Holes under the cutting of tubular tapered threads. Pipe thread sizes. Designation. GOST What hole for threads 1 2 inches

It would seem that in the trumpets of complex? Connect and twist ... But if you are not a plumbing and not an engineer with specialized education, then I will definitely have questions about the answers to which you have to go where your eyes look. And they look most likely the first thing online)

Previously, we have already spoken about the diameters of metal pipes in this material. Today we will try to clarify the threaded connections of the pipes of various purposes. We tried not to clutter an article by definitions. Basic terminology contains GOST 11708-82 With which everyone can familiarize themselves.

Pipe cylindrical carving. GOST 6357 - 81

Direction: left

Accuracy class: class A (elevated), class in (normal)

Why in inches?

Inch size came to us from Western colleagues, as the requirements of the current space in the post-Soviet space GOSTand formulated on the basis of thread BSW. (British Standard Whitworth or Cork Thread). Joseph Vitalit (1803 - 1887) Designer Engineer and Inventor Detached in 1841 demonstrated the screw profile of the connector connections and positioned it as a universal, reliable and convenient standard.

This type of thread is used both in the pipes themselves and elements of pipe connections: lock nuts, couplings, coal, tees ( see picture above). In the cross section of the profile, we see an equilibried triangle with an angle of 55 degrees and roundings on the vertices and depressures of the contour, which are performed for high tightness of the connection.

Cutting the threaded connection is carried out on the size of up to 6. All larger pipes for the reliability of the connection and prevent breaking are fixed with welding.

Conditional designation in the international standard

International: G.

Japan: PF.

United Kingdom: BSPP.

The letter G and the diameter of the feeding hole (inside Ø) pipes are in inches. The outer diameter of the thread directly in the designation is not present.

Example:

G 1/2. - Carving Pipe cylindrical outer, internal pipe Ø 1/2 ". The outer diameter of the pipe will be 20,995 mm, the number of steps at a length of 25.4 mm will be 14.

The accuracy class (A, B) and the direction of turns (LH) can also be marked.

For example:

G 1 ½ - in - carving pipe cylindrical, internal Ø 1 ½ inches, accuracy class V.

G1 ½ LH- in - Cylindrical pipe thread, internal Ø 1 ½ inches, accuracy class B, left.

The length of swing is indicated by the latter in mm: G 1 ½ -B-40.

For the inner tube cylindrical thread, only Ø pipes for which the hole is intended.

Pipe Cylindrical Thread Size Table

Thread size		Thread step, mm	Inch thread number	Thread diameters

How to determine step inch thread

We bring for you a picture of the English-speaking Internet, which clearly demonstrates the technique. The pipe thread is not characterized by the size between the peaks of the profile, but the number of turns is 1 inch along the thread axis. To help the usual roulette or ruler. We apply, measure one inch (25.4 mm) and we consider visually the number of steps.

In the picture with an example ( see above) Threads - from English it is literally "thread threads." In this case, their 18 pcs. One inch.

Even easier, if a threader for an inch threads in your drawer with a tool. Measurements are carried out very convenient, but it must be remembered that dum threads may differ around the corner of the vertex 55 ° and 60 °.

Conical pipe threads

figure Pipe Crew Threads

Conical Pipe Carving GOST 6211-81 (1st Size)

Unit of measurement of parameters: inches

Corresponds to the rounded profile of pipe cylindrical threads with an angle of 55 °. Cm. upper Part (i) of the three-dimensional image "Pattern pipe tape threads".

Symbol

International: R.

Japan: Pt.

United Kingdom: BSpt.

The letter R and the nominal DY diameter are indicated. The designation R is an outdoor thread type, an internal RC, RP internal cylindrical. By analogy with a cylindrical tube thread for the left thread used by LH.

Examples:

R1 ½ - outer tube conical thread, nominal diameter dy \u003d 1 ½ inches.

R1 ½ LH - Outer tube conical thread, nominal diameter DY \u003d 1 ½ inches, left.

Conical Inch Carving GOST 6111 - 52 (2nd Size)

Unit of measurement of parameters: inches

It has an angle of 60 ° profile. Cm. northern Part (ii) of the three-dimensional image "Figure Pipe Truck Threads". It is used in pipelines (fuel, water, air) machines and machines with relatively low pressure. The use of this type of compound involves the tightness and locking of the thread without additional special means (linen filaments, yarn with Surikom).

