Connecting dimension g1 2. Pipe thread dimensions. designation. guests. Symbol in the international standard

MAIN PARAMETERS OF INCH THREADS
(standards BSW (Ww), BSF, UNC, UNF)

The tops and bottoms of the profile of an inch thread, similarly to a metric thread, are flat cut. The pitch of an inch thread is determined by the number of threads (turns) per 1 inch, but it has a 55° point angle (Whitworth thread - British BSW (Ww) and BSF), a 60° point angle (American UNC and UNF standard ).

The outside diameter of the thread is measured in inches 1" = 25.4 mm- dash (") symbol for an inch. An inch thread is characterized by the number of threads per inch. According to American standards, inch threads are made with coarse (UNC) and fine (UNF) pitch.
NPSM- American standard for inch cylindrical pipe threads.
NPT- American standard for inch conical threads.

Standards:

ASME/ANSI B1.1– 2003 Unified Inch Screw Threads, UN & UNR Thread Form
ASME/ANSI B1.10M– 2004 Unified Miniature Screw Threads
ASME/ANSI B1.15– 1995 Unified Inch Screw Threads, UNJ Thread Form

AMERICAN INCH THREAD

The main parameters of the inch thread:

d(D) – outside diameter threads, respectively, of the bolt and nut;
dp (Dp)- the average thread diameter of the bolt and nut, respectively;
d i (D i)- the inner diameter of the thread, respectively, of the bolt and nut;
n is the number of threads per inch.

American Coarse Pitch Thread - UNS

American Fine Pitch Thread - UNF

American Extra Fine Pitch Thread - UNEF

Thread sizes are the outside diameter of the thread expressed in fractional inch. One of the main characteristics of an inch screw thread is the number of threads per inch of thread length (n). The number of turns and the thread pitch P are related by:

American standards provide for two forms of thread:

Thread with a flat cavity, which is indicated by the letters UN;
- a thread with a radius cavity, which is indicated by the letters UNR.

The standard defines three classes of thread accuracy. These classes are designated as 1A, 2A, 3A, 1B, 2B, 3B. Accuracy classes 1A, 2A, 3A refer to external threads; accuracy classes 1B, 2B, 3B refer to internal threads. Accuracy class 1A, 1B is the coarsest and is used in cases where quick and easy assembly is required, even with partially dirty and dented threads. Accuracy class 2A, 2B is the most common and is used for threads general purpose. Accuracy class 3A, 3B imposes the most stringent requirements on threads and is used in cases where it is required to ensure a minimum clearance in a threaded connection.

Thread designation. The nominal size is written first, then the number of threads per inch of the thread, the thread group symbols, and the accuracy class symbol. The letters LH at the end of the entry indicate the left-hand thread. The nominal size is the outer diameter, defined as a fractional size or thread number, or their decimal equivalent.
For example: 1/4 - 20UNS - 2A or 0.250 - 20UNC - 2A

BRITISH STANDARD INCH THREADS
(BSW(Ww) and BSF)

Related Documents:

GOST 3469-91: Microscopes. Thread for lenses. Dimensions
GOST 4608-81: Metric thread. Interference landings
GOST 5359-77: Ocular thread for optical instruments. Profile and dimensions
GOST 6042-83: Round Edison thread. Profiles, dimensions and limit dimensions
GOST 6111-52: Conical inch thread with a profile angle of 60 degrees
GOST 6211-81: Conical pipe thread
GOST 6357-81: Cylindrical pipe thread
GOST 8762-75: Thread round diameter 40 mm for gas masks and calibers for it. Main dimensions
GOST 9000-81: Metric thread for diameters less than 1 mm. Tolerances
GOST 9484-81: Trapezoidal thread. Profiles
GOST 9562-81: Trapezoidal single thread. Tolerances
GOST 9909-81: Conical thread of valves and cylinders for gases
GOST 10177-82: Thrust thread. Profile and main dimensions
GOST 11708-82: Thread. Terms and Definitions
GOST 11709-81: Metric thread for plastic parts
GOST 13535-87: Reinforced thrust thread 45 degrees
GOST 13536-68: Round thread for sanitary fittings. Profile, basic dimensions, tolerances
GOST 16093-2004: Metric thread. Tolerances. Landings with clearance
GOST 16967-81: Metric thread for instrumentation. Diameters and steps
GOST 24737-81: Trapezoidal single thread. Main dimensions
GOST 24739-81: Multi-start trapezoidal thread
GOST 25096-82: Thrust thread. Tolerances
GOST 25229-82: Metric conical thread
GOST 28487-90: Tapered tool joint thread for drill string elements. Profile. Dimensions. Tolerances

BSP British standard pipe thread- cylindrical pipe thread, also referred to as BSPP.

