Fitting family

SAE split flange fittings: Code 61 and Code 62

A flanged head clamped to a port with four bolts and sealed by an O-ring. Used on large, high-flow and high-pressure lines.

What it is

A flange fitting has a flat circular head with an O-ring groove in its face. Two clamp halves, or a one-piece clamp, sit behind the head and are bolted to the port with four bolts, pressing the O-ring against the flat port face.

There are two series. Code 61 is the standard-pressure series. Code 62 is the high-pressure series, with a thicker, larger head and wider bolt spacing for the same nominal size. They look alike and are told apart by measurement.

Thread: None on the fitting; four bolts through clamp halves
Seal: O-ring in a groove in the flange face
Standard: SAE J518 / ISO 6162-1 (Code 61) and ISO 6162-2 (Code 62)
Also called: 4-bolt flange, split flange, 3000 psi and 6000 psi flange

What it looks like

Flange head with face O-ring. Male end shown; the sealing surface is orange. Illustration, not to scale.

How to recognise it

No thread on the hose fitting: a round flanged head with an O-ring groove in the face.
Four bolt holes around the port in a rectangle.
Measure the flange head outside diameter and the bolt spacing, then compare with the charts below.
For the same size, Code 62 has the larger head, the thicker flange and the wider bolt pattern.

Where it is used

Pump and motor ports, main valve connections and large-bore lines on excavators and other heavy equipment from all regions. Caterpillar machines also use a Caterpillar-specific flange with a thicker head that fits Code 62 bolt patterns.

Size chart

SAE Code 61 flange dimensions
Dash size	Nominal size	Flange head OD	Bolt spacing
-08	1/2 in	30.2 mm	38.1 × 17.5 mm
-12	3/4 in	38.1 mm	47.6 × 22.2 mm
-16	1 in	44.5 mm	52.4 × 26.2 mm
-20	1-1/4 in	50.8 mm	58.7 × 30.2 mm
-24	1-1/2 in	60.3 mm	69.9 × 35.7 mm
-32	2 in	71.4 mm	77.8 × 42.9 mm

SAE Code 62 flange dimensions
Dash size	Nominal size	Flange head OD	Bolt spacing
-08	1/2 in	31.8 mm	40.5 × 18.2 mm
-12	3/4 in	41.3 mm	50.8 × 23.8 mm
-16	1 in	47.6 mm	57.2 × 27.8 mm
-20	1-1/4 in	54.0 mm	66.7 × 31.8 mm
-24	1-1/2 in	63.5 mm	79.4 × 36.5 mm
-32	2 in	79.4 mm	96.8 × 44.5 mm

Bolt spacing is centre to centre: long side × short side of the rectangle.

Match a measured thread with the thread identifier →

Commonly confused with

Code 61 versus Code 62: Head diameters differ by only a few millimetres in some sizes. Measure both the head and the bolt spacing.
Caterpillar flange: Same head diameter as Code 62 but a thicker flange. It needs the matching clamp.
Komatsu and other metric flanges: Some Japanese machines use flanges with different head sizes or metric bolts. Measure before ordering.

Interchangeability

Code 61 and Code 62 do not interchange: the heads, clamps and bolt patterns are different. Use the clamp halves and bolt grade specified for the series.

Frequently asked questions

What is the difference between Code 61 and Code 62 flanges?

Code 62 is the high-pressure series. For the same nominal size it has a larger and thicker flange head and a wider bolt pattern than Code 61. A 1 in Code 61 head is about 44.5 mm across; a 1 in Code 62 head is about 47.6 mm.

How do I identify an SAE flange size?

Measure the outside diameter of the flange head and the centre-to-centre bolt spacing on the port, then match both to the dimension chart for Code 61 and Code 62.

What pressure are SAE flanges rated for?

Code 61 is commonly called the 3,000 psi series and Code 62 the 6,000 psi series. Actual ratings vary by size, so check the standard or the fitting manufacturer for the size you are using.

Dimensions are nominal reference values. Confirm against the standard or the fitting manufacturer before ordering.