19 June 2001
timber piles that have been treated with quality preservatives and methods. Field
techniques should be used to eliminate or minimize cuts and holes made in the
members at the site, particularly for those members to be placed below water. If
cuts and holes must be made, special field PM preservative treatment is
required. In addition, there are other PM measures applicable to timber piles
using encasements and retardants. The most important field PM for the exposed
wood of waterfront buildings and related structures is the application of paint and
other coatings. Preventive maintenance measures discussed in this section are
summarized in Table 3-1.
3-2.3.1 Pressure Treatment. Pressure treatment of the outer sapwood of
timbers with preservatives is the most important and effective method of pro-
tecting wood. Using pressure treatment allows the preservative to uniformly
penetrate deeper and allows closer control of retention levels. The preservative
penetrates the wood from 1 cm to 10 cm (.39 to 3.93 inches), depending on the
type of wood, and provides protection from fungi, marine borers, insects and
bacteria. American Wood Preservers Association (AWPA) Standards govern the
treatment processes that must be performed on wood used in waterfront areas.
MO-312.2, A Field Guide for the Receipt and Inspection of Treated Wood
Products by Installation Personnel, is a field guide for acceptance of treated
wood products and must be consulted by Navy activities and followed whenever
treated wood is used.
The choice of preservative treatment depends on how and where the
wood is to be used. Wood preservatives are classified in three categories:
creosote preservatives, oil-borne preservatives, and water-borne preservatives.
3-126.96.36.199 Creosote. Creosote preservatives have been the most commonly
used preservatives at the waterfront because they are not easily leached from
the wood and are not corrosive to metals. Creosote and creosote-coal tar solu-
tions, both derived from bituminous coal, can be used for immersed wood.
Creosote is commonly diluted with petroleum oil for treatment of wood not
subject to immersion. An important disadvantage of creosoted piling, however, is
that it is readily attacked by the marine borer, Limnoria tripunctata. In addition,
creosote and creosote solutions cannot be used where it may come in contact
with people or where local environmental concerns have restricted its use in the
marine environment. Consult your environmental office for the latest policies and
regulations regarding its use.
3-188.8.131.52 Oil-Borne. Oil-borne preservatives are dissolved in a petroleum
solvent and include pentachlorophenol, copper naphthenate, tributyl tin oxide,
and copper-8-quinolinolate. Oil-borne preservatives are suitable for wood
members out of the water for protection against insects and fungi but does not
provide adequate protection against marine borers and, thus, cannot be used for
immersed wood. Treated wood can be painted, does not swell and distort, is
easily handled, and will not corrode metal. Before the solvent evaporates, it is
more flammable than untreated wood. Pentachlorophenol is the most effective of