overhauling of boiler non-pressure parts (air pre heater and flue/air ducts), unit 4- 1 overhauling of boiler non-pressure parts 2 replacement of aph tubes 3 cleaning of tube chokage for aph 4 ferruling of aph 5 erection of new expansion bellow for aph 6 fabrication, removal & refitting ofguard plates on expansion bellow for aph 7 fitting of liner plates on beams at top & intermediate aph tube bank. 8 blanking of tubes for aph 9 checking & repairing of air / flue ducts esp dampers & aph hoppers. 10 erection of air / flue duct expansion bellow at esp i/l & o/l. 11 replacement of cloth type expansion bellow at esp i/l & o/l. 12 fabrication & erection of guard plate for expansion bellow of air ducts/flue ducts. 13 old expanding failure aph tubere-expanding / welding. 14 hiring of escort crane with operator & & fuel. 15 cleaning of tubes for aph by lp water jet. 16 replacement of damage support beam along with top bearing plate of air / flue duct. 17 replacement of damage support beam partly along with top bearing plate of air / flue duct. 18 checking, servicing or renewal of roller bearing of air / flue duct. 19 removing & re-application of insulation work for boiler casing & air/flue duct.