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8/10/2019 Advanced Stainless Steel Specification and Problem Avoidance Presentation
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Advanced Stainless Steel Specification
Catherine Houska
International Molybdenum Association
The International Molybdenum Association is a Registered Provider
with The American Institute of Architects Continuing Education
Systems. Credit Earned on completion of this program will be reported
to CES records for AIA members. Certificates of Completion for non- AIA members are available upon request.
This program is registered with the AIA/CES for continuing
professional education. As such, it does not include content that maybe deemed or construed to be an approval or endorsement by the AIA
of any material of construction or any method or manner of handling,
using, distributing, or dealing in any material or product. Questions
related to specific materials, methods, and services will be addressedat the conclusion of this presentation.
CEN
This program is a registered educational program with the
Construction Specifications Institute of Alexandria, VA. The
content within this program is not created or endorsed by
CSI nor should the content be construed as an approval of
any product, building method, or service. Information on the
specific content can be addressed at the conclusion of this
program, by the Registered Provider.
Credit earned for completing this program will automatically
be submitted to the CSI CEN. Completion certificates can be
obtained by contacting the Provider directly.
This logo and statement identify Provider programs
registered with the CSI CEN and are limited to theeducational program content.
Copyright Materials
This presentation is protected by US and International
Copyright laws. Reproduction, distribution, display and use
of the presentation without written permission of the
speaker and the International Molybdenum Association
(IMOA) is prohibited.
Learning Objectives
• Learn about the expanded number of stainlesssteels that are being used for structural and
architectural applications.
• See examples of common problems and learn how
to avoid them.
• Review the industry standards that should be used
in stainless steel chemistry, strength, finish and
welding specification and how to tighten them to
ensure the desired level of performance and finish
uniformity.
Learning Objectives
• Review examples of suggested specification textfor avoiding common problems.
• Learn how to identify particularly corrosive
conditions where more corrosion resistant
stainless steels may be required.
• Learn how stainless steel performs in structural
applications exposed to fire, impact and seismic
loading.
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Stainless Steel = Long service life + low maintenance
Achieved through appropriate specificationSustainable Construction Characteristics
• Long service life = 100+ years
• Minimize material use, waste & impact
– No replacement
– High recycled content and diverted from
landfills (high recapture rate)
• Preserve natural resources & building
environment
– Minimize energy, potable water use and
toxic run-off
• Healthy productive indoor environment
– Stainless steel has no emissions
* ABC Industry ** All Applications
Recycled
Content %
EOL %
Recapture Rate
Stainless Steel 60-90 ** 92*
Carbon steel sheet/strip 25-35 ** 70
Carbon steel structural ≤95 ** 97
Zinc 23 ** 33
Copper wire 0 * >90
Copper - other products 70 – 95 * >90
Aluminum sheet 0 * 70
Aluminum extrusions Varies * 70
Aluminum castings ≤
100 * 70
Architectural Stainless Steels(Nominal Chemical Composition, Wt. Pct.)
Cr Ni Mo N C, max
Ferritic 430 17 --- --- 0.03 0.12
Austenitic 304 18 9 --- 0.06 0.08
Austenitic 316 17 11 2 0.06 0.08
Duplex 2205 22 5 3 0.15 0.03
Flat Rolled Product Specifications(Plate, Sheet and Strip)
Primary Specifications
• ASTM A240 - chemistry & mechanical properties
• ASTM A480 - finishes & dimensional tolerances
Rarely Used
• ASTM A666 – cold worked structural
applications
Do not use
• ASTM A167 – replaced by A240
Bar, Shapes & Tube Specifications(includes tees, channels, angles, etc.)
• ASTM A276 (bar and shapes)
– Chemistry & mechanical properties
• ASTM A 484 (bar and shapes)
– Dimensional tolerances, finish
• ASTM A 955M (stainless rebar)
• ASTM A 554 (structural tubing) – Mechanical properties
• ASTM A789 Duplex tubing
S t a i n l e s s
S t r u c
t u r a
l s I n c .
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What Factors Influence
Atmospheric Corrosion?
