7.4　Gas Sampling Device

7.4.1　The pressure test of the sampling pipe，the seal box and the cooler shall meet the requirements of the design document.The requirements of Appendix D of this standard shall be met when there is no requirement in the design document.

7.4.2　Before installing the gas sampling device，the installation precision of the flange and base of the blast furnace shell shall be rechecked and meet the requirements of Article 6.5.18 of this standard.

7.4.3　The allowable deviation of installation of trolley track of the sampling pipe of the gas sampling device shall meet the following requirements:

1　The center line of the installed flange stub pipe relative to the longitudinal center line shall be checked by steel ruler through drawing the wire and hanging the pendant，with the allowable deviation of 2.0mm.

2　The distance from the track surface to the center of the installed flange surface shall be checked by steel ruler，with the allowable deviation of±2.0mm.

3　The levelness of the track surface shall be checked by levelling ruler and leveling instrument or level gauge，with the allowable deviation of 1.0/1500mm.The height difference of the track surface within the full length range shall be checked by level gauge，with the allowable deviation of 5.0mm.

4　The height difference between two track surfaces in the same cross section shall be checked by level gauge，with the allowable variation of 2.0mm.

7.4.4　When the sampling pipe contacts with the support in the flange，the gap between the guide roller and the sampling pipe shall meet the requirements of the design document.When there is requirements in the design document，the feeler gauge shall be used for checked，and the gap should be 1.5mm-2.5mm.

7.4.5　After baking the blast furnace，the height of the vertical column of the braced frame of the trolley track of the sampling pipe shall be adjusted.