Radius of carbon steel welding elbows. What about it?

There is much confusion about the radius of carbon steel welding elbows. With the (old) type designations such as 3S, 1.5D and 5D, the impression is given that this can be used to calculate the radius. This is not the case.

The radius (R) of the various types of welding elbows according to EN10253-2 (formerly DIN2605) is given up to the center of the diameter. The radius can be determined or checked by subtracting half the diameter from the total height (W, Z or B).

Rather not do the math yourself? Then look here for a table with the different sizes for elbows in 2D (small radius), 3D (standard radius) and 5D (large radius).