Symbol

Example: k ½ GOST 6111 - 52

Deciphering as: Carving a conical inches with an outer and inner diameter in the main plane approximately equal to the outer and inner Ø of pipe cylindrical thread G ½

Table of the main parameters of the conical inch thread

Thread Size Design (D, Inch)	Number of threads per 1 "n	Step thread s, mm	Thread Length, mm		The outer diameter of the thread in the main plane d, mm
			Working L1.	From the end of the pipe to the main plane L2
1/16	27	0,941	6,5	4,064	7,895
1/8	27	0,941	7,0	4,572	10,272
1/4	18	1,411	9,5	5,080	13,572
3/8	18	1,411	10,5	6,096	17,055
1/2	14	1,814	13,5	8,128	21 793
3/4	14	1,814	14,0	8,611	26,568
1	11 1/2	2,209	17,5	10,160	33,228
1 1/4	11 1/2	2,209	18,0	10,668	41,985
1 1/2	11 1/2	2,209	18,5	10,668	48,054
2	11 1/2	2,209	19,0	11,074	60,092

Metric conical carving. GOST 25229 - 82

Unit of measurement of parameters: mm

Made on surfaces with taper 1:16

Used when connecting pipelines. The angle at the top of the coil is 60 °. The main plane is shifted relative to the end ( see Rice above).

Symbol

The letters of MK goes the diameter in the main plane and the thread step in mm: MK 30x2

Table of sizes of metric conical thread

Diameter D Thread For Row		Step R.	Thread diameter in the main plane
1	2		D \u003d D.	d2 \u003d d2.	D1 \u003d D1.	L.	L1.	L2.
6	---	1	6,000	5,350	4,917	8	2,5	3
8	---		8,000	7,350	6,917
10	---		10,000	9,350	8,917
12	---	1,5	12,000	11,026	10,376	11	3,5	4
---	14		14,000	13,026	12,376
16	---		16,000	15,026	14,376
---	18		18,000	17,026	16,376
20	---		20,000	19,026	18,376
---	22		22,000	21,026	20,376
24	---		24,000	23,026	22,376
---	27	2	27,000	25,701	24,835	16	5	6
30	---		30,000	28,701	27,835
---	33		33,000	31,701	30,835
36	---		36,000	34,701	33,835

Characteristics of the cylindrical tubular / inch thread relative to metric

The main characteristics of "inch" and "pipe" cylindrical threads with respect to the "metric" thread for the main sizes.

Nominal thread diameter in DM	Inch thread			Pipe thread
	outer diameter, in mm		number of threads per 1 "	outer diameter, in mm		number of threads per 1 "

To cut the inner thread on some details, you must pre-drill the hole. Its size is not equal to the diameter of the thread, but should be slightly smaller. You can find the diameter of the drill to the thread in a special table, but for this you need to know the type of thread.

Main settings

• diameter (D);
• step (P) - distance from one turn to another.

They are determined by GOST 1973257-73. A large step is normal, but it corresponds to some smaller. Small step is used when applied to thin-walled products (pipes with a thin wall). Also make a small twine if the applied thread is a method for adjusting any parameters. Also, a small step between the turns is made to increase the tightness of the compound and to overcome the phenomenon of the removal of the part. In other cases, the standard (large) step is cut.

Threaded types are many, as each has its own features of the formation, the diameter of the thread hole in each case is different. All of them are spelled out in GOST, but most often used triangular metric and conical metric threads. We will talk further about them.

We usually observe triangular threads on bolts and other similar fasteners, conical - on most plumbing products involving a detachable connection.

Fixtures

Small fixtures use with their own hands to apply:

All these fixtures of alloys, characterized by increased strength and abrasion resistance are performed. Grooves and grooves are applied on their surface, with which their mirror image is obtained on the workpiece.

Any tap or dice are marked - an inscription is applied on them, which denotes the type of thread that this device cuts - diameter and step. They are inserted into holders - groves and plastics holders - secure there with screws. Climbing the carving device in the holder, it is worn / insert into the place where you want to make a detachable connection. Scrolling the device form the coils. From how correctly the device is put up at the beginning of work depends evenly "ilut" the turns. Because the first revs do trying to keep the design smoothly, not allowing shifts and distortions. After several revolutions are made, the process will go easier.

Manually you can cut the thread of small or medium diameter. Complex types (two- and three-way) or work with large diameters with hands is impossible - too large efforts are required. For these purposes, special mechanized equipment is used - on the lathes with the tags and dies fixed on them.

How to chop correct

You can apply the thread into almost any metals and their alloys - steel, copper, aluminum, cast iron, bronze, brass, etc. It is not recommended to do it on a calene gland - it is too tough, it will not be possible to make high-quality turns to achieve high-quality turns, which means that the connection will be unreliable.

Tool for work

Preparation

It is necessary to work on the pure metal - remove rust, sand and other pollution. Then the place where the thread will be applied, it is necessary to lubricate (except for cast iron and bronze - with them you need to work "on dry"). For lubrication there is a special emulsion, but if it is not, you can use the operated soap. You can also use other lubricants:

Often you can hear the tips to use with a carving machine or mineral oil or even fat. They work well, but experts say that it is better not to do - chips will stick to a viscous substance, which will lead to a rapid wear of the tap or dice.

