Plastic Pellet Hopper Car Lining Issues

1

by

Cory AllenSeptember 20, 2005

200,000

250,000

300,000

350,000

400,000

450,000

NU

MB

ER

OF

RA

ILC

AR

SComposition of North America Railcar Fleet

2

0

50,000

100,000

150,000

200,000

PLA

IN B

OX

EQ

UIP

PED

BO

X

GO

ND

OLA

HO

PPE

R

CO

VER

ED

HO

PP

ER

FLAT

RE

FRIG

ER

ATE

D

TAN

K

OTH

ER

NU

MB

ER

OF

RA

ILC

AR

S

Source: Progressive Railroading’s Car & Locomotive Yearbook

200,000

250,000

300,000

350,000

400,000

450,000

NU

MB

ER

OF

CA

RS

Change in North America Fleet

3

0

50,000

100,000

150,000

200,000

1974 1980 1984 1988 1992 1996 1999 2000 2001 2002

NU

MB

ER

OF

CA

RS

PLAIN BOX COVERED HOPPER TANK GONDOLA

Source: Progressive Railroading’s Car & Locomotive Yearbook

7%

4%

3%

2%

3%

4%

8%

3%

GRAIN

ORES

COAL

AGGREGATES

MINERALS

GRAIN MILL

FOOD

Railcar Loads by Commodity

4

41%

5%

2%

3%

3%

2%

10%

LUMBER

CHEMICALS

PAPER

PETROLEUM

STONE,CLAY,GLASS

METALS

AUTOS

WASTE/SCRAP

Source: Progressive Railroading’s Car & Locomotive Yearbook

New car order booms in 1974 and 1992

100,000

120,000

140,000

160,000

NU

MB

ER

OF

CA

RS

Age of Covered Hopper Cars

5

0

20,000

40,000

60,000

80,000

NU

MB

ER

OF

CA

RS

1 - 10 yrs 11 - 20 yrs 21 - 30 yrs 31 - 40 yrs over 40 yrs

AGE RANGE (years)

Source: Progressive Railroading’s Car & Locomotive Yearbook

Plastic Pellet Hopper Cars

•AAR Field Manual Job Codes (Private Rail Car Standard Job Codes)•8025 – Air Cure•8026 – Force Cure

•Car Type Description• 5250 cu.ft. pneumatic hopper (purified terephthallic acid, polyvinyl chloride, polystryene, polypropylene, polyethylene, polybutylene terephthalate, polyester) • 5700 cu.ft. pneumatic hopper (polyvinyl chloride,

6

• 5700 cu.ft. pneumatic hopper (polyvinyl chloride, polypropylene, acrylates, polyethylene, Bis phenol-A)• 5800 cu.ft. ACF pneumatic hopper (polyethylene, polypropylene, polystyrene)• 5820 cu.ft. Pullman Standard pneumatic hopper (polyethylene, polypropylene, polycarbonate, polyvinyl chloride)• 5850 cu.ft. Pullman Standard pneumatic hopper (polyethylene, polypropylene, polyvinyl chloride, polyvinyl alcohol, acrylonitrile-butadiene-styrene, polycarbonate)

•Non-corrosive

•Polyethylene (PE)

•Polypropylene (PP)

•Polystryene (PS)

•Acrylonitrile-butadiene-styrene (ABS)

•Polybutylene terephthalate (PET)

•Poly[imino(1-oxo-1,6-hexanediyl)]) (Nylon 6)

Plastic Pellet Commodities

7

•Poly[imino(1-oxo-1,6-hexanediyl)]) (Nylon 6)

•Polybisphenol-A-carbonate (PC)

•Corrosive

•Terephthallic Acid (TPA)

•Ethylene Vinyl Acetate Copolymer (EVA)

•Isophthallic Acid (IPA)

•Polyvinyl Alcohol (PVA)

•Adipic Acid

•Purified Terephthallic Acid (PTA)

•Polyvinyl Chloride (PVC)

Hopper Car Sizes Increase

1990’s –

Clean Air Act

High Solids

Linings

1995 –

268K to

286K

2000 –

6200’s, 6400’s

Shell Thickness

Decreases

1970’s -

Low Solids

Linings

1964 –

First Curved

Side Wall

8

•High solids linings in 1990’s have reduced flexibility

•AAR increase rail load limits

• 1995 from 268,000 lbs. to 286,000 lbs.

