What is Hydraulic SAE Flange

You can find flanged connections in the most demanding mobile equipment because they are highly resistant to loosening and can withstand high pressure and shock. So what is a hydraulic SAE flange? What is it good for?

What is a hydraulic SAE flange

SAE flanges are a range of high pressure hydraulic flanges manufactured to SAE J518 standard. The acronym SAE stands for Society of Automotive Engineers. These flanges are used in oil hydraulic systems in many fields (shipbuilding, mobile hydraulics, machine tools, earth-moving machinery, etc.) and where pressure oil passes.

SAE flanges are also known as code 61 flanges or code 62 flanges. These 4-bolt flange connections are proven, leak-free connections, especially for large size high pressure applications. Due to the O-ring seal design, SAE flanges provide connections with a reasonable range of assembly torques.

Material:

Flanges are made of normalized forgings, usually in two materials, steel ST52.3 and stainless steel AISI SS316L.

Size range:

SAE Code 61 flanges are available in sizes from 3/8"NB (DN 10) to 5"NB (DN 125). For SAE code 62, flange sizes range from 3/8"NB (DN 10) to 3"NB (DN 80).

What is the difference between Code 61 and 62 flanges?

The flange design is available in two different code designations, code 61 and 62. The summary table is as follows:

Connection Type:

SAE flange connection types include socket weld (S/W) type, butt weld (B/W) type, British Standard Pipe Parallel Thread (BSPP) and American National Pipe Taper Thread (NPT) connection types. The most commonly used are socket welding and butt welding.

Break Yield Strength and Elongation:

For nominal size 13, the minimum yield strength is 220 MPa and the minimum elongation at break is 3%. For all other dimensions, the minimum yield strength is 415 MPa and the minimum elongation at break is 3%.

O-ring seal:

Minimum O-ring seal quality conforms to ISO 3601-3 Class N. Unless otherwise specified, O-rings shall be of NBR material with a hardness of 90 +/- 5 IRHD, measured in accordance with ISO 48.

O-ring dimensions are as follows:

Working pressure:

The standard pressure range is 34 to 345 bar for code 61 (3000 series) and 200 to 414 bar for code 62 (6000 series). Note that pressure information for flange and connecting device combinations may vary. For example: If the working pressure of the pipeline connected to the flange is low, it will result in a low working pressure of the system as a whole. Therefore, please take the lowest pressure as the highest working pressure for this combination.

temperature range:

Standard working pressure for carbon steel SAE flanges is between -40°C and +120°C. For stainless steel, the standard working pressure is between -60°C and +50°C. The working pressure of SAE flanges made of stainless steel and used at high temperatures must be:

4% reduction: +50°C to < +100°C

11% reduction: +100°C to < +200°C

20% reduction: +200°C to < +250°C

How SAE flanges work:

A complete kit includes a flat flange and an O-ring flange. The o-ring side flange contains a groove seat for a rubber o-ring (usually made of NBR material). The complete set forms a seal between the flat surface and the o-ring held in the other semi-circular groove. Tighten the bolts to pull the halves together and compress the o-ring.

Because of this use of o-rings, flanges with o-rings have an advantage over metal-to-metal flanges, as all-metal flanges are more prone to leaks because they must be tightened to a higher but narrower torque range. This makes metal-to-metal flanges more prone to threads or cracks.

Tighten the complete set of flanges using socket head cap screws and spring washers according to the recommended torque. The screw length is usually shorter than the overall length of the SAE flange, but this is normal according to the SAE J518 standard. Also, according to SAE J518, there are no requirements for hex nuts for securing flanges.

SAE flange configuration:

Common connection types include: Weld/Socket Weld, Weld/Butt Weld, NPT Thread, BSP Thread, Blind Flange, Split Flange.

On request, flanges can be equipped with screws, washers and NBR/Viton O-rings.

The simple SAE flange mount design has several advantages

• Capable of connecting pipes up to 5 inches.

• A single point of sealing between piping or system components.

• Four bolts require significantly less torque than other flange types of the same size

• Easy disassembly by using split flanges.

SAE flange assembly instructions:

Step 1: Make sure the sealing surfaces are clean and free of scratches and contamination.

Step 2: Thread the lock washers and bolts through the flange.

Step 3: Hand tighten the bolts in a cross sequence. Do not tighten the bolts in a clock or counterclockwise fashion.

Step 4: Tighten the bolts according to the torque chart.

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