Overview
ISO 1609:2020 - Vacuum technology - Dimensions of non-knife-edge flanges - specifies the dimensional requirements for non-knife-edge flanges and collars used in vacuum systems. The standard ensures mechanical and sealing interchangeability between bolted, clamped and rotatable flanges used in homogeneous or mixed assemblies, and covers compatibility with elastomer O‑rings and metal sealing rings when they meet the linear sealing load requirements in Annex A.
Key topics and technical requirements
- Dimensional tables and figures: Finished-part dimensions for bolted flanges, collars for clamped/rotatable flanges, and rotatable flanges with retaining rings are given in Tables 1–3 and Figures 1–3.
- Interchangeability rules: Flange and collar dimensions ensure parts from different systems (bolted, clamped, rotatable) mate correctly in both homogeneous and heterogeneous assemblies.
- Sealing compatibility: Elastomer O‑rings and metal sealing rings are permitted provided they are compatible with the linear sealing loads defined in Annex A (Table A.1). Annex A also explains the calculation basis for σ (N/mm).
- Nominal bores and tolerances: The standard defines a set of nominal bores (aligned with preferred-number series) and includes bore guidance, recess options and outside tube diameters in Annex B (Tables B.1–B.3).
- Mechanical details: Definitions and key dimensions such as bolt diameters, bolt‑hole diameters, mating face, collar width, outside diameter and number of bolt holes (n) are specified. Alignment and flatness of mating faces are required to achieve reliable vacuum seals.
- Finished-product basis: Dimensions are for finished products and do not include machining allowances; material selection should be compatible with vacuum applications and the listed dimensions.
Applications and who uses ISO 1609:2020
- Vacuum system designers and engineers specifying flanges, collars and tubing for research, semiconductor, coating, analytical and industrial vacuum equipment.
- Manufacturers and fabricators of vacuum components (flanges, clamps, retaining rings, tubes) for production and quality control.
- Procurement and standards compliance teams ensuring parts from different suppliers are interchangeable.
- Maintenance and service technicians replacing seals or mating parts in vacuum assemblies.
Related standards
- ISO 3669 (knife‑edge flanges) - for complementary flange types.
- ISO 1127 / ISO 4200 - tube dimensions referenced in Annex B.
- ISO 273 (fastener hole sizes), ISO 887 (washers), ISO 2861 (quick‑release couplings) - referenced for mating hardware and compatibility.
For designers and manufacturers working with vacuum flanges, ISO 1609:2020 is the authoritative reference for dimensioning non-knife-edge flanges to ensure interchangeability, reliable sealing and compatibility with standard tubing and hardware.
