One of the most overlooked elements of a new hydraulic system design is selection of types of fluid connection. Many designers use the “tried and true” options they always have because it is easy and familiar and it works. Pipe thread, JIC, SAE O-Ring and Code 61/62 flange connections are the most common and widely used.
Most designers have gotten away from pipe thread almost entirely. It is the least reliable technology and does not remake easily. It relies on compressed or distorted tapered (non-parallel) threads to make a seal and has caused many systems to leak or fail over the years. JIC also relies on a metal-to-metal seal on an angled cone interface. It is still quite common and is relatively reliable. However, it is subject to failure in high vibration applications and does not lend itself to remake very well. SAE O-ring and Code 61/62 flange connections are the best and most reliable in terms of remake, vibration resistance, pressure capability. They both use an elastomeric seal and are quite easy to assemble.
Having said that, there are many new and innovative designs available that make a system more reliable, leak and vibration resistant, easy to assemble. Most are variations on either the SAE O-ring or Code 61/62 flange design. First is the O-Ring Face Seal (ORFS) connection. This utilizes an o ring seal in a machined or formed groove at the end of the fitting. The threads are parallel and it is very easy to assemble and remake. This technology is also very vibration resistant and is widely used in the mobile equipment industry for this reason.
The other innovation is a variation on the Code 61/62 flange design. More specifically, it is a tube forming technology that interfaces with the traditional Code 61/62 patterns. It utilizes a special flaring machine that forms the tube end with a mating flange. The major advantage to this concept is that it avoids welding entirely. Traditionally, large hydraulic pipes or tubes with flange ends have the flange end welded onto the pipe or tube. This is time-consuming, often requires very special training, inspections, and certifications and therefore is a very expensive process. The alternative forming technology can be made up very quickly, requires no welding, inspections or certifications.
These are a few examples so as you are designing a new system, please don’t forget to look at the connector technology!!