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PDF| Treatment | | | | Bending | Compres- | Height | of the |
| | | | | modulus | sion | of drop | three |
| | Period | Pressure | Temperature | of | parallel | causing | strengths |
| | | | | rupture | to grain | complete | |
| | | | | | | failure | |
|-----------+--------+----------+-------------+----------+--
--------+----------+-----------| | | | Lbs. per | | Per cent | Per cent | Per cent | Per cent | | | Hrs. | sq. inch | deg.F. | | | | | | | | | | Untreated wood = 100% | | | | | | | | | | | Steam, | 4 | | 230[a] | 91.3 | 79.1 | 96.4 | 88.9 | | at | 4 | 10 | 238 | 78.2 | 93.7 | 93.3 | 88.4 | | various | 4 | 20 | 253 | 83.3 | 84.2 | 91.4 | 80.8 | | pressures | 4 | 30 | 269 | 80.4 | 78.4 | 89.8 | 82.9 | | | 4 | 40 | 283 | 78.1 | 74.4 | 74.0 | 75.5 | | | 4 | 50 | 292 | 75.8 | 71.5 | 63.9 | 70.4 | | | 4 | 100 | 337 | 41.4 | 65.0 | 55.2 | 53.9 | |-----------+--------+----------+-------------+----------+--
--------+----------+-----------| | Steam, | 1 | 20 | 257 | 100.6 | 98.6 | 86.7 | 95.3 | | for | 2 | 20 | 267 | 88.4 | 93.0 | 107.0 | 96.1 | | various | 3 | 20 | 260 | 90.0 | 93.6 | 84.1 | 89.2 | | periods | 4 | 20 | 253 | 83.3 | 84.2 | 91.4 | 86.3 | | | 5 | 20 | 253 | 85.0 | 78.1 | 84.2 | 82.4 | | | 6 | 20 | 242 | 95.2 | 89.8 | 76.0 | 87.0 | | | 10 | 20 | 255 | 73.7 | 82.0 | 76.0 | 77.2 | | | 20 | 20 | 258 | 67.5 | 65.0 | 99.0 | 77.2 | |-----------------------------------------------------------
-------------------------------| | [Footnote a: It will be noted that the temperature was 230 deg.. This is the maximum | | temperature by the maximum-temperature recording thermometer, and is due to the handling | | of the exhaust valve. The average temperature was that of exhaust steam.] | |-----------------------------------------------------------
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--------+----------+-----------| | | | Lbs. per | | Per cent | Per cent | Per cent | Per cent | | | Hrs. | sq. inch | deg.F. | | | | | | | | | | Untreated wood = 100% | | | | | | | | | | | Steam, | 4 | | 230[a] | 91.3 | 79.1 | 96.4 | 88.9 | | at | 4 | 10 | 238 | 78.2 | 93.7 | 93.3 | 88.4 | | various | 4 | 20 | 253 | 83.3 | 84.2 | 91.4 | 80.8 | | pressures | 4 | 30 | 269 | 80.4 | 78.4 | 89.8 | 82.9 | | | 4 | 40 | 283 | 78.1 | 74.4 | 74.0 | 75.5 | | | 4 | 50 | 292 | 75.8 | 71.5 | 63.9 | 70.4 | | | 4 | 100 | 337 | 41.4 | 65.0 | 55.2 | 53.9 | |-----------+--------+----------+-------------+----------+--
--------+----------+-----------| | Steam, | 1 | 20 | 257 | 100.6 | 98.6 | 86.7 | 95.3 | | for | 2 | 20 | 267 | 88.4 | 93.0 | 107.0 | 96.1 | | various | 3 | 20 | 260 | 90.0 | 93.6 | 84.1 | 89.2 | | periods | 4 | 20 | 253 | 83.3 | 84.2 | 91.4 | 86.3 | | | 5 | 20 | 253 | 85.0 | 78.1 | 84.2 | 82.4 | | | 6 | 20 | 242 | 95.2 | 89.8 | 76.0 | 87.0 | | | 10 | 20 | 255 | 73.7 | 82.0 | 76.0 | 77.2 | | | 20 | 20 | 258 | 67.5 | 65.0 | 99.0 | 77.2 | |-----------------------------------------------------------
-------------------------------| | [Footnote a: It will be noted that the temperature was 230 deg.. This is the maximum | | temperature by the maximum-temperature recording thermometer, and is due to the handling | | of the exhaust valve. The average temperature was that of exhaust steam.] | |-----------------------------------------------------------
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“(3) A high degree of steaming is injurious to wood in strength and spike-holding power. The degree of steaming at which pronounced harm results will depend upon the quality of the wood and its degree of seasoning, and upon the pressure (temperature) of steam and the duration of its application. For loblolly pine the limit of safety is certainly 30 pounds for 4 hours, or 20 pounds for 6 hours."[52]
