ISO 4200:1991

Overview

ISO 4200:1991 - Plain end steel tubes, welded and seamless - provides general tables of dimensions and masses per unit length for plain end steel tubes (both welded and seamless). Published as the fourth edition (1991), the standard gives a ready reckoner for outside diameters, preferred wall thicknesses and linear masses to support national and international standardization and consistent tube sizing. It is not applicable to tubes primarily intended to be screwed (see ISO 7-1).

Key topics

• Scope and purpose
  • Tables of outside diameters, preferred thickness ranges and masses per unit length (kg/m) for tubes grouped as Group 1 (general purpose) and Group 2 (precision).
  • Aims to avoid inconsistent masses for the same nominal tube size across countries.
• Classification of diameters
  • Diameters are classified into Series 1, 2 and 3 (Series 1 is for fully standardized piping-system accessories; Series 2 for partially standardized; Series 3 for special applications).
• Preferred thickness ranges
  • Table 1 defines seven ranges (A–G) of preferred wall thicknesses tied to Series 1 diameters to guide selection for tubes and butt-welding accessories.
• Mass calculation
  • Mass per unit length is calculated from outside diameter (D) and thickness (T) using the formula: M = (D − T) × T × 0.0246615 (kg/m), where 0.0246615 assumes steel density 7.85 kg/dm3.
  • Adjustment factors for stainless steels: multiply by 1.015 for austenitic and by 0.985 for ferritic/martensitic grades.
  • Calculation and rounding rules: values computed to at least five significant figures, then rounded (three significant figures for values