ASTM A748/A748M-87(2022) PDF

Overview

ASTM A748/A748M-87(2022): Standard Specification for Statically Cast Chilled White Iron-Gray Iron Dual Metal Rolls for Pressure Vessel Use establishes requirements for dual metal rolls used in pressure-containing applications. This standard covers rolls with an outer layer of chilled white iron and a core and journals made of gray cast iron, ensuring robust performance in environments where reliable pressure resistance and durability are essential.

The standard supports international alignment, adhering to recognized principles established by the World Trade Organization’s Technical Barriers to Trade (TBT) Committee. The rolls specified by this standard are suitable for use in pressure vessels at service temperatures up to 450 °F (232 °C).

Key Topics

• Dual Metal Composition: Specifies statically cast rolls featuring a hardened (chilled white iron) outer surface for wear resistance and a gray iron interior for strength and machinability.
• Metallurgical Bonding: Mandates controlled casting methods to ensure a strong metallurgical bond between the two iron layers, vital for roll integrity under pressure.
• Hardness and Strength Requirements:
  • The chilled white iron exterior must meet specified minimum hardness.
  • The gray iron core and journals must conform to a class determined by design and tensile strength requirements.
• Test Methods and Inspection:
  • Tensile testing protocols for the gray iron portion, drawing on referenced standards.
  • Measurement of chilled white iron thickness at the roll face.
  • Machining or grinding of all surfaces is required before the roll is used.
• Dimensional and Marking Requirements: All rolls must comply with dimensional specifications, with product marking identifying the manufacturer and iron class.

Applications

The ASTM A748/A748M standard is primarily applied in the pressure vessel industry, where the performance and safety of pressure-containing components are mission-critical. Typical applications include:

• Pressure Vessels: Rolls serve as integral parts of cylinders, drums, or other enclosures that must withstand internal pressure in industrial processing, chemical, and energy sectors.
• Equipment Operating at Elevated Temperatures: Suitable for use up to 450 °F (232 °C), these dual metal rolls facilitate prolonged service life and consistent performance under thermal stress.
• Enhanced Wear Resistance: Thanks to the chilled white iron exterior, rolls provide improved resistance to abrasion, making them ideal for environments with high mechanical wear.

By ensuring a durable bond between wear-resistant and strength-optimized materials, ASTM A748/A748M enables reliable fabrication of components where safety, durability, and regulatory compliance are paramount.

Related Standards

For comprehensive material selection and design, users frequently reference the following connected ASTM standards:

• ASTM A278/A278M: Specification for Gray Iron Castings for Pressure-Containing Parts for Temperatures up to 650 °F (350 °C); sets out classes of gray iron used in the core.
• ASTM A667/A667M: Specification for Centrifugally Cast Dual Metal (Gray and White Cast Iron) Cylinders; offers guidance on an alternative casting technique for similar applications.

These related documents provide a framework for specifying and verifying materials suitable for pressure vessel use, ensuring that all components meet demanding industry requirements.

Keywords: ASTM A748/A748M, dual metal rolls, chilled white iron, gray iron, pressure vessel, statically cast, standard specification, pressure-containing parts, hardness requirements, metallurgical bonding, industrial standards.