Metal-Seated vs. Soft-Seated Ball Valves: RFQ Guide

Compare metal and soft ball valve seats using service temperature, solids, shutoff leakage and actuator torque. See what to include in your RFQ.

ZHONGYUE VALVE

11/10/20261 min read

Seat selection affects how a ball valve seals, how much torque it takes to operate and how well it tolerates the process fluid. A useful enquiry specifies the operating conditions and the required shutoff test so suppliers can quote comparable designs.

Start with temperature, fluid and solids

Soft seats are worth evaluating when the seat material is compatible with the fluid and the required pressure–temperature range. Identify the proposed seat grade and ask for the assembled valve’s service limits. A body material or pressure class alone does not establish the operating limits of the seats, stem seals and body seals.

Consider metal seats where elevated temperature or abrasive particles make the proposed soft seat unsuitable. Provide the particle size and concentration when known. Ask which surfaces are hard-faced or coated, what materials are specified for the ball and seats, and how the sealing surfaces will be inspected. For cycling or standby service, include the expected duty and the maximum breakaway differential pressure.

Put the shutoff requirement in measurable terms

State the test standard and edition required by the project, the test medium, the applicable pressure, the allowable leakage and the directions to be tested. If shutoff is required in both directions, put that requirement explicitly in the RFQ. A general statement about tight shutoff leaves bidders free to assume different tests or acceptance limits.

Confirm operating torque before approving the actuator

Request the torque figures used for sizing at the specified differential pressure and service conditions. For an actuated valve, ask for the available actuator output across its travel, the minimum supply pressure where applicable and the sizing margin used. Have the supplier identify any assumptions about seat material, operating frequency or process deposits that affect the selection.

Comparing ball valve quotations? Share your fluid, temperature range, shutoff conditions and operating method with Zhongyue Valve.

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