Gas and Water Piping.Hydraulic Piping.
Internal
Diameter
of
Pipe.		External
Diameter
of
Pipe.		No. of
Threads
per Inch.		Internal
Diamter
of
Pipe.		External
Diameter
of
Pipe.		Pressure in
lbs. per
Square
Inch.		No. of
Threads
per Inch.		Internal
Diamter
of
Pipe.		External
Diameter
of
Pipe.		Pressure in
lbs. per
Square
Inch.		No. of
Threads
per Inch.
1⁄8.385 28 1⁄4- 5⁄84,000 -1411⁄4- 13⁄44,000 -11
1⁄4.520 19 3⁄46,00017⁄86,000
3⁄8.665 19 7⁄88,0002 8,000
1⁄2.822 141 10,00021⁄810,000
3⁄41.034 14 3⁄8- 3⁄44,000 -1413⁄8- 17⁄84,000 -11
1 1.302 -11 7⁄86,0002 6,000
11⁄81.4921 8,00021⁄88,000
11⁄41.65011⁄810,00021⁄410,000
13⁄81.745 1⁄2- 1 4,000 -1411⁄2- 2 4,000 -11
11⁄21.88211⁄86,00021⁄86,000
15⁄82.02111⁄48,000 -1121⁄48,000
13⁄42.04713⁄810,00023⁄810,000
17⁄82.245 5⁄8- 11⁄84,000 1421⁄210,000
2 2.34711⁄46,000 -1115⁄8- 21⁄84,000 -11
21⁄82.46713⁄88,00021⁄46,000
21⁄42.58711⁄210,00023⁄88,000
23⁄82.794 3⁄4- 11⁄44,000 -1121⁄210,000
21⁄23.00113⁄86,00013⁄4- 21⁄43,000 -11
25⁄83.12411⁄28,00023⁄84,000
23⁄43.24715⁄810,00021⁄26,000
27⁄83.367 7⁄8- 13⁄84,000 -1125⁄88,000
3 3.48511⁄26,00023⁄410,000
31⁄43.69815⁄88,00017⁄8- 23⁄83,000 -11
31⁄23.91213⁄410,00021⁄24,000
33⁄44.1251 - 11⁄24,000 -1125⁄86,000
4 4.33915⁄86,00023⁄48,000
13⁄48,00027⁄810,000
17⁄810,0002 - 21⁄23,000 -11
11⁄8- 15⁄84,000 -1125⁄84,000
13⁄46,00023⁄46,000
17⁄88,00027⁄88,000
2 10,0003 10,000

The English pipe thread is a sharp V-thread having its sides at an angle of 60°, and therefore corresponds to the American pipe thread except that the pitches are different.

The standard screw thread of The Royal Microscopical Society of London, England, is employed for microscope objectives, and the nose pieces of the microscope into which these objectives screw.

The thread is a Whitworth one, the original standard threading tools now in the cabinet of the society having been made especially for the society by Sir Joseph Whitworth. The pitch of the thread is 36 per inch. The cylinder, or male gauge, is .7626 inch in diameter.

The following table gives the Whitworth standard of thread pitches and diameters for watch and mathematical instrument makers.

WHITWORTH’S STANDARD GAUGES FOR WATCH AND
INSTRUMENT MAKERS, WITH SCREW THREADS FOR
THE VARIOUS SIZES, 1881.

No. of each
size in thou-
sandths of
an inch.		Size in
decimals of
an inch.		Number of
Threads per
inch.		No. of each
size in thou-
sandths of
an inch.		Size in
decimals of
an inch.		Number of
Threads per
inch.
10.01040034.034150
11.011„36.036„
12.01235038.038120
13.013„40.040„
14.01430045.045„
15.015„50.050100
16.016„55.055„
17.01725060.060„
18.018„65.06580
19.019„70.070„
20.02021075.075„
22.022„80.08060
24.024„85.085„
26.02618090.090„
28.028„95.095„
30.030„100.10050
32.032150

For the pitches of the threads of lag screws there is no standard, but the following pitches are largely used.

Diameter
of Screw.		Threads
per Inch.		Diameter
of Screw.		Threads
per Inch.
Inch. Inch.
1⁄4105⁄85
5⁄16911⁄165
3⁄883⁄45
7⁄1677⁄84
1⁄2614
9⁄166

Screw-Cutting Hand Tools.