We have had the occasional lower radiant furnace tube move off of its J-Hook support, which we believe is linked to uneven thermal growth of the tube during on-line spalling in combination with end-tube support restrictions (not able to freely slide through circular tube support hole into header box). The dropped or drooped tube often remains in service until a planned shutdown, though we have done on-line support installation in some cases to avoid shutdown. Does anyone use a bar or other device to supplement the basic J-hook to reduce the frequency of such events?
