CEMP-E
TI 809-02
1 September 1999
CHAPTER 12
BUILDINGS SUBJECT TO SEVERE ENVIRIONMENTS AND EXPLOSIVE EFFECTS
12-1. INTRODUCTION. In some cases, buildings may be constructed in severe corrosive
environments, constructed in environments with extreme temperatures, or constructed such
that protection of the environment due to toxic chemicals, wastewater, or explosives must be
provided. This chapter provides information so buildings constructed in severe environments
can meet their intended performance objectives without deterioration, and without degradation
that could increase maintenance costs or shorten service life.
12-2. STEEL STRUCTURES IN CORROSIVE ENVIRONMEMTS.
a. General. When steel members will be exposed to heavy industrial pollution, salt
spray, salt air, chemicals, or are to be embedded in corrosive soils, a corrosion engineer will be
consulted to recommend materials, protection, or both and to review design drawings to assure
the structure will be serviceable and durable. When appropriate, an increased thickness, i.e.,
corrosion allowance, will be used to attain the required service life. For additional discussion
and guidance in designing for corrosive conditions, see the National Association of Corrosion
Engineers (NACE) Corrosion Handbook and other relevant NACE publications. Additional
information can also be found in the NAVFAC Maintenance and Operations Manual MO-307,
"Corrosion Control" and in NAVFAC Interim Technical Guidance (ITG), "Cathodic Protection
Systems", dated May 1994.
b. Corrosion Protection of Steel Members. Corrosion protection is less of a problem in
structures which have been designed to provide good drainage, designed to provide air
circulation, and designed to provide access for maintenance. Both oxygen and moisture must
be present if corrosion is to occur. The most severe corrosion occurs in marine environments
where chloride ions are present. Paint systems and zinc coatings applied by the hot dip
process or by spray on process are all good corrosion protection systems when metal surfaces
are prepared properly and the coating systems are applied properly. In extremely corrosive
conditions, or where maintenance is difficult, the use of cathodic protection or stainless steel
may be warranted.
c. Design Considerations. Steel structures designed for corrosive environments should
consider the following corrosion protection measures.
(1) Box-shaped members should be designed so that all inside surfaces may be
readily inspected, cleaned, and painted, or should be closed entirely to prevent exposure to
moisture.
(2) The flanges of two (back to back)angle members, when not in contact, should
have a minimum separation of 3/8 inch to permit air circulation.
(3) Pockets or depressions in horizontal members should have drain holes to prevent
water from ponding in low areas. Positive drainage should be provided away from exposed
12-1
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