304 (A2) · 316 (A4) · Spring Steel
Spring Washer
Helical spring lock washers that keep tension on a joint to resist vibration loosening.
About the Spring Washer
Spring washers, or split lock washers, flatten under a nut or bolt head and bite into both faces to resist the turn that loosens a nut, on machinery, equipment and everyday bolted repairs. They come in flat or square section, in spring steel that is zinc plated, zinc yellow or hot dip galvanised, or 304 and 316 stainless, from M3 to M36 and 1/8 to 1-1/2 inch, plus hardened Neptune 316 spring washers for Neptune bolts and 316 volute spring washers. Choose the size, section and finish above; the guide below covers which side to fit it and flat or square section.
Also called split lock washers or split washers.
Features
- Maintains tension against vibration
- Flat- and square-section profiles
- Zinc-plated and stainless
- Metric and imperial
Applications
- Under nuts and bolt heads on machinery and equipment
- Repairs where the original joint had a spring washer
- Neptune 316 stainless bolts (Neptune spring washers)
How spring washers (split lock washers) work
A spring washer is a hardened ring of spring steel or stainless, split and twisted slightly out of flat. Hobson's washer guide describes it as the first washer made to stop bolted joints loosening: as the joint is tightened the washer flattens, its spring resists the compression and the corners of the split bite into the nut or head and the joint face, resisting the anticlockwise turn that loosens a nut, much like a ratchet.
Hobson notes split washers do not show when a bolt has been over-tightened. Other ways to lock a joint include nyloc nuts and two-piece wedge locking washers.
Which side does a spring washer go?
From Hobson's types of washers guide:
- Fit the spring washer under the head of the bolt, and tighten the joint by turning the nut.
- If it has to go on the nut side, fit a hardened flat round washer between the nut and the spring washer.
- Tighten until the spring washer is flat: Hobson says that is when the prescribed tension is reached.
Flat section, square section, Neptune and volute spring washers
- Flat section (HEC 127B in metric): a wide, flat ring, in zinc plated, zinc yellow and hot dip galvanised spring steel and 304 and 316 stainless. Imperial flat section washers (ANSI B18.21.1) are zinc plated, many sizes in two section sizes.
- Square section (HEC 7980 in metric): a narrower, thicker ring, in zinc plated and zinc yellow spring steel, several metric sizes in two or three thicknesses. Imperial square section washers come zinc plated or galvanised.
- Neptune spring washers (316, HEC 7980, A4-80, M4 to M20): Hobson says they have increased hardness over standard spring washers (HV380 to 415) to suit the higher tensile loads of a Neptune bolt and nut assembly, and are made for use with Neptune bolts and nuts.
- 316 volute spring washers for M16/M20 and M20/M24 bolts, listed by Hobson to AS 2837, in packs of 50.
- An AS 1085.7 plain M24 washer, which Hobson describes as a hard washer, is also on this page.
Metric spring washer sizes
Every metric spring washer we carry, one row per bolt size and section. The figures are outside diameter x thickness in mm, as Hobson lists them. Select a row to open it in the selector.
Metric spring washers, by section then bolt size. Outside diameter x thickness in mm from Hobson's data. zinc = zinc plated; galv = hot dip galvanised; 304 and 316 are stainless. Pack is the minimum order quantity. Neptune washers (hardened 316, HEC 7980) are outside diameter x thickness from Hobson's Neptune spring washer sheet. Tap a number to show it in the selector above.
