UTLX Coatings and Linings

By combining experience with experiments, UTLX Coatings Research and Development people help customers select the best protective systems for tank or hopper car fleets.

Although the shipper is responsible for selecting and providing lining and coating specifications and requirements for the commodity to be transported, Union Tank Car and its Canadian affiliate Procor set up an in-house coatings and linings consulting service for customers in the U.S., Canada and Mexico. That determination launched what is now known as UTLX Coatings Research and Development with a staff of professionals who become busier every day.

"Two trends fueled the thrust for the new venture." notes Jim Molnar, technical manager of coatings and linings. "One is a greater stress on absolute product purity, where even the slightest bit of contamination just isn't acceptable. The other is a stronger emphasis on appearance and durability of the car's exterior paint. Many shippers have told us that they really improve their image among end users when they present better looking railcars."

UTLX Coatings Research and Development draws upon a long legacy of expertise that began back in 1936 with Lithcote, the first company to apply a protective interior coating to a tank car. While Union Tank Car now offers a full line of Lithcote products, Molnar stresses that unlike many supplier services, UTLX Coatings Research and Development's goal is objective testing and analysis, not merely recommending in-house products.

Tank car coatings and linings have two main functions. Primarily, they are used to protect the commodity from contamination by the base metal of the tank or hopper car. However, coatings and linings are also used to prevent the base metal from corroding due to the chemical nature of the commodity being shipped.

The shipper is responsible for selecting and providing particular lining and coating specifications and requirements for the commodity to be transported.

The following links can be used to view the Lithcote Resistance Chart for your specific product:
A B C D E F G H I J K L M N O P Q R S T U V W X Z

Coating Types

According to the Association of American Railroads, a "coating" refers to any paint-type, protective covering applied in one or more layers to the interior of a tank (or hopper) car to act as a barrier between the base metal and the commodity.

There are several types of coating materials which may be applied to the interior of railcars. The type selection and thickness of the coating depend on the commodity to be shipped and the type of railcar.

The full thickness of the coating is achieved by layering coats of the material. Generally, thicker films are used to protect the car from the commodity and thinner films are used to protect the commodity from the railcar.

THIN FILM (less than 10 mils)

Phenolic
Epoxy
Epoxy Phenolic
Inorganic and Organic Zinc

MEDIUM FILM (10-20 mils)

Epoxy
Epoxy Phenolic
Epoxy Urethane

HEAVY FILM (20-25+ mils)

Elastomeric Urethane
Vinyl Ester
Plastic (thermal spray)

Lining Types

The Association of American Railroads defines a "lining" as any sheet or laminated type material, glass, or fused metal applied to the interior of a tank (or hopper) car to act as a barrier between the base metal and the commodity.

Linings generally come in sheet format and must be applied to the railcar interior using a specific cementing process. A variety of thickness (180+ mils) can be used, depending on the commodity being shipped and the type of railcar involved. The following list represents some, but not all, of the lining material options.

Natural rubber (black or white)
Butyl or Chlorobutyl (synthetic rubber)
Fluoropolymer
Metal

UTLX Coatings Research and Development works with more than 400 different coatings and linings from many suppliers. It uses the latest high-tech lab equipment to conduct a wide range of tests including:

Product effects on linings and coatings:

Technicians immerse coating samples, or coupons, into containers of actual customer products, simulating real-life shipping temperatures and movement. If necessary, the samples can be tested in a special "cold wall" cell that simultaneously creates different temperatures on each surface.

"This is helpful for customers who might be shipping a product loaded very warm, but traveling through very cold weather," Molnar explains. "It can provide a true test of how a coating will perform under very specific conditions."

Effect of coating film defects on performance:

If a paint finish is scratched or gouged during railcar use, how will a coating react around the damaged area? Will it peel or blister if exposed steel on the tank rusts?

UTLX Coatings R&D can test such a scenario using a cabinet that introduces purposely distressed samples to controlled moisture conditions simulating high humidity, rain, even salt water. The effects are microscopically examined to project the likely rate of any coating deterioration.

Impact of dry-loaded products on interior coatings:

Can a coating withstand potential abrasion from loading and unloading of dry products such as plastic pellets shipped in hopper cars? UTLX Coatings Research and Development technicians can find out using a tube-shaped apparatus that lets tested products free-fall against coating samples for time periods equal to loading/unloading cycles.

Effects of different weather conditions on exterior paint:

Since many customers are concerned about how their cars will look after several years, one frequently used instrument is a "weatherometer" chamber that subjects samples to alternate periods of simulated sunlight and darkness, even controlled "rainstorms". Weather effects can be tested either in real time, or accelerated in a device that compresses up to ten years' paint exposure into about six months.

Laboratory and field test results showing the resistance characteristics of Lithcote® coatings when exposed to various tank car commodities.

The chart below gives exposure data for a number of Lithcote interior coatings. The information, which is based on laboratory tests, service experience and field tests, does not include all possible mixtures, even of the listed materials.

