Carbon steel tube ovality standard

1. Definition of ellipticity

The ovality of carbon steel tubes refers to the degree of deviation between the major axis and the minor axis of the steel pipe section. Generally speaking, the smaller the ovality, the closer the shape of the steel pipe is to a circle. Ovality is an important indicator of the dimensional accuracy of steel pipes, and is also one of the important standards for measuring the production process level of carbon steel tubes.

2. Calculation method of ellipticity

Ovality, also known as out-of-roundness, refers to the difference between the maximum and minimum diameters of rolled materials with circular cross-sections, such as round steel and circular steel tubes.

The ovality measurement method of steel pipes basically belongs to the diameter method. Any method of measuring diameter can be used to measure ovality. That is, after measuring the maximum and minimum diameters respectively, the difference is found, which is the value of ovality. Calculation formula for steel pipe ovality: ovality = (difference between the maximum outer diameter of the steel pipe - the minimum outer diameter of the steel pipe)/nominal outer diameter

There are generally two methods for calculating the ovality of carbon steel tubes, namely calculating ovality and calculating roundness deviation. Among them, the method for calculating ovality is the difference between the long axis and the short axis of the steel pipe divided by the average of the inner diameter or outer diameter of the steel pipe, that is, Δ=(D_max-D_min)/(D_max+D_min)×100%. The method for calculating roundness deviation is the ratio of the difference between the maximum circumference and the minimum circumference of the steel pipe to the circumference of the steel pipe, that is, Δ=(L_max-L_min)/L×100%.

3. Standard value of ovality

The standard value of carbon steel tube ovality varies from different countries and standards. Common international standards include GB/T 17395, ASTM A500, ASTM A53, ASTM A513, EN10210, etc. Taking GB/T 17395 as an example, it stipulates that the ovality standard of steel pipes with DN<150mm is 1% or 0.8%, and the ovality standard of steel pipes with DN≥150mm is 0.7% or 0.5%. According to the ASTM A500 standard, the ovality of steel pipes should be less than or equal to 1% of the nominal diameter (OD).

Summarize:
The ovality of steel tubes is one of the important indicators indicating the dimensional accuracy and production technology level of steel pipes. There are two methods for calculating ellipticity, namely calculating ellipticity and calculating roundness deviation. The ovality standards of carbon steel tubes vary from different countries and standards. You can refer to relevant standards and specifications for judgment.