# Advice 1: How to measure pipe diameter

To measure the various elements of the technical facilities or laboratory equipment provide special tools and instruments. If you want to measure, for example, the diameter of the pipe, part of the system of water or gas, the choice of a particular method of measurement is determined by the availability of the object and its size.
You will need
• measuring ruler or measuring tape;
• - caliper;
• - camera.
Instruction
1
If you want to determine the pipe diameter, the cross section of which is available to direct observation and measurement, and accuracy requirements measurement minimum use a metal measuring tape or a ruler. Place the measuring tool to the end of the tube at its widest part and count the number of divisions corresponding to the diameter. This method allows you to set the size of the product with an accuracy to several millimetres.
2
To measure the outer diameter of the small pipe size, use the caliper. Attach the legs to push the instrument to the end of the tube and slide them so that they tightly clung to the walls. On the scale of values, determine the required diameter with a precision of tenths of a millimeter.
3
If the mechanical part of the pipe is inaccessible for measurements, for example, when a pipe is included in the current system, under operation, a caliper for measurement attach to the lateral surface of the product. This way you can measure the diameter of the pipe, if the length of the legs of the device exceeds half of the diameter.
4
To calculate the diameter of the larger pipe, use the formula known from the geometry course:

D = L / P; where
D – diameter;
L is the length of the circle;
P is the number PI, approximately equal to 3.14.

To start by means of a cord or tape measure, make the measurement of the pipe on its circumference to find the circumference. The resulting value of the divide by 3.14; the result you will get the diameter of the pipe.
5
If you hold a direct measurement of the pipe for some reason is not possible, use the copy method. To do so, attach to the pipe measuring tool (a ruler) or piece, the linear dimensions which is known in advance (matchbox). Then take a picture of a pipe section with a measuring instrument. Further measurements and calculations spend on photography. It is necessary to measure in the picture the visible thickness in millimetres and convert the calculated data to the actual size of the pipe, given the scale of the shooting.

# Advice 2: How to find the diameter of the pipe

The need to determine the diameter of the pipe often occurs when you replace sewer pipes, selection of towel warmer and other home jobs. It can be defined independently, for this you will need a tape measure or caliper.
You will need
• tube;
• roulette;
• - caliper;
• - the range.
Instruction
1
Measure a tape measure or measuring tape the circumference of the pipe, to do this, wrap it around and look at the value on the scale. Next, divide the resulting value by the number of PI = 3,1415. As a result, you will receive the outer diameter of the pipe.
2
If you have a caliper, you can measure the outer diameter directly (for pipes up to 15 cm). To do this, grasp the tube by the jaws of the tool and view on a double scale, how many cm is the diameter.
3
In order to know the internal diameter, measure the wall thickness on the cut pipe. Measure with a ruler or caliper (the second method, of course, more precisely). Subtract from the outside diameterand wall thickness, multiplied by two the resulting number is the internal diameter.
4
Often notations are made of tubes in inches. If you have measured in inches, try to translate them into inches. To do this, multiply the diameter at 0,398 and you will get the size in inches. On the contrary, you can bring the diameter in inches to centimeters, just multiply it by 2.54.
5
When choosing a towel warmer or other works for which you need to know the diameter of a standard plumbing pipeheld in your home, use the following simple way. Attach a line to the pipe and estimate its approximate diameter. If the eye is seen, that the tube has a width of about 32 cm – safely make the conclusion that the landing diameter of its 1 inch. Size 25-28 cm corresponds to a standard pipe of ¾ inch and the value in the 16 mm – 1.2 inches.
Note
In the designation of a tubular metal such as pipes for steel construction or stainless steel tube used outer diameter, and wall thickness. For example, the entry looks like the following: 530x12. For water-gas supply pipes are of great importance inside diameter, so they are referred to, for example, 15x2 (at first glance, exactly the same). To determine which pipe in front of you, look at GOST. Water-gas supply pipes (VGP)is made according to GOST 3262.
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