Fired Heater Inspection - Sagging and Bowing of tubes

[GL431]

This question pertains to the inspection of in-service fired heaters.

Is bowing of tubes the same as sagging? API 573 mentions both terms, but mentions details only on sagging.

The heater tubes we are looking at now are the vertical radiant tubes in a vertical cylindrical crude oil heater. They are "bowed" away from the wall towards the centre of the heater.

Do the same criteria as for "sag" apply? i.e. acceptance criterion 5 tube diameters? Just from the word, "sag" would describe "hanging through" of a horizontal tube. But I could be wrong. Does it also apply to vertical tubes?

Thanks for your help in advance

 

[metengr]

Yes, bowing and sgaging can be considered one in the same because they pertain to out of plane distortion (vertical or horizontal orientation).

 

[GL431]

Thanks metengr