The BSP thread is interchangeable with the thread of the domestic standard GOST 6357-81.

It is used in cylindrical threaded connections, as well as in connections of an internal cylindrical thread with an external BSPT conical thread (GOST 6211-81).

Main standards:

GOST 6357-81 - Basic norms of interchangeability. The thread is pipe cylindrical.

ISO R228

EN 10226

JIS B 0202

Thread parameters: inch thread with a profile angle at the top of 55°, the theoretical profile height H=0.960491R.

Symbol according to GOST 6357-81: the letter G, the numerical value of the nominal thread diameter in inches (inch), the accuracy class of the average diameter (A, B), and the letters LH for the left thread.

For example, a thread with a nominal diameter of 1.1/8", accuracy class A - is indicated as: G 1.1/8"-A.

The pitch of cylindrical pipe thread according to GOST 6357-81 has four values ​​indicated in table 2.

The main thread dimensions GOST 6357-81 (BSP) are shown in Table 2.

Comment to table 2.
d is the outer diameter of the external thread (pipe);
D is the outer diameter of the internal thread (coupling);
D 1 - internal diameter of the internal thread;
d 1 - inner diameter of the external thread;
D 2 - the average diameter of the internal thread;
d 2 - the average diameter of the external thread.

When choosing a size pipe thread first row should be preferred second.

* Whitworth cut

BSPT British standard pipe tapered thread - conical pipe thread.

Based on BSW (British Standard Whitworth) threads, known as Whitworth* pipe threads.
The BSPT thread is interchangeable with the thread of the domestic standard GOST 6211-81.
It is used in conical threaded connections, as well as in connections of external conical threads with internal cylindrical threads in accordance with GOST 6357-81.
Main standards for BSPT threads:
GOST 6211-81 - Basic norms of interchangeability. The thread is pipe conical.
ISO R7
DIN 2999
BS21
JIS B 0203

Thread parameters: inch thread with 1:16 taper (taper angle 3°34’48"). Profile angle at apex 55°.
Symbol according to GOST 6211-81: letter R for external thread and Rc for internal thread, numerical value of nominal thread diameter in inches (inch), letters LH for left thread. For example, a thread with a nominal diameter of 1.1/4" is designated as: R 1.1/4".

*Whitworth - (Whitworth) (Whitworth) Joseph (years of life 1803-87), English engineer and industrialist. Proposed in 1841 a screw thread profile Whitworth cut. In 1851 he created a measuring machine of great accuracy, developed a system for standardizing threads and gauges.

NPTF National Pipe Tapered Fuel is a national pipe taper fuel thread.

NPTF - sealed thread. Sealing occurs due to the collapse of the threads.
Tapered fuel pipe threads are described by ANSI/ASME B1.20.3

The NPTF fitting has a taper thread with a taper of 1:16 (taper angle φ=3°34’48").
The NPTF fitting is compatible with NPTF, NPSF or NPSM female threads.
NPTF threads are used in hydraulic systems, although the National Hydraulic Actuators Association (NFPA) does not recommend it for use in hydraulics.

On fittings with NPTF threads, to distinguish them from BSPT threads, a mark is usually placed on the faces of the hexagon

Tapered thread (NPT) with a taper of 1:16 (cone angle φ=3°34’48") or cylindrical (NPS) thread. Profile angle at the top 60°, theoretical profile height Н=0.866025Р.

Tapered NPT threads are described in ANSI/ASME B1.20.1.
NPT thread complies with GOST 6111-52 - Conical inch thread with a profile angle of 60 degrees.

Thread Metric Metric screw threads- is widely used both in Russia and in world practice. Metric connections widely apply ISO 8434-1 DIN 2353 pipe connections.

