166 STEAM BOILERS 



As soon as the water has been removed, the manhole covers, 

 handhole covers, and washout plugs should be taken out and 

 all loose mud and scale washed out with a hose. If the boiler 

 is externally fired, the tubes must be swept and the furnace, 

 the ash-pit, the smokebox, and the space back of the bridge 

 wall must be cleaned out. Any removable insulating cover- 

 ing that prevents the inspector from having free access to the 

 exterior of the boiler, must be removed to the extent deemed 

 necessary by him; it may even be necessary to take down some 

 of the bricks of the setting. 



Inspection of Externally Fired Boilers. In the inspection 

 of an externally fired fire-tube or flue boiler, the exterior is first 

 examined. The seams are gone over inch by inch; the rivet 

 heads and calking edges of the plates are carefully scrutinized 

 for evidence of leaks; and possible cracks are looked for between 

 the rivet heads, especially in the girth seams and on the under 

 side of the boiler. The plates must also be examined for cor- 

 rosion, bulges, blisters, and cracks. The heads are inspected 

 for cracks between the tubes or flues, cracks in the flanges, 

 leaky tubes, and leaks in the seams. The condition of the fire- 

 brick lining of the furnace and bridge and the top of the rear 

 combustion chamber is noted while making the exterior exami- 

 nation of the under side of the boiler. Every defect that is found 

 should be clearly marked. Attention must also be paid to the 

 condition of the grate bars and their supports. 



Inspection of Internally Fired Boilers. The inspection of 

 the shell and heads must be followed by examination of the fire- 

 box or furnace tubes or flues, and of the combustion chambers 

 if these are fitted inside the boiler. In fireboxes, special atten- 

 tion must be paid to the crown sheet. The ends of the stay- 

 bolts require close examination; if such ends are provided with 

 nuts, these must be examined, as they are liable to loosen and 

 are also liable to be burned off in time. Each stay bolt should 

 be tested for breakage, which is done by holding a sledge against 

 the outside end of the staybolt and striking the inner, or fire- 

 box, end with a light hammer; in making this test on the boilers 

 of locomotives it is customary, when practical, to subject the 

 boiler to an internal air pressure of from 40 to 50 Ib. per sq. in. 

 The internal pressure, by bulging the sheets, separates the ends 



