When will my cast iron radiator arrive in multiple sections?

Radiators longer than 1200 mm typically overhang a pallet and are sent in two blocks for transport and handling. These sections are joined on site.

Do I need a special tool to join cast iron radiator sections?

Yes. Most plumbers have a joining tool. If not, you can purchase one on a sale-or-return basis from the accessory section (Radiator Joining Tool).

What is the recommended tightening torque when joining sections?

A final tightening torque of approximately 200 Nm compresses the gaskets and creates a watertight seal.

Should I use jointing paste or tape on nipples when assembling?

No. Do not use jointing paste or tape. Insert the nipples one turn, seat the gasket, align, then alternate one-turn rotations until tight.

How to join two cast iron radiator sections together

Ben Clarke

18 November 2014

Types & Materials Cast Iron

How to join two cast iron radiator sections together

Large cast iron radiators often ship in two manageable blocks for safety and transport. Here’s when that happens and how to join the sections on site using a standard joining tool.

Key points:

Radiators longer than 1200 mm will typically arrive in two blocks for transport and handling.
Heavy weight requires manageable section sizes; assembly is done on site.
Use a joining tool and follow a nipple‑by‑nipple tightening sequence to create a watertight seal.
Recommended final tightening torque: 200 Nm to compress gaskets properly.

Ordering considerations

So you've taken your time, browsed our site and decided which cast iron radiator you want. You've also decided on what size it should be and what your ideal finish is, but is there anything further to consider?

Why sections are shipped

It should be noted that if a cast iron radiator is ordered in a size longer than 1200mm, it will overhang a pallet and will need sending in two blocks. These two blocks will then need to be joined together on site.

Cast iron radiators are also very heavy, meaning in order to be able to carry them, they need to be in manageable sized sections. So if you are ordering radiators with a length over 1200mm, it is highly likely that the radiator will be sent in two sections. You should ask your plumber if they have a joining tool, which most will have, although if they don't, you can buy one on a sale or return basis in the accessory section of our website:

For details on how to join the radiator please follow the below instructions:

In one end of the radiator screw a pair of nipples in 1 turn and place a gasket over (do not use any jointing paste or tape). The nipples are the chunky cylindrical steel components shown on the floor in the first picture below.
Line up the other section of the radiator with the nipples making sure the thread orientations are correct.
Hold the joining tool over the section of the radiator, you are looking to attach and mark the key at the point where it will engage with the internal lugs inside of the nipples.
Insert the joining tool into the radiator to the mark (so it is engaged with the internal lugs of the nipple) and rotate the nipple 1 turn so it pulls the two radiator sections together.
Repeat this operation with the other nipple again only using 1 turn, then switch back to the other nipple. Continue this process ensuring the two sections are kept parallel and are pulling together without too much force.
Once the two sections are tight together, it is recommended a tightening torque of 200 Nm (20 kgf-m, 150 lbf-ft) to compress the gaskets and create a water tight seal.