The process of cutting

When cutting out the outer thread, the cry placed strictly perpendicular to the surface of the pipe or rod. When working, it should not vive, otherwise the turns will turn out uneven and the connection will be ugly and unreliable. The first turns are especially important. From how they are "lying" depends on the connection with the distortion.

Applying internal threads, the detail is fixed motionless. If it is a small piece, it can be clamped in vice. If a large plate is to provide its fixedness by available methods, for example, by fixing the bars. M.

The tap in the hole is inserted so that its axis is parallel to the axis of the opening. With a little effort, little by little, begin to twist in a given direction. As soon as you feel that resistance has intensified, unscrew the tap back and clean it from chips. After cleaning, the process continues.

The process of cutting in the photo

When cutting the thread in the deaf hole, its depth should be a little more required - the tip of the tip should be included in this surplus. If it is not possible that it is impossible, the tip is cut at the tip. At the same time, it is not suitable for further operation, but there is no other way out.

In order for the turns to be high-quality, use two taps or dies - rough and finite. The first pass is made by Chernovaya, the second - clean. Also there are combined devices for carvings. They allow you to do everything in one pass.

Another practical advice: so that the chips do not get into the working area, when cutting one full turn clockwise, then floor turns against. After that, they return the tool to the place where they stopped and again make one turn. So continue to the desired length.

Drill Drill Diameter Tables for Threads

When performing the inner thread, the hole is previously drilled. It is not equal to the diameter of the thread, since when cutting, part of the material is not removed as chips, and extruded, increasing the size of the protrusions. Therefore, before applying, you need to select the diameter of the drill drill. This can be done on tables. They are for each type of thread, but we give the most popular - metric, inch, pipe.

Metric carving			Inch thread			Pipe thread
Thread diameter, inches	Thread step, mm	Drill diameter, mm	Thread diameter, inches	Thread step, mm	Drill diameter, mm	Thread diameter, inches	Hole diameter for threads, mm
M1.	0.25	0,75	3/16	1.058	3.6	1/8	8,8
M1,4	0,3	1,1	1/4	1.270	5.0	1/4	11,7
M1.7.	0,35	1,3	5/16	1.411	6.4	3/8	15,2
M2.	0,4	1,6	3/8	1.588	7.8	1/2	18,6
M2.6.	0,4	2,2	7/16	1.814	9.2	3/4	24,3
M3.	0,5	2,5	1/2	2,117	10,4	1	30,5
M3.5	0,6	2,8	9/16	2,117	11,8	-	-
M4.	0,7	3,3	5/8	2,309	13,3	11/4	39,2
M5.	0,8	4,2	3/4	2,540	16,3	13/8	41,6
M6.	1,0	5,0	7/8	2,822	19,1	11/2	45,1
M8.	1,25	6,75	1	3,175	21,3	-	-
M10	1,5	8,5	11/8	3,629	24,6	-	-
M12.	1,75	10,25	11/4	3,629	27,6	-	-
M14.	2,0	11,5	13/8	4,233	30,1	-	-
M16.	2,0	13,5	-	-	-	-	-
M18.	2,5	15,25	11/2	4,33	33,2	-	-
M20.	2,5	17,25	15/8	6,080	35,2	-	-
M22.	2,6	19	13/4	5,080	34,0	-	-
M24.	3,0	20,5	17/8	5,644	41,1	-	-

Once again we draw your attention that the diameter of the drill drill is given for a large (standard thread).

Table of rod diameters for external thread

When working in the outer thread, the situation is very similar - the metal is extruded, and not cut. Therefore, the diameter of the rod or pipe to which the thread is applied, should be slightly smaller. How accurate - see the table below.

Diameter of thread, mm	5,0	6	8	10	12	16	20	24
Rod diameter, mm	4,92	5,92	7,9	9,9	11,88	15,88	19,86	23,86

Despite the fact that cutting internal threads does not apply to complex technological operations, there are some features of preparation for this procedure. Thus, it is necessary to accurately determine the size of the preparatory hole for threading, as well as correctly select a tool, for which special tables of diameters are used for threads. For each of the thread types, use the appropriate tool and calculate the diameter of the preparatory opening.

Varieties and thread parameters

The parameters on which the threads are divided into different types are:

• units for calculating diameter (metric, inch, etc.);
• the number of bends of thread (one-, two- or three-way);
• the form in which the profile elements are made (triangular, rectangular, round, trapezoidal);
• rise direction of turns (right or left);
• placement on the product (outer or internal);
• surface shape (cylindrical or conical);
• purpose (fastening, fastening-sealing, chassis).

