Tapping a 1-inch pipe thread

All about threading pipes: 4 turner secrets

The detachable connection of metal pipes in a home plumbing, sewer system is made by threading. Inch pipe threads are performed on pipe ends and fittings. The diameter of its threading is determined by the size of inches, or their fractions, where the characteristic value. the number of turns made by the number of turns on the length of a single inch. The main advantage of threaded pipe joint is the possibility to disconnect and replace one worn part, instead of removing the entire structure and welding the other. Threading an inch thread is done with dies, taps, or special cutters.

tapping, pipe, thread

The pipe wall thickness is added to the size of the inside diameter of the pipe. If the size of the inch is 25.4 mm, the size of the pipe inch is 3.3249 cm. The choice of an inch part causes the exact size of the cross-section to match.

Tools and rules for tapping pipe threads

Of course, to perform this procedure, you can’t do without a pipe threading tool. In the trade, it is commonly referred to as a pipe threading set.

Useful information! A tool with the unusual name of a clupp may be included in the kit. It resembles a pipe threading die, but contains only its main functional part. a circular frame in the form of a short cylinder made of tool steel and equipped with sturdy cutters.

in addition to the clevis or tongs, the kit includes a bit holder (with or without a ratchet) and a few other additional tools such as pliers, clamps, etc.ะด.

Requirements for threading of pipes by hand are formulated as follows

  • mandatory preparation of the pipe. Dirt, rust and paint layers must be removed from the place of the future threading. The surface should be cleaned down to the metal;
  • the process of threading on pipes shall be accompanied by lubrication of their working surfaces and the cutters of the tool used. dies or caulk. A lubricant, which is a special liquid, is used for this purpose. It is applied both before and during the process of threading the pipe;
  • on the end of the product must first remove the outer chamfer;
  • The work must be carried out only with a sharp and serviceable tool for threading on water pipes.

In addition to technology, it is also important to know the subtleties of tool selection.

When threading, it is necessary to strictly follow the technology

Threading tools are not only the aforementioned dies and clips, but also taps. The latter are used to create internal threads by cutting chisel grooves. But there is a little nuance here. To thread the pipe, you need to use a set of two taps that differ in depth of penetration:

Threading dies for threading pipes can be:

Another tool, the clevis tool, has a guide in its construction. It serves to center the cylinder with cutters on the pipe.

At the same time, just knowing how to thread a water pipe is not enough. It is necessary to find out the requirements of GOST to the size of pipe threads, and already according to its pitch and diameter to select a set of threading tools. These are shown in the table below.

Thread pitch Thread diameter, mm Pipe thread size, inches
mm Threads per 1 inch Inner Outer
2,309 11,0 84,930 87,887 3
2,309 11,0 72,230 75,187 2 1/2
2,309 11,0 56,659 59,616 2
2.309 11,0 44,847 47,805 1 1/2
2,309 11.0 38,954 41,912 1 1/4
2,309 11,0 30,293 33,250 1
1,814 14,0 24,119 26,442 3/4
1,814 14,0 18,632 20,956 1/2

Self-tapping of pipe threads

What will be needed for the job

The industry uses machine tool equipment for cutting, which without the presence of a machinist can handle the alignment, movement of the die, subsequent finishing. Not an achievable task in an apartment or garage.

For the home, a special rifling tool is suitable, which can be bought at any construction store or at the market. Available as one-piece or split dies and taps.

In addition to clinches and dies, additional tools will be required:

  • Pipe cutter. Tools for cutting steel pipes. Equipped with several rollers and a carbide or diamond cutter. Gives a fine, almost imperceptible, burr-free cut. If you don’t have one, you can use an angle grinder with a cutting wheel. On the cut there are burrs and irregularities that need to be treated.
  • File or flap wheel. If after cutting there are surface defects, additional processing is required. Since the steel in the pipes is raw and soft, it can easily be ground with a file or file. To speed up the process, you can use an angle grinder.
  • A gas torch or a blow dryer. If you have to work on old piping, you will have to remove the paint and rust. Threading on pipes with paint will not give a firm grip or strength. The old paint coating, most often oil-based, is easily removed with heat. Use a gas torch or hair dryer to go over the surface and remove everything with a putty knife. Other paint types need to be removed chemically. Special rust removers and rust preventers are used for this.
  • Vise. Since you have to use a lot of force to cut them, they need to be secured. It is best to use a plumbing press with a special jaw profile. But, you can also use an ordinary locksmith’s vise.
  • Key. If you have to make repairs “on the spot”, the vise is not there. In this case you need a gas wrench. It has a large spacing between the jaws so it can hold the pipe firmly in place.
  • Oil. It is desirable to lubricate the part, so it can move more easily along the thread. In this case you need a lubricant like machine oil, WD-40, household grease or technical Vaseline.
  • Rags. After threading, it is necessary to remove all the dirt from the thread, so it is wiped with a rag after work.
See also  Stihl Does Not Start Candle Dry