| Bolt size | Section | Outside dia x thickness (mm): finish | Neptune | Pack |
|---|---|---|---|---|
| Flat section (HEC 127B) | ||||
| M3 | Flat section (HEC 127B) | 6.2 x 0.8: zinc, zinc yellow, 304, 316 | 200 | |
| M4 | Flat section (HEC 127B) | 7.6 x 0.9: zinc, zinc yellow, 304, 316 | 200 | |
| M5 | Flat section (HEC 127B) | 9.2 x 1.2: zinc, zinc yellow, 304, 316 | 200 (304 also in a bulk pack of 8,400) | |
| M6 | Flat section (HEC 127B) | 11.8 x 1.6: zinc, zinc yellow, galv, 304, 316 | 100 to 200 | |
| M8 | Flat section (HEC 127B) | 14.8 x 2.0: zinc, zinc yellow, galv, 304, 316 | 100 to 200 | |
| M10 | Flat section (HEC 127B) | 18.1 x 2.2: zinc, zinc yellow, galv, 304, 316 | 100 to 200 | |
| M12 | Flat section (HEC 127B) | 21.1 x 2.5: zinc, zinc yellow, galv, 304, 316 | 100 to 200 | |
| M14 | Flat section (HEC 127B) | 24.1 x 3.0: zinc, 316 | 100 to 200 | |
| M16 | Flat section (HEC 127B) | 27.4 x 3.5: zinc, zinc yellow, galv, 304, 316 | 100 to 200 | |
| M20 | Flat section (HEC 127B) | 33.6 x 4.0: zinc, zinc yellow, galv, 304, 316 | 100 | |
| M24 | Flat section (HEC 127B) | 40.0 x 5.0: zinc, zinc yellow, 316; 40.0 x 7.0: galv | 50 to 100 | |
| M30 | Flat section (HEC 127B) | 48.2 x 6.0: 316; 48.2 x 8.0: galv | 20 to 25 | |
| M36 | Flat section (HEC 127B) | 58.2 x 10.0: galv; 58.2 x 6.0: 316 | 25 | |
| Square section (HEC 7980) | ||||
| M4 | Square section (HEC 7980) | 7.0 x 1.2: zinc, zinc yellow; 7.0 x 1.5: zinc | 7.0 x 2.4: Neptune 316 | 200 |
| M5 | Square section (HEC 7980) | 8.8 x 1.5: zinc, zinc yellow | 8.8 x 3.2: Neptune 316 | 200 |
| M6 | Square section (HEC 7980) | 9.9 x 1.5: zinc, zinc yellow; 9.9 x 2.5: zinc | 9.9 x 3.2: Neptune 316 | 100 to 200 |
| M8 | Square section (HEC 7980) | 12.7 x 2.0: zinc, zinc yellow; 12.7 x 2.5: zinc | 12.7 x 4.0: Neptune 316 | 100 to 200 |
| M10 | Square section (HEC 7980) | 16.0 x 2.5: zinc, zinc yellow; 16.0 x 3.2: zinc | 16.0 x 5.0: Neptune 316 | 100 to 200 |
| M12 | Square section (HEC 7980) | 18.0 x 2.5: zinc, zinc yellow; 18.0 x 3.2: zinc; 18.0 x 4.0: zinc | 18.0 x 5.0: Neptune 316 | 100 to 200 |
| M14 | Square section (HEC 7980) | 21.1 x 3.2: zinc | 21.1 x 6.0: Neptune 316 | 100 to 200 |
| M16 | Square section (HEC 7980) | 24.4 x 3.2: zinc; 24.4 x 3.5: zinc | 24.4 x 7.0: Neptune 316 | 100 to 200 |
| M20 | Square section (HEC 7980) | 30.6 x 4.5: zinc | 30.6 x 9.0: Neptune 316 | 100 |
| M24 | Square section (HEC 7980) | 35.9 x 5.0: zinc | 100 | |
Imperial spring washer sizes
Imperial spring washers are sized by the bolt diameter in inches. For flat section washers the second figure is the section width, with the thickness after it where Hobson's description gives one; for square section washers it is the section size. Select a row to open it in the selector.
