Inspecting Used Drum Dryers
The following information is suggested as a guideline for inspecting used double drum dryers
One Set (2) Dryer Drums
a. The drum must pass a hydrostatic pressure test of 1.5 times the rated pressure for 1 hour.
b. Drums must have a wall thickness which will permit the reconditioning of the drum surfaces and pass a Hartford Boiler re-certification pressure rating test. The drum diameters must not be less than a 1/2 inch under the original drum diameters.
c. The faces of the drums must not be damaged or have indentations more than .015 inches deep.
d. The shoulders of the drum faces must not be damaged or worn in excess of 1/32 of an inch.
e. The bearing shafts must not be damaged. For shafts with roller bearings, the shafts must measure to a tolerance of + .000 – .006 inches of the bearing diameter. For shafts with sleeve bearings, the shafts should measure no more than .012 inches below the bearing diameter.
f. Threaded holes in the shafts and drums for mounting covers, steam joints, caps, etc., should not be stripped or worn.
g. Key-ways in the shafts for drive gears or sprockets should not be worn.
h. Documents on the registration of the drums, as well as National Board of Boilers and Pressure Vessel Inspectors numbers should be available.