Threading the male threads with a one-piece tap

How to thread a pipe? A special tool is used for this purpose. the die.

how and why to use a “TAPERED” tap (NPT thread) National Pipe Thread

The die is a metal disc that has two groups of holes: inner and outer (petal).

The inner ones have a threaded notch that creates slots in the metal. Higher-priced versions are threaded in tungsten carbide or coated with a diamond tungsten carbide coating. This makes it possible to cut even mild steel. But most pipes are made of raw, low-carbon ferrous metal. It can be cut with ordinary hardened metal.

Petal holes are designed for chip drainage. Since the grooves can be deeper than 1 millimeter, there is a lot of waste that needs to be removed to keep the cutters from clogging.

For low-carbon steels, HSS dies are suitable. They’re harder than the average metal in pipes. For a stainless steel water pipe, we need pobedite lancers.

As a rule, one bar has from 8 to 10 turns. They are arranged in the form of a cone. This is required so that it is easy to start cutting with less deep turns. But the height differences are too small and do not disturb the threads.

Some kits contain several bars of the same size. This is required for roughing and finishing cuts.

The die for threading the pipes can be:

  • One piece. Have high precision since the disc is closed. No coil movement prevents slicing. But because of the monolithic nature, there is a disadvantage. rapid wear of the cutters.
  • Separate. Have a slit from the edge of the disc to the center. They are used where high accuracy is not required, since the groove causes radial movements during operation. Since they have little cushioning, less wear.

For convenient rotation, a special screwdriver is used. It has a slot for installing a die and locking screws. Horizontally mounted handles for even pressure and twirling.

  • Tube is prepared. It should be cut to the required length, trimmed at the end, cleaned of paint and rust.
  • The tube is fixed in a vise or a gas key. The die is mounted perpendicular to the expanded side of the cone. Gentle rotations with pressure are used to cut through the thread.
  • The prepared coils are cleaned with a rag. If oil is used, use solvent.

Using a die with a ratchet holder

Cutting is made considerably easier when using ratchet handles. This is a one-handled design.

  • The undermost part of the screwdriver is mounted on the bottom. It is secured with clamping screws.
  • There is a ratchet in the middle, to which a handle is welded. Slightly higher is the ratchet for switching movements.
  • There is a centrifugal finder built in on top.

This design is especially convenient if space is limited and it is not suitable for a two-handed wrench. The ratchet allows you to make the cut with great comfort. By setting the ratchet into the screwing position, the metal is cut. Turning the lever backwards triggers the switch and the die does not move.

Here’s a video on how a ratchet works.

Using claw knives

A pipe threading tong is a universal tool, sometimes called a split die. To prepare for the job, you need:

  • Screw the cutters in their seat. They can be included or purchased separately.
  • After the taps are installed, they are sealed from above with special metal plates.
  • The head is screwed in place and the clipper is ready to work.

A pipe threader of the collapsible type has a high carrying capacity, copes well with increased loads and is easy to carry. Often they are bought in a set with all the necessary cutters.

Threading with the tool

In the standard kit the cluppe has several heads with cutters and bar for the torque transmission.

The threading process is simple and does not differ from the standard taps. The cutters are cone shaped so you have no problem getting in on the pipe.

