How to thread a water pipe

Threading. terms required

This process is the machining of a rod or hole by means of a special tool for threading pipes in order to obtain external or internal alternating protrusions-rolls and spiral grooves.

The main characteristics of threads are:

  • pitch. This is the distance between the tops or bases of adjacent coils;
  • profile. The cross section of the thread can be trapezoidal, triangular, rectangular, etc. Sanitary parts exclusively use a triangular profile;
  • profile angle. It is formed by the intersecting sides (side edges) of the coils;
  • depth. It is the distance from the top to the base of the thread;
  • outside, middle and inside diameters.

Outer is equal to the distance between the points of two opposite sides of the thread. Average diameter ˗ is the distance between the top and the base of the sections that are on opposite sides of the workpiece. The inner is the distance between opposite hollows.

thread, water, pipe

Every thread has its own technical characteristics

Tools required

You will need threading tools to perform the work:

  • Cutter or lancer. a device in the form of a nut made of hardened metal, has sharpened cutting edges (cutters). They come in round, square, and hexagonal shapes. Types of dies: solid, sliding, split. Holes are arranged to drain swarf.
  • A cluppe is a tool based on a sliding die. The two-piece body allows you to adjust the diameter of the cut. Handle is arranged for ease of operation. Some models are equipped with a ratchet that enables one-handed rotary movements. Professional tools are equipped with an electric drive.
  • Tapping. a screw made of hardened steel, which has cutting edges. Consists of a working part and a shank. The set includes equipment for roughing and finishing work.

Additionally prepare auxiliary devices:

Tools used must be of high quality, and tool metal must be sharp and durable. Vise is needed when working with dies and taps.

Preparing for work

The section on which you will work threading tool for water pipes, cleaned of rust, dirt, paint residues. Sandpaper is used. Surface must be cleaned to a metallic shine. Chamfering on the end face. It is necessary to prepare lubricant for pipe machining and cutting tools. A rag is needed to clean the swarf.

Threading methods

There are several ways to thread a pipe:

We suggest to consider the most common and easiest way of threading pipes with a crescent drill (threading tool).

So, before you start the threading process itself, you need to prepare the tools you will need for the job.

Tools for threading the pipe:

  • Clupp a set of thread cutters (dies). This is a special tool for threading and it comes with a few sets of radial cutting dies. These in turn have different diameters to fit the particular sewer or water pipe (for external threading);
  • Tap (for internal threading);
  • A gas wrench or a vise (to hold the pipe in place);
  • Machine oil or any lubricating oil;
  • Grinding machine for working on metal with cutting disc.

Please note: When working with grinders, utmost care must be taken and safety regulations must be observed. Protective goggles and gloves should be worn.

Sequential steps for cutting the external thread on the pipe

N.B.: Do not try to rethread the old threads, even if you succeed, the threaded joint will not be watertight enough. It could leak afterwards.

To get the perpendicular cut (it is necessary for screwing adapters and for convenient cutting) the tube is hold by a gas key or we clamp it in a vice, previously make a marking.

  • Next it is necessary to make the edge of the pipe a little thinner, that is cut the bevel so that the dies could be screwed on the pipe more accurately. To ensure good sliding of dies on pipe, we lubricate the place of future threading with machine oil.

Tip: If you do not have machine oil on hand, you can use regular lard.

  • Then turn the threading head in the right direction (clockwise) and cut the thread. It is not necessary to cut all the thread on the tube at once, after making a few turns it is necessary to twist the cluppe in the opposite direction, thus freeing the tube from the metal filings.

Tip: If your efforts are not enough for threading, you can screw an additional knob on the die holder handle to increase the leverage.

It is not desirable to thread more than 1 cm, it is enough, as tees, fittings and angles in their majority have a thread of exactly 1 cm.

The end result of tapping the male thread

In terms of how to thread the pipe, there are no particular difficulties. You have probably had time to see this after reading the above material.

Threading the inside of the pipe

For internal threading, you need to know the precise diameter of the hole. Thus, the required size of the tap is selected. The blind hole (depth), must be a few millimeters larger than the length of the thread.

Once the diameter of the drill bit has been determined follows:

How to Apply Teflon Tape the RIGHT Way

  • Before threading with a tap, drill a hole. Here you need to watch the position of the drill, which should be in a vertical position to the surface of the workpiece.

Note: If the tap is inserted at an angle, there is a greater chance of breaking it.

  • On this basis, you should first use a tap. and then go through the tap And also remember that the taps should be lubricated with machine oil.

Threading internal threads with a tap

A tap taps an internal thread in a pre-drilled hole. Hole should be smaller by about the size of the coil (the size of the coil is shown on the tap). Approximately as in the table:

Diameter for tap tapping the inside hole

It is worth remembering that the drill will not give an absolutely accurate diameter, it will be more on some fractions of mm. This is especially noticeable on diameters up to 3 mm. This should be taken into account and the drill bit should be smaller by a tenth of a mm.

As with tap bits, there is a tap holder.

There are roughing and finishing taps. Sometimes one cuts first with a roughing and then with a finishing tap, but mostly one uses the finishing ones at once.

Manual threading with a tap

The process is virtually identical to that of thread cutting with a tap. The tap is held in the holder and perpendicular to the hole. The piece with the hole should be firmly fastened.

