Overview - EN ISO 21049:2004 (Pumps - Shaft sealing systems)
EN ISO 21049:2004 / ISO 21049:2004 is a CEN-adopted international standard that specifies requirements and recommendations for shaft sealing systems used on centrifugal and rotary pumps in the petroleum, natural gas and chemical industries. It targets services that are hazardous, flammable or toxic where increased reliability, reduced emissions and lower life‑cycle sealing costs are critical. The standard covers seal hardware for pump shaft diameters from 20 mm (0.75 in) to 110 mm (4.3 in) and applies to both new equipment and seal spare parts or upgrades.
Key topics and technical requirements
- Seal classification system: Provides a structured classification into Categories (1–3), Types (A, B, C) and Arrangements (1–3), plus orientations and mounting options to guide selection.
- Performance envelopes: Defines temperature and pressure ranges and minimum seal-chamber conditions by category/type (e.g., temperature and absolute pressure limits vary by category).
- Materials and face choices: Recommends face and secondary sealing materials (examples in the standard include premium carbon and silicon carbide faces, and bellows materials such as Alloy C‑276 and Alloy 718).
- Cartridge and flexible element requirements: Specifies cartridge design, flexible element styles (pusher, bellows), orientation (rotating or stationary) and spring types.
- Seal chamber and flush requirements: Sets minimum seal-chamber pressures and flushing/cooling plans (mentions common flush plans and guidance for Plan selection) and minimum reservoir volumes for barrier/buffer fluids.
- Throttle/containment bushing and gland plate requirements: Details fixed vs. floating throttle bushing options and metal‑to‑metal gland plate contact requirements.
- Vendor qualification and testing: Outlines scope of vendor testing and data requirements, escalating in rigor from Category 1 to Category 3.
Practical applications and users
- Where used: Petroleum production, refining, petrochemicals, LNG, and chemical processing where pump leakage risk and emissions control are important.
- Who uses it: Pump manufacturers, rotating‑equipment engineers, procurement/specification teams, maintenance crews, mechanical integrity and reliability engineers, and API/CEN compliance officers.
- Why use it: To standardize seal selection, ensure safe operation in hazardous services, improve equipment availability, reduce fugitive emissions and support retrofit/upgrading of existing pumps.
Related standards and references
- ISO 3069, ISO 13709, ASME B73.1 / B73.2 (pump components and dimensions)
- Note in the standard allows alternative NDE standards (for example EN 13445‑5) where appropriate
- Prepared by ISO/TC 115 (Pumps) and adopted by CEN/TC 12
This standard is essential for specifying robust, industry‑grade shaft sealing systems for centrifugal and rotary pumps in demanding hydrocarbon and chemical services.