3 inches to mm. Converting numbers to different number systems with a solution

On the construction market popular 2 size designs:

• 1\2 and 3\4 - make up a separate category. due to special thread parameters (1.814), per 1 unit. measures accounted for 14 strands;
• within 1 - 6 inches, the pitch is reduced to 2.309, forming 11 threads that do not affect the decrease or increase in the quality of the connection.

One inch is 25.4 mm long, it is used to determine the internal parameters, but when laying reinforced pipes, the diameter is 33.249 mm (including the internal section and 2 walls). There is an exception in the range of steel structures - products in ½ inch, where the outer section is 21.25 mm. This parameter used when calculating the dimensions of pipes with a cylindrical thread type. When calculating for pipes with a cross section of 5 inches, the internal dimension will be 12.7 cm, and the external - 166.245 (reduced to 1 decimal place is allowed).

The difference between measurement systems

In terms of external parameters, inch designs do not differ from metric ones, the difference lies in the type of notches. There are 2 types of threads according to the inch system - English and American. The first option corresponds to a notch angle of 55 degrees, and the metric (American) system with an angle of 60 degrees. generally accepted.

At different degrees, it is difficult to distinguish the angle by 55 for inch and 60 for metric designs, and the rounding of the threads is immediately visible, the occurrence of an error is impossible. A thread gauge is used to measure the thread pitch, but an ordinary ruler or other device is well used instead.

Replacing steel pipes with polymer ones

In the gas and water supply network, steel products, whose diameter is indicated in inches (1", 2") or fractions (1/2", 3/4"). When measuring a 1" pipe cross-section, the result is 33.5 mm, which corresponds to 1" (25.4 mm). When arranging pipeline reinforcing elements, where the parameters are indicated in inches, there are no difficulties. But when installing products made of PP, copper or stainless steel instead of steel structures, it is required to take into account the difference in the name and parameters.

To create a given level of flow, the internal diameter of the pipes is taken into account. For inch ordinary pipes, it is 27.1 mm, for reinforced 25.5 mm, closest to 1 ". Pipelines are designated in conventional units of the flow area Du (DN). It determines the parameters of the pipe clearance and is indicated in digital values. sections are selected taking into account the increase in throughput characteristics by 40-60% with an increase in the index. cross section and the purpose of the structures, using the table of dimensions, the internal cross section is determined.

During connection steel pipes with polymer structures, replacing one with another, conventional adapters are used. Dimensional mismatch results from the use of copper, aluminum or stainless steel products manufactured to metric standards. The actual metric dimensions of the pipes are taken into account - internal and external.

Steel pipes of the Russian Federation in comparison with the European standard

To compare the range of pipes according to GOST RF and European standards, the following table is used:

How to decide on the choice of diameter?

From diameter water pipes their throughput characteristics depend - the volume of water passed for 1 unit. time. It depends on the speed of the water flow. With its increase, the risk of pressure drop in the line increases. Throughput characteristics are calculated according to formulas, but when planning intra-apartment wiring, they take pipes of certain parameters.

For the plumbing system:

• 1.5 cm (1/2 inch)
• 1 cm (3/8 inch).

For the riser, structures with an internal cross section are used:

• 2.5 cm (1 inch);
• 2 cm (3/4 inch).

Given that the inner cross section of the half-inch polymer pipes varies in the range from 11 to 13 mm, and one-inch - from 21 to 23, an experienced plumber will be able to determine the exact parameters when replacing. With a complex type of wiring, numerous joints, turns and network laying on long distance, reducing the pressure, it should be possible to carry out the wiring of pipes with a large cross section. As the diameter increases, the pressure level increases.

Below is a table for determining the patency of steel pipes:

Steel pipe diameter

The cross section of the pipes corresponds to a number of indicators:

• Nominal diameter (Dn, Dy) - nominal parameters (in mm) of the internal cross-section of pipes or their rounded indicators, in inches.
• Rated value (Dn Dn,).
• external size.