Hydraulic connections mainly use two metric thread pitches: 1.5 pitch and 2.0 pitch.

Dimensions of commonly used hydraulic threads with a pitch of 1.5 mm: M12x1.5; M14x1.5; M16x1.5; M18x1.5; M20x1.5; M22x1.2; M24x1.5; M26x1.5; M27x1.5; M30x1.5; M33x1.5; M36x1.5; M38x1.5 M45x1.5 M52x1.5.

Dimensions of commonly used hydraulic threads with a pitch of 2.0 mm: M30x2.0; M33x2.0; M36x2.0; M42x2.0; M45x2.0; M52x2.0.

Dimensions of metric threads in fittings for high pressure hoses of domestic production (the so-called DK standard): DK (G) M16x1.5; DK(G)M18x1.5; DK(G)M20x1.5; DK(G)M22x1.5; DK(G)M27x1.5; DK(G)M33x1.5; DK(G)M33x2.0; DK(G)M36x1.5; DK(G)M36x2.0; DK(G)M42x2.0.

All profile parameters are measured in fractions of a meter (millimeters). Nominal diameter from 1 to 600 mm. Thread pitch from 0.0075 to 6 mm. The profile is an equilateral triangle (the angle at the apex is 60°) with the theoretical height of the profile Н=0.866025404Р.

Basic standards for metric threads:
GOST 9150-2002 (ISO 68-1-98): Basic standards of interchangeability. The thread is metric. Profile. Replaces GOST 9150-81 from January 1, 2004
GOST 8724-2002 Basic norms of interchangeability. The thread is metric. Diameters and steps.
GOST 9000-81 Basic norms of interchangeability. Thread metric for diameters less than 1 mm. Tolerances.
GOST 11708-82 Basic norms of interchangeability. Thread. Terms and Definitions.
GOST 16093-81 Basic norms of interchangeability. The thread is metric. Tolerances. Gap landings.
GOST 24705-81 Basic norms of interchangeability. The thread is metric. Main dimensions.
Standards: GOST 9150-81 - Basic norms of interchangeability. The thread is metric. Profile.
GOST 8724-81: Basic norms of interchangeability. The thread is metric. Diameters and steps.
ISO 965-1:1998 - ISO metric threads for general use. Tolerances. Part 1. Principles and main characteristics.
ISO 965-2:1998 - ISO metric threads for general use. Tolerances. Part 2: Thread limits for general purpose bolts and nuts. Middle class accuracy.
ISO 965-3:1998 - ISO metric threads for general use. Tolerances. Part 3: Deviations for structural threads.
ISO 965-4:1998 - ISO metric threads for general use. Tolerances. Part 4: Dimensional limits for hot dip galvanized external screw threads for assembly with tapped internal screw threads to tolerance position H or G after galvanization.
ISO 965-5:1998 - ISO metric threads for general use. Tolerances. Part 5: Dimensional limits for internal screw threads of screws for assembly with hot dip galvanized external screw threads with a maximum tolerance position dimension h before galvanization.
ISO 68-1 - ISO screw threads for general use. main profile. Metric thread.
ISO 261:1998 — ISO metric threads for general use. General form.
ISO 262:1998 - ISO metric threads for general use. Selected sizes for screws, bolts and nuts.
BS 3643 - ISO metric screw threads.
DIN 13-12-1988 - Metric ISO basic and precision threads with a diameter of 1 to 300 mm. Choice of diameters and pitches.
ANSI B1.13M, ANSI B1.18M - Metric M thread with a profile based on the ISO 68 standard.

Symbol: the letter M (metric), the numerical value of the nominal thread diameter in millimeters, the numerical value of the pitch (for threads with fine pitch) and the letters LH for left-hand threads. For example, a coarse pitch thread with a nominal diameter of 16 mm is referred to as M16; thread with a nominal diameter of 36 with a fine pitch of 1.5 mm - M36x1.5; the same in diameter and pitch but left-hand thread M36x1.5LH.
Notes:
1. The shape of the thread root of the bolt is not regulated and can be either rounded or flat-cut. A rounded cavity shape is preferred.
2. The shape of the nut thread root is not regulated.

d - outer diameter of the outer thread (bolt); D - outer diameter of the internal thread (nut); d2 - average bolt diameter; D2 - average diameter of the nut; d1 - inner diameter of the bolt; D1 - inner diameter of the nut; P - thread pitch; H is the height of the original triangle; R is the nominal radius of the bolt root; H1 - profile working height

UNF / UTS (Unified Thread Standard - inch cylindrical thread widespread in the US and Canada.
Thread profile UN/UNF: corner angle 60°, theoretical profile height H=0.866025P.