The tap and the hole are lubricated and this is done periodically, after several threads. As with the tap, you need to make 1-2 turns and 0.5 back to remove swarf.

A square is used to check the accuracy of threading by checking the verticality of the tap after a few turns.

Threading on the inside

Tapping a self-tapping internal thread with a tap inserted in a screwdriver. A tap has a fence part (its end), which is necessary for tapping, a gauge part (the middle part), used for guiding when tapping the hole and calibrating, and a tail part, which has a square head in the cross section, to hold the tap in the gate when tapping.

When going from insufficient to full metric or fastening inch varieties, a set of taps that includes three taps of different depths is used.

Tapping with a die

Tools for threading pipes are subdivided into the following several types:

  • Round. Can work with different diameters of cylindrical constructions. Depending on the size of the pipe, the appropriate size of the die is selected.
  • Sliding. A special holder is used to thread different diameters.

It should be noted that the price of dies is much lower than the cost of other types of threading tools, so they are used more often.

The threading process is carried out in a certain sequence:

  • Using a caliper, the required diameter of the ram is selected.
  • Pipe and cutting tool surfaces are lubricated. It is allowed to use any kind of lubricant.
  • The tool is fixed in the holder. If this is not done, the track will be uneven, the connection will be leaky, and leaks will appear. The die holder should be turned clockwise.
  • To remove accumulated chips, the tool must be turned in the opposite direction.
  • At the end of the work all grease is removed.

At first, roughing dies are used. They cut the pipe well, but the work turns out to be inaccurate. The final cut is made with a finishing tool.

Threading with dies

How to thread with a die on a pipe? Pins can be either round or adjustable. Round dies can have different diameters depending on the diameter of the pipe. As for the sliding models, with this universal tool it is possible to process pipes of different diameters: for more convenience, it is equipped with a special holder. dies are very popular due to their low price. Before beginning the work, prepare the pipe according to the above procedure. How to thread the pipes depending on its type.

For the actual work of threading the pipe with a die, the following scheme is suggested:

  • Fitting a caliper to a suitable die with the correct diameter.
  • Lubricating the tool and the area of the pipe to be threaded with any grease.
  • Fixing of strip inside a special holder. The fixing of the threaded dies in the holder must be very firm. If this condition is not met, there is a skew in the application of the thread, which makes the place of connection very unreliable, up to the appearance of leaks.
  • Turning the die holder in the right direction. After a few rotations the same procedure as with the claw is followed: this makes it possible to remove the shavings that have formed. For this purpose the fixture must be unscrewed slightly backwards.
  • Clean the tool and pipe of grease at the end of the job.

The first stage is carried out by roughing dies, carrying out a clear cut through the pipe, but the accuracy of the thread in this case is negligible. For the final threading a finishing die is used.

Threading the pipe is not that difficult

To reliably connect the faucet to the pipe, or install the heater in the heating system, it is important to know how and what to thread the pipe.

Because most of the shut-off valves are threaded, therefore connection of such elements by welding is not possible.

For example, if you have to install a new sink or toilet in your apartment, and unscrewing a long-standing connection on the steel water pipe is not possible, then the best option:

  • Turn off the water supply;
  • Use an angle grinder to cut off a part of the pipe at the place where the basin is installed;
  • Carry out the threading of the pipe;
  • Install a ball valve or tee on the pipe;
  • Connect it with a flexible hose to the washbasin faucet.

This work can easily be done by a qualified plumber. However, and any apartment owner, having purchased a tool for threading pipes, can independently carry out this work.

Today, 2 types of threading devices are used to equip a pipe with a threaded connection:

With their help it is possible to thread any sewer or water pipe that is used in the engineering networks of apartment houses and private cottages.

Advice from!

If you have never threaded, it will be difficult to do it with a die. The slightest misalignment of the tool can lead to a defect.

Therefore, it is better to use a clevis, because it has a guide that greatly simplifies the threading process.

Let’s refresh our memory on the theory of the threading process.

  • Threading pipes is the formation of a helical surface on the outside of the pipe (water pipe or heating system);
  • the helical surface is the connecting element of a fitting rotating uniformly about the axis,
  • tee or crane, with a uniformly reciprocating movement along this axis;
  • Thread pitch is the progressive movement of a threaded item in relation to the thread axis, corresponding to one complete revolution of the thread.

In other words, in order to install stop valves, it is necessary to cut threads on pipes, the pitch of which coincides with the pitch of the connecting elements. Then such a connection of sewer or water pipes will be tight and strong, and able to withstand high pressure.

Grooving with a die

This type of threading tool is:

  • circular configuration. In order to thread pipes with different cross sections, different sized dies are used;
  • sliding. Such a part is used to cut grooves on hollow objects of different diameters.

This model of instrument is used more often. The reason. the low cost of the product.

Before proceeding to work, using a die (lerka), it is necessary, using the method described above, to prepare the pipe.

Only after that should proceed to the procedure under this scheme:

  • Choose a device of appropriate diameter (for this purpose, use a caliper).
  • Then lubricate the surface of the item and the inside of the die with any lubricant.
  • The next step is to clamp the pipe cleaner firmly in a vice.

After several revolutions it is necessary to remove the shavings.

At the first step, it is necessary to use a roughneck lathe (it makes a clean cut through the pipe).

But they don’t help you get the carving accuracy you want. The final cutting is done by means of a finishing lance.