What formula is used for calculating the face to center measurement for long radius 90 degree elbows?

What formula is used for calculating the face to center measurement for long radius 90 degree elbows?

• A. NPS x 1.5
• B. NPS x 1.0
• C. 2 x NPS
• D. NPS Plus 0.5

Answer: (A)

For long radius elbows, the distance from the end face to the elbow’s centerline is determined by the centerline radius. Standard piping practice sets the centerline radius of a long radius elbow at 1.5 times the nominal pipe size (NPS). So the face-to-center measurement equals NPS multiplied by 1.5. This reflects the elbow’s gentler bend compared to a short radius, where the centerline radius would be 1.0 × NPS, and aligns with common fabrication and layout dimensions. For example, a 4-inch NPS elbow has a centerline radius of 6 inches, making the face-to-center measurement 6 inches.

For long radius elbows, the distance from the end face to the elbow’s centerline is determined by the centerline radius. Standard piping practice sets the centerline radius of a long radius elbow at 1.5 times the nominal pipe size (NPS). So the face-to-center measurement equals NPS multiplied by 1.5. This reflects the elbow’s gentler bend compared to a short radius, where the centerline radius would be 1.0 × NPS, and aligns with common fabrication and layout dimensions. For example, a 4-inch NPS elbow has a centerline radius of 6 inches, making the face-to-center measurement 6 inches.