Threadolet Pipe Fittings

Threadolet pipe fittings generally include threaded elbows, tees, unions, pipe caps, pipe clamps, reducers, plugs, external threads, and core bushings.

Threadolet pipe fittings used in industry are generally metal, but industrial plastic threaded joints are also widely used under special working conditions. The primary materials are PVC-C, PVC-U, PPH, PVDF, FRPP, etc.; threaded joints used in life are generally PC, PVC, PE, PPR, etc.

Threadolet pipe fittings are divided into three categories: internal threaded pipe fittings, external threaded pipe fittings, and internal and external threaded pipe fittings.

① Internally threaded pipe fittings refer to pipe fittings with threads near the inner diameter. Common ones are pipe clamps, elbows, tees, crosses, unions, and root nuts.

②Externally threaded pipe fittings refer to pipe fittings with threads near the outer diameter. Common externally threaded pipe fittings include internal joints (also known as external threads) and thread plugs (also known as pipe plugs).

③Internally and externally threaded pipe fittings refer to fittings with threads near both the inner and outer diameter. Common ones include universal bushings.

Precautions For Assembling Stainless Steel Threadolet Pipe Fittings

Before assembly, it is necessary to confirm whether the internal and external threads match and whether they are clean and impurities-free.

Wrap the raw tape around the external threads clockwise for 3 to 6 turns (the specific number of turns depends on the thickness of the raw tape).

If the working conditions permit, apply appropriate lubricating oil on the threads to avoid locking (recommended item).

Press the raw tape on the thread by hand (clockwise rotation) to make the raw tape fit the thread.

After manually screwing in the thread, use the corresponding tool to tighten it according to the recommended torque.

Do not use force when tightening, and screw it in smoothly.

If the pipeline is too long after assembly, consider the support of the pipeline to avoid deformation, leakage or loosening.

When stainless steel valves and pipe fittings are connected by threads, in order to prevent the valve from deforming, please first hang and fix the valve on the end close to the pipe fitting with a wrench, and then tighten the pipe fitting. In addition, please be careful not to use a pipe clamp on the valve, and be sure to use an adjustable wrench.

Stainless steel is now widespread, mainly because of its environmental protection. The internal threads on stainless steel pipes are usually tapped with taps. Because of the high viscosity of stainless steel and its poor chip-breaking performance, it’s common for chips to scratch the workpiece thread or cause the tap edge to break during tapping.

This significantly impacts processing efficiency and thread quality. To enhance the tap’s service life and improve thread processing quality, it is crucial to note the following points:

Design And Manufacturing Of Threadolet Pipe Fittings

Consider upgrading tap materials by incorporating particular alloy elements into ordinary high-speed tool steel. This enhancement can significantly bolster the tap’s wear resistance and toughness.

By applying a titanium nitride coating to the surface of the tap thread, you can greatly enhance the tap’s ability to resist wear, withstand high temperatures, and provide improved lubrication.

Increase the tap rake angle appropriately. However, it should be noted that if the tap rake angle is too large, it can easily cause tap edge breakage and multi-edge tapped threads when retracting.

Increase the tap backing appropriately. However, it should be noted that if the backing is too large, chips can get stuck in the back angle of the tap when the tool is withdrawn, and the tapped thread will have a poor finish.

The tool heat treatment method should be reasonably selected to consider the tap’s hardness and toughness.

Pre-Processing Of The Bottom Hole Of The Workpiece

The bottom hole size of the workpiece should be pre-processed following the principle of minimizing the tapping processing volume, especially the American standard NPT thread and the British standard F, R thread, whose taper is 1:16.

However, most stainless steel manufacturers cast a straight hole according to the small end diameter of the thread as the tapping bottom hole L, resulting in a large amount of processing in the second half of the tapping, which easily cause the following adverse consequences:

 The tapping torque is ample, and the tap is easy to break or break;

The tapped thread has a poor finish;

 When tested with a plug gauge, the tapped cylindrical thread is more minor in diameter. The reason is not that the thread center diameter is inconsistent but that the chips scratch the thread and there are burrs.

The bottom hole size should preferably be the minor diameter of the thread being processed, plus a 0.1-0.2MM margin.

Using a customized reamer for hole expansion is best before tapping. American standard NF, R threads and British standard F, R threads should be processed into a tapered bottom hole. Many companies use waste taps to manually grind off the threads to make reamers so that waste taps can be reused. However, two issues should be noted when modifying the reamer:  When grinding off the threads, the back angle must be ground out; The front angle surface of the tap blade should be kept straight.

Reasonable Use Of Threadolet Pipe Fittings

When processing different types of workpieces, different chip directions should be considered. If necessary, new taps also need to be reground. The principle of regrounding is to try to discharge the chips from the chip groove during tapping to prevent scratching the processed threads. 

Elite Piping Manufacture is committed to producing and selling carbon steel flanges. Our carbon steel flanges are available in various models and can certainly meet your production needs. You are welcome to contact us at any time.