Where should wall thickness on deadlegs be monitored by the inspector?

Where should wall thickness on deadlegs be monitored by the inspector?

• A. Only the stagnant end
• B. Only the connection to the active line
• C. Both the stagnant end and the connection to an active line
• D. Neither

Answer: (C)

Deadlegs create zones where flow is minimal, so corrosion can develop differently than in active runs. The stagnant end is prone to deposition, chemistry changes, and corrosion under deposits, while the connection to the active line experiences different flow dynamics that can drive erosion or accelerated thinning at the weld and near the attachment. Monitoring both locations gives a complete view of wall thinning, catching problems that might only appear at one end. Therefore, the inspector should measure wall thickness at both the stagnant end and the connection to the active line.

Deadlegs create zones where flow is minimal, so corrosion can develop differently than in active runs. The stagnant end is prone to deposition, chemistry changes, and corrosion under deposits, while the connection to the active line experiences different flow dynamics that can drive erosion or accelerated thinning at the weld and near the attachment. Monitoring both locations gives a complete view of wall thinning, catching problems that might only appear at one end. Therefore, the inspector should measure wall thickness at both the stagnant end and the connection to the active line.