MIL-DTL-15606J
4.5.5.3 Burner tile. Abutting tile faces shall be inspected for non-parallelism greater than ⅛ inch (see figure 1).
A straight edge laid along the longest dimension on the working face of the tile shall not reveal warpage greater than
⅛ inch (see 3.5.3 and refer to ASTM C134 test method for Procedure and Apparatus for measuring warpage of
refractory brick). Warpage greater than ⅛ inch shall be cause for rejection of the lot.
4.6 Tests.
4.6.1 Chemical analysis. Alumina content of 57.5 percent for Grade A brick or tile shall be determined for two
bricks or tiles in accordance with ISO 12677 or ISO 21587 (see 3.8.1). If both bricks or tiles fail, the lot shall be
rejected without retest. If either fails, three additional bricks or tiles shall be tested. If any one of the three retest
bricks or tiles fails, this shall be cause for rejection of the lot.
4.6.1.1 Chemical certification. Certification of chemical analysis may be presented in lieu of chemical analysis
for those lots presented within 3 years of the previous acceptable analysis.
4.6.2 Pyrometric cone equivalent (grade A or B). Two test cones shall be made from two Grade A or Grade B
bricks or two tiles and tested in accordance with ASTM C24. If both cones fail, the lot shall be rejected without
retest. If either fails, three additional cones shall be made and tested, one from each of the additional bricks. If any
one of the three retest cones fails, this shall be cause for rejection of the lot (see 3.8.2 or 3.9.1).
4.6.3 Permanent volume change (grades A and B only). Three test bricks measured to the nearest 0.01 inch
shall be placed in a gas-fired furnace and the temperature gradually raised to 2910±10 °F. This temperature shall be
maintained for 5 hours, after which the furnace shall be allowed to cool to room temperature. The bricks shall be
again measured and the change computed. Grade A brick shall be given three cycles of this heat treatment and
Grade B one cycle. If three samples are not in accordance with 3.8.3 or 3.9.2, as applicable, a retest shall be made
on six additional bricks of the sample. Unless otherwise specified (see 6.2), if any sample fails to conform to this
specification, this shall be cause for rejection of the lot.
4.6.4 Modulus of rupture. Modulus of rupture shall be determined on five sample bricks in accordance with
ASTM C133. If these samples are less than specified in 3.7.1, 3.8.4, or 3.9.3, as applicable, a retest shall be made
on five additional bricks. Unless otherwise specified (see 6.2), if any sample fails to conform to this specification,
this shall be cause for rejection of the lot.
4.6.5 Stability (grade AA only). Three test bricks shall be measured in length and width to the nearest
0.01 inch. The length dimension, if greater than 9 inches, shall be cut to 9 inches for this test. The brick shall be
placed, lying on a 4½- by 2½-inch end, in a gas-fired furnace and the temperature gradually raised to 3000±10 °F.
The temperature shall be maintained for 5 hours, after which the furnace shall be allowed to cool to room
temperature. The brick shall be measured, and the changes in length and width dimension shall be calculated as
percent to the original dimensions. The stability value is calculated by subtracting the percent change in length from
the percent change in width, except that negative width changes (indicating shrinkage) shall be adjusted to zero
before calculating stability value. If these three samples are not in accordance with 3.7.2, a retest shall be made on
each of six additional bricks of the sample. Unless otherwise specified (see 6.2), if bricks fail to conform to this
specification, this shall be cause for rejection of the lot.
4.6.6 Permanent linear change, burner tile only. Permanent linear change shall be determined in accordance
with ASTM C133, or as specified below. If three samples are not in accordance with 3.10.1, a retest shall be made
on each of six additional tiles of the sample. Unless otherwise specified (see 6.2), if the tiles fail to conform to this
specification, this shall be cause for rejection of the lot.
a. Cut three sample tiles using a masonry saw so as to provide, from each, a specimen having parallel ends
approximately 9 inches apart (or as near 9 inches as possible) and perpendicular to a flat surface.
b. Measure the lengths of the three specimens before and after heating. Measurements shall be to the nearest
0.01 inch using a vernier caliper or dial gage device. Specimens shall be heated at 2910±10 °F according to
schedule C of ASTM C113. Calculate the percentage linear change based on the original length of each specimen.
c.
Each specimen shall be given three cycles of this heat treatment (see 3.10.1).
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