Tank Liners

Although many have learned the hard way, a growing number of transporters are recognizing that successful maintenance of lined trailers actually begins during the manufacturing process -- not after the equipment has been put into use. In fact, an incorrect choice of liner before installation even begins can make it virtually impossible for any maintenance program to work effectively.

"Too many transporters still believe one liner fits all products, and that's a big mistake,'' said Shawn Evans, project manager for the industrial division of Tank Services Co., based in Canton, Ohio. "Some of these folks simply don't want to spend the money to buy extra trailers, and that's understandable. But if you're using the wrong liner, you're going to have to keep replacing it and that's expensive, too.''

Founded in the early 1970s, privately owned Tank Services Co. operates three divisions focusing on oil and gas, shop services and industrial services. Within the industrial division, the company installs and repairs lined trailers for a variety of companies in the Midwest, including Manfredi Motor Transit Co.

Although Tank Services lines trailers of all sizes, most are 6,000 to 7,000-gallon bulk trailers with multiple compartments. It normally takes about five days to install a liner, Evans said. The DOT-certified company, located on a seven-acre tract, employs about 50 workers at its 30,000-square-foot inspection, installation and repair facility.

It isn't uncommon for Tank Services to receive a trailer needing liner repairs prematurely, Evans said. Usually that's because the wrong ! liner was installed, or the right liner was not installed correctly.

"One liner does not fit all,'' Evans said. "There are different types of liners that can be used depending on the type of product that will be transported. Depending on the product, you might use an epoxy liner that may be a phenolic or novolac epoxy. A lot of what we do is educate customers about the type of liner they need. The truth is, a lot of people do not do enough research. They don't know, for instance, that rubber often is the best liner for concentrated sulfuric acid.''
Many transporters also do not understand how liners can be damaged. External welding can cause damage to trailer liners, Evans said, and so can improper cleaning. Dropping heavy tools, including wrenches, on the liners also can damage them

Key to the long-term success of a lined trailer, and one of the biggest challenges for those who install them, is the surface preparation, Evans emphasized. Any trailer that has had previous exposure must be completely free of all residue and hydrocarbons before a liner can be installed. To eliminate contamination, Tank Services uses a "white-metal abrasive blast cleaning'' process to reach the proper anchor profile. During the pre-bake process, a high-velocity heating system blows 300-degree air into the trailer.

Once the trailer is free of contaminants, the liner coating can be applied. Upon completion of the installed lining Tank Services Co. has the ability to force cure the lining. The goal is to raise the temperature of the metal 60 degrees per hour until the desired cure temperature is achieved and held for the specified time duration.

"This is another area where a lot of mistakes can be made,'' Evans said. "There are a lot of misconceptions relating to the coating process. Thicker is not better, although that's what a lot of users were told for many years. In fact, if there's too much coating, you're going to have a lot of cracking caused by normal heat and stress. It's important you give close consideration to the product you are hauling and the manufacturer's specifications on the coating.''

Unfortunately, many transporters haul a different product every day -- often in the same trailers. Even with regular cleaning, no liner can accommodate a wide assortment of products.

"That's not what they are designed to do,'' Evans said. "They have many benefits, but they aren't designed to be a dumping ground! for everything you want to haul. Fortunately, transporters are becoming much more knowledgeable in terms of both installation and use of liners.''

Coating Solutions Article