Industrial globe valves for power generation

Operating context and duty

Power-plant systems include feedwater, service water, condensate, steam and auxiliary fluids with different transient cases and availability requirements.

The engineer should connect the valve duty to the operating cases. The following conditions are especially relevant to power generation.

The application review should connect start-up and shutdown cases and thermal cycling to the risks of thermal shock and high-velocity erosion. Acceptance planning should request piping class and line list, design operating cases and material certificates before manufacture.

• start-up and shutdown cases
• thermal cycling
• vibration and piping loads
• failure criticality
• availability of redundant equipment

Why the design needs verification

Linear disc travel toward the seat gives controlled movement and a compact sealing pair while creating a more tortuous flow path.

The design advantages apply only within the confirmed execution and operating envelope.

• controlled opening and closing
• useful for bypass and steam duties
• replaceable or hardfaced seat options

Execution details for this duty

For power generation, the characteristics of industrial globe valves must be evaluated as one system. Body, closure member, seat, stem, seals and actuator must all suit the same design case.

The maintenance plan should explicitly cover pressure direction, disc and seat materials and packing and gaskets. Acceptance should demonstrate controls for the limitations “higher hydraulic resistance” and “flow direction can be design-specific”. The final datasheet should also state allowable differential pressure and cycle frequency. Review the limitation “precise automatic modulation needs a dedicated control-valve calculation” against failure criticality.

• controlled opening and closing: confirm it for start-up and shutdown cases while accounting for the limitation “higher hydraulic resistance”.
• useful for bypass and steam duties: confirm it for thermal cycling while accounting for the limitation “flow direction can be design-specific”.
• replaceable or hardfaced seat options: confirm it for vibration and piping loads while accounting for the limitation “precise automatic modulation needs a dedicated control-valve calculation”.

Technical selection criteria

For power generation, valve type, DN and PN alone do not form a complete specification. The inquiry must include fluid, design cases, connections, materials, controls and acceptance criteria.

• pressure direction
• disc and seat materials
• packing and gaskets
• allowable differential pressure
• cycle frequency

Application-specific design review

Industrial globe valves must be reviewed against the operating characteristics of power generation. The checks below connect each condition to a design input, a project risk and the required evidence.

The benefit of controlled opening and closing should be demonstrated under vibration and piping loads through ITP with hold and witness points. Where the limitation “higher hydraulic resistance” coincides with the risk “seizure after long standby”, add a dedicated ITP point and measurable acceptance criterion.

• start-up and shutdown cases: verify pressure direction, address thermal shock, and include piping class and line list in the acceptance package.
• thermal cycling: verify disc and seat materials, address high-velocity erosion, and include design operating cases in the acceptance package.
• vibration and piping loads: verify packing and gaskets, address seizure after long standby, and include material certificates in the acceptance package.
• failure criticality: verify allowable differential pressure, address insufficient actuator torque, and include ITP with hold and witness points in the acceptance package.
• availability of redundant equipment: verify cycle frequency, address loss of material traceability, and include manufacturing record book in the acceptance package.

Project risks and limitations

The combination of industrial globe valves and power generation needs a specific failure and maintenance review. Check the risks below before fixing the execution and actuator.

• higher hydraulic resistance
• flow direction can be design-specific
• precise automatic modulation needs a dedicated control-valve calculation
• thermal shock
• high-velocity erosion
• seizure after long standby
• insufficient actuator torque
• loss of material traceability

Procurement and acceptance records

The technical evaluation should end with a traceable document package. Agree its contents before purchase so certificates and records can be linked to the supplied item.

TAZ evaluates industrial globe valves for power generation against actual project data. Availability of the required DN, PN/Class, materials, actuator and standard is confirmed in the technical quotation.

• piping class and line list
• design operating cases
• material certificates
• ITP with hold and witness points
• manufacturing record book

Technical inquiry checklist

• pressure direction
• disc and seat materials
• packing and gaskets
• allowable differential pressure
• cycle frequency
• start-up and shutdown cases
• thermal cycling
• vibration and piping loads
• failure criticality
• availability of redundant equipment