Standard Valve Trim Chart – Trim Numbers 1 to 18
Complete reference for standard valve trim numbers 1 through 18, listing the material for each internal component — seat ring, disc (wedge/plug), backseat bushing, and stem. Covers standard 410 SS, 304, 316, Stellite, Monel, Alloy 20, Ni-Cr, Cu-Ni, and hardfaced trims per API 600, API 602, and BS 1414. Includes trim selection guide for different service conditions. Published by Supreme Valves India.
On This Page
Quick Reference
- Trim 1 (all 410 SS) — Standard for general non-corrosive service (most common)
- Trim 5 (Stellite-faced seat & disc, 410 stem) — High-temperature, erosive, and high-cycle service
- Trim 8 (Stellite seat + 410 disc, 410 stem) — Cost-effective hardfaced option
- Trim 10 (all 316 SS) — Corrosive service, chemical, and pharmaceutical
- Trim 9 (all Monel) — Seawater, HF acid, and high-chloride environments
- Trim 13 (all Alloy 20) — Sulfuric acid and highly corrosive chemical service
- Trim 4/7 (Hard 410, 750 BHN min) — Hardened 410 for moderate wear without Stellite cost
Standard Trim Chart
Standard valve trim numbers per API 600 / API 602 / BS 1414. Each trim number defines the material combination for seat, disc, backseat, and stem components.
| Trim # | Material | Seat | Disc | Backseat | Stem | Note |
|---|---|---|---|---|---|---|
| 1 | 410 | 410 | 410 | 410 | 410 | Standard — most common general-purpose trim |
| 2 | 304 | 304 | 304 | 304 | 304 | Austenitic SS — moderate corrosion resistance |
| 3 | F310 | 310 | 310 | 310 | 310 | High-temperature austenitic SS |
| 4 | Hard 410 | Hard 410 | Hard 410 | 410 | 410 | Seat 750 BHN min. |
| 5 | Hardfaced | Stellite | Stellite | 410 | 410 | Premium — best wear & erosion resistance |
| 5A | Hardfaced | Ni-Cr | Ni-Cr | 410 | 410 | Ni-Cr hardfacing (nuclear-grade, Co-free) |
| 6 | 410 and Cu-Ni | Cu-Ni | Cu-Ni | 410 | 410 | Seawater / marine service |
| 7 | 410 and Hard 410 | Hard 410 | Hard 410 | 410 | 410 | Seat 750 BHN min. |
| 8 | 410 and Hardfaced | Stellite | 410 | 410 | 410 | Cost-effective — Stellite seat only |
| 8A | 410 and Hardfaced | Ni-Cr | 410 | 410 | 410 | Ni-Cr seat hardfacing (Co-free) |
| 9 | Monel | Monel | Monel | Monel | Monel | Seawater, HF acid, high-chloride |
| 10 | 316 | 316 | 316 | 316 | 316 | Corrosive service — chemical, pharma |
| 11 | Monel and Hardfaced | Stellite | Monel | Monel | Monel | Monel body with Stellite wear surfaces |
| 12 | 316 and Hardfaced | Stellite | 316 | 316 | 316 | 316 SS with Stellite seat hardfacing |
| 13 | Alloy 20 | Alloy 20 | Alloy 20 | Alloy 20 | Alloy 20 | Sulfuric acid, highly corrosive chemicals |
| 14 | Alloy 20 and Hardfaced | Stellite | Alloy 20 | Alloy 20 | Alloy 20 | Alloy 20 with Stellite seat hardfacing |
| 15 | 304 and Hardfaced | Stellite | Stellite | 304 | 304 | 304 SS with Stellite seat & disc |
| 16 | 316 and Hardfaced | Stellite | Stellite | 316 | 316 | 316 SS with Stellite seat & disc |
| 17 | 347 and Hardfaced | Stellite | Stellite | 347 | 347 | 347 SS (Nb-stabilized) with Stellite |
| 18 | Alloy 20 and Hardfaced | Stellite | Stellite | Alloy 20 | Alloy 20 | Alloy 20 with Stellite seat & disc |
Note: Trim numbers are per API 600 (cast steel gate valves), API 602 (compact forged steel gate valves), and BS 1414. "Hardfaced" refers to overlay welding of a hard alloy (Stellite or Ni-Cr) onto the seating surface. "Hard 410" means 410 SS heat-treated to achieve minimum 750 BHN on the seating surface. All 410 refers to ASTM A276 Type 410 (13% Cr martensitic SS). Stellite is typically Grade 6 (Co-Cr-W) or Grade 21 (Co-Cr-Mo).
