84 BULLETIN 1216, U. S. DEPARTMENT OF AGRICULTURE. 
4. The amount of galvanizing or spelter coating wll be deter- 
mined in accordance with the methods for testing the amount 
of spelter coating on culvert metal, page 81. 
TEST AND INSPECTION OF CAST-IRON CULVERT PIPE. 
1. All cast-iron culvert pipe shall be made of cast iron of the 
quality specified and of such character as shall make the metal 
of the castings strong, tough, and of even grain. The size and 
weight of the pipe shall be as specified. 
PHYSICAL PROPERTIES AND TESTS. 
Test 2. The transverse test specimens (arbitration test bars) speci- 
specimens. fied in section 4 shall be placed horizontally upon supports 12 
inches apart and tested under a centrally applied load. The 
average load and deflection shall not be less than that specified. 
3. The form and dimensions of the mold for the arbitration 
test bar shall be in accordance with Figure 13. The bottom of 
the bar shall be one-sixteenth inch smaller in diameter than the 
top to allow for draft and for the strain of pouring. The pat- 
tern shall not be rapped before withdrawing. The flash shall 
be rammed up with green molding sand, a little damper than 
usual, well mixed, and put through a No. 8 sieve, with a mix- 
ture of 1 to 12 bituminous facing. The mold shall be rammed 
evenly and fairly hard, thoroughly dried, and not cast until it is 
cold. The test bar shall not be removed from the mold until cold 
enough to be handled. It shall not be rumbled or otherwise 
treated, being simply brushed off before testing. 
4. From each melt of metal not less than three test specimens 
(arbitration test bars) shall be poured, the first of which shall 
be poured within five minutes after the first ladle is tapped and 
the remainder at intervals not exceeding one hour throughout 
the melt. 
5. The manufacturer shall afford the inspector representing 
the purchaser, free of cost, all reasonable facilities to satisfy 
him that the castings are being furnished in accordance with 
the specifications. All tests and inspections shall be so con- 
ducted as not to interfere unnecessarily with the operation 
of the work, and shall be made prior to shipment unless other- 
wise specified. 
METHODS OF SAMPLING AND TESTING METALLIC 
MATERIALS. 
(A. S. T. M. standard method, serial designation E 1-18.) 
I. METHODS FOR TENSION TESTS OF METALS. 
Definition of Terms. 
1. Elastic limit is the greatest load per unit of original cross 
section which does not produce a permanent set. 
Note. — This determination is rarely made in the commercial test- 
ing of materials. 
Proportional Umit is the load per unit of original cross section 
at which the deformations cease to be directly proportional to the 
loads. 
Note. — This determination is rarely made in the commercial test- 
ing of materials. 
Yield point is the load per unit of original cross section at 
which a marked increase in the deformation of the specimen oc- 
curs without increase of load. It is usually determined by the 
drop of the beam of the testing machine or by the use of dividers. 
