1.Michigan Seamless Tube LLC produces seamless carbon and alloy tubing in sizes from 1 to 5 in rounds, squires, hex and shapes. We have a capacity of 36,000 tons per year and a workforce of 250 people. The plant has been in operation for eighty years. 2. We sell to the heat exchanger, boiler tube and mechanical markets. 1.Our steel supply is SBQ bars purchased in sizes from 2.75 to 4.5 .