How to Read This Chart: Each trim number defines a complete set of internal materials. The "Material" column gives the general description. "Seat" is the body seat ring (or seat face). "Disc" is the gate/wedge or globe disc face. "Backseat" is the backseat bushing in the bonnet. "Stem" is the valve stem. Highlighted rows (1 5 8 10) are the most commonly specified trims.
Trim Selection Guide by Service
Recommended trim numbers based on service conditions, media type, and operating temperature. Always verify with the project specification.
| Service / Application | Recommended Trim | Key Reason |
|---|---|---|
| General non-corrosive (water, oil, gas, steam ≤425°C) | 1 | Standard 410 SS — economical, adequate corrosion resistance |
| High-temperature steam (400–550°C, power plants) | 5 | Stellite maintains hardness at high temperature; prevents galling |
| High-cycle / frequent operation | 5 8 | Hardfaced surfaces resist wear from repeated open/close cycles |
| Erosive media (sand, solids, high-velocity) | 5 | Stellite has superior erosion resistance |
| Budget-conscious with moderate wear | 8 | Stellite seat only — lower cost than full Trim 5 |
| Corrosive chemicals, pharma (acids, alkalis) | 10 12 | 316 SS for corrosion resistance; add Stellite for wear |
| Seawater, marine, desalination | 6 9 | Cu-Ni or Monel resists seawater corrosion and biofouling |
| HF acid service | 9 | Monel is the standard material for HF (hydrofluoric acid) |
| Sulfuric acid (H₂SO₄) | 13 14 | Alloy 20 (Carpenter 20) excels in sulfuric acid service |
| Nuclear service (cobalt-free requirement) | 5A 8A | Ni-Cr hardfacing instead of Stellite (no cobalt activation) |
| Cryogenic service (LNG, liquid nitrogen) | 2 10 | Austenitic SS retains toughness at cryogenic temperatures |
| High-temperature with corrosion | 15 16 | SS body with Stellite hardfacing for combined resistance |
Important: Trim selection must consider: (1) media composition and corrosivity, (2) operating temperature and pressure, (3) cycle frequency, (4) required leakage class, and (5) project specification requirements. The above recommendations are general guidelines — always consult the valve manufacturer and project engineer for critical applications.
Trim Material Properties
Key properties of materials used in standard valve trims. Useful for comparing corrosion resistance, hardness, and temperature limits.
| Material | Type | Hardness (HRC/BHN) |
Max Temp | Key Properties |
|---|---|---|---|---|
| 410 SS | 13Cr Martensitic | ~22 HRC | 650°C | Standard trim material; good hardness, moderate corrosion resistance |
| Hard 410 | Heat-treated 410 | ≥750 BHN | 400°C | Hardened 410; better wear than standard 410; loses hardness above 400°C |
| 304 SS | 18Cr-8Ni Austenitic | ~80 HRB | 816°C | Good corrosion resistance; non-magnetic; cryogenic-suitable |
| 316 SS | 16Cr-12Ni-2Mo Austenitic | ~80 HRB | 816°C | Superior pitting/crevice corrosion resistance vs 304; Mo addition |
| 310 SS | 25Cr-20Ni Austenitic | ~80 HRB | 1150°C | High-temperature oxidation resistance; furnace service |
| 347 SS | 18Cr-11Ni-Nb Austenitic | ~80 HRB | 816°C | Nb-stabilized; resists intergranular corrosion after welding |
| Stellite 6 | Co-28Cr-4W | ~39 HRC | 800°C | Premium hardfacing; excellent wear, galling, and erosion resistance |
| Ni-Cr | Ni-Cr alloy overlay | ~35 HRC | 700°C | Cobalt-free hardfacing alternative for nuclear service |
| Cu-Ni | 70Cu-30Ni or 90Cu-10Ni | ~65 HRB | 300°C | Excellent seawater resistance; anti-biofouling properties |
| Monel 400 | 67Ni-30Cu | ~75 HRB | 480°C | HF acid, seawater, and alkaline service; non-sparking |
| Alloy 20 | 35Ni-20Cr-3.5Cu-2.5Mo | ~80 HRB | 538°C | H₂SO₄ acid service; superior intergranular corrosion resistance |
Material Cross-Reference: For complete chemical composition and mechanical properties of these materials, see our Material Composition & Mechanical Properties reference page.
Hardfacing & Stellite Reference
Technical details on hardfacing alloys, application methods, and minimum thickness requirements.
