The Hawle screw-type surface box for gate valves is to be used for installation in bituminous traffic areas. Height adjustment is achieved through the male thread permitting a continuous adjustment to road level.
When installing the bituminous base course a "meshing" is created with the coarse male thread of the box. Via this meshing the traffic load is discharged into the base course. This bond ensures that the surface box remains on the same level as the road surface. By heating the surface box the height position can be adjusted upward and downward using a special turning tool (model no. 597). Compared to conventional surface boxes the angle seat at the cover and the box provides for reduced rattling of the cover.
To avoid contact corrosion between the cover and the box, on the one hand, and to ensure that the cover comes loose easily, on the other hand, the latter is powder-coated.