What is the radius measurement of an 8" welded long radius 45 degree elbow?

The radius measurement of an 8" welded long radius 45 degree elbow is indeed 12 inches. To understand why this is the case, it's important to recognize that the terminology "long radius" refers to elbows that have a centerline radius that is typically 1.5 times the nominal pipe size.

In this case, since the nominal size of the elbow is 8 inches, you would calculate the radius by multiplying that size by 1.5. Thus, the calculation would be:

8 inches (nominal size) × 1.5 = 12 inches (radius measurement).

This measurement is significant in piping systems as it influences the flow characteristics and pressure drop across fittings. Knowing the radius is essential for proper layout and design in piping systems to ensure efficient flow and to meet the required specifications for installations.