  The metric calculation system allows classifying structures into small ones - from 5 ... 102 mm, medium - from 102 ... 426, large - 426 mm and more.

• Wall thickness.
• inner diameter.

The internal cross section of pipes with different threads corresponds to the following parameters:

• 1/2 inch pipeline - 1.27 cm;
• 3/4 inch - 1.9 cm;
• 7/8 inch - 2.22 cm;
• 1 inch - 2.54 cm;
• 1.5 inches - 3.81 cm;
• 2 inches - 5.08 cm.

The following indicators are used to determine the thread diameter:

• pipeline 1/2 inch - 2.04 - 2.07 cm;
• 3/4 inches - 2.59 - 2.62 cm;
• 7/8 inch - 2.99 - 3 cm;
• 1 inch - 3.27 - 3.3 cm;
• 1.5 inches - 4.58 - 4.62 cm;
• 2 inches - 5.79 - 5.83 cm.

Table of correspondence between the diameter of steel pipes and polymer structures:

Steel pipe prices:

Pipe diameter PP

PP pipes are produced with a diameter of 0.5 to 40 cm or more. The diameter is internal and external. The first indicator allows you to find out the volume of environments traversed in 1 unit. time. The external cross section is used for construction calculations, namely the choice of a niche or pit for laying a highway. External parameters allow you to choose the right fittings with the corresponding internal indicators.

• Small - 0.5; one; 1.5; 2; 2.5; 3.2; 4; 5; 6.3 and 7.5 cm is used for heating systems, drains and water supply in private buildings. An internal cross section of 3.2 cm is most popular in multi-storey buildings.
• Medium - 8; 9; 10; eleven; 12.5; sixteen; twenty; 25 and 31.5 cm is used for arranging plumbing and sewer systems, allowing you to change cast iron products with similar external parameters. Internal dimensions of 8, 9 and 10 cm are ideal for chemical environments.
• Large - 40 cm or more is used for arranging cold water supply and ventilation systems.

Pipes are marked in inches and mm. When choosing designs for plumbing and heating system, the wall thickness is taken into account, which affects the conditional patency of highways with the same external parameters. With an increase in its parameter, an increase in pressure in the plumbing system is allowed. Small dimensions allow to reduce the level of costs for the purchase of material and water consumption.

Cost of PP pipes:

Video

This article will discuss such concepts related to threaded connections as metric and inch threads. To understand the subtleties associated with a threaded connection, it is necessary to consider the following concepts:

Conical and cylindrical thread

The rod itself with applied to it tapered thread is a cone. Moreover, according to international rules, the taper should be 1 to 16, that is, for every 16 units of measurement (millimeters or inches) with increasing distance from the starting point, the diameter increases by 1 corresponding unit of measurement. It turns out that the axis around which the thread is applied and the conditional straight line drawn from the beginning of the thread to its end along the shortest path are not parallel, but are at a certain angle to each other. To explain even more simply, if we had a threaded connection length of 16 centimeters, and the diameter of the rod at its starting point would be 4 centimeters, then at the point where the thread ends, its diameter would already be 5 centimeters.

rod with cylindrical thread is a cylinder, respectively, there is no taper.

Thread pitch (metric and inch)

The thread pitch can be large (or basic) and small. Under thread pitch is understood as the distance between the threads from the top of the thread to the top of the next thread. You can even measure it with a caliper (although there are special meters). This is done as follows - the distance between several vertices of the turns is measured, and then the resulting number is divided by their number. You can check the accuracy of the measurement according to the table for the corresponding step.

Nominal thread diameter

The label usually contains nominal diameter, for which in most cases the outer diameter of the thread is taken. If the thread is metric, then a regular caliper with scales in millimeters can be used for measurement. Also, the diameter, as well as the thread pitch, can be viewed from special tables.

