Brass pipe fittings buying guide

Threaded fittings are used to connect the copper pipes that carry water around the home to sanitary appliances such as bathroom taps, kitchen taps and water heaters. Usually made of brass, these fittings should be chosen with the following characteristics in mind:

• material (brass or galvanised steel);

• fitting type (elbow, tee, etc.);

• connection type (male or female);

• size (usually 1/4’’ to 1’’).

Common threaded pipe fittings

1. Brass vs. galvanised steel

Threaded pipe fittings are usually made of brass but they may also be made of galvanised steel.

These fittings are commonly used in standard copper pipe systems.

Galvanised steel pipes should be joined using galvanised steel fittings to prevent the type of corrosion that occurs when two dissimilar metals are coupled. Copper and brass should never be connected directly to galvanised steel as this can provoke galvanic corrosion. To prevent this from happening – in a domestic hot water system such as a storage heater, for example – the two materials should be isolated using dielectric unions.

2. Fitting type: elbow, nipple, reducer or tee

Different types of fittings are used for different purposes.

• Elbows are used to change direction.

• Nipples are used to join two male pipes or fittings of the same size.

• Straight couplers are used to join two female pipes or fittings of the same size.

• Reducers are used to join pipes or fittings of different sizes.

• Tees are used to join three connections of the same size or different sizes.

• Full couplings are designed to connect two fittings that are too far for a nipple but not far enough to merit adding copper pipe.

• End caps are used to close the end of a pipe.

Threaded fittings can be made watertight using PTFE tape or pipe sealing cord and sealant.

3. Type: male or female

All variations of male and female threads are available to cater to any installation:

• Male - Male fittings (M-M)

• Female - Female fittings (F-F)

• Male - Female fittings (M-F)

4. Fitting sizes: imperial vs. metric

Pipe fittings are measured in BSP thread sizes (in inches) but you may occasionally come across a metric size in millimetres which may indicate inner and outer diameter.

Imperial to metric

In the absence of an existing fitting or if you are fitting a mixed connector like a compression fitting, the size of the brass fitting should be chosen to match the copper pipe.

• PEX pipe buying guide

• How to use a compression fitting