The first thread type is BSP:

BSP - is shown on the left, it has a flat or recessed end, and the thread is slightly tappered, getting wider the further it is tightened.

Thread tape is used when joining these.

This is a MALE BSP fitting. The thread is on the outside.

Sizes of BSP fittings: (image shows SAE to BSP)

The outside diameter (OD) of the thread can be measured to give you the PROPER name of the fitting.

3/8"    measured thread is a Male BSP 1/8", search for m-bsp-1/8
1/2"    measured thread is a Male BSP 1/4", search for m-bsp-1/4
5/8"    measured thread is a Male BSP 3/8", search for m-bsp-3/8
3/4"    measured thread is a Male BSP 1/2", search for m-bsp-1/2
1"       measured thread is a Male BSP 3/4",

The BSP female fitting (the thread is on the inside) has a protruding section within the fitting. This fits into the concave or flat male BSP fitting end.

If measuring the thread from inside a female fitting.
5/16"    measured thread is Female BSP 1/8" , search for f-bsp-1/8
7/16"    measured thread is Female BSP 1/4", search for f-bsp-1/4
9/16"    measured thread is Female BSP 3/8", search for f-bsp-3/8
11/16"  measured thread is Female BSP 1/2", search for f-bsp-1/2

The thread type is SAE:

The outside diameter (OD) of the copper pipe, is how the SAE fittings are described.

This NUT is a 1/4" NUT because it fits on a 1/4" pipe.

Colour codes used at Caravans Plus:

Pipe size - is shown for many SAE fittings by the colours on the left.
1/4"       or 6.35mm
5/16"     or 7.95mm
3/8"       or 9.25mm

SAE - is shown here. It has a 45 degree flare at the end, and the thread is constant. They achieve the seal when the brass flare is screwed against the softer copper pipe flare.

This is a MALE SAE fitting. The thread is on the outside.

Sizes of SAE fittings:

The outside diameter (OD) of the thread can be measured to give you the PROPER name of the fitting.


7/16"  measured thread is Male SAE 1/4" search for m-SAE-1/4
1/2"    measured thread is Male SAE 5/16" search for m-SAE-5/16
5/8"    measured thread is Male SAE 3/8"search for m-SAE-3/8

The SAE female fitting (the thread is on the inside) has a 45 degree flare section pointing into the fitting.

Photo shows fitting on a flexible hose.

Photo shows SAE female fitting fitting on a copper pipe.

If measuring the thread from inside a female fitting.

3/8"      measured thread is Female SAE 1/4" search for f-SAE-1/4
7/16"    measured thread is Female SAE 5/16"search for f-SAE-5/16
9/16"    measured thread is Female SAE 3/8"search for f-SAE-3/8

IMPORTANT: some SAE fittings available, REDUCE to a smaller pipe size. This is indicated in their title.