Banjo Fittings Deserve More Attention for MRO & Aftermarket

    Banjo fittings are comprised of multiple assembled components to achieve a compact 90° connection in hydraulic and conveyance applications. They utilize a bored and perforated bolt that intersects a spherical hollow body containing a thread, hose-barb, or braze receptacle perpendicular to the bolt and port. Metallic washers or soft seals are then utilized to seal the components when stacked. The bolts typically go into port connections, while the spherical body connects to a hose or tube. Typical bolt/port threads include BSPP, Metric, and SAE/UNF while common hose/tube connections on the 90° stud include JIC, hose-barb, DIN 2353, 60° Metric, BSPP, and braze/weld.

    By Mike Rennie, General Manager, Adaptall

    Benefits of the Banjo Fitting

    There are intrinsic benefits to the Banjo fitting design in terms of time savings during assembly and ability to install in compact spaces compared to traditional elbows. Banjo fittings also work with copper and aluminum seals, allowing operation at extreme temperatures or conveyance of mediums that induce premature seal failure in rubber compounds. Banjo fittings are popular in OEM environments for these reasons, such as automotive, power equipment, off-road and motorcycles for fuel, brake, and transmission lines. As more hydraulic technicians become aware of the benefits, Banjo fittings are being requested more and more in non-OEM applications.

    Why Banjo Fittings for the Aftermarket?

    All of the inherent benefits of Banjo fittings can also be value added for MRO uses and markets, such as replacing or improving fittings in an existing system. In fact, as the world experiences staffing shortages and increasing labor rates, it may be the best option for large scale and time-consuming projects. Compact manifolds may now be possible, reducing assembly size and overall project costs. Banjo fittings with metallic washers may also be the perfect solution for operating temperatures and mediums that rubber seals may not survive in. Banjo fittings could be the answer for some MRO projects to remain competitive and differentiated in this current environment.

    The Challenges of Installing & Orienting Elbows

    One of the major benefits to Banjo fittings that also translates to the aftermarket is the ability to easily orient and install the 90° connection during assembly. Simply assemble or stack the components, thread the bolt into the port until slightly loose, then orient the 90° connection to the desired position, and finally torque the Banjo bolt. Traditional elbows must be fully turned or threaded a full 360° numerous times before tightening the adjustable nut (if it exists), requiring even more distance between the ports. The current best practice is to stagger long/extended and regular elbows to avoid these obstructions, but this can be an expensive solution, not to mention large and bulky. One can also utilize 90° hose ends, but they have similar drawbacks.


    Figure 1: Height savings amount to 56% compared to traditional elbows in this example (Dash 08 JIC x 18mm Metric port).

    Simplified Torquing

    Traditional elbows also present challenges when torquing in cramped workspaces while performing maintenance or repairs. These elbows usually require access to the adjustable nut, located right above the port, which can be impractical for wrenching and torquing laterally with other components close-by. Torquing this way also requires a Crowfoot adapter, which may require additional calculations to factor the torque values as the force is being applied is off-axis to the ratchet. Banjo fittings however can be torqued parallel to the port, above the array of fittings and clear of obstacles. Socket wrenches can instead be used which are more compact and faster to operate compared to open-end wrenches, especially in tight spaces. No Crowfoot calculations need be performed, in fact socket extensions can be used without affecting torque settings whatsoever.

    Flow Paths and Patterns

    Another unique benefit to Banjo fittings is the ability to achieve numerous flow patterns beyond simple 90° connections. Tee like flow paths can be achieved by use of double Banjo bolts, however double Banjo bodies (E.g. straight through braze) are also an option. Double Banjo bolts are typically twice as long as regular Banjo bolts with additional perforations, allowing you to stack two Banjo bodies instead of one. On the other hand, double Banjo bodies have two studs facing in opposite directions. Technically it is possible to utilize a double Banjo bolt with two double sided Banjo bodies to achieve five total connections (one port, and four hose/tube connections). One can also incorporate multiple thread and connector types, instead of being limited to one or two threads on a traditional Tee fitting.

