WITH the introduction of its second generation Lean Duplex stainless steel tanks, Brenner Tank LLC has trimmed about 700 pounds from the typical DOT407 chemical trailer constructed of 316 stainless steel. Less tare weight means more payload for tank fleets.
The weight savings come from being able to fabricate these second-generation Lean Duplex tanks from 12-gauge material. First-generation Lean Duplex tanks — as well as 316 stainless steel — usually are specified with 10-gauge shells. Lean Duplex 2 tank trailers with 12-gauge shells are built under DOT Special Permit.
”We received the permit in early 2010, and we have built 17 Lean Duplex 2 DOT407 trailers so far this year,” says John Cannon, vice-president of engineering for Walker Group Holdings. “We have an order for 10 more, and we expect demand to continue growing as more fleets learn about the benefits of this stainless steel.
“A key motivation for moving forward with Lean Duplex 2 tanks was the realization that the 2010 diesel truck engines would add more than 800 pounds to a tractor trailer rig. We knew that 12-gauge Lean Duplex could offset much of the engine weight gain. In addition, Lean Duplex simply has better tensile and yield strength. Yield strength alone is 2½ times greater than 316 stainless steel. Fatigue characteristics are good, and Lean Duplex does very well with temperature fluctuations.”
Produced by Outokumpu, a leading stainless steel manufacturer based in Finland, Lean Duplex's official designation is LDX 2101. Cargo tanks built of this material can handle any chemical currently hauled in a tank constructed of 316 stainless steel. Sulfuric acid is one of the few products that cannot be transported in a Lean Duplex tank.
LDX 2101 provides the pitting resistance of 316 stainless steel but with twice the mechanical strength of 304 or 316, according to Outokumpu officials. In addition, LDX 2101 is less costly to manufacture because it contains one-fifth the nickel (a mineral that has seen major price increases in recent years) of 304 and 316 stainless steel.
Cargo tanks built of Lean Duplex are very robust, according to Cannon. Tanks built of this stainless steel should be able to remain in service well in excess of 20 years, as long as they are properly used and maintained, he says.
Brenner Tank introduced its first-generation Lean Duplex chemical tank trailers in 2007, and about 100 of these units are in service today. These tanks were fabricated from 10-gauge Lean Duplex stainless steel and weighed roughly the same as a comparable DOT407 tank made of 316 stainless steel.