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How to write a carbide spec for choke valve trim

There is no universal grade number for choke trim — write the duty, not just a grade code. Carbide grades are each manufacturer's internal system; a grade code alone gets you three quotes for three different materials.

• 1. The duty — media chemistry (H₂S, CO₂, pH), solids content and size, pressure drop and flow rate (velocity is the erosion driver), temperature, impact characteristics.
• 2. Performance targets — hardness window (HRA/HV), binder content and type (cobalt vs nickel), toughness indicator (TRS), grain size class.
• 3. Standard anchor — reference GB/T 18376 or ISO 513 as a cross-check, not a substitute for your numbers.
• 4. Failure history — what the previous part did (eroded through? chipped? leached?) tells the supplier which way to bias the material.

Quick direction: sour/acidic service → nickel-binder grades · sand-laden wells → coarser grain, higher binder · fine-particle high-velocity gas → fine-grain high-hardness · thermal cycling → fine-grain low-binder · extreme ΔP → geometry review first (multi-stage trim cuts velocity more than any grade change).

Send the drawing with a duty sheet and a photo of the failed part — we map the duty to a material direction and quote within 1–2 business days.