Depending on the above parameters, the following types of thread differ:

• cylindrical, which is denoted by letters MJ;
• metric and conical, indicated respectively M and MK;
• tubular, to indicate which the letters G and R are used;
• with a round profile, named after Edison and marked letter E;
• trapezoidal, denoted tr;
• the round used for the installation of sanitary fittings - kr;
• stubborn and resistant reinforced, marked as S and S45, respectively;
• inch thread, which can also be cylindrical and conical, - BSW, UTS, NPT;
• used to connect pipes mounted in petroleum wells.

Application of the tester

Before proceeding with threads, it is necessary to determine the diameter of the preparatory opening and perform its drilling. To facilitate this task, an appropriate GOST has been developed, which contains tables that allow you to accurately determine the diameter of the thread hole. This information allows you to easily choose the size of the drill.

To cut the metric type thread on the inner walls made by the hole drill, a tap is used - a screw-shaped tool with cutting grooves, made in the form of a rod that can have a cylindrical or conical shape. On its side surface there are special grooves located along its axis and separating the working part into separate segments, which are called combs. Sharp edges of the comb are just the working surfaces of the tap.

So that the turns of the inner threads are clean and neat, and its geometric parameters corresponded to the required values, it must be cut gradually, by phased removal of thin layers of metal from the surface being processed. That is why this purpose uses either taps whose working part is divided into sections with various geometric parameters or sets of such tools. Single testers whose working part has the same geometric parameters throughout their entire length, are needed in cases where it is necessary to restore the parameters of the existing thread.

A minimal set, with which it is possible to high qualityly perform the processing of holes for the thread, is a set consisting of two testers - rough and clean. The first cuts off the holes of the hole under the cutting of the metric thread. The thin layer of metal and generates a shallow groove on them, the second not only deepens the formed groove, but also cleales it.

Combined two-pass taps or sets consisting of two tools are used for threads in the holes of small diameters (up to 3 mm). To process holes for metric larger diameter threads, it is necessary to use a combined three-pass tool or a set consisting of three testers.

For manipulations with a tank, a special device is applied - the knob. The main parameter of such devices that may have different structural execution is the size of the planting opening, which must accurately coincide with the size of the tool shank.

When using a set of three testers, characterized in both its design and geometrical parameters, the sequence of their use should be strictly observed. You can distinguish them from each other both by special risks applied to shanks and in constructive features.

1. The tap, which the hole for cutting the metric thread is processed primarily, is characterized by a minimum diameter among all set tools and cutting teeth, the upper part of which is strongly cropped.
2. The second tap has a shorter intake part and longer ridges. Its working diameter occupies an intermediate value between the diameters of the remaining tools from the set.
3. The third tap, which the hole for slicing the metric thread is processed last of all, is characterized by full ridges of cutting teeth and a diameter, which should accurately correspond to the size of the formed thread.

Taps are used mainly to cut the metric type thread. Significantly less often than metric, taps designed to process the inner walls of pipes. In accordance with their appointment, they are called pipes, and they can be distinguished by the letter G, present in their marking.

Internal thread cutting technology

As mentioned above, before starting work, it is necessary to drill a hole, the diameter of which should be accurately approaching the threads of a certain size. It should be borne in mind: if the diameters of the holes intended for cutting the metric thread are incorrect, it can lead not only to its low-quality execution, but also to the damage of the tap.

Given the fact that the tap, forming threaded grooves, not only cuts off the metal, but also pursues it, the diameter of the drill to perform the thread must be somewhat less than its nominal diameter. For example, the drill to perform a thread M3 must have a diameter of 2.5 mm, under M4 - 3.3 mm, for M5, you should choose a drill with a diameter of 4.2 mm, under the thread M6 - 5 mm, M8 - 6.7 mm, M10 - 8.5 mm, and for M12 - 10.2.

Table 1. Basic diameters of holes for metric threads

All diameters drill under the thread of GOST leads in special tables. In such tables, the diameters of the drill to perform a thread both with a standard and reduced step, it should be borne in mind that the holes of different diameters are drilled for these purposes. In addition, if the carving is cut into products from fragile metals (such as, for example, cast iron), the diameter of the drill drill, obtained from the table, must be reduced by one tenth millimeter.

You can get acquainted with the provisions of GOST, regulating the cutting of metric thread, by downloading the document in the PDF format on the link below.

The diameters of the drill under metric thread can be calculated independently. From the diameter of the thread, which is required to cut, it is necessary to subtract the value of its step. The thread itself is the size of which is used when performing such calculations, you can learn from special matching tables. In order to determine what diameter the hole must be performed using a drill if a three-point tap will be used for threads with the following formula:

D o \u003d d m x 0.8, Where:

Before - this is the diameter of the hole that must be performed using the drill,

D M. - The diameter of the tier to which the drilled element will be processed.