Metric and inch thread examples

Metric thread- has a designation of the main parameters in millimeters. For example, consider an elbow fitting with an external parallel thread EPL 6-GM5. In this case, EPL says that the fitting is angled, 6 is 6 mm - the outer diameter of the tube connected to the fitting. The letter "G" in its marking indicates that the thread is cylindrical. "M" indicates that the thread is metric, and the number "5" indicates a nominal thread diameter of 5 millimeters. Fittings (of those that we have on sale) with the letter “G” are also equipped with a rubber o-ring, and therefore do not require fum tape. The thread pitch in this case is - 0.8 millimeters.

Main settings inch thread, according to the name - are indicated in inches. It can be 1/8, 1/4, 3/8 and 1/2 inch threads, etc. For example, take a fitting EPKB 8-02. EPKB is a type of fitting (in this case, a splitter). The thread is conical, although there is no reference to this with the letter “R”, which would be more literate. 8 - indicates that the outer diameter of the connected tube is 8 millimeters. A 02 - that the connecting thread on the fitting is 1/4 inch. According to the table, the thread pitch is 1.337 mm. The nominal thread diameter is 13.157 mm.

The profiles of the conical and cylindrical threads coincide, which allows fittings with conical and cylindrical threads to be screwed together.

Inch thread is used primarily to create pipe connections: it is applied both to the pipes themselves and to metal and plastic fittings necessary for the installation of pipe lines for various purposes. The main parameters and characteristics of the threaded elements of such connections are regulated by the relevant GOST, giving tables of sizes for inch threads, which specialists are guided by.

Main settings

The normative document, which specifies the requirements for the dimensions of a cylindrical inch thread, is GOST 6111-52. Like any other, inch thread is characterized by two main parameters: pitch and diameter. The latter usually means:

• outer diameter, measured between the upper points of the threaded ridges located on opposite sides of the pipe;
• internal diameter as a value characterizing the distance from one lowest point of the cavity between the threaded ridges to another, also located on opposite sides of the pipe.

Knowing the outer and inner diameters of an inch thread, you can easily calculate the height of its profile. To calculate this size, it is enough to determine the difference between such diameters.

Second important parameter- step - characterizes the distance at which two adjacent ridges or two adjacent depressions are located from each other. On the entire area of ​​the product on which pipe thread, its step does not change and has the same value. If such an important requirement is not met, it will simply be inoperative, it will not be possible to pick up the second element of the created connection to it.

You can familiarize yourself with the provisions of GOST regarding inch threads by downloading the document in pdf format at the link below.

Table of sizes of inch and metric threads

Learn how metric threads relate to various types inch threads, you can use the data from the table below.

Similar sizes of metric and various varieties of inch threads in the range of approximately Ø8-64mm

Differences from metric thread

According to their external features and characteristics, metric and inch threads do not have many differences, the most significant of which include:

• threaded comb profile shape;
• the procedure for calculating the diameter and pitch.

When comparing the shapes of threaded ridges, you can see that in inch threads such elements are sharper than in metric ones. If speak about exact dimensions, then the angle at the top of the crest of the inch thread is 55 °.

The parameters of metric and inch threads are characterized by different units of measurement. So, the diameter and pitch of the first are measured in millimeters, and the second, respectively, in inches. However, it should be borne in mind that in relation to an inch thread, not the generally accepted one (2.54 cm), but a special pipe inch, equal to 3.324 cm, is used. Thus, if, for example, its diameter is ¾ inch, then in terms of millimeters, it will correspond to a value of 25.

To find out the main parameters of an inch thread of any size, which is fixed by GOST, just look at a special table. In the tables containing the sizes of inch threads, both integer and fractional values ​​\u200b\u200bare given. It should be borne in mind that the pitch in such tables is given in the number of cut grooves (threads) contained in one inch of the length of the product.

To check whether the pitch of the thread that has already been made corresponds to the dimensions specified by GOST, this parameter must be measured. For such measurements, carried out for both metric and inch threads according to one algorithm, standard tools are used - a comb, gauge, mechanical gauge, etc.

