Internal thread g1.1.2 lh decoding. Pipe thread sizes. designation. guests. Varieties of inch threads

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

Tapered and cylindrical threads

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 (millimeters or inches) as the distance from the starting point increases, the diameter increases by 1 corresponding unit. It turns out that the axis around which the thread is drawn 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 it even easier, if the length of the threaded connection were 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, therefore, there is no taper.

Thread pitch (metric and inch)

The thread pitch can be large (or basic) and small. Under thread pitch the distance between the threads from the top of the thread to the top of the next thread is understood. 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 measurement accuracy using the table for the corresponding step.

Cylindrical pipe thread according to GOST 6357-52
Designation	Number of threads N by 1 "	Thread pitch S, mm	Outside diameter thread, mm	Average diameter thread, mm	Inner diameter thread, mm
G1 / 8 "	28	0,907	9,729	9,148	8,567
G1 / 4 "	19	1,337	13,158	12,302	11,446
G3 / 8 "	19	1,337	16,663	15,807	14,951
G1 / 2 "	14	1,814	20,956	19,754	18,632
G3 / 4 "	14	1,814	26,442	25,281	24,119
G7 / 8 "	14	1,814	30,202	29,040	27,878
G1 "	11	2,309	33,250	31,771	30,292

Nominal thread diameter

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

Metric and inch threads in examples

Metric thread- has the designation of the main parameters in millimeters. As an example, consider an elbow fitting with an external straight thread EPL 6-GM5... In this case, EPL says that the fitting is angled, 6 is 6 mm - external diameter 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 the nominal diameter of the thread, equal to 5 millimeters. Fittings (of those that we have on sale) with the letter “G” are also equipped with a rubber sealing ring, and therefore do not require fum tapes. The thread pitch in this case is 0.8 millimeters.

main parameters inch thread, according to the name - are indicated in inches. This can be 1/8, 1/4, 3/8 and 1/2 inch threads, etc. For example, let's take a fitting EPKB 8-02... EPKB is a type of fitting (in this case, a splitter). The thread is tapered, 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. And 02 - that the connecting thread on the fitting is 1/4 inch. According to the table, the pitch is 1.337 mm. The nominal thread diameter is 13.157 mm.

The profiles of the tapered and cylindrical threads are the same, which allows you to screw together fittings with tapered and cylindrical threads.

inches	mm.	inches	mm.	inches	mm.	inches	mm.	inches	mm.
-	-	1	25,4	2	50,8	3	76,2	4	101,6
1/8	3,2	1 1/8	28,6	2 1/8	54,0	3 1/8	79,4	4 1/8	104,8
1/4	6,4	1 1/4	31,8	2 1/4	57,2	3 1/4	82,6	4 1/4	108,8
3/8	9,5	1 3/8	34,9	2 3/8	60,3	3 3/8	85,7	4 3/8	111,1
1/2	12,7	1 1/2	38,1	2 1/2	63,5	3 1/2	88,9	4 1/2	114,3
5/8	15,9	1 5/8	41,3	2 5/8	66,7	3 5/8	92,1	4 5/8	117,5
3/4	19,0	1 3/4	44,4	2 3/4	69,8	3 3/4	95,2	4 3/4	120,6
7/8	22,2	1 7/8	47,6	2 7/8	73,0	3 7/8	98,4	4 7/8	123,8

Inch thread parameters

Outside diameter of the connected pipe		SAE thread rating	UNF thread rating	Outer thread diameter, mm	Average thread diameter, mm	Thread pitch
mm	inch					mm	threads / inch
6	1/4""""	1/4""""	7/16""""-20	11,079	9,738	1,27	20
8	5/16""""	5/16""""	5/8""""-18	15,839	14,348	1,411	18
10	3/8""""	3/8""""	5/8""""-18	15,839	14,348	1,411	18
12	1/2""""	1/2""""	3/4""""-16	19,012	17,33	1,588	16
16	5/8""""	5/8""""	7/8""""-14	22,184	20,262	1,814	14
18	3/4""""	3/4""""	1""""-14	25,357	23,437	1,814	14
18	3/4""""	---	1""""1/16-14	26,947	25,024	1,814	14
20	7/8""""	---	1""""1/8-12	28,529	26,284	2,117	12
22	7/8""""	7/8""""	1""""1/4-12	31,704	29,459	2,117	12
22	7/8""""	---	1""""3/8-12	34,877	32,634	2,117	12
25	1""""	1""""	1""""1/2-12	38,052	35,809	2,117	12

