Figure 1. Hydraulics power mammoth technologies — but only if the fluid transfer system is secure and reliable. Source: Adobe/antoniotruzziIn a wide range of heavy industries, hydraulics transfer an incredible amount of power in the blink of an eye. The use of hydraulics is a time-tested technique — capable of such feats as lifting massive oil rigs beyond the reach of the waves below during a storm, or powering large stamping presses that stand three to six stories high.

Key to the strength of a hydraulic system is secure connections between fluid power fittings, hoses, pipes and flow control components. In a world with just one standard, and ample space between installed equipment, such connections would be rather straightforward. In reality, standards such as SAE, JIS, ISO and DIN, along with the usage of U.S. units and metrics can potentially make hydraulic connections an issue. Further complicating things, hydraulic lines often must be run at a 90° angle to the equipment, or even rotated, for space considerations.

MAIN Manufacturing offers solutions to both sets of challenges. Their flange adapters can convert one standard to another, while optionally providing ways to re-route connections, add tees to break off one line into many and even gauge ports for pressure monitoring.

What are flange adapters?

Industrial equipment is supplied with a variety of flange mounting patterns (also known as pads), which must, in many scenarios, be mated to flanges that have different bolt patterns.

Main’s flange adapter bolts to the component flange pad with one pattern and the other component bolts to the adapter pad effectively sandwiching the adapter between the two and making two connections. Each connection will have one “flat faced (FF)” side and an O-ring (OR) side. This is a tried and true way of making a leak-free connection and it is why there are so many different configurations of adapters (FF/FF, FF/OR, OR/FF, OR/OR). The adapters can be in-line, with the two patterns being aligned or rotated. The adapters can also be elbows.

Adapters are also available in tees to split hydraulic ports into two directions. Going further, cross fittings are available for breaking hydraulic lines into four, and double elbows can be used to modify hose geometry about a second axis. This flexibility can be incredibly important in restricted spaces, such as when equipment is arranged in close proximity or when there is a central hydraulic line running in a trench. A gauge port can also be added to adapters, allowing for an easy way to monitor pressure at the equipment’s hydraulic application.

MAIN produces adapters that accommodate SAE J518, ISO, JIS, DIN standards and more, and can even produce special flanges, which do not conform to any established bolt spacing. With an extensive inventory of finished parts, it is possible that they even have a niche adapter on the shelves ready to ship.

Bolt pattern measurement technique for flanges

Figure 2. Measuring bolt patterns helps identify suitable flange adapters. Source: MAIN ManufacturingWhen specs are unavailable, or access to them is prohibitive, this paper outlines an easy method of measuring socket head cap screw bolt spacing. The cap diameter is first measured with digital calipers, which are zeroed while still in this position. With this new zero set up, measurement from the outside of one cap to another produces a value where the diameter is already subtracted, and thus displays the centerline-to-centerline distance automatically. One will need to keep in mind that some patterns are specified as a bolt circle, where the furthest bolts from each other are measured (diagonally), while others are specified as a square, where the distance to the nearest adjacent bolt dictates the arrangement.

Metallurgy and customization options

While adapting one pattern to another, and potentially modifying the pad’s geometric orientation, heavy industrial hydraulic power users need to maintain the correct metallurgical composition for their environment. MAIN has a large catalog of carbon steel, as well as 304L and 316L stainless steel flange adapters, available in both SAE and metric configurations.

When needed, MAIN can also manufacture flange adapter parts from any commercially available metal quickly and efficiently, including materials such as aluminum, Inconel, cupro-nickel, Monel and more. MAIN keeps 150 tons of special quality carbon steel on hand, along with 50 tons of stainless steel, allowing custom non-stock parts to be shipped in days, not weeks.

MAIN’s standard part numbers do not include a mounting kit, allowing the customer to specify the type of screw and O-ring material required as a separate package. Engineers can, for instance, specify stainless steel screws, which have significant anti-corrosive properties, with the tradeoff that they may de-rate the assembly’s maximum pressure rating.

Case study: JIS to hose adapter for shock absorption

A U.S. importer of Japanese equipment has a system that would develop fatigue cracks at the hydraulic pump, which features a Japanese Industrial Standard (JIS) square pattern mounting pad. The system was hard piped, with a working pressure of 31 MPa (4,500 psi), and experienced significant shock loading during operation.

To alleviate this issue, the company wanted to add a section of flexible hose to reduce the impact, but JIS to hose end adapters are not readily available in the U.S., normally necessitating the use of hard pipe. To allow for flexible hose usage, MAIN proposed the following options:

1. A JIS flange to straight thread flange, which is often a stock item at MAIN. In this case, the port size did not allow for an adjustable O-ring fitting to operate at that pressure with spikes, so it was not implemented.
2. A JIS to SAE J518 flange adapter. This setup allows the use of SAE split flanges and a flange head. These are readily available in the U.S., facilitating customer replacement and maintenance. This option was chosen, which MAIN had in stock for immediate shipment. If it was not immediately available, this part could have otherwise been turned around in a quick three to four days.

This flexible hose installation alleviated the fatigue cracking issue in the equipment.

MAIN Manufacturing

With headquarters, production and a wide range of in-stock parts and raw materials in Grand Blanc, Michigan, MAIN stands ready to help with heavy industrial flange adapter challenges. They are able to fulfill 95% of its flange adapter orders in four days or less, with many shipped on the same day.

MAIN personnel are active on the ISO and SAE committees, so not only are they highly knowledgeable about relevant specifications, but they actually help write them. MAIN has 60 years of experience in designing, developing, manufacturing and distributing quality hydraulic flanges and components, and stands ready to help with hydraulic power transmission challenges now and in the future. Visit their website for more information.