Imperial spring washers to ANSI B18.21.1, by bolt size. Section sizes in inches from Hobson's data: flat section as width, or width x thickness; square section as the section size. The 1-1/2 inch flat washer is listed at 3/8 inch, while its description reads 7/16 x 3/8 inch. zinc = zinc plated; galv = hot dip galvanised; the 304 and 316 stainless washers are flat section. Pack is the minimum order quantity. Tap a number to show it in the selector above.
| Bolt size | Flat section, zinc (width, or width x thickness) | Square section (section size) | Stainless | Pack |
|---|---|---|---|---|
| 1/8 inch | 3/64" | 3/64" zinc | 316 | 200 |
| 5/32 inch | 1/16" | 3/64" zinc, 1/16" zinc | 304, 316 | 200 |
| 3/16 inch | 1/16", 3/32" | 3/64" zinc, 1/16" zinc | 304, 316 | 200 |
| 1/4 inch | 3/32", 1/8" | 1/16" galv/zinc, 3/32" zinc | 304, 316 | 100 to 200 |
| 5/16 inch | 1/8", 9/64" | 5/64" galv/zinc, 3/32" zinc | 304, 316 | 100 to 200 |
| 3/8 inch | 1/8", 5/32" | 3/32" galv/zinc, 1/8" zinc | 304, 316 | 100 to 200 |
| 7/16 inch | 5/32", 3/16" | 3/32" zinc | 316 | 100 to 200 |
| 1/2 inch | 3/16" x 1/8", 3/16" x 5/32" | 7/64" galv/zinc, 1/8" zinc, 5/32" zinc | 304, 316 | 100 to 200 |
| 9/16 inch | 3/16" x 1/8" | 200 | ||
| 5/8 inch | 7/32" x 5/32", 7/32" x 3/16" | 1/8" galv/zinc | 304, 316 | 100 to 200 |
| 3/4 inch | 1/4" x 3/16" | 3/16" zinc, 1/4" zinc | 304, 316 | 50 to 200 |
| 7/8 inch | 1/4" x 7/32", 5/16" x 1/4" | 3/16" galv/zinc | 316 | 50 to 100 |
| 1 inch | 5/16" x 1/4" | 3/16" galv/zinc, 5/16" zinc | 316 | 50 to 100 |
| 1-1/8 inch | 5/16" x 1/4" | 25 | ||
| 1-1/4 inch | 5/16" x 1/4", 3/8" x 5/16" | 25 | ||
| 1-1/2 inch | 3/8" | 25 |
Spring washer finishes: zinc, galvanised or stainless?
Match the washer to the bolt and nut, so nothing in the joint corrodes first. Hobson's corrosion guide for metal connectors puts zinc plated steel in enclosed, low corrosion areas only, and calls for hot dip galvanised or stainless where it is exposed, with 316 within 2m of a pool edge.
- Zinc plated: 5 micron zinc with a clear passivate, for indoor and non-corrosive conditions.
- Zinc yellow passivate: more corrosion resistant than zinc plated, for low corrosion conditions or temporary fixing.
- Hot dip galvanised: for long term outdoor work, with galvanised bolts and nuts.
- 304 and 316 stainless: for outdoor, wet and coastal work; 316 near the sea. Neither 304 nor 316 is made to sit in seawater.
Spring washers in Adelaide
Allmat supplies spring washers, flat washers, nuts and bolts to fabricators, mechanics, builders and trade across Adelaide and South Australia. Add them to a quote with the bolts they go on, and we will price the lot.
Spring washers for the job
Spring washers, flat washers, nuts and bolts are available to order from Allmat for fabricators, mechanics, builders, farmers and trade across Adelaide and South Australia. Order through Allmat, we pick and pack it, then click and collect from the Allmat yard or have it delivered to site.
Goes with
Questions
What is a spring washer used for?
To help stop a nut or bolt working loose. The split, twisted ring flattens as the joint is tightened, and its corners bite into the nut or head and the joint face to resist the nut turning back.
Are spring washers and lock washers the same?
A spring washer (split lock washer) is one kind of lock washer. Star (tooth lock) washers and two-piece wedge locking washers are other kinds, each on their own page.
Does a spring washer go under the nut or the bolt head?
Hobson's guide says under the bolt head, tightening by turning the nut. If it has to go on the nut side, put a hardened flat washer between the nut and the spring washer.
