BS EN 10242 is the definitive European and British standard for threaded pipe fittings in malleable cast iron
. It governs the design, manufacturing, and performance requirements for fittings used in the transmission of fluids and gases. BSI Knowledge
The standard was originally published in 1995 but was recently updated; BS EN 10242:2025
is the current version, having superseded the 1995 edition as of December 2025. BSI Knowledge 1. Scope and Technical Specifications
The standard covers a comprehensive range of fittings, including elbows, tees, couplings, unions, and plugs. BSI Knowledge Size Range: Covers threaded fittings from 1/8" to 6" (DN 6 to DN 150).
Primarily uses high-strength malleable cast iron, such as grade EN-GJMB-350-10 (blackheart) or EN-GJMW-400-5 (whiteheart). Threading: Specifies requirements for jointing threads (typically
, which uses tapered external and parallel internal threads) and fastening threads. Surface Finishes: Governs both (uncoated or lacquered) and hot-dip galvanized surfaces. Galvanized coatings must meet a minimum mass of Https://Www.En-Standard.Eu 2. Design Symbols (Classification)
BS EN 10242 uses "Design Symbols" to help engineers specify the exact material and thread combination required for a project: Design Symbol A:
The highest tier, requiring specific material grades (like EN-GJMB-350-10) and the use of tapered external (R) and parallel internal (Rp) threads. Design Symbols B, C, and D: Represent other combinations of material and thread types. 3. Performance and Pressure Ratings
BS EN 10242:1995 Threaded pipe fittings in malleable cast iron
The malleable cast iron must be either:
The standard dictates required elongation and tensile strength to ensure the fitting is ductile, not brittle.
Piping systems are the lifelines of modern industrial infrastructure, requiring components that can withstand significant internal pressure, thermal expansion, and mechanical stress. Among these components, malleable cast iron fittings play a critical role in changing the direction of flow and joining pipe sections.
BS EN 10242, officially titled "Fittings made of malleable cast iron for threaded pipe joints," is the governing standard in the United Kingdom and across Europe for these components. It supersedes the long-standing British Standard BS 143, harmonizing requirements with European norms. This paper outlines the technical specifications of BS EN 10242 and its implications for engineering design and safety.
Tensile testing is performed on separately cast test bars or samples taken from the fitting to verify the tensile strength and elongation properties promised by the grade designation.
Compliance with BS EN 10242 is not merely a regulatory checkbox; it is a matter of operational safety. A failure in a threaded fitting can lead to:
By standardizing the density of the iron and the thread engagement depth, the standard ensures that the fitting fails at a pressure significantly higher than the system's design pressure, providing a safety factor.