•Larger cubes

•5250, 5800, 6200, 6400

•Sprayer access more difficult

•Fabricators reduce wall thickness to reduce weight

•More stress on linings

•Weld seam stresses

Weld Seam Repair

9

Spot Blast Cleaning of Weld Seams

Pre-1990 Clean Air Act Amendments

•Epoxy linings with low volume solids

•Solid flake epoxy resins

•Dissolved with solvents

•40 – 50% solvents to attain sprayable viscosity – 60 to 70 KU

•High VOC’s (3.3 – 3.5 lbs/gal) and HAPs

•High EEW (500), Shell Epon 1001F

•Fast dry from solvent evaporation, leaving solid resin

•Built-in flexibility, resistant to cracking

10

•Built-in flexibility, resistant to cracking

•Lower cross-link density, less chemical resistance

•Solvent improves wetting of substrate

•Surface tension of xylene – 29 dynes/cm

Post 1990 Clean Air Act Amendments

•Epoxy linings with high volume solids

•Liquid epoxy resins

•Low EEW = 192, Shell Epon 828

•Little or no thinning, heat used to reduce to spray viscosity

•Surface wetting reduced

•Longer dry times

•Less dependent on solvent evaporation

•Accelerators added to formulation

11

•Accelerators added to formulation

•Substantial decrease in flexibility and surface wetting

•Plasticizers/leveling agents and silicone surface additives required

•Substantial decrease in impact resistance

•Greater cross-link density

•More brittle

•Improvement in chemical and corrosion resistance

•Internal (residual) stresses during cross-linking due to volumetric contraction

Effect of Equal phr of Modifiers to EEW 200 Epoxy

Cured with Cycloaliphatic Amine

10,500

9,0508000

10000

12000

Str

ess, p

si

12

0000

2,850

5,700

0

2000

4000

6000

0 5 10 15 20 25 30 35 40 45 50

Strain, %

Str

ess, p

si

Epoxy Resin Epoxy Resin with Benzyl Alcohol

Epoxy Resin with Dibutyl Phthalate Epoxy Resin with Nonylphenol

Mechanical Properties

•Traditional Flexibility / Crack Resistance Tests

•ASTM D 522 Mandrel Bend Test of Attached Organic Coatings

•Coated panel bend over conical mandrel

•Length of crack gives % elongation

•ASTM D 2794 Effect of Rapid Deformation (Impact)

13

•ASTM D 2794 Effect of Rapid Deformation (Impact)

•Sledge hammer strikes

Empirical Tests Used for Ranking Selections, butDo Not Provide Prediction of Long-term Performance

