Test Report for Accelerated Aging of Weathering Steel ... - TurnaSure

(412) 788-1300
(412\ 788-1306 Fax
http://www.kta.com
e-mail: info@kta.com
KTA.TATOR, lNG.
115 Technology Drive, Pittsburgh, PA 15275
February 8,2002
Mr. Jonathan Turner
TurnaSure LLC
340 E. Maple Avenue, Suite 305
Langhorne, PA 19047
SUBJECT:
KTA-Tator,Inc. Test Report for Accelerated Aging of
Weathering Steel Joint - TurnaSure Project No. 210756
Dear Mr. Turner:
In accordance with KTA-Tator, Inc. Proposal PN011969 and TurnaSure LLC Purchase Order No.
PO384, KTA-Tator, Inc. (KTA) has completed 500 hours of accelerated aging testing of the weathering
steel joint. This report contains a description of the accelerated test conditions and the results of the
evaluation of the weathering steel joint after 500 hours of testing.
TEST SPECIMEN
The test specimen consisted of a weathering steel joint assembled from 2 steel plates measuring
6" x 8 ll2" x 5/8" thick, sandwichedbetween 2 additional steel plates measuring 6" x17" xIl2" thick.
The steel plates were fastened together with 127/8" diameter x 3" long ASTM A325 Type 3 structural
bolts, each mated with a matching heavy hex nut and hardened washer. Each bolt assembly included 1
ASTM F959 DTI washer produced from Type 3 weathering steel. (See Photo 1)
Coatings & Corrosion Consulting r Construction Inspection I Laboratory Analysis
Materials Testing I Environmental, Health & Safety

Mr. Jonathan Turner
February 8,2002
(Photo I - Example of Fastener Set Used for Test)
The weathering steel joint test specimen was designed and constructed in accordance with
TurnaSure LLC instructions by High Steel Structures, Inc. of Lancaster, PA and assembled at Laboratory
Testing, Inc. (LTI) of Hatfield, PA. The test joint design was intended to simulate a typical joint of a steel
highway bridge. (See Photos 2 through 5, provided courtesy of LTI.)
@hoto 2 - Cross-section of joint before Tightening)

Mr. Jonathan Tumer
February 8,2002
@hoto 3 - Joint Assembly using Torque Multiplier)
(Photo 4 - Tightened joint dfeeler-gages in residual DTI gaps)

Mr. Jonathan Turner
February 8,2002
@hoto 5 - Tightened Jointdfeeler gauges in residual Steet gaps)
TESTING PROTOCOL
The objective of the accelerated aging testing was to determine the corrosion protection of the
joint in typical atnospheric exposures. To that end, the weathering steel joint was subjected to 500 hours
of cyclic testing in the Q-Fog test cabinet according to ASTM G85, *Modified Salt Spray (Fog) Testing",
AnnexA5, *Dilute Elecfolyte Cyclic Fog/Dry Tesf'.
The testing consisted of exposing the specimen to continuous cycling of I hour fog at ambient
temperature,z4 ! 3" c (75 + 6' F) followed by I hour d.y-off at 35 + 1.5'c (95 + 3' F). The fog was
provided by an electrolyte solution composed of 0.05% sodium chloride and, 0.35%o ammonium sulfate.
The pH of the fog condensate ranged between 5.1 and 5.4 throughout he duration of the testing.
The specimen was oriented in the test cabinet in the horizontal position, with one of the faces of
the specimen always skyward in order to enable comparisons between exposure of both a 'top flange' as
well as a 'bottom flange' to 'weathering'. The test was concluded after 500 hours of exposure and the
weathering steel joint test specimen was removed and disassembled for evaluation.
TEST RESTILTS
The weathering steel joint was carefully disassembled on bctober l7,2OOl at KTA headquarters
in Pittsburgh, in the presence of Mr. Jonathan Turner and Mr. David Sharp. The condition of the
specimen, prior to disassembly, was photographically documented. Photographs were also taken to
document the condition of the steel plates, bolts, washers, and load indicator washers drning the entire
disassembly process.
The exterior surface of the joint that was oriented skyward during testing was severely rusted and
covered with rust scale. It was rated as Rust Grade 0-G, (>50 o/o rusted), according to SSPC-VIS 2,
"Standard Method of Evaluating Degree of Rusting on Painted Steel Surfaces". Severe rust and rust scale,
also rated 0-Go was present along the sides of the joint. (See Photos 6 & 7)

