Method for repairing housing of hot blast heater in late service period

The invention relates to a method for repairing a housing of a hot blast heater in late service period. The method includes steps of I, restoring a housing crack: welding two supports on two outer sides of the crack respectively, adopting two jacks to transversely support between the supports and parts and to jack the cracking crack back from two sides; II, welding the crack: adopting an angle grinder to clean a breach and a crevasse with an angle, bottoming an Austentic 002 stainless steel electrode in the crack and welding into a joint by a common welding electrode; III, reinforcing the housing: arranging an annular belt at the housing crack and hooping the housing; IV, drilling a manhole and scooping residual brick: drilling a circular manhole not smaller than DN600mm in a burned position of the housing and scooping the burned residual brick; V, casting a formwork: blowing the manhole by a compressed air pipe, and fastening a circular steel plate at a hole of the housing and casting; VI, roasting cast mate