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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
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