Mr. Jonathan Turner
February 8,2002
@hoto 6 - exterior sur{ace rust) (Photo 7 - side surface rust)
The exposed portions of the bolts, bolt threads, and nuts were fairly clean of rust. When the nuts
were removed from the top of the joint it was noted that there was no rust between the nuts and the load
indicator washers. (See Photo 8.) There was also minimal rusting, Rust Grade 4-G (10% rusted),
between the bolt heads and the load indicator washers. No rust was present on the bolt shanks where the
Ioad indicator washers were adjacento the bolt heads. (See Photo 9.)
@hoto 8 - Lack of corrosion on DTI where it was against hex nut)
@hoto 9 - Lack of corrosion on bolt shank or between load indicator bumps)

Mr. Jonathan Turner
February 8,2002
It was noted that any rust that was present on the load indicator washers was at the periphery of
the washers. An intentional gap of up to 0.005" is normally present during installation between the load
indicator washer and the bolt head or the between the steel plate and the load indicator washer. The gap
was not existent at the periphery of the load indicator washers, but was filled with a patina of rust
measuring 0.005 inches in thickness. However, the gap remained at the interior portion of the load
indicator inside the patina build-up. The area of the washer adjacent to the steel plate and/or bolt was free
of any rust.
Similarly, corrosion between the plates where gaps had been present appeared to become sealed
off from further corrosion upon build-up of the patina. (See Photo 10.)
@hoto 10 - Patina build-up inhibited further ingress of corrosion.)
Nuts removed from the top (skyrvard) side of the joint revealed clean load indicator washers free
of rust on the inner portion of the washers as well as on the surface of the nuts that were adjacent to the
load indicator washers. One of the bolts, when removed from the joint, was so severely rusted at the bolt
head, that the top of the bolt exfoliated. The numerals designating the bolt head were still legible in the
exfoliated portion of rust scale. (See Photo 11.)

Mr. Jonathan Turner
February 8,2002
@hoto 11 - Edoliated portion of an A325 Bolt Head)
Apparently, the load indicator washers oflered protection against rusting to the bolts themselves.
It was observed that many of the bolts that were fastened using the load indicator washers were free of
rust on the bolt shafts. In fact, it was seen that the original oil used to protecthe bolt in the field was still
present on the threads at time of disassembly.
The internal steel plates of the joint were approximately 50% rusted, Rust Grade l-G. The rust
was also surrounding several of the bolt holes, on both the sides with and without load indicating washers.
No rust was observed at the junction of several of the bolt heads with the plate due to the protection
of[ered by the load indicator washers. Rust was very minimal, Rust Grade 9-G (0.03% rusted), at the bolt
holes on which the load indicating washers had been present. No rust was present within 1/8" of the bolt
holes at these locations, likely due to the high clamping forces in this region. (See Photo 12.)
(Photo 12 - Lack of corrosion in regions of high clamping force.)

Mr. Jonattran Turner
February 8,2002
CONCLUSIONS
It became apparent, during disassembly of the joint, that the load indicator washers prevented
rusting from occurring on those areas of the plate, bolt, and nut that were fastened with the load indicator
washers. It was theorized that a barrier of corrosion material stopped the ingress of moisture into the
0.005-inch gap present at the load indicator washer, thereby contributing to areas that were fiee of
corrosion and rust.
If you have any questions concerning the information contained in this report, please call me at
412/788-1300, ext. 181.
Very truly yours,
KTA-TATO& INC.
FAM/BRAjas
Frank A. Mozelewski
Senior Chemist
cc:
William B. Corbett
Bernard R. Appleman
Cynthia L. Fairfull
Scott Rice
JN: 210756
(JAS02049
NOTICE: This report represents the opinion of KTA-TATOR, INC. This report is issued in conformance with generalty acceptable industry
practices. While customary precautions were taken to insure that the information gathered and presented is accurate, oomplete, and technioally
conect, it is based on the informatiorl dan4 time, materials, and/or samples afforded