Overview
SIST ISO 6708:1995 is an important international standard for the piping industry, titled Pipework Components - Definition and Selection of DN (Nominal Size). Published by SIST, this standard specifies the definition of DN (nominal size) for components used in pipework systems. It provides a consistent system for referencing pipe sizes, ensuring clarity and interoperability among manufacturers, suppliers, and engineering professionals worldwide.
Replacing the first edition from 1980, the 1995 revision incorporates updated definitions and an expanded list of preferred DN values. The standard is essential for anyone involved in the design, manufacturing, or specification of metallic pipes and fittings, particularly where the DN designation system is applied.
Key Topics
- Definition of DN (Nominal Size):
- DN is an alphanumeric size designation for pipework components, represented as "DN" followed by a dimensionless whole number. It is indirectly related to the physical bore or outside diameter of pipe ends.
- The DN figure is primarily for reference and not a directly measurable value unless specified in related standards.
- Preferred DN Values:
- SIST ISO 6708:1995 includes a comprehensive list of preferred DN values, ranging from DN 10 up to DN 4,000.
- Designation System Usage:
- The standard addresses the relationship between DN and component dimensions such as outer diameter (OD) or inner diameter (ID) when applied within other relevant standards.
- Distinction from Other Sizing Methods:
- DN is distinguished from other size designation methods such as NPS (nominal pipe size), OD (outside diameter), and ID (inside diameter), which are not defined within this standard.
Applications
- Piping System Specification:
- DN is widely used for specifying pipework components such as pipes, valves, flanges, and fittings across various industries including water supply, HVAC, petrochemical, and industrial process systems.
- Product Interchangeability:
- Adopting the DN size system improves product compatibility and interchangeability among different manufacturers and regions.
- Standardized Documentation:
- DN references streamline technical documentation and enable accurate communication of design requirements across multidisciplinary teams.
- Procurement and Supply Chain:
- Clearly specified DN sizes facilitate smoother procurement processes and inventory management for pipework components.
- Compliance and Quality Assurance:
- Utilizing components labeled with standardized DN sizes ensures compliance with international norms, supporting consistent safety and performance benchmarks.
Related Standards
When working with SIST ISO 6708:1995, consider these related international standards for a comprehensive approach to piping and pipework component specification:
- ISO 7005: Metallic flanges - General requirements and dimensions
- ISO 4200: Plain end steel tubes, welded and seamless - General table of dimensions and masses per unit length
- ISO 3126: Plastics piping systems - Measurement of dimensions
- ISO 4161: Steel tube, non-ferrous tube - Size designation systems
These standards complement ISO 6708 by providing additional dimensional, material, and connection standards for pipes and associated components.
Keywords: pipework components, DN nominal size, piping standard, ISO 6708, selection of DN, dimensioning, piping systems, size designation, standardization, metallic pipes, SIST
