Threaded Rod (Allthread)

What threaded rod is used for

• •Hanging ducting, cable tray and pipework for air conditioning, ventilation and services.
• •Concrete anchoring with chemical anchors, and foundation studs.
• •Cyclone tie-down rods in timber framing: Hobson's sheet says to install them to AS 1684.3 and publishes no capacity, so the rod size, class and spacing come from the plans, AS 1684 or an engineer.
• •Cross bracing in steel structures, and custom studs and long bolts cut to length.

Choosing the grade and finish

• •Class 4.6 (mild steel): the general purpose rod. Zinc plated for indoors and services; hot dip galvanised for outdoors, foundations and tie-downs (Hobson publishes no tie-down capacity, so follow the plans or engineer).
• •Class 8.8 and 10.9 (high tensile): about twice and two and a half times the tensile strength of class 4.6, for structural and heavy duty studs. Hot dip galvanised class 8.8 rod suits building foundations.
• •304 and 316 stainless: for wet, food and coastal areas; 316 near the sea. High strength A4-80 and BUMAX grades are also available.
• •Specialist: ASTM A193 B7 and B16 for petrochemical stud bolts, brass, nylon, and weathering steel.
• •Threads: metric coarse and fine, UNC, UNF, BSW, BSF, left hand and ACME.

Class 4.6 threaded rod strength

The minimum proof load is the load the rod must carry without permanent stretch. It is a test value, not a safe working load: apply the design factors for your application, or follow the engineer.

How to spot undersized threaded rod

Threaded rod sells on the price of steel, so cheap imported rod is sometimes rolled from undersized wire or with altered thread angles to save steel. It still looks right, but it is weaker and nuts rattle on it.

Two quick checks: weigh it, and run a nut down it. An M10 x 3m zinc plated rod made to specification weighs about 1.40 to 1.43kg; undersized rod comes in around 1.24 to 1.32kg, up to 13% lighter. A nut should run down a good rod smoothly without wobbling.

Cutting and fitting threaded rod

1. Run a nut onto the rod past the cut line before cutting.
2. Cut square with a hacksaw, bandsaw or rod cutter.
3. File off any burr, then wind the nut back off over the cut end to clean up the thread.
4. On galvanised rod, touch up cut ends with zinc-rich paint outdoors.

Threaded rod in Adelaide

Allmat supplies threaded rod, nuts, washers and anchors to builders, services trades and fabricators across Adelaide and South Australia. Add the rod to a quote with the nuts, washers and anchors to suit, and we will price the lot.

Questions