Designing a reliable, leak free, and easy to maintain hydraulic system is every engineer’s objective. Following these six basic techniques can ensure you achieve that objective every time.
1) Use straight thread adjustable fittings and ports whenever possible, they have several advantages over fittings using tapered pipe threads:
Adjustable straight thread connections:
- Permit exact positioning with up to 360° alignment
- Provide a leak free joint
- No need for additional sealants or tape
- Eliminate distortion and cracking of boss due to over-tightening
- Torquable and reusable
- Are easier to maintain
Top view of an adjustable straight thread connection showing the ability for 360° positioning of the fitting prior to tightening.
2) Use swivel nut fittings with a straight connector to allow for assembly in tight spaces, when an elbow or tee adjustable fitting cannot be fully rotated.
Swivel fitting + straight connectors allow:
- 360° positioning in tight spaces without fitting rotation
- May reach higher pressures than adjustable fittings and taper pipe thread fittings
- Can be combined with taper pipe thread straight connectors to allow for 360° alignment
- Torquable and reusable
- Easy to maintain
Using a swivel nut fitting with a straight connector will allow for assembly in tight spaces.
3) Use a combination of adjustable fittings and swivel fittings + straight connector to allow for an easy way to stack tube lines to provide clearance for ports that are relatively close and within the same plane.
A swivel fitting + straight connector (right) provides clearance above an adjustable elbow (left).
4) Use reducers/expanders and jump size fittings to connect tube lines of different sizes or tube lines to ports of different sizes.
This is typically done using either tube reducers, port expanders/reducers, or jump size fittings. Achieving the reduction or enlargement is the main objective, but care should be used to minimum number of connections. See our blog post, Hydraulic Fittings: Don't Stack, Jump!, on how best to determine and accomplish this.
5) Use conversion fittings and adapters when it becomes necessary to connect a fitting to a port with different style threads.
Conversion adapters are very useful for connecting components that have limited port options due to country of origin. There are also some instances when it is necessary to connect tube ends or hose ends with different style terminations to one another or to a fitting. This can be achieved by using conversion fittings.
6) Use specialty fittings and components to improve plumbing, reduce connection points, and increase tube availability options.
Use a close coupling, like the fitting shown below to connect two components to minimum space and leak paths. This one has two SAE straight thread studs, a non-adjustable end and an adjustable end (Parker's F5OHAO).
For several fitting types, use a metric sleeve to adapt a metric tube to an inch sized fitting (Parker Seal-Lok o-ring face seal fittings or Triple-Lok 37° flare fittings) to allow for broader tube selection options.
Use stacking elbows to reduce space and improve tube routing.
Do you have any additional plumbing and assembly tips? If so, please share by commenting using the link above. If you have any questions or comments, please post them and we will respond if warranted. To talk to our techConnect engineer team directly, they can be reached at Parker Tube Fittings Division, 614.279.7070.
Did you find this post helpful? Subscribe to TFD techConnect posts by email. TFD techConnect is a technically-focused monthly blog written for engineers specifically around motion and control engineering challenges.
Do you want to receive new product announcements and technology updates from Parker Tube Fittings Division? Subscribe today and stay informed.
Contributed by Ted Amling, senior project engineer, Parker Tube Fittings Division
Additional related content about hydraulic tube, hose, and port fitting connections:
How Many Times Can I Reassemble a Hydraulic Fitting?
Turn vs. Torque? How Making the Right Choice Keeps Your Hydraulic Fitting Connections Leak-Free
Four Easy Steps to Identify Hydraulic Threads
10 Things Not to Do When Your Hydraulic Fitting Leaks
Tube End Preparation Best Practices for Leak-Free Hydraulic Tube Fitting Connections