How to measure the diameter of a pipe: methods

Installation and troubleshooting of the water supply system can only be carried out when the pipe parameters are known. It happens that it is difficult to get to them, but you need to perform a measurement. How to measure the diameter of the pipe in this case? Various instruments are used for this purpose: calipers, roulette, ruler, laser sensors, etc. It is not so difficult to use them, but measurements should be carried out correctly.

Outer and inner diameter

Most often this design parameter is measured in inches, which are easily converted into centimeters (the value is multiplied by 2.54). First of all, it is necessary to decide what to measure: the inner diameter of the pipe or the outside. Products used for water and gas supply are usually measured by the internal diameter. This is due to the fact that this indicator determines the throughput of the structure.

The outer diameter can have different values depending on the wall thickness (the mechanical strength of the whole product depends on it). According to GOST 355-52, each next pipe diameter differs from the previous one by better capacity (by 50%). The structural permeability is often called the nominal diameter. In this case, the indicator is usually different from the internal diameter (by 1-10 mm). This important parameter is considered the main characteristic of the product, which is repelled during design and installation.

We measure with a caliper

With the help of this high-precision tool, the parameters of various designs are measured. How to measure the diameter of the pipe with a caliper? To do this, it is necessary to dilute its sponges, insert the product into them and bring them together so that they are pressed against the surface. Sponges when closing should be parallel to the plane of the section of the pipe, otherwise the measurement will be incorrect. The inner diameter is also measured by a caliper. On the back of it there are sponges, which are placed inside the structure and are bred to abutment against the walls.

Sometimes it is required to measure the diameter of a mounted pipe, which is too large. In this case, you can measure the tool with a chord and calculate the diameter in a mathematical way. We spread his sponge to the maximum distance and apply it to the pipe. The resulting indicator is the length of the chord. For calculation, you will also need to measure the height of the device's jaws. Diameter is calculated by the formula:

D = (2L / 4H) + H.

If the sponges are too long, then you can put some detail (bar, etc.). Then the height will be calculated by the formula:

H = H1-H2.

We measure the ruler and the tape measure

If the cross section is visible on the pipe, the diameter can be measured with a conventional ruler. Apply it to the cutoff area so that the scale passes exactly in the center. Take the distance between the desired points (for inner or outer diameter). The distance between the extremities is the outside diameter. If you need an internal size, you can learn the thickness of the walls and subtract them from the resulting figure.

With a ruler, everything is clear, but how to measure the diameter of a pipe with a tape measure? This tool is suitable for solid and large structures, which are difficult to get. We wrap the product so that the ribbon with the scale fits snugly, and we find the place of its intersection. The resulting digit is the length of the circle. To obtain a diameter, divide it by the number Pi (3,14).

Copying method

If there are no tools at hand, but there is a camera, then you can use the copy method. How to measure the diameter of a pipe? For this:
- We take an object with known dimensions (for example, brick);

- we lay it on the pipe, along its length or next to the cut;
- We photograph this area so that it is possible to estimate the difference in size;
- we carry out calculations on a photo;
- Based on the received data, we estimate the actual dimensions (it is important to take into account the scale).

Measured with a micrometer

Precision measurements (up to 0.01) of the pipe can be done with a micrometer. It should be noted that it is convenient for them to measure small items. The tool is a bracket equipped with a support heel and a stem with high-precision thread (for screwing in the micro-screw). On the stem you can see a scale with millimeters and their hundredths. Such equipment allows obtaining more accurate indicators.

How to measure the pipe diameter with a micrometer? We place the construction between the end of the screw and the heel. Begin to rotate the handle of the ratchet until it snaps three times. First look at the lower stem scale, showing the number of whole millimeters. We check the existence of risks, which is on the right. If it is not visible, we take readings from the drum. If there is a risk, add 0.5 mm to the resulting number. Measurements on the drum are determined relative to the line on the stalk between the scales.

Laser sensors

To remove the dimensions from the pipes (and not only), modern laser sensors have been created. Their advantages: lack of contact with the surface, the possibility of use on different designs (hot, sticky), durability and speed of obtaining results. How to measure the diameter of a pipe with such sensors? There are several methods of measurement.

With laser triangulation, the beam from the sensor creates a spot on the surface of the structure. Behind the laser is a camera scanner that sees it from different angles. With these indicators, the digital processor calculates the distance between the sensor and the product.

We measure the diameter by shading. In this case, the sensor serves as an emitter and receiver, but they are located in different housings. Inside it, the laser beam reflects off the rotating mirror, bends around the measurement area and creates a virtual light strip. Inside the device, the moving beam passes through a special diode, which measures the duration of the shading (corresponds to the size of the object).

Another option is the principle of the light section. The sensor is equipped with a laser, a camera and an electronic circuit. The laser creates a line perpendicular to the product, and the camera is located at a certain angle to it. With any distortion, the laser line is deformed, which is why the sensors are repelled when calculating the dimensions.

The above was told how to measure the diameter of a pipe. But it is important to know that some designs have curvature (maximum 1.5 mm per 1 m of length). In this case, they speak of their ovality. This parameter is determined by the formula: the difference between the large and small diameters is divided by the nominal. Admissible ovality: no more than 1% for pipes with a wall up to 20 mm, not more than 0.8% - with a wall more than 20 mm. This parameter is very important, since it affects the performance characteristics of the structure.