Hobson Metric Hex Bolt, M20 / 55mm

The Hobson metric hex bolt range has 177 items in class 8.8, plain finish: sizes M6 to M36, with lengths from 16mm to 300mm. Class 8.8 is high tensile, and corresponds to imperial grade 5.

Where this product is used

• Fixing machinery feet, guards and mounting brackets where the bolt may need to come out again for servicing
• Screwing into a tapped hole in a casting, plate or housing where there is no room for a nut
• Replacing worn or missing bolts of the same thread form, diameter and length
• Assemblies that will be painted, oiled or enclosed after fitting
• Machinery, frames and equipment where a high tensile bolt is specified
• The 177 items cover diameters from M6 to M36 and lengths from 16mm to 300mm, confirm the size against your drawing before ordering

Features

• 10 sizes: M6 to M36
• Class 8.8, Plain finish
• Lengths from 16mm to 300mm
• Pack quantity and part number for every item
• Proof load and minimum tensile strength
• Spanner size (A/F) by size
• Uncoated plain steel: paint, oil or enclose it for protection
• Class 8.8 high tensile steel

Key specifications

Choosing the right option

Choose the thread form first: the nut must match the bolt in thread form, diameter and pitch. Length is measured from under the head to the end of the bolt. For a bolt and nut set: see Hobson Metric Hex Bolt and Nut, Class 8.8, Plain, M6 to M36 x 16 to 300mm.

Plain steel carries no protective coating apart from a light oil film, which is why it rusts quickly if it gets wet. That makes it a good fit for dry indoor work, machinery, and assemblies that are painted, oiled or enclosed after fitting. For anything outdoors or damp, choose a hot dip galvanised or 316 stainless option instead.

Property class 8.8 is high tensile, medium-carbon steel. It is the common step up from class 4.6 for machinery, frames and equipment, and the minimum tensile strength is shown against each size. For load-critical, structural or lifting joints, confirm the fastener against the engineer's specification. Fasteners are not lifting rated unless marked.

Related hex bolts: Hobson Metric Hex Bolt and Nut, Class 8.8, Plain, M6 to M36 x 16 to 300mm, Hobson Metric Hex Bolt and Nut, Class 8.8, Plain, M6 to M36 x 60 to 400mm and Hobson Metric Hex Bolt and Nut, Class 8.8, Hot Dip Galvanised, M8 to M16 x 20 to 50mm.