DIN1629 is a standard for seamless circular tubes of non-alloy steel with special quality requirements.It is made up of unalloyed steel, and it can be manufactured with no limiting working pressure values.Its main grades are DIN 1629 ST 35, DIN 1629 ST 52, and DIN 1629 ST37. ST52 tube is the material grade designation for this standard, which specifies a minimum yield strength of 355 N/mm�² and a maximum tensile strength of 650 N/mm�². This material is commonly used in the construction of machinery, structural engineering, and other applications where high strength and durability are required.