High Tensile Steel Fasteners
Woodstock industrial supplies are a leading supplier of standard and non standard high tensile fasteners. We supply high tensile fasteners in grades 8.8, 10.9, 12.9 and 14.9
High tensile steel hexagon bolts to DIN931 in standard grades 8.8 & 10.9. Higher grades of 12.9 & 14.9 made to order.
High tensile steel hexagon setscrews to DIN933 in standard grades 8.8 & 10.9. Higher grades of 12.9 & 14.9 made to order.
High tensile steel nuts in grades 8, 10 & 12.
Through hardened washers to DIN6916
Socket Capscrews in high tensile grades 8.8, 10.9 & 12.9
Socket Countersunk Screws in high tensile grades 8.8 & 10.9
Socket Button's are available in high tensile grade 10.9
Socket Setscrews are available in high tensile grade 14.9 and in plain cup point, cone point, flat point, dog point and knurled cup point.
High tensile Socket Shoulders.
Taper Pressure plugs with BSPT and NPTF threads.
What is the difference between grade 8.8, 10.9, and 12.9 bolts?
The first number represents the ultimate tensile strength in hundreds of N/mm² (so 8.8 = 800 N/mm²). The second number multiplied by the first gives the yield strength. Grade 8.8 is the standard for general high tensile use. Grade 10.9 is used where greater clamping force is needed, such as in structural steelwork. Grade 12.9 is typically used in socket screws and precision assemblies.
Do high tensile bolts need special washers?
For structural applications using grades 10.9 and above, through-hardened washers to DIN 6916 are recommended. These prevent the bolt head or nut from digging into softer steel surfaces under high preload, which would cause loss of clamp force. For grade 8.8 in general engineering, standard flat washers are usually adequate.
Are high tensile fasteners suitable for outdoor use?
Standard high tensile fasteners are zinc plated or self-colour (plain) steel, which provides limited corrosion protection. For external or wet environments, hot-dip galvanised high tensile bolts are available, or consider switching to stainless steel. Note that galvanising is not recommended for grades above 10.9 due to the risk of hydrogen embrittlement.
