1.-
Sorting
and inspection of the wood for crossties, switch ties and bridges. The
material is inspected visually and dimensionally to see if it meets with
the quality requirements, both from the client and
A.R.E.M.A.
(American Railway Engineering and Maintenance of
Way Association).
We inspect for:
• Size and form of Knots
• Grain direction
• Consistency of the wood
• Size of cracks
• Wood malformations
• Degradation of the wood
• Others
2.-The wood is stored for its natural drying process according to A.R.E.M.A. specifications and we take samples, periodically, to check that the humidity level reaches 25% in soft woods and 40% in hard woods.
The extraction sample
process is in accordance with A.R.E.M.A.
specifications, done in the following way:
A) With a presley drill or a drill bit 20 samples are extracted from each lot and are taken to the lab.
B) In the lab the samples are weighted, and dried in a 175 Fº to 215 Fº oven for about an hour.
C) Once the sample dries it is removed from the oven, weighed again to determine the humidity content using the following formula:
Dry weight
3. The wood , according to its use, must be marked with the information the client requires so the wood can be traced once it exits the plant and the quality control department verifies that the marks are clear and the data is correct.
4. Inspection and analysis of wood preservers When the creosote a sample of creosote is analyzed in the lab to verify it meets the A.W.P.A. (American Wood Preservers Association) standards.
The tests done on the creosote sample are:
A) Distillation of the creosote to determine its water content
B) Specific Gravity
C) Specific gravity on distilled fractions
5. Analysis and inspection of penetration and retention of the preserver in the wood. When the lot finishes the impregnation process 20 samples are taken with the presley drill and taken to the lab for its further analysis.
A) Each sample is measured to determine the percentage of penetration of the preservers in the sapwood. The penetration should be at least of 90% in softwoods, 95% in white oak and 65% in red oak.
B) Once the penetration is determined the samples are weighted and are introduced in a Soxhlet extractor so they can be washed with xilene so the preserver can be extracted; this process last approximately 2 to 3 hours. After this extraction process has ended the samples are weighed again, and by the difference in weight the retention of the preserver is determined and expressed in Kg/M3 or Pnd/ft3.
The retention formula is:
Retention (kg/m3) =
TVWhere:
w1 =
w2 =
w3 =
vt =
Weight of the sample with creosote
Weight of water in the sample
Weight of washes and dried samples
Total weight of samples
