7.2　Tuyeres Device

7.2.1　Tuyere large sleeve，tuyere middle sleeve and tuyere small sleeve may be lifted in place by an electric hoist below the hot blast ring pipe and accompanied by the chained crane.The tuyere middle sleeve and tuyere small sleeve may be lifted by a counterweight balance method.

7.2.2　For the large sleeve，middle sleeve and small sleeve attached with the water cooling device，the pressure test before installation shall meet the requirements of the design document.When there is no requirement in the design document，the test pressure shall be 1.25 times of the working pressure，the pressure shall be stabilized for 10min，the test pressure shall be reduced to the working pressure，and the pressure shall stop for 30min.In this way，the test pressure is qualified in case no pressure drop and no leakage occur.After completing installation，the water test shall be taken at the working pressure.The inlet and outlet water shall be smooth.The joint shall be free of leakage.

7.2.3　The conical surfaces matched with the tuyere shall be cleaned up and be free of burrs before installation.After two suits of fixed devices of the tuyere are supported tightly，the gap between the flanges shall meet the requirements of the design document.When there is no requirement in the design document，the gap should not be less than 10mm.The tightly-closing face between the large sleeve and the middle sleeve shall be checked by the 0.10mm feeler gauge，and the filling depth shall not be larger than 1/3 of the contact length.

7.2.4　There shall be no gap of larger than 0.05mm between the tightly-closing faces of the spherical surface joint of the tuyere device.The spherical surface at the front end of a belly pipe shall be free of damage to trenches.

7.2.5　The sealing of the filling（padding）between the joint surfaces of various flanges of the tuyere device shall meet the requirements of the design document.The contact shall be tight.The flange joint shall meet the requirements of Item 5 of Article 6.11.1.

7.2.6　The stub pipe with flange below the hot blast ring pipe of the blast furnace may be positioned by the set up in turn of the tuyere device and blast branch pipe.The blast furnace with capacity of above 4000m3should be positioned by a special tool.The measures of preventing welding deformation shall be taken for the welding of the stub pipe，and the welding quality shall meet the requirements of the design document.When there is no requirement in the design document，the requirements of the current national standard GB 50236 Code for Construction of Field Equipment，Industrial Pipe Welding Engineering related to Class IV of quality grading standard of welding seam shall be met.

7.2.7　When the stub pipe with the flange below the hot blast ring pipe of the blast furnace is positioned by the set up in turn of the tuyere device and the blast branch pipe，the belly pipe and the elbow shall be installed in sequence after installing the tuyere device，and the allowable deviation of installation of elbow shall meet the following requirements:

1　The levelness of the flange face of the elbow shall be checked by leveling instrument，with the allowable deviation of 0.50mm.

2　The horizontal distance from the flange face of the elbow to the center of the tuyere shall be checked by steel ruler through drawing wire，with the allowable deviation of±5.0mm.

3　The distance from the perpendicular line of the center of the flange face of the elbow to the large head end of the middle sleeve shall be checked by steel ruler through hanging the pendant，with the allowable deviation of±5.0mm.

4　The perpendicular line of the center of the flange face of the elbow shall be intersected with the horizontal line of the center of the tuyere，shall be checked by steel ruler through drawing the wire and hanging the pendant，with the allowable deviation of 5.0mm.