It is desirable to follow a few rules for working with a clevis:

  • Lubricant. You need to use oil or grease to make a good cut. For easy removal of chips, it’s best to use solidol or other thick liquids that can easily pick up metal scraps.
  • Center. It is important not to be out of alignment. Because the cutters are much harder than the pipes, it’s easy to chamfer the threads, which would render the threads unusable.
  • Rotation change. Every half turn, you need to turn the turnbuckle back a little.
See also  How to properly trim a ceiling plinth inside corner

And what about the internal threads in pipes

Above described how to thread the pipe. It’s a little different on the inside. In standard piping, this is not customary. Usually used with a swivel joint, as screwing inward shrinks the plumbing. This can cause clogging of metals and minerals.

Sometimes it’s hard to find adapters for a fitting in stores, so it has to be made by hand. Taps are used for this. They look like bolts on the outside, but have segmented cutters rather than solid.

Often sold in pairs, for roughing and finishing work. They’re much easier to work with. They can be done manually with a screwdriver or an electric screwdriver.

There is no need to machine the hole, remove burrs, but it is advisable to lubricate.


Metric, pipe inch dies, trapezoidal threading tools are differentiated by profile. Each variety has its own special features:

Metric. As the name implies, metric threads are tapped. Metric tools are identified by an “M” followed by a number indicating the thread diameter in millimeters. Standards provide sizes up to 68 mm, each corresponds to a fine or coarse pitch. Dimensions, examples of symbols, the rules of acceptance of such dies according to GOST 9740.

Read here: Steel pipe cutter. types, specifications and applications

Cylindrical pipe. Easy to identify by the letter “G” on the body. Threads of this type are measured using the English unit, the inch, which is 25.4 mm.

So the designation G 1/2″ means that we have a pipe thread handler for half-inch threads. Widely used for heating pipes and water supply systems. Size range from G 1/8″ to G 2″.

Tapered Pipe. Not to be confused with the other varieties, they are marked with the symbol “K”. Used when it is necessary to obtain a tapered threaded surface. in critical connections, working under pressure or machine assemblies.

Trapezoidal. The cross-section of the threads is an equilateral trapezoid. Common in power pairs that convert rotation to translational motion. The simplest example is a driving screw and nut of a machine tool and bench vice.

What threads are used for

The basic parameters of such a threaded connection is considered a diameter, which is counted in inches, and the number of cut on the length of an inch turns (1 inch equals 25.4 mm).

Cylindrical pipe inch threads are more commonly used in home improvement.

As a result, when connecting a metal pipe to a plastic pipe, private homeowners in the home more often use only a threaded connection. In a similar situation, you can easily cut the thread.

In addition, pipe products with inch threads are used when repairing water pipes and installing segments of the heating system.

Such pipe products are used when ordering design elements of the living room. In this situation, inch threads are applied to one of the components of the interior of the room.

When installing a washing machine is also done threading the pipes.

Threading on pipes

Let’s say we have a pipe that needs to be connected to another pipe. You can of course use and welding, but this is only possible if the iron with the iron needs to be connected.

And if you need to connect the metal pipe with a plastic one, you need a thread. There are of course other ways, such as Gebo, but the carving is better.

In this post, I’ll talk about how I thread metal pipes.

So, have the pipe cut off and cleaned of paint/dirt. Next, we need a thread cutter. They can be manual and electric.

A little bit about the electric: There is such a set. 4 spigots for different diameters and an electric device. Here’s an example of how it works:

It’s very handy if you need to thread a small section of pipe that you have in your shop. In that case you don’t have to rack your brains about how to hold the pipe. The thing is very handy, but not very cheap. If you’re cutting a thread a couple of times a month. do not spend money on an electric thread cutter. There are disadvantages to this device. One of these disadvantages is its rapid heating and even overheating. Of course if you only have to cut one thread, that’s no problem. But if you need to make more than two pieces (long threads) at least on an inch pipe, it is for him, the impossible task. it also has another important disadvantage. it is too wide. You can’t put it on a pipe if it’s close to the wall. So in those places, we use a hand carver or just a lumberjack.