Copper conductors, wires and cables

Conductor cross-section, mm	Copper conductors, wires and cables
	Voltage, 220 V		Voltage, 380 V
	current, A	power, kWt	current, A	power, kWt
1,5	19	4,1	16	10,5
2,5	27	5,9	25	16,5
4	38	8,3	30	19,8
6	46	10,1	40	26,4
10	70	15,4	50	33,0
16	85	18,7	75	49,5
25	115	25,3	90	59,4
35	135	29,7	115	75,9
50	175	38,5	145	95,7
70	215	47,3	180	118,8
95	260	57,2	220	145,2
120	300	66,0	260	171,6

Aluminum conductors, wires and cables

Conductor cross-section, mm	Aluminum conductors, wires and cables
	Voltage, 220 V		Voltage, 380 V
	current, A	power, kWt	current, A	power, kWt
1,5	19	4,1	16	10,5
2,5	27	5,9	25	16,5
4	38	8,3	30	19,8
6	46	10,1	40	26,4
10	70	15,4	50	33,0
16	85	18,7	75	49,5
25	115	25,3	90	59,4
35	135	29,7	115	75,9
50	175	38,5	145	95,7
70	215	47,3	180	118,8
95	260	57,2	220	145,2
120	300	66,0	260	171,6

Inch thread sizes

	Thread diameter in mm			Thread pitch in mm	Number of threads per 1 "
	outer d	middle d	inner d
3/16	4,762	4,085	3,408	1,058	24
1/4	6,350	5,537	4,724	1,270	20
5/16	7,938	7,034	6,131	1,411	18
3/8	9,525	8,509	7,492	1,588	16
1/2	12,700	11,345	9,989	2,117	12
5,8	15,875	14,397	12,918	2,309	11
3/4	19,05	17,424	15,798	2,540	10
7/8	22,225	20,418	18,611	2,822	9
1	25,400	23,367	21,334	3,175	8
1 1/8	28,575	26,252	23,929	3,629	7
1 1/4	31,750	29,427	27,104	3,629	7
1 1/2	38,100	35,39	32,679	4,233	6
1 3/4	44,450	41,198	37,945	5,080	5
2	50,800	47,186	43,572	5,644	4 1/2

Nominal thread diameter in inches
	Thread diameter in mm			Thread pitch in mm	Number of threads per 1 "
	outer d	middle d	inner d
1/8	9,729	9,148	8,567	0,907	28
1/4	13,158	12,302	11,446	1,337	19
3/8	16,663	15,807	14,951	1,337	19
1/2	20,956	19,794	18,632	1,814	14
5/8	22,912	21,750	20,588	1,814	14
3/4	26,442	25,281	24,119	1,814	14
7/8	30,202	29,040	27,878	1,814	14
1	33,250	31,771	30.293	2,309	11
1 1/8	37,898	36,420	34,941	2,309	11
1 1/4	41,912	40,433	38,954	2,309	11
1 3/8	44,325	32,846	41,367	2,309	11
1 1/2	47,805	46,326	44,847	2,309	11
1 3/4	53,748	52,270	50,791	2,309	11
2	59,616	58,137	56,659	2,309	11

Unit conversion table

Conversion of energy units	Pressure Unit Conversion
1 J = 0.24 cal	1 Pa = 1 N / m * m
1 kJ = 0.28 W * h	1 Pa = 0.102 kgf / m * m
1 W = 1 J / s	1 atm = 0.101 mPa = 1.013 bar
1 cal = 4.2 J	1 bar = 100 kPa = 0.987 atm
1 kcal / h = 1.163 W	1 PSI = 0.06895 bar = 0.06805 atm

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 the fact that it is necessary to select the appropriate dimensions, taking into account the parameters of the equipment, the customer has to independently convert the data into suitable units of measurement. This process is time-consuming.

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

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 diameters of pipes.

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

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

Straight pipe threads are mainly used for pipe connections, pipe fittings and fittings. This thread spans 1/16 to 6 "with 28 to 11 threads per 1".

The nominal diameter of the pipe thread is conventionally referred to the inner diameter of the pipe. In terms of the ratio of pitches and diameters, the pipe thread is a crushed inch thread according to OST 1260. Therefore, pipe thread at one time, before the standardization of small metric threads, was used not only for pipe connections, but also for fasteners, when there was a need for threading with a comparative in small steps, with large diameters. Pipe threads are the European-wide standard for pipes and pipe connections.