The easiest way to measure the pitch of an inch pipe thread is by using the following method:

• As the simplest template, a coupling or fitting is used, parameters internal thread which exactly correspond to the requirements given by GOST.
• Bolt, parameters external thread to be measured is screwed into a coupling or fitting.
• In the event that the bolt formed with a coupling or fitting is tight threaded connection, then the diameter and pitch of the thread, which is applied to its surface, exactly match the parameters of the template used.

If the bolt is not screwed into the template or is screwed, but creates a loose connection with it, then such measurements should be taken using a different coupling or other fitting. An internal pipe thread is also measured using a similar technique, only a product with an external thread is used as a template in such cases.

You can determine the required dimensions using a thread gauge, which is a plate with notches, the shape and other characteristics of which exactly match the parameters of the thread with a certain pitch. Such a plate, acting as a template, is simply applied to the thread being checked with its serrated part. The fact that the thread on the element under test corresponds to the required parameters will be indicated by the tight fit of the serrated part of the plate to its profile.

In order to measure the size of the outside diameter of an inch or metric thread, you can use a regular caliper or micrometer.

Slicing technologies

Cylindrical pipe thread, which belongs to the inch type (both internal and external), can be cut by hand or mechanical method.

Threading with hand tool, which is used as a tap (for internal) or a die (for external), is performed in several steps.

1. The pipe being processed is clamped in a vice, and the tool used is fixed in a wrench (tap) or in a die holder (die).
2. The die is put on the end of the pipe, and the tap is inserted into the inside of the latter.
3. The tool used is screwed into the pipe or screwed onto its end by rotating the knob or die holder.
4. To make the result cleaner and more accurate, you can repeat the cutting procedure several times.

Mechanically, pipe threads are cut according to the following algorithm:

1. The pipe being processed is clamped in the machine chuck, on the support of which the thread-cutting tool is fixed.
2. At the end of the pipe, using a cutter, they chamfer, after which they adjust the speed of movement of the caliper.
3. After bringing the cutter to the surface of the pipe on the machine, the threaded feed is turned on.

It should be borne in mind that the inch thread is cut mechanically using lathe only on tubular products, the thickness and rigidity of which allow this. Performing pipe inch threads mechanically allows you to get a high-quality result, but the use of this technology requires the turner to have appropriate qualifications and certain skills.

Accuracy classes and marking rules

A thread related to the inch type, as indicated by GOST, can correspond to one of three accuracy classes - 1, 2 and 3. Next to the number indicating the accuracy class, put the letters "A" (external) or "B" (internal). The full designations of the thread accuracy classes, depending on its type, look like 1A, 2A and 3A (for external) and 1B, 2B and 3B (for internal). It should be borne in mind that the 1st class corresponds to the coarsest threads, and the 3rd - the most accurate, the dimensions of which are subject to very stringent requirements.

Inch thread options

Copper conductors, wires and cables

Aluminum conductors, wires and cables

Inch thread sizes

Unit conversion table

Size conversion tables: simple and fast

The process of selecting the required cross-sectional dimensions of threads, cables and pipes is often time consuming. In addition to choosing suitable sizes, taking into account the parameters of the equipment, the customer has to independently convert the data into suitable units of measurement. This process is costly in terms of time.

We simplify this task, as we suggest you use ready-made translation tables. On the page of our website you will find tables that will help you easily select the necessary threads inch pipes, copper and aluminum conductors of wires and cables. Also, you can use the inch to metric conversion table, thereby accurately calculate required dimensions sections.

Unfortunately, most equipment manufacturers leave the customer alone with the calculations. Therefore, a person has to independently search the Internet for translation tables in order to select optimal sizes cross-sections of wires and pipe diameters.

We value the time of our customers, providing everyone with the opportunity to use ready-made solutions. In our tables translated standard sizes from inches to millimeters.

On this page you will also find translations of the main energy units and units of pressure, therefore, you will be able to choose the right refrigeration equipment, taking into account the individual conditions of placement and modes of operation of the units.