Tips to Help You Better Identify Hydraulic Threads

Tips to Help You Better Identify Hydraulic Threads

April 24, 2020

Hydraulic systems for industrial machines and equipment use a wide variety of different types of adapters, fittings and sealing methods. What can be confusing is that thread forms across brass adapters in San Jose, CA might look alike, making it difficult to identify the specific type, not to mention time consuming if you don’t know exactly what you’re looking for.

You need to know the thread type if you’re going to be able to select the proper replacement part when you’re performing maintenance and repairs on your equipment. If you install the wrong part, this could result in some significant damage to the thread during the installation process, which could compromise the seal reliability of the fitting and the overall performance of the part.

There are six different types of hydraulic threading. Here are the steps you can take to determine which type of hydraulic threads you have:

  • Check to see if the thread is parallel or tapered: NPT/NPTF, metric tapered and BSPT threads are tapered, while BSPP, metric parallel and UN/UNF threads are parallel. You might be able to determine if the thread is parallel or tapered simply upon visual inspection, as tapered threads will get smaller in diameter the closer you get to the end of the fitting. Parallel threads, meanwhile, maintain the same diameter the whole way. However, this isn’t always obvious, so you might need to use the parallel jaws of a caliper to compare. In addition, if there’s an O-ring or if you need to remove a tube nut, this is probably indicative of a parallel thread.
  • Check the pitch: You can use a pitch gauge for comparison in this step, or measure and calculate how many threads exist in a particular span. It’s much easier to compare the threads when you have a lighted background and a pitch gauge to help you see better. There are some thread pitches that can be similar, so try multiple gauges before deciding on the best one. Most types of threads have a very distinct pitch to them, so this can help you narrow down the possibilities.
  • Check the size: After performing the first two steps, you’ll be able to determine (or predict) the procedure to use here. The method you’ll use depends on whether or not the thread is a pipe thread. Just because it’s tapered does not mean it’s a pipe thread. You can determine the size of pipe thread by comparing it with a nominal size profile. For non-pipe thread, you can determine the actual size by measuring the outside diameter with a caliper.
  • Determine the thread: Designate the thread type in a format that is easy for others to understand. Maintenance and repair professionals will understand how to do so in a way that easily indicates the thread size, type and, in some circumstances, pitch.

For more information about the steps you can take to identify the type of hydraulic threading you have on your equipment like BSPP hydraulic fittings in San Jose, CA, we encourage you to contact the team at Royal Brass Incorporated today.

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