CYLINDRICAL PIPE THREAD DIMENSIONS
(GOST 6357-81)

The standard applies to cylindrical pipe threads used in cylindrical threaded connections, as well as in connections of an internal cylindrical thread with an external tapered thread in accordance with GOST 6211-81.

Tolerances (according to GOST 6357-81) of the average thread diameter are established in two classes of accuracy - A and B. Tolerances of the average thread diameter are cumulative. Tolerances of diameters d 1 and D are not specified.

dimensions, mm

Thread designation		Number of steps z at a length of 25.4 mm	Step P	Thread diameter			Working height of the profile H 1	Radius of curvature R	H	H / 6
1st row	2nd row			outer d = D	average d 2 = D 2	internal d 1 = D 1
1/16" 1/8"	-	28	0,907	7,723	7,142	6,561	0,580777	0,124557	0,871165	0,145194
				9,728	9,147	8,566
1/4" 3/8"	-	19	1,337	13,157	12,301	11,445	0,856117	0,183603	1,284176	0,214029
				16,662	15,806	14,950
1/2"	5/8"	14	1,814	20,955	19,793	18,631	1,161553	0,249115	1,742331	0,290389
				22,911	21,749	20,587
				26,441	25,279	24,117
				30,201	29,039	27,877
1"	1 1/8" 1 3/4"	11	2,309	33,249	31,770	30,291	1,478515	0,317093	2,217774	0,369629
				37,897	36,418	34,939
				41,910	40,431	38,952
				44,323	42,844	41,365
				47,803	46,324	44,845
				53,746	52,267	50,788
				59,614	58,135	56,656
2 1/2" 3 1/2"	2 1/4" 3 3/4"			65,710	64,231	62,752
				75,184	73,705	72,226
				81,534	80,055	78,576
				87,884	86,405	84,926
				93,980	92,501	91,022
				100,330	98,851	97.372
				106,680	105,201	103,722
4"	4 1/2" 5 1/2"			113,030	111,551	110.072
				125,730	124,251	122,772
				138,430	136,951	135,472
				151,130	149,651	148,172
				163,830	162,351	160,872
When choosing thread sizes, the 1st row should be preferred to the 2nd.

SCREWING LENGTHs in accordance with GOST 6357-81

Make-up lengths are divided into two groups: normal N and long L.

dimensions, mm

Designation thread size	Step P	Make-up length
		N	L
1/16", 1/8"	0,907	cv. 4 to 12	cv. 12
1/4", 3/8"	1,337	cv. 5 to 16	cv. 16
1/2", 5/8"	1,814	cv. 7 to 22	cv. 22
1", 1 1/8", 1 1/4", 1 3/8"	2,309	cv. 10 to 30	cv. thirty
1 1/2", 1 3/4", 2", 2 1/4", 2 1/2", 2 3/4", 3"		cv. 12 to 36	cv. 36
3 1/4", 3 1/2", 3 3/4", 4", 4 1/2", 5", 5 1/2", 6"		cv. 13 to 40	cv. 40
The numerical values ​​of make-up lengths are established empirically.

Symbol for left-hand threads, it is supplemented with the letters LH.

Examples of designation for thread accuracy class A:

G 1 1/2-A
left-hand thread accuracy class B:

G 1 1/2 LH-B

Make-up length N is not indicated in the thread designation.
Make-up length L is indicated in millimeters.

G 1 1/2 LH-B-40

Landing is indicated by a fraction: in the numerator of which the designation of the accuracy class of the internal thread is indicated, and in the denominator - the designation of the accuracy class of the external thread.

G 1 1/2-A / A; G 1 1/2 LH-A / B

The connection of an internal pipe cylindrical thread of accuracy class A according to this standard with an external pipe tapered thread according to GOST 6211-81 is designated as follows:

G / R 1 1/2 - A

P.S. At one time, the profile of a cylindrical pipe thread (according to OST 266) extended to diameters up to 18 "with the number of threads per 1" from 28 to 8.