ASTM D 522 - % Elongation

for Epoxy Hopper Car Linings

5.5

7.5

5

6

7

8

14

3 3 3

0

1

2

3

4

5

Lining 1 Lining 2 Lining 3 Lining 4 Lining 5

Str

ain

, %

Mechanical Properties

•Traditional Flexibility / Crack Resistance Tests

•ASTM D 2370 Tensile Properties of Organic Coatings

•Free film pull on tensile tester, ie Instron

•Ultimate Tensile Strength and Elongation at break

15

ASTM D 2370 – Stress / Strain Properties

for Hopper Car Linings

3000

3500

4000

4500

5000

Str

es

s,

ps

i

16

0

500

1000

1500

2000

2500

0 50 100 150 200 250 300 350 400 450

Strain, %

Str

es

s,

ps

i

Polyurea Epoxy 1 Epoxy 2 Epoxy 3 Epoxy 4

ASTM D 2370 – Stress / Strain Properties

for Heat Aged Epoxy Hopper Car Linings

Mechanical Properties

Removing Hypalon Sheet Lining

17

4000

5000

6000

ASTM D 2370 – Stress / Strain Properties

for Heat Aged Epoxy Hopper Car Linings

18

0

1000

2000

3000

4000

0 1 2 3 4 5 6 7Strain, %

Str

ess, p

si

ASTM D 2370 - Stress / Strain Properties

for Epoxy Hopper Car Linings

4508

53945163

5000

6000

Heat Aged

@ 140ºF

Ambient Cured

19

0000

1219

0

1000

2000

3000

4000

0 5 10 15 20 25

Strain, %

Str

ess, p

si

Ambient Cured

y = 405.17x

2000

2500

3000

ASTM D 2370 – Stress / Strain Properties

for Epoxy Hopper Car Lining

20

0

500

1000

1500

0 1 2 3 4 5 6 7

Strain, %

Str

es

s,

ps

i

Area Under Curve

is the Energy

Needed to Break

the Material

8,091

9,018

7,000

8,000

9,000

10,000

Toughness Values for Epoxy Hopper Car Linings

21

2,581

3,620

5,427

1,498

764

1,728 1,565

2,581

0

1,000

2,000

3,000

4,000

5,000

6,000

1 2 3 4 5 6 7 8 9 10

Polymers Exhibiting High Degree of Cross-

Linking Exhibit Very High Crack Growth Rates

Mechanical Properties

22

High Strength and Modulus of Highly

Cross-Linked Polymers Have Low Toughness

And Account for Poor Fatigue Performance

Mechanical Properties

Polymers differ in the Degree of Viscoelasticity

23

Failures are Influenced by Chain Orientation,

Chain Entanglement, Chain Attraction,

Cross-Linking, Steric Effects from the Structure,

Degree of Crystallinity, Molecular Weight

Mechanical Properties

Viscoelasticity

a – Hookean Solid, no change in displacement with time

b – Newtonian Liquid, displacement is directly proportional to time.

24

proportional to time.

c – Viscoelastic solid with complete recovery

d- Viscoleastic solid with permanent deformation

Mechanical Properties

•Non-Traditional Flexibility / Crack Resistance Tests

•Four Point Bending – Dynamic Fatigue

•Coated panels on MTS

•U. of Utah four point bending experiments show lining

toughness not only a property of the formulation chemistry, but

also depends on substrate properties – smooth substrates

minimize coating cracks

•Dynamic Mechanical Analysis (DMA)

25

•Dynamic Mechanical Analysis (DMA)

•Measures viscoeleastic properties of polymers over range of test

conditions.

•Viscoelastic solids have a time dependent modulus

•Creep and Recovery – strain vs time

•Apply constant load for long time, and remove load from

sample, and measure recovery – shows how polymer relaxes

•Damping

•Glass Transition Temperature – storage modulus vs temperature

Mechanical Properties

Creep and Recovery

26

Surface Tension

•Surface additives

•Silicones

•PTFE

•Tests

For a liquid coating to wet out the steel substrate, the coating

must have a lower surface tension than the surface.

27

•Tests

•ASTM D 3825 Dynamic Surface Tension By the Fast-Bubble Technique

•Sensadyne Surface Tensiometer

•Dyne solutions

•Dyne test markers

Surface Tension

Solid Surface

Tension

(dynes/cm)

PolytetraFluoroethylene 18

Silicone oil 21

Xylene 29

Hydrophobic

– lacks

functional

groups to

form

28

Xylene 29

Polypropylene 29

Polyethylene 31

Polyvinyl Chloride 39

Hopper Car Lining ?

Epoxy resin 47

Steel 50

Water 73

form

hydrogen

bonds with

water.

