How to correctly measure square tube size?

How to correctly measure square tube size?

A) Measurement method

There are two methods for measuring the size of square tubes: outer diameter measurement and wall thickness measurement.

1. Outer diameter measurement
Use a caliper or compass to measure the outer diameter of the square tube. It should be fixed at a certain position for measurement. For example, the square tube can be clamped in a clamp to ensure the accuracy of the measurement results. The unit of outer diameter measurement is usually millimeters or inches. Measurement should be carried out strictly in accordance with the standards to avoid errors.

2. Wall thickness measurement

Wall thickness measurement is usually measured using a thickness gauge. The thickness gauge needle is placed on both sides of the square tube to measure the thickness, usually in millimeters or inches.

B) Standard size
The standard size of square pipe is usually called the specification, which represents the outer diameter size, wall thickness size and length of the square pipe. Square tube specifications are usually expressed as "outer diameter × wall thickness × length", such as 40 × 40 × 2.5mm × 6m.
Square tubes of different sizes are suitable for different occasions. Choosing appropriate specifications can greatly improve the use effect and life of the square tube.

C) Square tube size measuring tool
1. Use calipers to measure
The commonly used tool for measuring square tubes is calipers. First, you need to open the caliper, place the square tube on the scale between the calipers, and then read the value of the caliper to get the diameter of the square tube. It should be noted that when measuring, you need to ensure that the angle between the caliper and the square tube is 90 degrees, otherwise it may cause measurement errors.

2. Use a protractor to measure
Another method is to use a protractor to take measurements. First, you need to place the protractor at the end of the square tube, turn the pointer to a position tangent to the square tube, and then read the scale of the protractor to get the diameter of the square tube. This method can be more accurate when measuring irregularly shaped square tubes, but care needs to be taken to ensure the stability and accuracy of the instrument.

D) Precautions
When measuring the size of square tubes, you need to pay attention to the following points:
1. Before measuring, the measuring tool needs to be calibrated to ensure the accuracy of the measurement results.
2. When measuring the outer diameter of a square tube, the surface of the square tube needs to be cleaned to prevent dirt and oxide layers from affecting the measurement results.
3. When measuring the wall thickness, it is necessary to measure once on both sides of the square tube and take the average value as the wall thickness measurement result to avoid the uneven wall thickness of the square tube affecting the measurement results.
4. When purchasing square tubes, you need to select appropriate specifications based on actual usage scenarios and requirements, and choose square tubes with good quality, accurate dimensions, and smooth surfaces to ensure usage effects and service life.

In short, correctly measuring the size of square tubes is the prerequisite for using square tubes. Only by selecting square tubes with appropriate specifications and good quality can the effectiveness and lifespan of the square tubes be improved during use.

ASTM A500 — Carbon steel cold-formed round and special-shaped cross-section welded square tubes and seamless square tubes for structural use