Related documents:

- holes for threading
GOST 3469-91: Microscopes. Lens thread. Dimensions (edit)
GOST 4608-81: Metric thread. Interference landings
GOST 5359-77: Eyepiece thread for optical instruments. Profile and dimensions
GOST 6042-83: Round Edison thread. Profiles, sizes and limit sizes
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: Round thread with a diameter of 40 mm for gas masks and gauges for it. Basic dimensions
GOST 9000-81 - Metric thread for diameters less than 1 mm. Tolerances
GOST 9484-81: Trapezoidal thread. Profiles
GOST 9562-81: Single-start trapezoidal thread. Tolerances
GOST 9909-81: Thread of tapered valves and cylinders for gases
GOST 10177-82: Threaded 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, main dimensions, tolerances
GOST 16093-2004: Metric thread. Tolerances. Clearance landings
GOST 16967-81: Metric thread for instrument making. Diameters and steps
GOST 24737-81: Single-start trapezoidal thread. Basic dimensions
GOST 24739-81: Trapezoidal multi-start thread
GOST 25096-82: Threaded thread. Tolerances
GOST 25229-82: Metric tapered thread
GOST 28487-90: Tapered tool joint thread for drill string elements. Profile. Dimensions. Tolerances

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

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

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

Basic standards:

GOST 6357-81: Basic standards of interchangeability. Cylindrical pipe thread.

ISO R228

EN 10226

JIS B 0202

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

Designation according to GOST 6357-81: letter G, numerical value nominal thread diameter in inches (inch), middle diameter accuracy class (A, B), and letters LH for left hand threads.

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

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

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

Commentary on 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 outer thread;
D 2 - the average diameter of the internal thread;
d 2 - the average diameter of the external thread.

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

table 2

Designation of the size of the pipe cylindrical thread (G), steps and nominal values ​​of the outer, middle and inner thread diameters (according to GOST 6357-81), mm

Thread size designation Thread pitch P, mm Thread pitch per inch Thread diameters First row Second row BSP thread 1/16 " Thread G1 / 16 " BSP thread 1/8 " Thread G1 / 8 " BSP thread 1/4 " Thread G1 / 4 " BSP thread 3/8 " Thread G3 / 8 " BSP thread 1/2 " Thread G1 / 2 " BSP thread 5/8 " Thread G5 / 8 " BSP thread 3/4 " Thread G3 / 4 " BSP thread 7/8 " Thread G7 / 8 " BSP thread 1 " Thread G1 " BSP thread 1.1 / 8 " Thread G1.1 / 8 " BSP thread 1.1 / 4 " Thread G1.1 / 4 " BSP thread 1.3 / 8 " Thread G1.3 / 8 " BSP thread 1.1 / 2 " Thread G1.1 / 2 " BSP thread 1.3 / 4 " Thread G1.3 / 4 " BSP thread 2 " Thread G2 " BSP thread 2.1 / 4 " Thread G2.1 / 4 " BSP thread 2.1 / 2 " Thread G2.1 / 2 " BSP thread 2.3 / 4 " Thread G2.3 / 4 " BSP thread 3 " Thread G3 " BSP thread 3.1 / 4 " Thread G BSP thread 3.1 / 2 " Thread G3.1 / 2 " BSP thread 3.3 / 4 " Thread G3.3 / 4 " BSP thread 4 " Thread G4 " BSP 4.1 / 2 " Thread G4.1 / 2 " BSP thread 5 " Thread G5 " BSP thread 5.1 / 2 " Thread G5.1 / 2 " BSP thread 6 " Thread G6 "

* Whitworth slicing

BSPT British standard pipe tapered thread - tapered pipe thread.

Based on BSW (British Standard Whitworth) threads, known as Whitworth pipe threads *.
BSPT thread is interchangeable with Russian standard GOST 6211-81 thread.
It is used in tapered threaded connections, as well as in connections of an external tapered thread with an internal cylindrical thread in accordance with GOST 6357-81.
Basic standards for BSPT threads:
GOST 6211-81: Basic standards of interchangeability. Conical pipe thread.
ISO R7
DIN 2999
BS 21
JIS B 0203

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

Table 1

Thread size designation, steps and nominal values ​​of the outer, middle and inner diameters of the tapered pipe thread (R), mm

