electrical insulation, vibration damping, and resistance to many chemicals and solvents. They are used to protect delicate surfaces (aluminium panels, plastic enclosures, glass) from metal contact marks, and to prevent galvanic corrosion between dissimilar metals in mixed assemblies.
Can a plain washer be used as a locking washer?
No. A plain flat washer provides zero locking action — it will not prevent a nut or bolt from loosening under vibration. Its function is load distribution and surface protection only. For vibration resistance, use a nyloc nut (DIN 982), spring washer (DIN 127), thread locker, or lock wire. The correct practice is to use a plain washer in combination with a locking device — the plain washer protects the surface while the nyloc nut or spring washer prevents back-rotation.
What is the difference between DIN 125 Form A and Form B?
DIN 125 Form A has a standard outer diameter for general-purpose steel-to-steel bolted joints. DIN 125 Form B has a significantly larger outer diameter — providing greater bearing area for softer substrates like timber, aluminium, plastic, and thin sheet metal where the bolt head must not pull through or cause surface deformation. RM Traders stocks both forms — contact us for Form B availability in your required size and material.
What size plain washer do I need for my bolt?
Select the washer by its "For Thread" designation matching the bolt's nominal diameter. For an M8 bolt, specify an M8 plain washer (d1 = 8.4–8.62 mm, d2 = 15.57–16 mm, h = 1.4–1.8 mm per DIN 125). The inner diameter d1 is slightly larger than the nominal bolt size for easy assembly. If you have an oversized hole, specify a Form B (large OD) washer. The full dimensional tolerance table for M1.6 to M36 is on this page.
Ready to order?
Need Plain Washers?