SAE Flange Components (Code 61 & Code 62)

The Shop Floor Truth: Code 61 vs. Code 62 Flanges

Flanges are the heavy artillery of hydraulic connections. They are not complicated, but getting them wrong has big consequences. Here’s what every serious technician and engineer needs to know.

How It Works: A Bolted-Down O-Ring Seal

The seal on an SAE flange is brutally simple and effective. A "flange head" has a flat face with a groove for an O-ring. You press this head against the flat port on a pump or valve. Then, you use a set of split flange clamps (or a one-piece captive flange) and four bolts to clamp the whole assembly down tight. The bolts provide the immense clamping force, and the O-ring creates a bulletproof seal. It's the same principle as an ORFS fitting, but scaled up for the big leagues.

Code 61 vs. Code 62: Know the Difference or Pay the Price

This is the most important part. They look similar, but they are absolutely not the same. Mixing them up will cause a catastrophic failure.

• Code 61 (Standard Duty): This is your workhorse flange for pressures up to around 3000-5000 PSI, depending on the size. You'll find it on a ton of industrial and mobile equipment.
• Code 62 (Heavy Duty): This is for the 6000 PSI systems. The flange heads are thicker, the bolt holes are spread further apart, and the bolts themselves are beefier. Everything about it is built to handle more pressure.

There is no in-between. A Code 61 clamp will not fit a Code 62 head. A Code 62 head will not line up with a Code 61 port. Don't even try.

Why You Use a Flange (The Big Advantages)

• Handles Massive Pressure & Flow: For lines bigger than an inch or so, a threaded fitting is impractical. Flanges are designed for this.
• Resists Vibration: The four-bolt pattern distributes the clamping load evenly, making it far more resistant to loosening from vibration than a single-threaded fitting.
• Easier Assembly on Big Lines: It's a lot easier to torque four bolts correctly than to try and turn a giant 2-inch hex fitting in a tight space.

How to Install It Right (The Pro Checklist)

Sloppy work here will get you a high-pressure leak in a hurry. Do it right, every time.

1. Check Your Code. Triple-check that your flange head, clamps, and port are all the same code (61 or 62).
2. Wipe Everything Down. The O-ring, the groove, and the port face must be perfectly clean. A single piece of grit can ruin the seal.
3. Inspect and Lube the O-Ring. Make sure there are no nicks or cuts. Put a light coat of clean hydraulic oil on it before seating it in the groove.
4. Assemble and Hand-Tighten Bolts. Seat the flange head, put the clamps on, and start all four bolts by hand.
5. Torque in a Cross Pattern. Use a torque wrench. Tighten the bolts in a crisscross pattern (like the lug nuts on a wheel) to draw the flange down evenly. Sneak up on the final torque value in a few stages.