Nuts
Full nuts for general use, thinner lock (half) nuts, and nyloc nuts with a nylon insert that resists vibration loosening. Flange nuts spread load and can remove the need for a separate washer. Browse nuts.
Knowledge base › Fasteners
A guide to fasteners and their uses
Fasteners are usually the smallest line on an order and the one most likely to stop a job when it is wrong. Get the type, the grade and the coating right and a joint outlives everything around it; get any of the three wrong and it fails early, sometimes dangerously. This is a plain-English tour of the fasteners a site or workshop gets through, and how to pick between them.
Bolts, set screws and machine screws
The three get used interchangeably in conversation and mean different things on a drawing.
- Bolt — partially threaded, with a plain shank under the head. It is designed to pass through a clearance hole and be tightened against a nut. The plain shank locates the joint and takes shear load.
- Set screw — in UK trade usage, a fully threaded hex-head fastener. Thread runs all the way to the head, so it suits shallow tapped holes and thinner assemblies where a bolt's shank would foul. (Confusingly, "grub screw" is also called a set screw — a small headless screw that clamps a component onto a shaft.)
- Machine screw — smaller diameter, usually driven with a screwdriver or hex key rather than a spanner, into a tapped hole or a nut.
Browse bolts, sockets & set screws and screws in the catalogue.
Grade and property class
The stamped numbers on a bolt head are its property class under EN ISO 898-1, and they tell you how strong it is. The common structural grades are:
- 8.8 — the general-purpose high-tensile grade, used for most structural and machinery work.
- 10.9 — higher tensile strength, for more heavily loaded joints.
- 12.9 — the highest common grade, typically socket-head cap screws for tooling and machinery.
Stainless fasteners are marked differently — usually A2 (general-purpose stainless) or A4 (higher corrosion resistance, the grade specified where chlorides or marine exposure are a factor). A2 and A4 are chosen for corrosion resistance rather than raw strength, so do not treat an A2 bolt as a like-for-like swap for an 8.8 on a highly loaded joint without checking. If a drawing calls a grade, match it — do not substitute up or down.
Thread: coarse or fine
The same diameter of bolt can come in more than one thread pitch. Coarse thread is the everyday default — faster to run down, more tolerant of dirt and damage, and less likely to cross-thread. Fine thread gives a slightly stronger joint and finer adjustment, and turns up on precision and automotive work. If you are matching an existing fastener or a tapped hole, the pitch has to match exactly. Our metric thread pitch guide has the reference table and shows how to measure a pitch you are unsure of.
Coating and material — matching the environment
The finish decides how long the fastener lasts outdoors.
- Bright zinc plated (BZP) — a thin decorative and mildly protective finish. Fine indoors and in dry conditions; it will not last long outside.
- Hot-dip galvanised (HDG) — a thick zinc coating for exterior and exposed structural work, where it lasts far longer than BZP.
- Stainless A2 / A4 — where corrosion has to be designed out entirely: A2 for general use, A4 for marine, coastal and chemical environments.
Nuts, washers and anchors
Washers
Flat washers spread the load and protect the surface; spring washers resist loosening under vibration; penny (repair) washers have a large outside diameter for oversized or soft-material holes. Browse washers & rings.
Anchors & threaded bar
For fixing into masonry and concrete, anchor fixings transfer load into the substrate. Threaded bar (studding) is cut to length for hanging and bracket work. Anchor fixings and all-thread.
Need a non-standard or made-to-drawing fixing?
Standard fixings and fasteners are on the fixings & fasteners catalogue. For specials, odd sizes or made-to-drawing items, TES bespoke components sources them through a single point of contact — one-offs through to repeat production runs.