KWK Steel is one of best carbon seamless steel tube manufacturer and exporter in China which own ISO9001:2008 certificate. Our process include cold drawing, cold rolling, hot rolling and hot expanding. Our size rang for seamless is as below: OD:6.0-273.1mm WT:1.0-35.0mm Boiler tube standard such as ASTM A179, A192, A210, DIN17175, EN10216-2, etc. It's widely use in heat exchangers,cooling systems,condensers,etc. Contact us for more information!