STEAM BOILERS 167 



of a broken staybolt, which renders it comparatively easy to 

 find them by the hammer test. 



Inspection of New Boilers. As made in boiler shops, the 

 external inspection of new boilers, whether fhey are internally 

 or externally fired, and whether they are of the water-tube or 

 the fire-tube type, usually consists of a thorough examination 

 for visible defects and testing under water pressure to locate 

 leaks, if any. If a new boiler subject to official inspection during 

 construction successfully passes such a hydrostatic test as the 

 regulations prescribe, it will usually be permitted the working 

 pressure it was designed for, the design having been approved 

 officially before construction. The working pressure will be 

 reduced, however, if the inspection discloses poor workmanship. 



In the external inspection of water-tube boilers that have 

 been in use, the tubes that are exposed directly to the heat of 

 the fire must be particularly well examined for evidence of 

 overheating. The plugs or handholes placed in headers to 

 permit the insertion of the tubes and the cleaning of them are 

 inspected for leakage, and the headers are inspected for cracks. 

 Steam drums and mud-drums should be examined as carefully 

 and for the same defects as the shells of externally fired fire- 

 tube boilers. The firebrick lining of the furnace, and the 

 interior of the brick setting in general, as well as the baffle 

 plates controlling the direction of flow of the gases of combus- 

 tion, must be examined for cracks and any other defects. The 

 external inspection of the setting can usually be made very 

 rapidly, as everything is in plain sight. 



INTERNAL INSPECTION 



Preparation. Before the internal inspection is begun all 

 loose mud should be washed out with a hose. In a horizontal 

 return-tubular boiler and flue boiler, the shell plates and heads 

 should be examined for corrosion and pitting; if the boiler has 

 longitudinal lap seams, these should be inspected at the inside 

 calking edge for incipient grooving and cracks. All seams 

 should be examined for cracks between the rivet holes. Ob- 

 viously, if the boiler is scaled to an appreciable degree, the 

 scale must be removed before inspection. The tubes or flues 

 should be examined for pitting, as well as for uniform corrosion. 



