Rust Never Sleeps
This case study explores how Union Tank Car protects its torch-cut steel plate with an environmentally friendly corrosion inhibitor.
Posted: August 11, 2008
Union Tank Car Company traces its history from 1859, when the discovery of oil in western Pennsylvania necessitated moving petrochemical bulk liquids to refineries and on to commercial outlet firms. The forerunner of the present cylindrical tank car, having a capacity of 4,200 gal introduced in 1869, was assembled with rivets.
By 1878, Standard Oil acquired the vast majority of bulk liquid tank cars and in 1880 placed the fleet under a newly-acquired rail line called Union Tank Line (UTL), which later incorporated into Union Tank Line Company (UTLC). In 1909 the federal government broke up Standard Oil and UTLC became a publicly held corporation. In 1919 the name changed to Union Tank Car Company (UTC) to avoid the inference it operated a railroad line.
The modern steel tank car was designed in 1901 by John Van Dyke, a UTC employee. Without internal framing, this design utilized double riveted sections attached to cast iron saddles that greatly reduced the car's weight. Additional improvements continued during this period, including the innovative securing of the container to a centerline under frame, for which UTC received a patent. Other innovations included special cars fitted with steam jackets to ship and unload viscous products in cold weather.
In the 1920s the Association of American Railroads, under the authority of the Interstate Commerce Commission (ICC), began issuing standard tank design and car classifications to ensure safety and uniformity among competing tank car companies. In 1931 UTC began using a new welding process called "fusion" that efficiently produced a more rigidly sealed car.
It took ten years for this method to be fully approved by the ICC. During that period, a fusion produced car survived a serious train wreck that accident investigators concluded would have been impossible with the older types of cars. Tank car construction, usage and efficiencies took a dramatic upswing during the heavy, long haul requirements of World War II.
In the 1950s UTC expanded its manufacturing, repair and leasing services in the U.S. and through its relationship with PLT Canada (Procan) began its international services of railcar design, manufacturing, maintenance and interior coating and lining services. The East Chicago, IN facility began as the flagship of the company over 40 years ago.
In the mid-1950s, the modern "Hot Dog Car" designed by UTC eliminated the underframe, tank bands, running boards, and the expansion dome, leading to larger capacity cars of 20,000 gal in 1958 and 30,000 gal by 1960. The East Chicago facility has built more than 75,000 tank cars.
Since that time, UTC changed its reporting marker to UTLX and expanded its manufacturing and repair facilities to Sheldon, TX and Alexandria, LA. The company remains the innovative leader in tank car design, construction, and repair techniques, utilizing modern ISO quality systems with manufacturing safety procedures.
Modern railroads carry petrochemical products and other hazardous chemicals efficiently and safely because UTLX continues to work with shippers and government regulators to ensure that productivity, durability and quality are harmoniously welded together.
PLASMA CUTS STEEL AT UTLX
In the early 1990s, the East Chicago facility purchased two TMC4500 CNC-controlled plasma cutting tables from MG Systems & Welding, Inc. (Menomonee Falls, WI) to accurately cut sections and shapes that make up the rail cars.
In this process, compressed gas blows at high speeds out of a nozzle as a high voltage electrical arc forms through that gas from the nozzle to the surface being cut, turning some of the gas into a hot plasma that typically reaches 15,000 deg C. The plasma is sufficiently hot to melt the metal being cut and moves fast enough to blow molten metal away from the cut.
UTLX improved its productivity because the TMC4500s produced sections more rapidly by making clean sharp cuts with accurate dimensions and contours compared to older cutting methods. These new sections could be formed and welded into the basic cylindrical containers, with end caps and support components utilizing an automotive-like progression of assembly, testing, finishing and painting stages.
The flat rolled plate sizes cut on these plasma units are typically 12 to 50 ft in length, 6 to 12 ft wide, with a typical gauge of 7/16 in, ranging in weight from 100 to 1,000 lb. Sections for tank car reinforcements are also routinely cut from TC 120 carbon steel plate and A516 for part sections.
One MG unit is an Oxygen type (#1) for the carbon steel and the other a Nitrogen type (#2) for stainless grades. Each has an 8,000 gal water tank to help cool the areas being cut so scale will not form or undesirable metallurgical effects occur.The water raises and lowers by a series of bladders. Table slats support the sections during cutting. The #1 unit cuts more sections and runs around the clock when production demands peak.
RUST PREVENTION
One of the prime concerns immediately facing UTLX personnel was the damaging consequence of rust that could occur after the cutting process. Rust can negatively affect weld integrity and reduce surface quality, preventing proper paint adhesion. This meant a water soluble corrosion inhibitor was needed and UTLX turned to PICO Chemical Corporation (Chicago Heights, IL) for assistance.
At the invitation of UTLX personnel, PICO technical and sales personnel surveyed the situation and concluded that a an environmentally friendly synthetic based product would be the best choice.
They also confirmed that using deionized water would help keep corrosive ions from accumulating. Synthetic-based corrosion inhibitors have important advantages over water-soluble oil types, depending on protection requirements and subsequent processing steps.
The advantages and disadvantages of these inhibitors are shown in Table 1.
THE SOLUTION
Plant Manager Tony Mehok and other UTLX personnel were offered PICOGUARD 17625 because it promised the best rust protection for the solution's use cost, was fully synthetic, would produce no harmful bad odors or smoke from the heat of burning, and would not go bad or lose its corrosion inhibitor properties under the contamination of metal sludge build up or stagnant conditions often found in water tanks.
This modern synthetic oil-free inhibitor technology eliminates the need for any emulsified oil or other objectionable chemicals. It eliminates the disadvantages of soluble oil containing fluids and those synthetics containing nitrites or nitrates.
After passing all chemical content hurdles, EPA and OSHA regulations, the 17625 was accepted for trial to closely monitor its effectiveness for rust protection and any downstream processing issues.
Over the years since its introduction at UTLX, 17625 met and exceeded every requirement, including: welding quality (no smoke and excellent weld integrity); non-interference with forming operations; cleanliness; excellent coating adhesion for paints; and no bleed through or color variation.
Because the concentrate is used at low concentrations (3 to 5 percent) and the solution lasts a full six months or more under heavy usage, 17625 is "very cost effective" according to Area Foreman Tom Shambo.
The workers who set up and monitor the cutting process report little or no odor, and the sections are not slippery when handled. Pieces transfer by gantries using vacuum lift plates. A tacky or slippery coating may make this handling difficult or unsafe, but 17625-coated surfaces on flat stacked steel pieces do not stain or stick from having the fluid in-between, even after long periods of waiting for the next step in the processing cycle.
Since using 17625, UTLX personnel no longer check the concentration. They simply replenish the fluid as needed because of drag out. 17625 is formulated for plasma cutting tables and other water-based systems with sufficient lubrication and biological protection for use on tables where light machining operations are also performed.
17625 is classified as a "green" fluid by being long lasting, used at low concentrations and containing no environmentally harmful chemicals.
Joe Manfreda is the marketing services manager for PICO Chemical Corporation, 400 East 16th Street, Chicago Heights, IL 60411, 708-757-4910, Fax: 708-757-4940, www.picochemical.com.
Union Tank Car Company (UTLX), 151st Street & Railroad Avenue, East Chicago, IN 46312, 219-392-6385, Fax: 219-392-6167, www.utlx.com.
MG Systems and Welding Inc., W141 N9427 Fountain Boulevard, Menomonee Falls, WI 53051, 262-255-5520, Fax: 262-255-5170, www.messer-mg.com.