Size designation carvings Thread length Thread diameter in the main plane From the end of the pipe to the main plane Outer d = D Average d 2 = D 2 Interior d 1 = D 1 BSPT thread 1/16 " Thread R1 / 16 " BSPT thread 1/8 " Thread R1 / 8 " BSPT thread 1/4 " Thread R1 / 4 " BSPT 3/8 "thread Thread R3 / 8 " BSPT 1/2 "thread R1 / 2 "thread BSPT 3/4 "thread Thread R3 / 4 " BSPT thread 1 " Thread R1 " BSPT 1.1 / 4 " Thread R1.1 / 4 " BSPT 1.1 / 2 "thread Thread R1.1 / 2 " BSPT thread 2 " R2 "thread BSPT 2.1 / 2 "thread Thread R2.1 / 2 " BSPT thread 3 " Thread R3 " BSPT thread 3.1 / 2 " Thread R3.1 / 2 " BSPT thread 4 " Thread R4 " BSPT thread 5 " Thread R5 " BSPT thread 6 " Thread R6 "

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

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

NPTF - sealed thread. Sealing takes place by crushing the threads.
Tapered fuel pipe threads are described in ANSI / ASME B1.20.3

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

On fittings with NPTF threads, to distinguish from BSPT threads, a mark is usually put - a risk on the faces of the hexagon

Nominal size	Outside diameter, mm	Hole for thread, mm	TPI, threads per inch	Coil pitch, mm
NPTF thread 1/16 "
NPTF 1/8 "thread
NPTF 1/4 "thread
NPTF 3/8 "thread
NPTF 1/2 "thread
NPTF 3/4 "thread
NPTF thread 1 "
NPTF 1.1 / 4 "thread
NPTF 1.1 / 2 "thread
NPTF thread 2 "
NPTF 2.1 / 2 "thread
NPTF thread 4 "

Tapered thread (NPT) with a taper of 1:16 (taper angle φ = 3 ° 34'48 ") or cylindrical (NPS) thread. Apex angle 60 °, theoretical height H = 0.866025Р.

Tapered thread NPT is described by ANSI / ASME B1.20.1.
NPT thread corresponds to GOST 6111-52 - Conical inch thread with a profile angle of 60 degrees.

Nominal size	Outside diameter, mm	Hole for thread, mm	TPI, threads per inch	Coil pitch, mm
1/16 "NPT thread Thread K1 / 16 "
1/8 "NPT thread Thread K1 / 8 "
NPT 1/4 " Thread K1 / 4 "
NPT 3/8 " Thread K3 / 8 "
1/2 "NPT thread Thread K1 / 2 "
NPT 3/4 " Thread K3 / 4 "
NPT thread 1 " Thread K1 "
NPT 1.1 / 4 " Thread K1.1 / 4 "
1.1 / 2 "NPT thread Thread K1.1 / 2 "
NPT thread 2 " Thread K2 "
NPT thread 2.1 / 2 "NPT
NPT thread 3 "
NPT thread 3.1 / 2 "
NPT thread 4 "
NPT thread 5 "
NPT thread 6 "
NPT thread 8 "
NPT thread 10 "
NPT thread 12 "

Metric screw threads- has a wide application both in Russia and in world practice. Metric connections are widely used pipe connections ISO 8434-1 DIN 2353.

Hydraulic connections mainly use two steps metric thread: step 1.5 and step 2.0.

Sizes of frequently used hydraulic threads with a pitch of 1.5 mm: М12х1.5; 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.

Sizes of frequently used hydraulic threads with a pitch of 2.0 mm: М30х2.0; M33x2.0; M36x2.0; M42x2.0; M45x2.0; M52x2.0.

Sizes of metric threads in fittings for high pressure hoses 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 (apex angle 60 °) with a theoretical profile height H = 0.866025404P.

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

Designation: the letter M (metric), the numerical value of the nominal thread diameter in millimeters, the numerical value of the lead (for threads with a fine pitch) and the letters LH for the left-hand thread. For example, a thread with a nominal diameter of 16 mm with a coarse lead is designated as M16; thread with a nominal diameter of 36 with a fine pitch of 1.5 mm - М36х1.5; the same in diameter and pitch but left hand threadМ36х1,5LH.
Notes:
1. The shape of the bolt thread is not regulated and can be either rounded or flat-cut. A rounded trough shape is preferred.
2. The shape of the thread root of the nut is not regulated.

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

Step R

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

Nose angle and profile heights are fully metric, however all dimensions are based on inch units and are 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).
The hydraulic connections are mainly used fittings with UNF thread.

