Prism Ball Back-Point Location
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Back Point Measurement
Establishing pipe orientation and centerline vectors using direct prism observations in automet® FAB.
Overview
The back point establishes the trajectory and orientation of the attached pipe run relative to the measured flange face plane.
Unlike diameter points or stop points, the back point is measured using the standard 44 mm prism ball directly on the pipe surface without any survey adapter device (such as a type 7 device).
Direct prism ball placement for back point observation on pipe body
Measurement Guidelines
- Hardware setup: Place the prism ball directly against the outer pipe wall along the pipe centerline. Do not attach the type 7 device.
- Placement location: Position the observation anywhere along the pipe run heading away from the flange face.
- Data purpose: automet® FAB uses the back point vector in conjunction with the diameter points to calculate spatial alignment and determine elbow/fitting offsets during analysis.