The Torque Wrench

When You should (and shouldn't) use one


The most recommended method for installing straight port fittings, especially those with an O-ring seal, is the torque method. This method of tightening requires (you guessed it) a torque wrench compatible with your particular connector. Using a preset value known as foot pounds (lbs-ft) the thread is turned until the value is met. Most manufacturers have torque values for various fitting/thread styles using a torque wrench. This is typically a good place to start, depending on your fitting-type. With certain thread-types however, one should forgo the torque wrench in favor of a more traditional method. The best (and only) time to use a torque wrench is for new installations, not in replacement or repair cases where old and new components are mixed.


One issue with the torque wrench is that differences in connector plating, lubrication, and surface finishes must be known. Sure, if you manufacture the connections yourself, you may be able to control those factors. But, if item shortages or other circumstances force you or your supplier to procure fittings elsewhere, can you ensure they are exactly the same in these respects?

Consider the cost of torque wrenches, including buying presets for dedicated connection hex sizes, thread sizes, styles and torque value settings. Depending on your setup, this could easily equal a dozen wrenches needed to install your products. And, if you use a mix of thread styles such as JIC, O-Ring Boss, Face Seal, Pipe, and metric on a unit, the number of wrenches and therefore cost rises astronomically. In these situations one could always use an adjustable torque wrench, but this will add additional labor to your processes and allows other issues to emerge if torque values aren't changed correctly for each installation.

If you go the former route and procure a few dozen wrenches, you now belong to an elite club group of mechanics that must frequently recalibrate, repair, and replace wrenches. Unless one undergoes a lengthy and expensive process to calibrate equipment within your facility, the recalibration process may take your wrenches out of service for up to three weeks, leaving you without the tools required to perform basic job functions. Of course you could always keep a few backups on hand for these situations, right? Money grows on trees, after all.

Another issue to consider is the ever-present space issue. Do you have enough room to operate a torque wrench and backup wrench when installing your assemblies? Do you have enough room to store your fancy new wrenches, keep them locked away every night, and stop Greg from accidentally leaving them in his personal toolbox?

Now that we have thrown the torque wrench under the bus, ran it over, backed up, and ran over it again, let’s take a moment to breathe. For the sake of clarity. In theory, torque wrenches are often the best method for installing fittings. In practice, the procedures necessary to maintain properly working torque wrenches may not be worth the hassle when more convenient methods are available.

There are two different types of the Flats methods. The Flats From Finger Tight (FFFT/TFFT) method works well on assembling the following thread types:

  • JIC 37° Flare (not including tubing that has a 2 or 3 piece nut) This is for adapter fitting to adapter fitting only, depending on your terminology.
  • Threaded tapered pipe fittings, such as NPTF, NPT, BSPT, and Metric tapered threads

Fitting manufacturers have published values for the FFFT/TFFT method for the above fitting types, yet many people use the FFFT/TFFT method for the following unsupported thread types:

  • SAE O-RIng Boss (adjustable and non-adjustable)
  • O-Ring Face Seal
  • NPSM, or National Pipe Straight Mechanical

 The Flats From Wrench Resistance (FFWR) method works best for the following thread types:

  • JIC 37° flared fittings to flared tubing with a 2 or 3 piece nut setup.
  • Flareless tube fittings, using straight cut tubing also known as "bite-type"

Tapered Threads

Use the Flats method for these fittings. Avoid over-tightening these threads and cracking ports from over-wrenching. This includes JIC threads.

Port Threads

Use a torque wrench for O-Ring Boss, O-Ring Face Seal, BSPP Port, or any O-Ring/port connector to ensure the best results.

Align Flats

Use paint markers or other indicators to mark the position of hex flats to ensure proper FFFT



No, and how dare you!?

Threads used in hydraulic applications typically convey media at extremely high pressures, high temperatures, and sometimes transport hazardous chemicals that are much better off any place other than your skin. Because these products operate in potentially dangerous applications, it's imperative we exercise the finest safety practices whenever possible. Proper torque and turns values are typically much lower than one would expect. It's extremely easy to over-tight threads without exerting much physical strength, which can lead to cracked nuts, leaking end-connections, and in the worse case scenarios...failure. And, because most of us prefer to keep our skin firmly intact and free of unsightly charred holes, we follow the published turn or torque values for each thread type to keep our connections safe and secure.

Thanks for reading! If you'd like to obtain the torque or turn values for your fittings please contact us today! We'd be more than happy to provide you this data to keep your operators safe and happy.

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