Transactions of the American Society of Civil Engineers, vol. LXX, Dec. 1910

Transactions of the American
Society of Civil Engineers, vol.
LXX, Dec. 1910

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Title: Transactions of the American Society of Civil Engineers, vol.
LXX, Dec. 1910 Tests of Creosoted Timber, Paper No. 1168
Author: W. B. Gregory
Release Date: February 16, 2006 [EBook #17776]
Language: English
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AMERICAN SOCIETY OF CIVIL ENGINEERS
INSTITUTED 1852
TRANSACTIONS
Paper No. 1168
TESTS OF CREOSOTED TIMBER.
BY W. B. GREGORY, M. AM. SOC. C. E.

During the last few years a quantity of literature has appeared in which
the treatment of timber by preservatives has been discussed. The
properties of timber, both treated and untreated, have been determined
by the Forest Service, United States Department of Agriculture, and
through its researches valuable knowledge has come to engineers who
have to deal with the design of wooden structures. There is very little
information, however, regarding the effect of time on creosoted timber,
and for this reason the results given herewith may prove of interest.
The material tested consisted of southern pine stringers having a
cross-section approximately 6 by 16 in. and a length of 30 ft. For the
purpose of testing, each beam was cut into two parts, each about 15 ft.
long. This material had been in use in a trestle of a railroad near New
Orleans for 26 years. The stringers were chosen at random to determine
the general condition of the trestle. The timber had been exposed to the
weather and subjected to heavy train service from the time it was

treated until it was tested. The annual rainfall at New Orleans is about
60 in., and the humidity of the air is high. In spite of these conditions,
there was no appearance of decay on any of the specimens tested. The
specifications under which the timber was treated were as follows:
TIMBER.
The timber for creosoting shall be long-leafed or southern pine. Sap
surfaces on two or more sides are preferred.
Piles.--The piles shall be of long-leafed or southern pine, not less than
14 in. at the butt. They shall be free from defects impairing their
strength, and shall be reasonably straight.
The piles shall be cleanly peeled, no inner skin being left on them. The
oil used shall be so-called creosote oil, from London, England, and
shall be of a heavy quality.
The treatment will vary according to the dimensions of the timbers and
length of time they have been cut. Timbers of large and small
dimensions shall not be treated in the same charge, neither shall timbers
of differing stages of air seasoning, or the close-grained, be treated in
the same charge with coarse or open-grained timbers.
The timbers shall be subjected first to live steam superheated to from
250 to 275° Fahr., and under a 30 to 40-lb. pressure. The live steam
shall be admitted into the cylinders through perforated steam pipes, and
the temperature shall be obtained by using superheated steam in closed
pipes in the cylinders.
The length of time this steaming shall last will depend on the size of the
timbers and the length of time they have been cut. In piles and large
timbers freshly cut, as long a time as 12 hours may be required. After
the steaming is accomplished, the live steam shall be shut off and the
superheated steam shall be maintained at a temperature of 160° or more
and a vacuum of from 20 to 25 in. shall be held for 4 hours or longer, if
the discharge from the pumps indicates the necessity.

Oil Treatment.--The temperature being maintained at 160° Fahr., the
cylinders shall be promptly filled with creosote oil at a temperature as
high as practicable (about 100° Fahr.). The oil shall be maintained at a
pressure ranging from 100 to 120 lb., as experience and measurements
must determine the length of time the oil treatment shall continue, so
that the required amount of oil may be injected.
After the required amount of oil is injected, the superheated steam shall
be shut off, the oil let out, the cylinders promptly opened at each end,
and the timber immediately removed from the cylinder.
In the erection