Duplex S31803 Tubing is a type of stainless steel tubing that contains about 10% chromium, providing high chloride stress corrosion cracking resistance. The tubing's structure comprises austenite pools surrounded by a constant ferrite phase, which doubles the yield force of standard austenitic stainless steel grades. This tubing is the most commonly used duplex grade, but it's recommended for use at least 300 degrees Celsius due to embrittlement.