Stellite Grades Used in Valve Trims
| Grade | Composition | Hardness | Use |
|---|---|---|---|
| Stellite 6 | Co-28Cr-4W-1C | 38–44 HRC | Most common; seat & disc hardfacing |
| Stellite 21 | Co-27Cr-5.5Mo-0.25C | 28–34 HRC | Better ductility; lower hardness; weldable |
| Stellite 12 | Co-30Cr-8W-1.4C | 43–49 HRC | Higher hardness; severe erosion service |
Hardfacing Requirements
- Min. thickness: 1.5 mm (0.060") per API 600
- Application: PTA (Plasma Transferred Arc) or GTAW (TIG weld overlay)
- PT/MT inspection: Required after hardfacing per API 600
- Hardness check: Per ASTM E18 or E10 on finished surface
- Dilution: Max 5–10% base metal dilution in first pass
- Preheating: 200–300°C for Cr-Mo steel bodies; none for SS
- PWHT: As required by body material specification
Nuclear Note: Stellite contains ~60% cobalt, which becomes radioactive (Co-60) when exposed to neutron flux. For nuclear service, Trim 5A or 8A (Ni-Cr hardfacing) must be specified as a cobalt-free alternative. This is mandatory per most nuclear plant specifications (ASME Section III, NRC guidelines).
Frequently Asked Questions
What is a valve trim number?
A valve trim number is a standardized designation that identifies the combination of materials used for the internal wetted parts of a valve — specifically the seat ring, disc (wedge/plug), backseat bushing, and stem. Trim numbers are defined in API 600 (cast steel gate valves), API 602 (compact forged steel gate valves), and BS 1414. For example, Trim 1 uses 410 SS for all components, Trim 5 uses Stellite-faced seats and disc with 410 stem, and Trim 10 uses 316 SS throughout.
What is the most common valve trim?
Trim 1 (all 410 SS) is the most common general-purpose trim for non-corrosive service. Trim 5 (Stellite-faced seat & disc, 410 stem) is standard for high-temperature steam, erosive, and high-cycle service. Trim 8 (Stellite seat + 410 disc) is a cost-effective alternative. For corrosive service, Trim 10 (all 316 SS) is most commonly specified.
What is the difference between Trim 5 and Trim 8?
Both use 410 SS stems and backseats. Trim 5 has Stellite hardfacing on both seat and disc — best for severe service. Trim 8 has Stellite on the seat only with a standard 410 disc face — more economical and suitable for moderate service. Trim 5 provides 5–10× longer seat life in high-temperature and erosive conditions.
When should I specify Stellite trim?
Specify Stellite trim (5, 5A, 8, 8A, 11, 12, 14–18) when: (1) Service temperature exceeds 400°C where 410 SS loses hardness. (2) High-cycle applications with frequent opening/closing. (3) Erosive media containing solids or high-velocity fluids. (4) High-pressure steam service. (5) When ANSI/FCI Class V or VI tight shutoff is required over extended service life. Stellite maintains hardness up to 800°C.
What trim is used for seawater and marine service?
Trim 6 (Cu-Ni seats, 410 stem) for standard marine applications — Cu-Ni has excellent seawater resistance and anti-biofouling properties. Trim 9 (all Monel) for more aggressive marine service. Trim 10 (316 SS) is also common. For severe offshore/subsea, Trim 12 (316 + Stellite) provides combined corrosion and wear resistance.
What does 'hardfaced' mean in valve trim?
Hardfacing is a welding process (PTA or GTAW) where a layer of hard, wear-resistant alloy (typically Stellite 6 or Stellite 21) is deposited onto valve seating surfaces. Benefits: (1) Superior wear resistance — Stellite maintains hardness up to 800°C. (2) Galling resistance — prevents metal seizure. (3) Erosion resistance. (4) 5–10× longer seat life. Minimum thickness per API 600 is 1.5 mm (0.060").
What is the minimum hardness for Trim 4 and Trim 7?
Trim 4 and Trim 7 use "Hard 410" — 410 SS heat-treated (quench and temper) to achieve a minimum hardness of 750 BHN on the seating surface. This provides better wear resistance than standard 410 without Stellite cost. However, Hard 410 is limited to <400°C because the hardness is lost at higher temperatures due to over-tempering.
Related Technical Resources
Material Composition Chart
Chemical composition & mechanical properties for 30+ valve materials
Valve Test Pressure ChartAPI 598 test pressures & ASME B16.34 P-T ratings
Valve Material GuideWCB vs SS316 vs Duplex — temperature limits and corrosion guide
Valve Standards ReferenceAPI 600, API 602, ASME B16.34, BS 1414 and more
Need Valves with Specific Trim?
Supreme Valves India manufactures gate, globe, and check valves in all standard trims (1–18) and custom trim combinations. Complete with material test certificates (EN 10204 3.1) and hardness reports for hardfaced trims.