Internal Headers Inspection
Inspect the inside surface of return headers, junction boxes, inlet and outlet headers, pipe headers, flanges, fittings and valves, for cracks, corrosion, erosion, or mechanical damage from tube cleaning. If seal welds are used,
check for cracks.
Inspect the plug seat for cracks and mechanical damage from cleaning or arc strikes if welding has been done through the plug hole. Inspect arc weld deposit lined headers for cracks in the lining and corrosion which usually takes the form of deep pits. To make a satisfactory inspection, lined headers must be cleaned by sandblasting or by burning out any coke deposit. Check the condition of holding member bearing surfaces on breech lock headers.
Inspect flanges, fittings, and valves for corrosion and cracks. Check flange faces for dishing and tongue-and-groove or ring-type joints for corrosion and mechanical damage. Check pyrometer wells for corrosion and erosion and pressure connections for cracks in welds and corrosion. In lined fittings, flanges, and valves, inspect deposited lining for pitting and sheet lining for bulging and cracks at the welds.
When corrosion is evident in headers and fittings, take gage measurement at points of maximum metal loss. Pipe headers may be ultrasonically gaged and other headers and fittings measured by calipers through plug holes or over flanges.