ISO 12573:2010

Overview

ISO 12573:2010 - Aircraft - Tubing tolerances - Inch series specifies the dimensional tolerances for round-section inch-series tubing used in aircraft. Its purpose is to harmonize tolerance limits across aerospace tubing specifications so manufacturers, designers and procurement teams have a consistent reference. Nominal sizes are identified by dash numbers (e.g., −04 = 4/16 in = 0.250 in = 6.35 mm). Although called an “inch series”, dimensions are given in SI units with inch equivalents for convenience.

Key topics and technical requirements

• Scope and reference: Applies to round-section aircraft tubing. Standard dimensions are referenced from ISO 8575 (Aerospace - Hydraulic system tubing).
• Materials covered: Titanium and titanium alloys; aluminium alloys; corrosion resistant steel (CRES); nickel alloys.
• Dimensional characteristics defined:
  • Outside diameter (OD) - mean or absolute OD and associated tolerances (tables per material and nominal size).
  • Inside diameter (ID) - tolerances for ID where specified.
  • Wall thickness (t) - tolerances or minimum allowable thickness (e.g., titanium: actual thickness not less than 95% of nominal; CRES: ±10% unless specified).
  • Ovality - difference between max and min OD; usually no additional allowance beyond OD limits except specific aluminium cases.
  • Concentricity - defined in terms of variation in wall thickness; normally contained within thickness tolerances.
  • Straightness - maximum depth-of-arc (curvature) limits for given tube lengths (tables provided).
  • Fixed length tolerances - default length tolerances for ordered fixed lengths (different limits for common lengths like 3.7 m / 7.3 m).
• Application rules: Order documents should specify which material section applies and whether tolerances on OD and either ID or thickness are required. Default tolerances apply unless otherwise stated.

Practical applications and users

Who uses ISO 12573:2010:

• Aerospace designers and stress analysts specifying tubing for fluid systems.
• Tube manufacturers and suppliers producing inch-series aircraft tubing.
• Quality assurance and inspection teams checking OD, ID, wall thickness, ovality, concentricity and straightness.
• Procurement and contracts teams specifying acceptance criteria in purchase orders.
• Maintenance and repair organizations assessing replacement tubing compliance.

Practical benefits:

• Ensures interchangeability and reliable fit for fittings and assemblies.
• Reduces ambiguity in purchasing and inspection by providing harmonized tolerance tables.
• Supports material-specific tolerance practice (titanium, aluminium, CRES, nickel alloys).

Related standards

• ISO 8575 - referenced for standard nominal sizes and thicknesses (Aerospace - Hydraulic system tubing).
• Use ISO 12573:2010 alongside material and process specifications when defining complete acceptance criteria.

Keywords: ISO 12573:2010, aircraft tubing tolerances, inch series tubing, outside diameter tolerances, wall thickness tolerances, ovality, concentricity, straightness, titanium tubing, aluminium tubing, CRES, nickel alloy tubing.