"Room temperatures" are 77F." Elevated temperatures" are given in degrees Fahrenheit.

Temperatures listed are neither maximum nor minimum, but serve as guides only. Exposures under conditions where galvanic action is present would modify the results and the recommendations.

Wherever possible, exposure on less noble metals, in contact with uncoated more noble metals, immersed in an electrolyte, should be avoided. At the very least, the more noble metal, as well as the less noble, should also be coated.

Reliance on thin film (less than 10 mils) coatings as barriers to very aggressive (more than 10 mpy) solutions, in mild steel vessels, is not recommended even when the coating itself is completely inert. Coating damage, pinholes on metal welds, pits, sharp edges, and normal wear inject the probability of metal exposure with consequent concentrated corrosion. Heavier films such as LC-82 are indicated in these instances.

Most of the coatings involved in these tests are suitable for use in contact with foods; contact your sales representative for specific information.

We have compiled the test results as listed, conservatively, to the best of our ability and in good faith. However, no guarantee is expressed or implied for similar service in the field or plant when not under our operating control. Guarantees are properly discussed only when complete data on specific undertakings are at hand. Our technical service laboratory may have data on coatings not included herein. Such coating may be experimental or may be materials available from other manufacturers.

TYPICAL PRODUCTS	RECOMMENDED LITHCOTE® COATINGS	COLOR AND TYPE	CHARACTERISTICS
Phenol, Oils, Waxes, Formaldehyde	LC-19H	Silver-brown phenolic	Special corrosion-resistant metallic pigments
Alcohols, Solvents, Glycols, Gasoline, Fuel Additives, TiO2	LC-24H	Deep orange phenolic	Pure phenolic
Latex, Molten Sulfur, Alkaline products (pH > 11), resins, slurries	LC-34H	Gray, mauve, teal epoxy phenolic	One-component high bake alkali-resistant
Sugars, Foods, general chemical services	LC-82	Gray, white polyamide epoxy	High degree of general resistance; protects taste, odor, clarity
Caustic Soda, Salts, Pesticides, Brines	PlasChem 2310	Gray, white amine epoxy	Outstanding performance in corrosive environments
Sulfuric Acid over 62.5%	LC-73H	Deep reddish-brown phenolic	Excellent acid and chemical resistance
Corn syrup, food products	LC-25H	Silver-tan	One-component high bake heat and alkali-resistant
special applications	"C" Series	Black hi-bake modification to LC-24H or LC-34H	Enhanced heat-cycle and permeation resistance
Plastic pellets and resins, granular foods	LC-88	White, cruiser blue	Flexible polyamide epoxy for dry services

Since coating and lining work represents a major share of the services provided at many UTLX and Procor repair shops throughout the U.S. and Canada, we frequently conduct research to determine optimal application guidelines such as thickness, best mix of coating material with solvents, and procedures for spray applications.

"Customers can expect prompt answers to their inquiries, often in their initial conversation with a UTLX Coatings Research and Development representative," reports Molnar. The group's greatest success, however, has been in helping customers overcome tough problems that might otherwise go unresolved. Even better, such value-added service is generally performed at no charge for Union Tank Car and Procor customers. Here are a few cases from the UTLX Coatings Research and Development's files:

• Amoco Oil's transportation executives had observed that the once-shiny paint on their new tank cars began to fade noticeably after a couple of years, particularly in areas most often facing the sun. They challenged us to figure out how to improve the finish without using special gloss-retentive paints that can cost up to four times as much as standard coatings.

After screening dozens of reasonably-priced paints, we subjected samples of selected candidates to several months of ultraviolet exposure and moisture. One paint demonstrated gloss retention similar to higher-priced paint systems and was subsequently applied to the company's cars.

• Hoechst Celanese was using stainless-steel tank cars to ship dimethyl terepthalate (DMT), but wondered whether a coated carbon steel car could provide adequate product protection at a lower cost. UTLX Coatings Research and Development helped locate another coating that could stand up to the product, as well as developed specific application procedures and inspection schedules with the help of Procor's Oakville, Ontario, shop. After several month

s of trial shipments, the company's executives became confident enough to use the product as the new standard for DMT shipments.

• Canadian customer Cominco Ltd. noticed some of its recently lined sulfuric acid cars developing a bathtub ring where their coatings were beginning to peel off. UTLX Coatings Research and Development learned through discussions with Cominco representatives that a clarifying agent was being added to each loaded tank just before shipping. Tests determined that this agent was the culprit causing the lining reaction, and the condition ended when the clarifying procedure was appropriately modified.

Some of our efforts have led to residual benefits for many other shippers. For instance, Lithcote Direct To Metal Epoxy Paint was internally developed and now has been adopted as the proprietary finish for leased UTLX cars."

"A few years ago, we used perhaps 20 different types of exterior paint on UTLX cars," recalls Molnar, "and now we have standardized on one. By consolidating our options to one effective paint, we can develop much more consistency in our application and maintenance procedures."