A manual threader, a little more compact, but I usually don’t even use a manual. There is such a thing. a Swede! Let’s go:

We see a painted pipe. The pipe should be clean. The arrow shows an irregularity, this is a leak of construction material, which is also painted on top. If this layer is not removed, you will not be able to put the riser on the pipe. Cleaned and we take the necessary size of a sharpener: On the picture we see two sharpers, a good one and a cheap one. The cheap lerker can cut the thread well, only until it’s new, then it doesn’t cut deep enough, so screwing something on to this thread becomes a problem. In some cases, having two lancers makes it easier for us. If the first one doesn’t cut through the thread to the right depth, then it’s easier to torque. Then we put a good pipe on the same half-thread and distill again. This is done only for large diameter pipe, we cut small pipes at once with a good pipe cutter. ๐Ÿ™‚

See also  How to make a rotary snowplow on a single-axle tractor

And so, you take the crow bar, clean the pipe and start the threading process, clockwise. Before threading, it is recommended to grease the pipe. Either oil/lubricant/brake fluid, or a specially formulated grease. Here’s a bunch of photo examples for you:

You can’t cut a thread in one fell swoop. Cut it gradually, half a turn forward, then a little backward. There’s no rush in this business. You can bend a pipe and not have a crowbar.

After threading, try screwing what you are going to mount on it. That’s how you check if the thread is good and if its length is long enough. If it’s a good fit, you can seal and mount it.

Now a little bit on the possible nuances. After you have threaded it, take a flashlight and look at the new thread from all sides. The thing is that if the pipe is old, there is a risk that you could cut through the thread seams. Not only that, it happens that the pipe is simply twisted and a part of the thread is left in the tool. This sucks. To get it out of there, oooooooo hard. (in this case, do not disassemble the lerku, and it will turn into scrap metal, because the adjustment of the cutters, very fine). If the pipe sucks and there is no way to replace the pipe, do not cut the thread, install the hebo.

What to do if the lance turned out to be too long and you can’t thread? Then you just have to cut off a piece of the lance, but leave a place for you to grip it:

Not only that, but if you cut the whole tail off, you probably won’t be able to thread it straight. This very tail properly guides and aligns the threading device/lercu.

I think I explained everything about threading. Best wishes for success in this endeavor.

One of our regular readers, his name is Alexey, sent me a photo of another device he uses for tapping.

Thank you Alexey. Here is his photo and a comment:

The handbrake pulls out separately (in this case, it’s half an inch). But if you remove the ring, a three-quarter-inch bit can be inserted.

There is also a removable ring on the guide. which you can adjust the inside diameter of the guide. Under 3/4 or 1/2 inch.

This ratchet can be used to thread half inch pipe and three-quarter inch pipe.

The main thing is to get a hitch (To start threading evenly) and then you can twist the guide, if there is not enough space for it.

This ratchet can be reversed and tapped almost flush.

The details of threading with a crescent drill

The pipe tongs are compact tools for forming external threads on pipes. The product is characterized by ease of operation and simple design, through which you can quickly and accurately thread an element by hand.

The dimensions of the runs, undercuts, and grooves

List of the main structural elements of the external pipe threads:

Schematic illustration of the main constructional elements

Additional attachments

Depending on the version, the clipper models can have different optional extras. For example, the set can include interchangeable cutters. Rotary part can be included.

It consists of a head with a handle-holder that is placed on the cylindrical area of the clipper with faces. Thanks to the ratchet, the tool can be turned 360 degrees without axial rotation.

The sizes of dies included in the set are 15, 20, 25, 32, 40, 50 mm. The manufacturer defines the type of auxiliary tools.

For example, the domestic brand “Zubr” sells clips without tools and in a set with lancets in quantities of 3, 4, 5 pcs. The heads are powder-coated in red.

“Sibrteh” (another Russian brand), offers separately purchased ratchets and heads at the best price. Kupp is designed by the manufacturer for cutting of self-shrinking BSPT threads as well as smooth BSPP threads.

Thanks to the separate delivery of parts, the buyer can buy only the necessary accessories, saving on the price of the set. For example, you can buy a ratchet with an extension cord.

Separate heads for power tools are offered by Stayer brand. They are powder-coated in black.

The devices from the French company Virax are equipped with 4 heads of different sizes. expensive professional models have 4-6 bits.

Rems supplies club heads for tapered and bolt threading. They are equipped with a steel handle with ratchet mechanism and a protective plastic coating. Additionally, they have a rubber pad to prevent slipping of hands in the course of work. The devices are completed with 7 ratchets.