Malleable iron fittings are a durable threaded pipe connector designed for the high-pressure transportation of water, gas, oil, steam and air and are used in a wide variety of applications from plumbing to fire suppression systems.
According to the BMTFA[1] (British Metals Tubes and Fittings Association) malleable iron fittings are available in both whiteheart and blackheart forms, and both perform satisfactorily in service. However, the association notes each material type can be manufactured in a range of different material grades, meaning not all fittings have the same performance characteristics.
Whiteheart malleable iron is produced using a longer, higher-temperature annealing process that decarburises the outer layer of the casting. If the fitting is cut in half, the core appears silvery white, giving the material its name. This improves ductility and machinability while producing a smoother external surface perfect for galvanising.
Blackheart malleable iron has a grey core and also offers good ductility. However, its rougher surface makes achieving a high-quality galvanised finish more challenging.
GF is almost exclusively the only supplier of whiteheart malleable iron fittings in the UK, manufacturing under the updated BS EN 10242:2025 ‘Threaded pipe fittings in malleable cast iron’ standard, at its production facility in Traisen, Austria. The manufacturing process delivers consistently high-quality fittings while supporting sustainable production practices.
GF malleable iron fittings incorporate an advanced thread design, improving joint integrity, corrosion resistance and long-term reliability. Unlike conventional fittings that may contain "wash-out" threads, GF fittings feature fully cut precision threads, reducing the amount of exposed, uncoated metal in galvanised fittings. This improves corrosion protection and reduces the potential for water to reach vulnerable areas of the fitting. The fittings also have increased wall thickness around the threaded section, providing additional strength where the highest mechanical stresses occur, to withstand higher assembly loads.
Each fitting is machine chamfered at the leading edge of the thread. This guides thread sealing materials into the joint during assembly, helping to produce a more effective seal, reducing the likelihood of leaks. The extended annealing process means fittings require less torque to make the watertight connection and can withstand up to 30% higher assembly forces.
Sustainability is at the heart of GF’s manufacturing process. The fittings comprise of 96% iron with the remainder consisting of carbon and a small amount of other trace metals and elements. 100% of this iron comes from recycled sources. For example, old railway tracks that once carried millions of people are now trusted to carry services through miles of pipework.
GF offers the most comprehensive range of malleable iron fittings available, with more than 1,700 individual fittings, enabling complete pipework systems to be specified from a single manufacturer, simplifying procurement and ensuring product compatibility.
With BIM files, Environmental Product Declarations (EPDs) and experienced project teams available you can be sure specifications meet the latest standards and project requirements. Find out more about our range of malleable cast iron fittings today.
[1] https://www.bmtfa.org/about-us/