• Pollution (acid rain, sulfur dioxide, particulate)
• Coastal and deicing salt exposure
• Weather conditions• Maintenance
• Design/specification – Finish topography, roughness & application method
– Crevices
• Handling & post fabrication cleaning
Index of Relative Pitting Corrosion Resistance
I n c r e a s
i n g
C o r r o s
i o n
R e s
i s t a n c e
Type 304 Type 316 P h o
t o s c o u r t e s y o
f T M R
C o n s u
l t i n g
Stainless Steel
Factors: salt (chlorides), sulfur dioxide, particulate
Type 430
Select Type 316
• Pollution – Moderate to high urban
– Low to moderate industrial
• Marine and deicing salt – Low to moderate exposure
Select Type 304
• Rural/suburban
• Low to moderate pollution
Type 316 railings
Hong Kong ConventionCenter - seawater spray
exposure, rough finish
P h o
t o c o u r t e s y o
f t h e
N i c k e
l I n s
t i t u t e
• High levels industrial pollution
• Coastal or deicing salt
–Splashed by or immersed in salt
water
–Sheltered or unwashed
applications
–Significant salt deposits
–Rough surface finishes
Use More Corrosion
Resistant Stainless Steel
18
Critical Temperature/Humidity
Combinations for salt (chloride) corrosionCoastal & deicing salts
Critical Critical Humidity Level, %
Temperature °C(°F) Sodium
Chloride
Calcium
Chloride
Magnesium
Chloride
25 (77) 76 30 50
10 (50) 76 41 50
0 (32) --- 45 50
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Salt (Chloride) Deposition (kg/ha) - 2008 Salt (Chloride) Ion Rain Concentration - 2008
Deicing Salt (Chloride) Corrosion
• Multi-year study• IL DOT, NADP, Argonne
National Lab
• High seasonal
accumulation
• Large saltwater droplets• Splash zone (≤ 49 ft.)
• Dry particles – ≤ 1.2 miles from roads
– ≤ 59 floors – Stays in the air for days
Rain Acidity (pH) - 2008 Data
Generalized US and Canadian Corrosion Map
T h e C a t a l y s t , I s s u e
N o .
2 ,
1 9 9 7
, A R M C O
I n c .
Corrosion Map for China
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25
Extremely
severe
Severe
Moderate
Mild
Negligible
Corrosion Map for India
M a p
d o w n
l o a
d e
d f r o m
h t t p : / / w w w . c
o r r o s
i o n - d o c
t o r s . o
r g
26
Extremely severe
Severe
Moderate
Mild
Negligible
Corrosion Map for Great Britain
M a p
d o w n
l o a
d e
d f r o m
h t t p : / / w w w . c
o r r o s
i o n - d o c t o
r s . o
r g
27
Extremelysevere
Severe
Moderate
Mild
Negligible
Corrosion Map for Portugal
M a p
d o w n
l o a
d e
d f r o m
h t t p : / / w w w . c
o r r o s
i o n - d o c
t o r s . o
r g
Central Resource Site for Locating
Pollution, Salt Exposure, Weather
and Corrosion Data
www.imoa.info
•Architecture, building & construction section
•Climate & pollution data resources
•Links are grouped by region and country
•Literature, free software and resource articles
28
Wall
Roof
Eave
45°
15 to 60°
Chloride Accumulation In Sheltered Locations
C h l o r i d e s o z
/ i n c
h 2
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Type 316 stainless steel
57 years exposure
Corrosion Test Site, Kure Beach, NC
244 meters from the ocean, Never washed
Aluminized carbon steel
48 years exposure
Predict Service Life With Corrosion DataStanding seam example
Corrosion Causes Metal Run-Off From Other Roofs(Testing in Australia, Washington, Wisconsin - micrograms/liter)
Roof Type Copper Lead Zinc
Rusty galvanized 20 302 12,200
Plywood w/Tar Paper 11 10 1,980
Tar Roof w/ Al paint 25 10 297
Anodized Al 16 15 101
Galvanized iron ND 100 3,600
Concrete tile ND 90 1,600
Concrete Tile ND 50 200Watershed Protection Techniques 1(2): 84-85
Metal Loss From Swedish Test Roofs
Material Average Annual Run-off Per Square Meter
Zinc 2800 - 3000 mg/m2
Copper 1300 - 2000 mg/m2
Type 304 Stainless*
Nickel
Chromium
0.3 - 0.4 mg/m2
0.25 - 0.3 mg/m2
*In many samples, nickel and chromium levels were below
detectable limits. The average concentration per liter was well
below typical drinking water levels.
