Advanced Stainless Steel Specification and Problem Avoidance Presentation

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.



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 .



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



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



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



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



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



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



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



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



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



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



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



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?

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Advanced Stainless Steel Specification and Problem Avoidance Presentation

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