Corner angle and profile height are fully compliant with metric threads, however, all dimensions are based on the inch system of measurement and are indicated in fractions of an inch.
Depending on the step, it is divided into : UNC (Unified Coarse), UNF (Unified Fine), UNEF (Unified Extra Fine), UNS (Unified Special).
Hydraulic connections are mainly used fittings with UNF thread.

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 was 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 parameters 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 conical and cylindrical threads coincide, which allows fittings to be screwed together with conical thread and cylindrical.

Parameters such as the quality of the pipe thread, its compliance with the axis of the pipe play a key role in the installation of plumbing and heating systems. In some cases, do-it-yourself cutting with a die is used. It must be said that this work difficult, inefficient and time consuming. It is better to cut with a cutter using lathe.

General thread information

Pipe threads are protrusions and cavities with the same section, evenly spaced on a cylindrical or conical surface (for example, nuts, screws, bolts). They are located along a helix with the same pitch.

In everyday life, parts with a cylindrical thread are usually used. However, there are other types as well. There are two defining parameters for metric threads: pitch and diameter. An inch thread is so named because its defining characteristics are the diameter, expressed in inches or fractions of an inch. Also an important parameter in this case is the number of turns located on the length of an inch. The size in inches indicates the clearance in the element, while the outer diameter of the part is large.

Pipe thread table according to GOST

Important: One inch equals 2.54 cm. There is also another unit of measurement - a pipe inch. It is equal to 33, 249 mm. What is this inch unit of measurement? They brought it out like this: a value characterizing the thickness of both walls of the pipe was added to the value in inches.

There are two types of pipes, the parameter for the classification of which is the pipe inch:

• Product with an outer diameter of 33, 249 mm;
• Product with an outer diameter of 21.25 mm.

An inch thread is a set of parameters necessary for connecting pipes, fittings and other parts. From metric, among other things, it differs in such features as:

• Pointed ridges-hollows;
• Rounded hilltops.

Dimensions

In domestic conditions, you can most often find pipes with the following parameters and dimensions determined by GOST:

• Thread 14 threads per 1 inch. In this case, the pitch is 1.814 mm. The diameter can be ½ or ¾;
• 11 threads per 1 inch. In this case, the pitch is 2.309 mm. The diameter can be 1, 1 ¼, 1 1/2, 2.

Inch threads are made only on pipelines whose dimensions do not exceed 6″. If the parameters of the pipe are greater, it is mounted in the system by means of welding work. Its designations according to GOST: G (the value of the passage of elements, indicated in inches), A, B (the degree of accuracy of diameters).

The selection of inch threaded pipes requires knowledge of many parameters. For this purpose, there are a number of tables that indicate all important values. There are tables from which you can find out the steps and their relationship with threads per inch. So you can quickly and easily get acquainted with all necessary information. You can find all the necessary tables on our website. They will help not only amateurs, but also professionals in working with pipes.

Inch thread is used primarily to create pipe connections: it is applied both to the pipes themselves and to metal and plastic fittings required 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 parameters

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 tops of the threaded ridges located on opposite sides pipes;
• 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.

The second important parameter - step - characterizes the distance at which two adjacent ridges or two adjacent depressions are located from each other. Throughout the entire section of the product on which the pipe thread is made, its pitch 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 from 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

By their own outward signs 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, the parameters of the internal thread of which exactly correspond to the requirements given by GOST.
• The bolt, the parameters of the external thread of which must 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 being checked corresponds to the required parameters will be indicated by snug fit to its profile of the serrated part of the plate.

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 inner part last.
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 a lathe only on tubular products whose thickness and rigidity allow this. Making pipe inch threads mechanically allows you to get a high-quality result, but the use of such technology requires the turner to have appropriate qualifications and the presence of 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.