What is the difference between flat and square section spring washers?
The shape of the ring. Flat section washers are wider and flatter; square section washers are narrower and thicker, and come in two or three thicknesses in several sizes.
What size spring washer for an M10 bolt?
An M10 spring washer. In flat section it is 18.1mm outside diameter x 2.2mm thick; in square section 16.0mm x 2.5 or 3.2mm.
Do you have stainless spring washers?
Yes: 304 stainless M3 to M20 and 5/32 to 3/4 inch, 316 stainless M3 to M36 and 1/8 to 1 inch, and hardened Neptune 316 washers M4 to M20.
Where can I buy spring washers in Adelaide?
Order through Allmat. Order ahead by phone on 1300 03 03 63 or send your list for a quote, then click and collect from 25 Kapara Road, Gillman, or have them delivered to site.
Spring Washer: sizes and finishes we supply
161 lines by type and finish. Pick one above for its product code, pack sizes and dimensions.
| Type | Finish | Sizes | Lengths | Lines |
|---|---|---|---|---|
| Flat section | Zinc Plated | 1/8, 5/32, 3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 9/16, 5/8, 3/4, 7/8, 1, 1-1/8, 1-1/4, 1-1/2 | x1/4 to x9/64 (10 lengths) | 25 |
| Square section | Zinc Plated | 1/8, 5/32, 3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4, 7/8, 1 | x1/4 to x7/64 (10 lengths) | 21 |
| Square section | Zinc Plated | M4, M5, M6, M8, M10, M12, M14, M16, M20, M24 | x7.0x1.2 to x35.9x5.0 (17 lengths) | 17 |
| Flat section | 316 Stainless | M3, M4, M5, M6, M8, M10, M12, M14, M16, M20, M24, M30, M36 | x6.2x0.8 to x58.2x6.0 (13 lengths) | 13 |
| Flat section | 316 Stainless | 1/8, 5/32, 3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4, 7/8, 1 | - | 12 |
| Flat section | Zinc Plated | M3, M4, M5, M6, M8, M10, M12, M14, M16, M20, M24 | x6.2x0.8 to x40.0x5.0 (11 lengths) | 11 |
| Flat section | Zinc Yellow Passivate | M3, M4, M5, M6, M8, M10, M12, M16, M20, M24 | x6.2x0.8 to x40.0x5.0 (10 lengths) | 10 |
| Flat section | 304 Stainless | M3, M4, M5, M6, M8, M10, M12, M16, M20 | x6.2x0.8 to x33.6x4.0 (9 lengths) | 9 |
| Square section | 316 Stainless | M4, M5, M6, M8, M10, M12, M14, M16, M20 | - | 9 |
| Flat section | Galvanised | M6, M8, M10, M12, M16, M20, M24, M30, M36 | x11.8x1.6 to x58.2x10.0 (9 lengths) | 9 |
| Flat section | 304 Stainless | 5/32, 3/16, 1/4, 5/16, 3/8, 1/2, 5/8, 3/4 | - | 8 |
| Square section | Galvanised | 1/4, 5/16, 3/8, 1/2, 5/8, 7/8, 1 | 1/16, 5/64, 3/32, 7/64, 1/8, 3/16 inch | 7 |
| Square section | Zinc Yellow Passivate | M4, M5, M6, M8, M10, M12 | x7.0x1.2, x8.8x1.5, x9.9x1.5, x12.7x2.0, x16.0x2.5, x18.0x2.5 | 6 |
| Volute | 316 Stainless | M16/M20, M20/M24 | x60x26, x85x32 | 2 |
| Hard washer | Steel | M24 | - | 1 |
| Flat section, bulk carton | 304 Stainless | M5 | x9.2x1.2 | 1 |
Data sheets and documents
The documents for the product you choose are listed with the selector above. Here is every Spring Washer document from Hobson Engineering.
All Spring Washer documents (12)
Data sheets and technical data (4)
Did You Know flyers (3)
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