Flexible Connector Couplings For Cast Iron to Plastic 4 inch to 6 inch

Flexible Connector Couplings For Cast Iron to Plastic let you connect a new plastic soil or drain pipe to an existing cast iron one, using a rubber sleeve shaped to suit both and tightened with clips. They come in 4 inch and 6 inch.

What it’s used for

Replacing part of an old iron stack, adding a new WC branch, or tying a new plastic drain into the iron pipe coming out of the building are the usual reasons. Cast iron and plastic pipes of the same nominal size don’t have the same outside diameter, so a plain plastic coupling won’t seal. This one takes up the difference and copes with slight misalignment. It’s for gravity drainage, not pressure pipe.

Sizes available

These are nominal sizes. Measure the outside of the iron pipe, since old pipe can be thicker with paint or corrosion, and confirm the size of your plastic pipe before buying.

Fitting tips

Cut the iron with a chain cutter or disc and wire-brush the end back to sound metal; loose rust and flaky paint let water past. Deburr the plastic end. Push both pipes fully in, keep them in line, and tighten the clips evenly. On a stack, fit a support bracket under the iron pipe above the joint, because the rubber coupling won’t hold the weight of the iron. Spare clips and other flexible rubber connectors are in the same range.

Drainage couplings in Glasgow

Collect these couplings in person from Plumb Parts, 555 South Street, Glasgow G14 0QX, or order online. Open Mon-Fri 8am-5pm, Sat-Sun 8am-1pm.

Specification

• Material: Rubber
• Connection: Clamped onto each pipe with clips
• Sizes: 4″ x 4″ and 6″ x 6″
• Suitable for: Joining existing cast iron soil or drain pipe to new plastic pipe, gravity drainage only

Common Questions

Why will a plain plastic coupling not fit my cast iron pipe?

Cast iron and plastic pipe of the same nominal size have different outside diameters. This coupling is shaped to grip both, so the joint seals without packing or sealant.

Can I use one where the iron stack carries weight above the joint?

Only if the iron above is held by its own bracket. The rubber coupling seals the joint but is not there to hold up a heavy iron stack, so fix support just above the coupling before you cut.

How should I prepare the cast iron end?

Cut it square, then wire brush back to sound metal so no rust flakes or old paint sit under the rubber. Check the outside diameter with a tape before you order, as old iron can be thicker than you expect.