ISO 14691:2008

Overview

ISO 14691:2008 specifies requirements for flexible couplings used for mechanical power transmission in the petroleum, petrochemical and natural gas industries. It applies to couplings that transmit power between rotating shafts of two machines for general-purpose applications, typically up to 4 000 r/min, where the first lateral critical speed is above the running speed range (stiff-shaft machines). By agreement, the standard can be applied outside these limits.

Key topics covered

• Coupling types: gear (and other mechanical contact types), metallic flexible‑element and various elastomeric couplings; all‑metal and mixed construction (including composites) are covered.
• Misalignment accommodation: design for parallel (lateral) offset, angular misalignment and axial displacement without imposing excessive loads on connected machines.
• Design and materials: general requirements for coupling design and materials of construction to suit industrial service conditions.
• Attachment methods: approved methods for attaching couplings to shafts (including tapered sleeve and other proprietary devices).
• Inspection and testing: requirements and methods for factory inspection and testing of couplings to verify conformity with the standard.
• Scope exclusions: explicitly does not apply to special coupling types such as clutch, hydraulic, eddy‑current, rigid and radial‑spline couplings.
• Limitations: ISO 14691:2008 does not define criteria for selecting coupling types for specific applications - selection remains the responsibility of the user, designer or OEM.

Practical applications

• Use ISO 14691:2008 when specifying, procuring or evaluating flexible couplings for rotating equipment in oil & gas facilities, refineries and petrochemical plants.
• Typical applications include coupling drivers and driven machines (e.g., pumps, compressors, turbines and generators) where shaft misalignment and axial movement must be accommodated without excessive machine loads.
• Useful for manufacturers, mechanical designers, maintenance teams and inspection authorities to ensure couplings are designed, manufactured and tested to a consistent industrial benchmark.

Who should use this standard

• Mechanical and rotating‑equipment engineers in petroleum, petrochemical and natural gas sectors
• OEMs and coupling manufacturers for product design and certification
• Procurement and QA/QC teams specifying acceptance criteria
• Maintenance and reliability engineers performing inspections, testing and replacements

Related guidance

• ISO 14691:2008 is the second edition and replaces the 1999 edition. It should be used alongside equipment manufacturer guidance and other industry standards or codes where selection criteria, application‑specific design or installation practices are required.

Keywords: ISO 14691:2008, flexible couplings, mechanical power transmission, petroleum industry, petrochemical, natural gas, gear couplings, elastomeric couplings, shaft misalignment, coupling inspection and testing.