Do you ever feel like the selection process for appropriate hydraulic lines, valves and manifolds is very difficult and confusing?

You are not alone! With thousands of tapping options available, selecting one that fits perfectly can sometimes be very difficult. Do not worry, though; we have a few tips for you to make the selection process more manageable.

First off, let’s talk about taps – why they even matter in the first place. Just imagine a world without them…pipes leaking like sieves, valves closing with great difficulty and manifolds involuntarily doing awesome but totally unintended fountain impressions. This is definitely not an ideal situation for any hydraulic system. Proper tapping ensures tight, secure connections that keep everything flowing smoothly.

So, what is the perfect tap? Think about these three things:

1) Material compatibility

2) Thread type 

3) Tapping method

Let’s look into each one more deeply.

Thread type

Threads can affect anything from the strength of the connection to its ability to seal properly. That’s why selecting the correct thread type is quite important.

Some common examples of this include:

  • NPT (National Pipe Taper) - Tapered threads that allow tightening for a leak-proof seal for wet applications
  • NPTF (Dryseal American Standard Taper) - Tapered threads for a leak-proof seal for applications that have gas. The dryseal connection can be created without using a sealing compound.
  • NPS (National Pipe Straight) - This is a common thread designation for hydraulic assemblies where hydraulic fluids are used.
  • NPSF (Dryseal American Standard Fuel) - These are often combined with an NPTF external thread to create a dryseal connection.

Straight threads are commonly used in valves and manifolds, e.g.

  • UNC (Unified National Coarse) - A strong option for general-purpose hydraulic plumbing
  • UNEF (Unified National Extra Fine) - Fine threads ideal for high-pressure lines
  • UNF (Unified National Fine) - Another option, but less common

Tapping method

Hand tapping

Use an old-style tap wrench that gives full control (if you are a strong person)

Machine tapping

Letting a drill, mill, or engine lathe do the work for high-volume production. 

Roll forming

An innovative process using rollers to “form” threads without cutting (great for preventing chips/burrs)

Each has its own advantages and disadvantages as well as ideal applications. On one hand, hand tapping provides flexibility but is laborious. On the other hand, machine setup is very quick and requires expensive equipment to be bought beforehand. What about roll forming? It eliminates chip headaches but works only with thin wall thickness.

At the end of the day, taking the time to choose the right taps will ensure that your hydraulic system functions without leakage at high pressure throughout its life. Who wouldn’t want such an easy ride? Thus, go out and tap it out confidently.

FAQs

Q: Why is it important to use the correct tapping dies and methods?

A: Using incompatible or incorrect taps can lead to improperly formed threads, creating leak paths or insufficient sealing in hydraulic lines, valves, and manifolds. Proper tapping ensures secure connections for optimal system performance.

Q: How does UNC differ from UNEF when it comes to hydraulic line threads?

A: Unified National Coarse has a coarser thread, which is suitable for general hydraulic plumbing with lower pressures. Unified National Extra Fine employs finer threads that are better for high pressure hydraulic lines. 

Q: When is rolling forming a better choice than cutting threads?

A: Roll forming can be useful when you want to prevent burrs or chips from threading cuts, especially thinner walled components like some manifolds, but it has some thickness limitations compared to cutting.  It is recommend to only roll tap the NPT threads and avoid the NPTF threads.

Q: How do I determine whether hand, machine, or roll form tapping is most appropriate for my application?

A: Hand tapping allows maximum flexibility but is labor intensive. Machine setups enable high-volume efficiency but require expensive equipment. While roll forming eliminates chips, it only works with certain wall thicknesses. Review your production needs, volumes, and part specifications.