Coastal Galvanized Steel CorrosionLess then 10 years
Stadium Australia
Type 316 , 2B finish
Drainage system collects water
in underground tanks for
irrigation
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Coastal US Private ResidencePeninsula surrounded by salt water & wild life preserve
No run-off permitted
Type 316, standing seam roof & walls, 2D finish
Avoid Use
If the design will be exposed to salt (chlorides) and
moisture, avoid crevices or seal them to prevent corrosion
Sites for Crevice Corrosion
Inappropriate Strippable Film Use Can
Cause Crevice Corrosion
• UV rated films protect
surfaces during
shipping/installation
• Remove film quickly in high
salt environments• Film is water & chloride
permeable
• Film creates conditions for
crevice corrosion
Corrosion Caused By Residual Adhesive
•Causes
• Protective film was not UV rated
• Film used past service life
• Exposure to extreme temperatures
•Residual adhesive retains more
salt, moisture, dirt accelerating
corrosion
•Use solvents for adhesive removal
• Contact film manufacturer
Galvanic Corrosion Requires...
• Dissimilar metals
• Electrical connection between metals
(i.e., metal-to-metal contact)
• Moisture is present and connects themetals on a regular basis
Solution
• Prevent direct contact
– Inert washers, paint
– Other non-conducting barriers
• Surface area ratio is important!Stainless steel plate &
rapidly corroding galvanized
steel fasteners
Corrosion Caused by Sparks From Abrasive
Cutting Carbon Steel
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SVB Building
Flat panels with a uniform finishUniform Appearance
• Use one coil or consecutive
coils from one supplier
• Mark rolling direction on
film• Install panels and coils
consecutively
• Failing to follow these rules
can produce a
checkerboard appearance
Achieving Flatness
• Use adequate panel thickness
• Curving conceals uneven surfaces
• Avoid long or wide unsupported panels
• Provide for thermal expansion!
Column Covers 0.078 – 0.109 in (2 – 2.8 mm)
Wall panels 0.05 – 0.063 in (0.5 – 3 mm)
Roofing, supported 0.019 – 0.025 in (0.5 – 0.6 mm)
Countertops 0.078-0.109 in (2 - 2.8 mm)
Dull or Embossed Finishes
• Both samples are equally flat
• Light diffusion makes finishes look flatter
Achieving A Flat Appearance
Un-laminated Panels
Reflectivity Width-to-Thickness Ratio
High 150 max.
Medium-to-low 200 max.
Coined/Embossed 200 or higher
Metal Thermal Expansion
µin/in ºF
Type 304/316 9.6
2205 7.22
Carbon steel 6.7
HSLA steel 6.7
Alloy 400 7.7
Copper 9.4
AA 3003 12.9
Zinc 12.0
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Require “stretcher or tension leveled
quality of flatness” to minimize problems
with wavy panels
•Optional in ASTM A480 – must be
specified
•Waviness can reoccur after cutting
•Minimize problem = use full panel width
if possible
•Post fabrication panel flattening may be
needed
Flat Rolled Product Specifications(Plate, Sheet and Strip)
• Tighten finish specification text using surface
roughness (Ra) and gloss (reflectivity)
Ra 0.5 microns
or 20 micro-inches
I n c r e a s
i n g
C o r r o s
i o n
R a
t e
Typical Sheet Surface Roughness Range
Finish 2D 2B BA No. 3 No. 4 Hair-
line
No. 7 No. 8 Super
No. 8
Ra
Micro-inch
5 -
39
2.4 - 20 0.5 -
4
10 -
43
7 -
25
5.5 -
8.0
2.4 -
8
0.8 -
4
0.4 -
0.8
Ra
Micron
0.13
-
1.0
0.06 -
0.5
0.01 -
0.10
0.25 -
1.1
0.18 -
0.64
0.14 -
0.2
0.06 -
0.2
0.02 -
0.10
0.01 -
0.02
International Finish Cross Reference
Finish ASTM A 480 JSSA EN10088
Mill 2D 2D 2D
2B 2B 2B
BA BA 2R
Polished No. 3 No. 3 1G or 2G
No. 4 No. 4 1J or 2J