Nominal thread size UNF	Outside diameter, Inch	Outside diameter, mm	Tap hole diameter (nut inner diameter), mm	TPI Threads Per Inch	Coil pitch, mm
UNF thread 0-80
UNF thread 1-72
UNF thread 2-64
UNF thread 3-56
UNF thread 4-48
UNF thread 5-44
Thread UNF 6-40
UNF thread 8-36
UNF thread 10-32
UNF thread 12-28
UNF thread 1/4 "-28
UNF thread 5/16 "-24
UNF thread 3/8 "-24
UNF thread 7/16 "-20
UNF thread 1/2 "-20
UNF thread 9/16 "-18
UNF thread 5/8 "-18
UNF thread 3/4 "-16
UNF thread 7/8 "-14
UNF thread 1 "-12
UNF thread 1.1 / 8 "-12
UNF thread 1.1 / 4 "-12
UNF thread 1.3 / 8 "-12
UNF thread 1.1 / 2 "-12

Inch thread is used mainly 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 threaded elements of such connections are regulated by the corresponding GOST, giving tables of inch thread sizes, which specialists are guided by.

main parameters

The normative document, which specifies the requirements for the dimensions of the 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:

• the outer diameter, measured between the tops of the threaded ridges on opposite sides of the pipe;
• internal diameter as a value characterizing the distance from one lowest point of the depression 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. Throughout the entire section of the product, on which the pipe thread is made, its pitch does not change and has the same meaning. If such important requirement will not be respected, it will simply be inoperative, it will not be possible to pick up the second element of the created connection to it.

You can get acquainted with the provisions of GOST regarding inch threads by downloading the pdf document from the link below.

Size Chart for Inch and Metric Threads

Find out how metric threads compare with different kinds inch threads, using the data in the table below.

Similar sizes of metric and different types of inch threads in the range of approximately Ø8-64mm

Differences from metric threads

According to their outward signs and the characteristics of metric and inch threads do not have so many differences, the most significant of which are:

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

When comparing the shapes of the threaded ridges, you can see that the inch threads are sharper than the metric ones. If we talk about the exact dimensions, then the angle at the top of the ridge of an inch thread is 55 °.

Metric and inch threads have different measurement units. 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 the inch thread, not the generally accepted (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 standard size, which is fixed by GOST, it is enough to look at a special table. In tables containing inch thread sizes, both integer and fractional values ​​are given. It should be noted that the pitch in such tables is given in the number of grooves (threads) cut per inch of the length of the product.

To check whether the pitch of the already made thread 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 the same algorithm, standard tools are used - a comb, a gauge, a mechanical gauge, etc.

The easiest way is to measure the pitch of the inch pipe thread 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, are screwed into the coupling or fitting.
• In the event that the bolt formed with a coupling or fitting a tight threaded connection, then the diameter and pitch of the thread, which is applied to its surface, exactly correspond to the parameters of the template used.

If the bolt is not screwed into the template or is screwed in, but creates a loose connection with it, then such measurements should be taken using another coupling or another fitting. The internal pipe thread is measured by 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 serrated plate, the shape and other characteristics of which exactly correspond to the parameters of the thread with a certain pitch. Such a plate, acting as a template, is simply applied to the tested thread with its serrated part. The fact that the thread on the element under test corresponds to the required parameters will be evidenced by the tight fit of the serrated part of the plate to its profile.

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

Slicing technology

Cylindrical pipe threads, which are of the inch type (both internal and external), can be cut by hand or mechanical method.

Manual threading

Tapping with hand tool, which is used as a tap (for inner) or die (for outer), is performed in several steps.

1. The pipe to be processed is clamped in a vise, and the tool used is fixed in the wrench (tap) or in the 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 turning the knob or die holder.
4. To make the result cleaner and more precise, you can repeat the slicing procedure several times.

Threading on a lathe

The pipe thread is mechanically cut according to the following algorithm:

1. The pipe to be processed is clamped in the chuck of the machine, on the support of which the threading cutter is fixed.
2. At the end of the pipe, using a cutter, chamfer is removed, after which the speed of movement of the caliper is adjusted.
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 stiffness of which allow it to be done. Making pipe inch thread mechanically allows you to get a high-quality result, but the use of such technology requires the turner to have appropriate qualifications and certain skills.

Accuracy classes and marking rules

The 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). Full designations of 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 coarsest threads correspond to the 1st class, and the most accurate threads, to the dimensions of which very strict requirements are imposed on the 3rd.