    Shortcomings of the Banjo Fitting

    There are however some down sides to Banjo fittings which must be considered when choosing between connector types. For one, the components of Banjo fittings may be difficult to match for compatibility. Some distributors will provide complete assemblies which can help avoid this confusion. Banjo fittings are also notorious for components being lost and misplaced. Due to the awkward nature of assembly, it is not uncommon to have a copper washer slip off and go bouncing across the shop floor, never be seen again. Also, with multiple non-elastomeric seals and therefore potential leak points, metal sealed Banjo fittings are not ideal for high pressure applications. While the bolt is relatively simple to manufacture, the spherical bodies are also time consuming and require special machinery and tools to produce. These shortcomings have mostly been addressed with the improved ‘Compact’ Banjo design.

    Improved Banjo Fitting Design

    Compact Banjo fittings are like conventional fittings except that they are fully assembled, utilize a forged or milled block body instead of a machined spherical one, but are similar to conventional Banjo fittings in that they come with both metal seal as well as soft seal options. The compact Banjo fittings are therefore able to overcome the short-comings of a classic Banjo fitting but still retain the many benefits of the original design; they can withstand higher pressures when using soft seals, it is virtually impossible to lose components, they take the guessing game out of matching components, and they are generally leak proof. These Banjo fittings can also be ordered in some cases with metal seals, meaning all of the benefits of copper and aluminum washers are possible without all the draw backs of a conventional Banjo fitting. However, the compact Banjo fittings are typically only available in Metric and BSPP on the bolt, and DIN 2353 on the 90° connection. Both conventional and compact Banjo types have their advantages and disadvantages, just like any connector technology. There are multiple variations to each design (high flow bolts, high pressure bodies, metal seal vs soft seal) that result in an endless combination of assemblies so as to best meet the project requirements.


    Figure 2: Multiple flow paths and patterns are possible with Banjo fittings.

    S.T.A.M.P.E.D

    In order to remain competitive and differentiated, it then becomes imperative to consider Banjo fittings when performing a S.T.A.M.P.E.D analysis. “STAMPED” is an acronym that stands for Size, Temperature, Application, Media, Pressure, Ends, and Delivery and is a guide for matching optimal hose and fitting parameters to a given job’s requirements.

    • Size: Banjo fittings typically cover up to one-inch nominal thread size in most cases, and up to 26mm Metric.
    • Temperature: metallic washers are an option for operating temperatures below 35°C/30°F and/or above 205°C/400°F where traditional NBR and Viton seals do not perform well.
    • Application: are there space constraints? How will the fittings and hoses/tubes be connected?
    • Material: is there a medium being conveyed that is incompatible with NBR and/or Viton seals? Are there environmental conditions that should be considered?
    • Pressure: up to 5,800 psi max working pressure can be achieved using soft seals, depending on a number of variables. Metallic washers can typically achieve up to 2,400 psi max working pressure.
    • Ends: as previously mentioned, Banjo covers the major port threads (BSPP, Metric, SAE/UNF) with Banjo bolts, and popular hose and tube connections are available via the Banjo bodies (JIC, BSPP, DIN 2353, 60° Metric, hose-barb, and braze). ORFS is typically not available on the hose/tube side, just as NPT is not common as a port (bolt) thread but is available in some cases.
    • Delivery: it should be considered that Banjo fittings do not move
    in the same volume as traditional elbows, so stock could be limited; lead times and availability may vary.

    Conclusion

    Banjo fittings have many advantages and make them ideal for some projects, however they are an underutilized connector within the hydraulic community. It will take more time and education at the distributor level for banjos to gain a fraction of the acceptance that other threaded connector technologies have. They are simply a different tool in your arsenal to provide increasing value for end users.

    ABOUT THE AUTHOR

    Michael Rennie, General Manager of Adaptall, has over 15 years of experience as a technical writer covering various topics on thread and fitting identification, selection, and installation with a focus on international thread types. Mike holds a Bachelor of Business Administration (Honors) degree with Marketing concentration from Brock University.

     

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    Sara Mathov is a feature editor contributing to Valve World Americas, Stainless steel World Americas and other related print & online media.