When a hydraulic hose break while carrying load it’s not just noisy, but it damages your system too. It’s also dangerous, messy and costly.
Tube fittings is common for lower pressure hoses on most types of fluid power systems. For higher pressure applications such as found in big bore circuits on heavy equipment, they need to be stronger. That’s where split flange fittings come into play. They has structural strength to maintain massive flow rates while preventing leakage and bursting. The required dimension are shown in the chart above so that you can ensure that the system stays sealed.
How to Install Split Flange Fittings Correctly
Code 62 is a different animal altogether. It may appear almost identical to code 61 in the field. However, they have same bolt circle pattern at each size, so you can usually swap between them without any change to your manifold mounts. The difference comes down to wall thickness and pressure rating.
Code 61 (the regular workhorse) rate to 3000 PSI. This means it’s good for medium duty applications. It works for general agricultural implement or mobile equipment where the work isn’t too heavy. By saving on materials cost here, it adds up if you’re outfitting an entire fleet of tractors.
Rated for 6000 PSI, this body has a thicker flange as well, which is why it’s called Code 62. That extra thickness can contains all that energy. Code 62 is the only option if you are dealing in high pressure industrial presses or subsea blowout preventers for offshore drilling rigs. You need a thick enough piece of metal to prevent any kind of deformation under load. Not using the right code in this situation isn’t just a leak problem, it’s a catastrophic failure waiting to happen.
But how do you install these? They are called “split flanges.” Rather than sliding on and off like a slip joint, they clamp around the pipe so they can be installed in places that don’t leave enough room to get a full ring on line. You simply seat the two halves of flange head against the port and tighten down the bolts. It pulls them together and compresses the O-ring seal between them.
The critical element here is the torque setting. The infographics spell out the foot pound settings for the bolts (from 10 foot pounds for smaller fittings up to more than 150 foot pounds on the biggest ports). Never guess at the torque; this will cause one side to tighten more or less then the other and warp the face of the seals. And warped faces means leaks. Leaks mean loss of pressure. Loss of pressure means money lost.
Tighten with lubricated threads. This may seem odd for an oil application. However, because friction can hide the real clamp load in your torque reading, wetting the bolt threads with a little hydraulic fluid will help you apply the right amount of tension to hit your target. As you would do when changing a tire, torque in a star pattern to maintain parallel flange faces.
The assembly also uses O-rings. These are not the rubber ones that you put into the grooves; these are installed in the machined grooves and compressed against the surfaces they seal with a face seal. Each port size has a corresponding Parker AS568 dash number of an O-ring. For example, an 012 is used for a 1/2-inch flange or a 048 for a giant 4-inch one. If you use a small O-ring in a large groove there will be excess squeeze out room. If you have a large one in a small groove, it gets squeezed too hard and will fail or pop out too soon. Most applications use nitrile as the standard o-ring material, but in extreme temps, you may require something different.
You’ll want elbows, if your routing allows for them; otherwise go straight inline. Since hydraulic fluid flows along a path of least resistance, going straight will minimize pressure drop. An elbow (either 90 degree or 45) create some turbulence resulting in pressure loss. Route around that if possible. Reduce a large main line to a smaller branch with a reducer, maintaining the integrity of the bigger circuit.
Hydraulics are all about controlling flow, direction and force. The first step to doing that well is getting the flange size correct. That keeps high-pressure fluid contained properly. Don’t skimp on seals or torque. Understand the pressure rating. These fittings works reliably when installed correctly. Reliable means no leaks or noise. And that quiet says you’re doing it right.
