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IS 1239:2004 Part 1 is the Indian Standard (BIS) for mild steel tubes, tubulars and other wrought steel fittings - part 1: mild steel tubes. This standard specifies the requirements for welded and seamless plain end or screwed and socketed mild steel tubes used for water, non-hazardous gas, air, and steam. It classifies steel tubes into Light, Medium, and Heavy grades based on thickness and mass.
Specifies requirements for plain and galvanized mild steel tubes for water, gas, steam, and air.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Pipes are commonly identified at the site by painted colour bands: Yellow for Light (Class A), Blue for Medium (Class B), and Red for Heavy (Class C).
! Medium and Heavy class tubes are generally recommended for underground laying or high-pressure plumbing to ensure adequate durability and corrosion allowance.
! For potable water supply, always ensure tubes are Hot-Dip Galvanized (GI) according to IS 4736, as ungalvanized 'black' tubes will quickly rust.
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
mild steelgalvanized ironblack steelsteel pipes
International Equivalents
Similar International Standards
BS EN 10255:2004BSI (UK) / CEN (EU)
HighCurrent
Non-alloy steel tubes suitable for welding and threading - Technical delivery conditions
Covers non-alloy steel tubes for water, gas, and other fluids; very similar application scope.
ASTM A53/A53M-22ASTM (US)
MediumCurrent
Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless
Covers general-purpose steel pipe for mechanical and pressure applications, including conveying fluids.
JIS G 3452:2019JISC (Japan)
MediumCurrent
Carbon Steel Pipes for Ordinary Piping
Specifies carbon steel pipes for low-pressure steam, water, oil, gas, and air piping.
BS 1387:1985BSI (UK)
HighWithdrawn
Specification for screwed and socketed steel tubes and tubulars and for plain end steel tubes suitable for welding or for screwing to BS 21 pipe threads
Historically, this was the direct basis for IS 1239, covering the same 'Light', 'Medium', 'Heavy' classes.
Key Differences
≠IS 1239 classifies pipe wall thickness into 'Light', 'Medium', and 'Heavy' series based on nominal bore. In contrast, ASTM A53 uses a 'Schedule' system (e.g., Sch 40, Sch 80), which defines wall thickness for a given nominal pipe size (NPS).
≠Pipe threads specified in IS 1239 conform to IS 554 (based on British Standard Pipe thread - BSP). American standards like ASTM A53 specify NPT (National Pipe Taper) threads as per ASME B1.20.1. These thread types are not interchangeable.
≠IS 1239 specifies steel grades primarily by yield strength (e.g., YSt 210, YSt 240). ASTM A53 uses Grades (e.g., Grade A, Grade B) with different chemical composition and strength requirements. EN 10255 uses a steel designation like S195T.
≠While all standards specify hot-dip galvanizing, the minimum required zinc coating mass can differ. For instance, ASTM standards often require a slightly heavier coating weight compared to the minimums specified via IS 1239's reference to IS 4736.
Key Similarities
≈The primary scope of all standards is to provide specifications for low-carbon (mild) steel tubes for general-purpose conveyance of fluids like water, air, non-hazardous gas, and low-pressure steam.
≈All standards cover both seamless and welded (typically Electric Resistance Welded - ERW) manufacturing processes for the tubes.
≈The standards provide options for similar finishes, principally 'black' (uncoated or with a temporary protective varnish) and hot-dip galvanized (zinc-coated).
≈All mandate a core set of mechanical and quality tests, including tensile tests, flattening/bend tests, and a hydrostatic pressure test to ensure pipe integrity and material properties.
Parameter Comparison
Parameter
IS Value
International
Source
Material Grade (Typical)
YSt 240
S195T
BS EN 10255
Minimum Tensile Strength (for typical grade)
320 MPa (for YSt 240)
320 - 520 MPa (for S195T)
BS EN 10255
Thickness Designation System
Light, Medium, Heavy classes
Schedules (e.g., Sch 40, Sch 80)
ASTM A53/A53M
Wall Thickness (50mm NB 'Medium' vs Sch 40)
3.65 mm (for 50mm Medium)
3.91 mm (for 2" NPS Sch 40)
ASTM A53/A53M
Pipe Thread Standard
IS 554 (BSP based)
ASME B1.20.1 (NPT)
ASTM A53/A53M
Hydrostatic Test Pressure
5.0 MPa (for all sizes)
50 bar / 5.0 MPa (for all sizes)
BS EN 10255
Max Carbon Content (for comparable welded grade)
0.20%
0.25% (for Grade A)
ASTM A53/A53M
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Hydraulic test pressure5 MPa (approx. 50 kgf/cm²)
Tolerance on thickness (Light tubes)+ Not limited, -8 percent
Tolerance on thickness (Medium and Heavy tubes)+ Not limited, -10 percent
Tolerance on mass (Single tube, Medium/Heavy)± 10 percent
Minimum mass of zinc coating (if galvanized as per IS 4736)360 g/m²
Standard random length of tubes4 to 7 meters
Tables & Referenced Sections
Key Tables
Table 2 - Dimensions and Nominal Masses of Steel Tubes - Light
Table 3 - Dimensions and Nominal Masses of Steel Tubes - Medium
Table 4 - Dimensions and Nominal Masses of Steel Tubes - Heavy
What do the Yellow, Blue, and Red colour bands indicate on MS pipes?+
They indicate the pipe class: Yellow for Light, Blue for Medium, and Red for Heavy thickness.
What is the standard hydraulic test pressure required for IS 1239 pipes?+
Every tube must withstand a hydraulic pressure of 5 MPa (approx. 50 bar) without showing any signs of leakage.
What is the difference between Nominal Bore (NB) and Outer Diameter (OD)?+
NB is the approximate internal bore size used for designation. The actual Outer Diameter (OD) is strictly specified in Tables 2 to 4 and is significantly larger than the NB.