No. 4 No. 240 1K or 2K
No. 7 No. 7 1P or 2P
No. 8 1P or 2P
Embossing and Coining
• ASTM 947M
• Increases rigidity and impact
resistance
• Conceals scratches and reduces
scratch depth
• Coining
– One roll is patterned
– One roll is smooth
• Embossing
– Both rolls are patterned
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Potential Variation In Appearance Problem
• Pattern depth variations from rollor polishing belt wear – Number coils as they are produced
– Install consecutively
• UV rated strippable film witharrows marking direction
• Variations in underlying finish
• Specify maximum pattern depthvariation and finish reflectivity
• More visible at higher light levels
Other Mechanically Applied Finishes
• Not covered by an ASTMstandard
• Proprietary designs
• Use control samples
Abrasive Blasted Finishes
• Texture and color vary
• Susceptible to fingerprinting & corrosion
• Require virgin blast media
Fine sand Dark, coarse
Glass beads Light, smooth, grainy
Silicon carbide Dark, coarse
Stainless shot Small, curved indentations
Ground quartz Shiny, coarse, angular
Electrochemical &
Sputtered Color
Bronze Blue Gold Red
Purple Black Green
• Not covered by standards
• Acceptable color variance mustbe determined
• Any corrosion destroys color
• Not suitable for abrasiveexposure
Shakaden Temple Roof, Japan
•Electrochemically colored black with gold details
•Completed 1975 – inspected in 2002 after 27 years
• No color overall
change
• Minor wear where
water was channeled
Woven Stainless
• No ASTM standard for
architectural finishes
• Broad range of styles & weights
• Hides scratches & impact
resistant
• Tight crevices can lead to crevice
corrosion when salt is present
• 304 and 316 are susceptible
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Low Sulfur
• Sheet, strip or plate
specify “low sulfur”
– 0.005 or less
– Improved corrosion
performance & finishappearance
• For mirror finishes
– Specify 0.002 or less
• Low sulfur tube and pipe
may not be available
• A 240 chemistry & mechanical properties• Sulfur 0.005 max. (0.002 for mirror)
• A 480 – tighten requirements• Typical No. 4 = Ra 20 micro-inches max.
• Very fine No. 4 = Ra 12 micro-inches max.
• Stretcher or tension leveling required
• Agree with finish supplier
• Gloss (reflectivity) within agreed range
Sample Specification - Sheet, Strip, Plate
No. 4 Finish, Type 304 or 316
Tube and Pipe Finishes
• No aesthetic specification
– A 270 (sanitary tubing) or apply A 480
• Pickled
• Abrasive blasted
• Ordered by Grit Number
– 150, 180, 240, 320 grit, wet or dry polishing
– Polishing along length or circumference
• Buffed (similar to a No.7 or 8 sheet finish)• Coined or embossed finishes with weld line
Reducing Heat Island Effect (LEED)• Options
– Meet minimum Solar Reflective Index (SRI) values on
at least 75% of roof
– Install a vegetated roof on at least 50% of roof area
Roof Type Slope SRI %
Low-Slope ≤ 2:12 78
Steep-Slope > 2:12 29
Product SolarReflectance
InfraredEmittance
TemperatureRise, C (F)
SRI
Stainless Steel, bare 0.60 0.10 - 0.21 39-60
Galvanized steel, bare 0.61 0.04 30 (55F) 46
Aluminum, bare 0.61 0.25 27 (48F) 56
Metal, white coating 0.85 0.91 9 (16F) 107
Clay tile, red 0.33 0.9 32 (58F) 36
Concrete tile, red 0.18 0.91 39 (71F) 17
Concrete tile, white 0.73 0.9 12 (21F) 90
Asphalt, generic white 0.25 0.91 36 (64F) 26
Asphalt, generic black 0.05 0.91 46 (82F) 1
Wood shingle, brown 0.22 0.90 37 (67F) 22
Wood shingle, white 0.84 0.89 6 (10F) 106
Sources: LBNL Cool Roofing Materials
Database and Contrarian Metal Resources
