A Guide to BS Standard Malleable Iron Fittings

Apr 9, 2024 | News

Fluid Tech Malleable iron fittings come in different shapes and sizes to match different pipe types and needs. Commonly, they adhere to standards like the British Standard (BS) and the American Standard. Usually, they are essential components in plumbing and HVAC systems to link pipes and manage the flow of fluids.

BS Standard Details

  • Classes 150 and 300: These classes refer to pressure-temperature ratings.
  • Material: ASTM A197.
  • Dimensions: ASME B16.3 and ANSI/ASME B1.20.1.
  • Coatings: ASTM A153 and ASTM B633.
  • Available in black and hot-dip galvanized versions.
  • Threaded according to EN 10226-1.
  • Tested at 80 psig for quality assurance.
  • Common sizes: 1/8″ to 4″.

Example dimensions (in inches):

  • 1/2″: Outside Dia. of Band = 1.20, Thread Length = 0.43
  • 3/4″: Outside Dia. of Band = 1.46, Thread Length = 0.50
  • 1″: Outside Dia. of Band = 1.77, Thread Length = 0.58
  • 2″: Outside Dia. of Band = 2.96, Thread Length = 0.75
  • 3″: Outside Dia. of Band = 4.28, Thread Length = 0.98

Quality Assurance:

Ward Class 150 Malleable Iron Fittings undergo rigorous quality control.

Accurate threads machined to ASME standards.

Chamfered opening for easy pipe engagement and thread protection.

Why BS Standard Malleable Iron Fittings Matter:

Essentially, “BS standards” are guidelines established by the British Standards Institution (BSI) to ensure that fittings meet certain quality criteria. Adhering to these standards ensures that manufacturers maintain high-quality and high-performing fittings.

malleable iron fittings dimensions

Common Uses of Malleable iron fittings:

  • Plumbing Systems:

Connecting pipes in residential and commercial plumbing.

Changing direction and reducing/enlarging pipe sizes.

  • Gas Systems:

Connecting gas pipes.

Regulating gas flow.

  • Steam Systems:

Connecting steam pipes.

Regulating steam flow.

  • Fire Protection Systems:

Connecting pipes.

Controlling water flow.

  • Industrial Piping Systems:

Connecting pipes for water, oil, and chemical transport.

Used in both high and low-pressure systems.

Advantages and Limitations of Malleable iron fittings:

High Tensile Strength:

  • Malleable iron has high tensile strength, making it suitable for high-stress applications.
  • Comparable to many steel grades, it’s a popular choice where steel is unavailable or too expensive.


  • Malleable iron is highly ductile, allowing it to be molded and reshaped without breaking.
  • Ideal for creating intricate shapes that are challenging with other ferrous materials.

Excellent Machinability:

  • Relatively easy to machine compared to other materials.
  • Ideal for tasks like cutting, drilling, and shaping.

Corrosion Resistance:

  • Malleable iron exhibits excellent corrosion resistance.
  • Suitable for outdoor applications, even in harsh weather conditions.

However, keep in mind the following disadvantages:


  • Despite its strength and ductility, malleable iron remains brittle.
  • Prone to cracking or breaking under excessive pressure.

Limited Weldability:

  • Unlike steel, malleable iron cannot be welded.
  • Unsuitable for applications requiring welding.

Low Fatigue Resistance:

  • Not ideal for cyclic loading applications (e.g., crankshafts).


  • Relatively expensive compared to some materials like steel.

In summary, malleable iron is versatile, but understanding its pros and cons is crucial for informed decision-making. Always consult Fluid Tech wholesale malleable iron fitting manufacturer before choosing materials for your projects!