92. All materials should be inspected when received and before accepting them.

Black sheet iron should be examined for flaws or holes on its surface, for equality of thickness, and as to its liability to crack if bent sharply either with or across the grain.

93. Galvanized sheet iron should be examined for the same defects as black sheet iron. The zinc coating may be tested by bending the iron at a temperature of about 60° or 70° F. If the zinc adheres properly to the iron, it will not scale or peel off.

94. Sheet copper, sheet lead, and sheet zinc are generally accepted as they are placed upon the market.

95. Lead pipe should be soft and pliable. Examine for kinks, bruises, and punctures, caused by rough handling during shipment. In other respects, it is usually placed on the market in good condition and requires no further inspection.

96. Tin-lined lead pipe should have its interior surface examined, if possible, to see if it is tin lined. Shave off the end of the pipe square and clean, and ascertain the thickness of the tin lining by breathing on the highly polished end. The breath will discolor the surface of the lead with a thin blue coating, and the tin will remain bright. The thickness of the tin lining will thus become visible.

97. Block-tin pipe, like lead pipe, is generally accepted as reliable in the form placed upon the market. Pure block tin may be detected by a peculiar crackling noise it makes when being bent at ordinary temperatures.

98. Seamless brass tubing should have an equal thickness all around, and should be slightly annealed to prevent its being too brittle for working.

99. In brazed brass and copper tubing, the brazed seam should be examined carefully. It should be uniformly loaded with hard solder and thoroughly sweated. If possible, examine both the inside and outside of the seam. The best and strongest form of brazed seam is dovetailed. Lap or butt brazed seams are liable to warp in the process of brazing, and are not very strong.

100. Galvanized-iron pipe placed upon the market is usually accepted as good. Sometimes, however, it is partly choked by the zinc, used to galvanize it, clogging in lumps. This may be detected by rolling a marble a size smaller than the pipe through its entire length, or, if possible, by looking through it. The quality of the galvanizing may be observed by bending the pipe at an ordinary temperature, to an easy bend. If the galvanizing is good, it will remain intact. Galvanized-iron pipes are liable to be quite brittle, but this brittleness does not seem to affect the durability of the pipe. The ductility of galvanized-iron pipes is less than that of black iron, and sometimes is so low that if the pipe is bent successfully, it cannot be bent back without breaking.

101. In wrought-iron pipe (black) the welded seam which runs the whole length of the pipe should be examined. A good welded seam is scarcely visible, and the pipe should have a smooth external and internal surface. The pipes should be straight and the threads should be cut clean.

102. Cast-iron drain and soil pipes should be examined for sand holes in the metal or splits in the pipe. A fracture can be detected by tapping the pipe with a chisel or small hammer. If the pipe is sound, it will ring clearly when struck, and if cracked, it will give a dull, harsh sound.

Sometimes the core will shift when a pipe is being cast, particularly if the pipe is cast horizontally, in which case the core is liable to rise. This will cause the metal to be thicker at the bottom than at the top of the pipe. Irregularities in thickness can be detected by irregularities of the sound when rapped with a hammer at various points.

103. Earthen drain pipes are liable to warp and twist in firing. They should be examined for an equal caliber, smooth, glazed internal and external surface, and particularly for cracks around the back of the socket and irregularities within the socket. Pipes having broken or crooked sockets should be rejected.

104. Fittings for wrought-iron and brass pipe should be inspected for sand holes and flaws, and it should be seen that the screw threads are deep and full. All screwed fittings should be reinforced with a heavy bead cast on the edge.

105. Fittings for cast-iron drain pipes should be examined for sand holes, splits, and other flaws, and for lumps and other obstructions to the free flow of sewage through them.

106. Fittings for earthen pipe should be examined for irregularities in cross-section, or caliber, cracks, protruding pieces of salt glaze, abrupt turns, etc. The sockets should be examined to see that they are round and of proper depth.