ISO 5752:2021

Overview

ISO 5752:2021 - "Metal valves for use in flanged pipe systems - Face-to-face and centre-to-face dimensions" defines standardized face-to-face (FTF) and centre-to-face (CTF) dimensions for two‑way metal valves used as isolating and check valves in flanged piping. It covers gate, globe, diaphragm, ball, plug and butterfly valve designs and provides a harmonized set of basic series dimensions that are compatible with mating flanges conforming to equivalent EN or ASME flange series.

Key scope elements included in the standard:

• Valve types: gate, globe, diaphragm, ball, plug, butterfly (two‑way isolating/check valves)
• Pressure/size coverage: multiple PN ratings and Class ratings and a wide range of DN / corresponding NPS sizes (see Annex B for DN–NPS relationship)
• Edition: third edition (2021), prepared by ISO/TC 153 (Valves)

Key Topics

• Face-to-face (FTF) and centre-to-face (CTF) dimensions: defined for straight and angle pattern valves to permit dimensional interchangeability.
• Basic series and dimension tables: Table 1 summarizes basic series; detailed FTF/CTF values appear in Tables 2–19. Tolerances are given in Tables 20–21.
• Valve design types: treatment and alternatives (short/medium/long basic series) for gate, globe, diaphragm, ball, plug and butterfly valves.
• Pressure and size designations: supported PN values, ASME Class equivalents, and a broad DN / NPS range for international interoperability.
• Tolerances and alignment: requirements for parallelism/perpendicularity of mating faces and permitted tolerances on FTF/CTF dimensions.
• Annexes for application detail:
  • Annex A (normative): additional length for valves with ring‑joint flanges
  • Annex B (informative): DN ↔ NPS relationship
  • Annex C (informative): origin of each basic series

Applications and Users

Practical uses of ISO 5752:2021:

• Ensures dimensional interchangeability when specifying or manufacturing metal flanged valves for process piping.
• Used by:
  • Valve manufacturers and designers for product dimensioning
  • Piping and mechanical engineers for system layout and spool dimensions
  • EPC contractors and plant builders for procurement and installation tolerances
  • Maintenance and operations teams for replacement valve selection
  • Specification writers and quality assurance for compliance checks

Typical industries benefiting from the standard: oil & gas, petrochemical, power generation, water treatment, HVAC and general industrial process plants where flanged valve interchangeability and precise piping geometry are required.

Related Standards

• Mating flanges: compatible with equivalent EN or ASME flange series (refer to those flange standards when matching end connections).
• Product and valve‑type ISO standards: ISO 5752 is intended to be used alongside specific valve product standards that define pressure/temperature ratings and additional design requirements.

Keywords: ISO 5752:2021, face-to-face dimensions, centre-to-face dimensions, metal valves, flanged pipe systems, FTF, CTF, DN, NPS, PN, valve interchangeability.