Key risks

• Cuts or punctures from edges, points and burrs on screws.
• Ejection of parts or swarf when tightening or loosening, with risk of eye injury.
• Choking hazard from small parts; risk to children and pets.
• Fastening failure due to choosing an unsuitable size, thread or material, potentially causing objects to fall.
• Damage to the workpiece or breakage due to over-tightening or cross-threading.
• Corrosion from moisture or chemical agents that can weaken the fastening.
• Skin reactions in people sensitive to certain metal alloys.
• Confusion between metric and imperial threads, which can damage the threads and reduce strength.

Safe use

• Select the appropriate type of screw and nut: diameter, thread pitch, length and head, according to the base material and the intended load.
• Verify that screw and nut are of the same thread system (metric or imperial) and fit together without force.
• Use the correct tool in good condition (bit or spanner that fully engages) and keep aligned with the screw head.
• Tighten progressively, without over-tightening; if the driver has a clutch, set a moderate torque.
• Where multiple fasteners are present, tighten alternately and gradually to distribute the load.
• For brittle materials or timber, consider drilling a pilot hole and using washers to distribute pressure.
• Secure and stabilise the workpiece; keep fingers away from the tightening area.
• Wear eye protection and, if there is a risk of burrs, suitable gloves.
• Keep threads clean; remove dust, loose rust or debris that hinders threading.
• In environments with vibration, use compatible locking systems (e.g., self-locking nuts or lock washers) where appropriate.
• Do not use bent screws, damaged heads or stripped threads; replace them.

Storage and maintenance

• Store screws and nuts dry, in their original packaging or labelled containers, to avoid mix-ups.
• Keep them organised by size, thread type and material to select each piece correctly.
• Avoid humidity, salt air and contact with corrosive substances; dry any part that has become wet before storing.
• Inspect periodically: discard rusted, deformed or thread-damaged parts.
• If appropriate, apply a light anti-corrosion protection before storing for long periods.
• Do not mix parts of different materials in the same container in humid environments to reduce the risk of contact corrosion.
• Keep out of reach of children and pets.

Restrictions on use

• Do not use screws and nuts in safety-critical applications (lifting loads, suspending people, protective equipment, vital structures) unless the product is specifically designed for that purpose.
• Avoid use in high-temperature, marine or highly corrosive environments if the product is not expressly rated for those conditions.
• Do not modify the parts (drilling, filing, heating or bending) as this may compromise their strength.
• Do not mix screws and nuts of different thread systems or unequal strength grades in the same joint.
• Avoid reusing locking elements that have lost their effectiveness (e.g., worn self-locking nuts or damaged lock washers).
• In installations subject to vibration or heavy use, periodically check tightness.
• Supervise any handling by minors; they contain small parts.