19 June 2001
Maintenance of steel structures and components will entail repair or
replacement of damaged or corroded steel, periodic coating of steel surfaces for
corrosion protection, and maintenance of cathodic protection systems. Although
physical damage from impact or loading may occur, corrosion is the major cause
of the deterioration of steel structures. The extent or severity of corrosion will
vary with the exposure zone of the material; that is, whether it is in the
atmospheric zone, the splash or tidal zone, or the submerged zone. The
selection of materials for waterfront use must consider each of these varied
The use of steel should follow design guidelines in NAVFAC MIL-
HDBK-1025/6, General Criteria for Waterfront Construction; NAVFAC MIL-
HDBK-1002/3, Structural Engineering - Steel Structures, and the American
Institute of Steel Construction's Manual of Steel Construction. The material
specifications of ASTM and other organizations document chemical and physical
characteristics of the various types of steel. Material selection and procurement
should conform to these specifications.
Steel for Waterfront Construction. Carbon steel and carbon steel
alloys are the most important types of metals used for construction of waterfront
facilities. In general, only low carbon steels with a carbon content less than 0.35
percent by weight are used due to welding characteristics.
3-4.1.1 Carbon Steel. Carbon steel is an alloy of iron and carbon with a
carbon content less than 2 percent. The requirements for structural carbon steel
are contained in ASTM A 36 and this grade is suitable for welding.
Carbon steel will corrode in all exposure zones, but the most severe
corrosion occurs in the splash zone and just below MLW. Coatings and cathodic
protection are necessary to prevent excessive corrosion of steel in the waterfront
environment. Coatings are covered in Paragraph 3-4.3.1. Cathodic protection is
covered in Paragraph 3-4.3.3.
3-4.1.2 Low-Alloy Carbon Steels. Corrosion resistant, low-alloy carbon steel
may be used instead of carbon steel if greater corrosion resistance is required.
Low-alloy carbon steels contain small amounts of other elements such as
percent of these elements is added for increased strength or heat treatment
does not easily break away from the metal surface.
The common low-alloy steels include:
ASTM A 690, Specification for High-Strength, Low-Alloy Steel H-
Piles and Sheet Piling for Use in Marine Environments, (also called