Rev. 6-20-96
STRUCTURAL STEEL ASTM A
709 GRADE 50W
711-B-118
The Standard Specifications are revised as follows:
SECTION 711, LINE 334, DELETE AND INSERT AS FOLLOWS:
711.30 Blank
Fabricating ASTM A 709M Grade 345W (ASTM A 709 Grade
50W) Steel. This steel shall be left unpainted except
as shown on the plans. The finish coat for painted steel shall be
in accordance with Federal Color Standard 595a, color No. 30045.
(a) Surface Preparation.
A sound uniform surface for the formation of a protective oxide
coating on surfaces shall be prepared as described below. The
time of surface preparation and the method used shall be at the
option of the Contractor, and shall be subject to approval.
1. Hot-Rolled Products.
These shall include structural shapes, plates, bars, hot-rolled
sheets, and hot-rolled strip. The outside of each facia beam or
girder including the bottom of the bottom flange shall be cleaned
as set out in the SSPC Surface Preparation Specifications SSPC-SP
10-63T. Contamination from grease, oil, or shop marking shall be
avoided. Such surfaces shall be satisfactorily solvent-cleaned.
2. Welded Areas. All
exposed welds on facia surfaces shall be prepared by means of
power grinding or blast cleaning in accordance with SSPC-SP3-63
or SSPC-SP6-63 to removed welding flux, slag, or spatter.
(b) Fabrication and Handling.
Welding shall be in accordance with 711.32.
The fabricator and erector shall
handle and store bare steel sections and sub-assemblies so as not
to damage them. Scale produced due to welding shall be removed
from all exposed surfaces.
Staining by means of concrete,
mortar, plaster, oil, paint, grease, food, or other foreign
substances shall also be avoided. The use of paints, crayons, or
other materials used for identification purposes shall be avoided
as they shall be removed during final cleaning of the structure.
If the use of such marks is unavoidable, additional cleaning will
be required to remove such blemishes. The use of acids to remove
scale and stains in the field will not be permitted due to severe
pitting which may result from acid concentration at joints and
crevices. Storage in transit, in open cars, outside in yards, or
on the project site shall be positioned to permit free drainage
to avoid moisture pockets which may cause unsightly, uneven
weathering.
SECTION 711, LINE 677, DELETE AND INSERT AS FOLLOWS:
711.62 Blank
Field Cleaning of ASTM A 709 Grade 345W (ASTM A 709
Grade 50W) Steel. Foreign matter which adheres to
steel after it has been blasted, and which inhibits formation of
the oxide film shall be removed as soon as practical.
Cleaning of structural steel
specified to be left unpainted will not be required except for
such cleaning necessary to remove grease, oil, concrete spatter,
or foreign matter which affects natural oxidation of the steel.
Such cleaning shall be in accordance with SSPC Surface
Preparations Specifications SSPC-SP1-63, or SSPC-SP7-63,
depending on the severity of the soilage.