Hydrophillic

– forms

hydrogen

bonds with

water

Surface Tension

29

Probe Damage to Liningin PTA Service

Surface Tension

30

Low Surface Tension Lining

Chemical Resistance

•Chemical Resistance

•Test chemicals

•Acetic acid

•Hydrochloric acid

•Spot Tests

•Panel Immersion

•Acceptance Criteria

•Blistering

31

•Blistering

•Rusting

•Cracking

•Discoloration

•Softening

•Test Duration

•1 week

•1 month

•3 months

Lining Design Properties

•Mechanical

•Flexibility – crack resistant

•Heat Aged - Tensile Strength, Elongation, Toughness

•Creep and Recovery

•Damping

•Physical

•Surface Tension, dynes/cm

32

•Surface Tension, dynes/cm

•Abrasion Resistance, mg

•Impact Resistance

•Heat Resistance

•Chemical Resistance

•Acetic Acid (terephthallic acid)

•Hydrochloric Acid (polyvinyl chloride)

Application Properties

•EHS

•Low VOC’s

•Low HAP’s

•Nontoxic, nonsensitizing

•Low odor

•Sag Resistance

Lining Design Properties

33

•Sag Resistance

•DFT + 5 mils

•Potlife time

•Can Storage Stability

Lining Application

Hand Mix Application•Material control•Potlife time

•Thinning adjustment

34

Hand Mixing•Different methods•Drums

•Unlined drums•Lined drums•Plastic drums•PE bag liners

•5 gallon cans•Less mix volume, better

Lining Application

35

•Less mix volume, better potlife control•Labor intensive

•Stainless steel cone-bottom tank

Lining Application

Weld Striping•Manufacturer’s requirements•Old cars have rough welds•Striping kits

•Plural component vs hand mix

36

Boards•Fixed

•Screw locked for safety•Paper becomes heavy

Lining Application

37

•Paper becomes heavy•Collapsible

•Lightweight•Strapped to outlet frame

Lining Application

Wood Boards•Slide over support

•Only need one •Bolted to outlet frame

38

Collapsible Aluminum Boards•Strapped to outlet frame

•Must have two•Prevents dry spray

Lining Application

39

Lining Application

Locked Boards•Short ladders•All slope sheets paper

40

Lining Application

Collapsible Aluminum Boards•Paper to prevent overspray

41

Tape Creates Edge On Slope

Outlet Frame Flange•Plastic for over spray•Rolled flange vs spray •Boards/plastic/tarps on trucks

Lining Application

42

trucks•Light held by painter during spray application

Locked Board•Paded ends•Touchup for topcoat•No board marks in primer

Lining Application

43

Ladder for long slope sheets•Prevents warts•Prevents dry spray in corners

Lining Application

44

•Warranty Period

•Start date

•Scope of Work

•Number of cars and car type

•Application requirements

•Film thickness, pinhole-free, striping, cure, etc.

•Description of service

•Commodity chemistry

•Loading conditions

Warranty

45

•Definition of failure - defects

•ASTM Standards – rusting, blisters, cracking, loss of adhesion

•Frequency of defects

•Spot – isolated area

•Uniform – over entire area

•SSPC Guide to Visual Standard No. 2

•Table 2 – Re, ASTM D610, ISO

•Excluded defects – discoloration, staining, cosmetic changes

•Weld Seams

SSPC Guide to Visual Standard No. 2

46

Re Corrosion Numbers

47

•Conditions •According to procedures and product data sheet•Holiday-free

•Exclusions•Application versus defective material•Mechanical abuse, cleaning, vibrating•Normal wear and tear•Nonapproved commodity or concentration•Excessive temperatures

Warranty

48

•Excessive temperatures•Claim Procedure

•Notification period•Access for inspection

•Reimbursement•Materials•Labor•Maximum amount•Limit of liability•Payment schedule

•Payment schedule

Warranty

100% payment if lining fails over weld seam occurs within 2 years

50% payment if lining fails over weld seam between years 2 – 3

In the event of failure, the prorated value of the lining shall be worth:

for year 1 through 3, the value of the lining shall be worth 100%

for year 4, the prorated value of the lining shall be worth 75%

for year 5, the prorated value of the lining shall be worth 50%

49

•Addendums•Procedures•Photographs, reference standards, etc.

50% payment if lining fails over weld seam between years 2 – 3

25% payment if lining fails over weld seams between years 3 – 4

10% payment if lining fails over weld seams between years 4 – 5