Strength Comparison
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Stress-Strain Behavior
00.002 0.005 0.010 0.015
σ0.2
Type 2205
Strain, ε
S t r e s s ,
σ
E
Carbon steel
E
σ0.2 Type 304
Japanese Structural DemonstrationBuilding, Osaka, Japan
No damage after major 1995 earthquake
Pio of Pietrelcina Church,Italy
Type 316
Seismic design
Duplex 2205 stainless steel & structural glass
High strength 2205 minimized structural support requirements
Fire & Thermal Radiation Resistance
• Aluminum is least resistant
– Aluminum’s strength decreases above 100ºC
– 6061-T6 tensile strength decreases 60% at 200ºC
• Carbon and weathering steel
– Carbon steel limited to 370ºC under continuous loading
– Carbon steel tensile strength drops 30% at 500ºC
– Weathering steel tensile strength drops 50% >540ºC
• Stainless steel = better strength & stiffnessretention
Fire Testing Video Fire Resistance Testing Summary
Metal Result Comments
Stainless
Steel
Passed Test extended to 45 minutes when gas ran out.
No failure occurred. Deflection was 80.5 mm (3.2
inches) after 45 minutes.
Galvanized
Steel
Passed Deflection was 166.5 mm (6.6 inches) after 5
minute test, some molten zinc observed
Aluminum Failed 26
seconds
Collapsed
Fiberglass Failed 30
seconds
Collapsed and started to burn, releasing fumes
Test: Loaded structural cable supports exposed to 1,000 – 1,050 C
(1832-1922ºF) flames
Requirement: Retain structural integrity for 5 minutes
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Conduction Through Walls Test
Metal Result CommentsStainless
Steel
Stabilized
90 minutes
No ladder deformation during test. Cold
side legs stabilized at 80 and 58 C (136
and 176 F)
Aluminum Stabilized
37 minutes
Total collapse by melting after 1:08
minutes. Test continued on protrudingsections. Cold side legs stabilized at 134
and 152 C (273 and 306 F)
Loaded structural supports separated by insulated cavity wall. One side
exposed to 1,000 – 1,050 C (1832-1922ºF) flame.
Determine time until temperature stabilizes on cold side
Stiffness Retention at Elevated Temperature
Elevated temp tangent modulus/ room temp tangent modulus
7 times the stiffness retention of carbon steel at 1472 F
Stainless Steel
Carbon steel
Temperature oF
S t i f f n e s s r e
t e n
t i o n ,
k E
‚ θ
392 752 1112 1472 1832 2192
700 KG Ball Impact – Carbon Steel Reinforced Concrete 700 KG Ball Impact – Type 304 Stainless Reinforced
Welding Structural Applications
• Use AWS D 1.6 StructuralWelding Code – Stainless Steel – Requirements for prequalification,
qualification, fabrication, inspection
– During bidding – require submission
• Welding procedures
• Current welder certifications
• For structurally critical welds, hirea welding inspector
• Restore weld corrosion resistance – Require cleaning per ASTM A 380
Chromium Depleted under Weld DiscolorationRemove heat tint & additional metal
to restore corrosion resistance
Cr Cr Cr
WeldDiscoloration
Base
Material
ChromiumContent
(schematic)
P h o
t o c o u r t e s y o
f A S S D A
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Effect of Post-Weld Cleaning on Critical Pitting
Temperature (CPT)Pickling
• Pickling is described in ASTM A 380
• Chemical treatment thatremoves
• Heat tint
• Chromium-depleted layer
• Surface contamination
Pickling with paste
Preventing Water Staining
• Occurs when surface ispickled or cleaned with acid – Caused by high solids content
rinse water
• Prevent staining – Require de-ionized or low-
solid content water per ASTM A 380
Thank You For Your
Time!
Questions?