The engineering foundation of industrial valves β body materials, trim systems, hardfacing, bolting, and end connections. The decisions that determine what survives the service.
Valves are not commodity items. They are pressure-retaining safety components. Pipe fails by rupture; valves fail by loss of operability, leakage, seizure, or internal damage. Material and trim selection is what separates a valve that lasts 20 years from one that fails in 18 months.
This page covers the wetted-side decisions: body and bonnet metallurgy, cast vs forged equivalency, API trim numbers, hardfacing, bolting compatibility, and end-connection sealing. For the governing standards framework (API, ASME, ASTM, MSS, NACE, ISO) and pressure-class fundamentals, see the Valve Standards reference β
Body material determines pressure containment, corrosion resistance, temperature capability, weldability, and cost. Get this wrong and no trim selection can save the valve.
| Material | Common Name | Typical Service |
|---|---|---|
| WCB / A105 | Carbon Steel | General hydrocarbon, steam |
| LCC / LF2 | Low-Temp Carbon Steel | Cold service, impact-rated |
| WC6 / F11 | 1ΒΌ Cr-Β½ Mo | Elevated temperature |
| WC9 / F22 | 2ΒΌ Cr-1 Mo | Higher temp & pressure |
| C5 / F5 | 5 Cr | High temperature |
| C12 / F9 | 9 Cr | Power generation |
| CF8M / F316 | 316 Stainless Steel | Corrosive service |
| Duplex (F51) | 2205 | Chloride service |
| Super Duplex (F53) | 2507 | Seawater, severe chloride |
| Alloy 20 | β | Acid service |
| Monel | β | Marine, HF acid |
| Inconel / Hastelloy | β | Severe corrosion / temperature |
Cast valves dominate large sizes. Forged valves dominate small bore and high pressure. Material equivalents across both production methods:
| Cast ASTM | Forged ASTM | Common Name |
|---|---|---|
| A216 WCB | A105 | Carbon Steel |
| A352 LCC | A350 LF2 | LTCS (low-temp carbon steel) |
| A217 WC6 | A182 F11 | 1ΒΌ Cr |
| A217 WC9 | A182 F22 | 2ΒΌ Cr |
| A351 CF8M | A182 F316 | 316 SS |
| A890 CD3MN | A182 F51 | Duplex 2205 |
| A494 CW6MC | B564 N06625 | Inconel 625 |
Trim is not decoration. Trim defines the internal, wetted, wear-critical parts of the valve β the components that determine shutoff class, leakage rate, and service life under cyclic operation.
Transmits actuation force from operator or actuator to the closure element. Subject to axial load, bending, and corrosion.
The moving closure element. Geometry determines control behavior; material determines wear resistance.
The fixed (or sometimes replaceable) sealing surface in the body. The primary leak boundary.
Allows packing replacement under pressure (with valve fully open). Not a substitute for proper isolation.
Maintain disc and stem alignment during travel. Wear here causes seat damage.
Trim selection controls wear resistance, corrosion resistance, galling tendency, and shutoff reliability.
Hardfacing is a weld-applied overlay, typically Stellite 6 or equivalent Co-Cr alloy, applied to seat surfaces and disc edges.
API trim numbers define the material combination of seat, disc, stem, and backseat in gate, globe, and check valves (API 600 / 602 / 623). One number on a datasheet replaces a paragraph of material callouts β provided both parties read it the same way.
API trim numbers apply to gate, globe, and check valves. Ball valve trim is typically specified directly (ball / stem / seat materials with coatings or hardfacing) rather than by API trim numbers. Pipeline ball valves under API 6D follow this convention.
| Trim # | Nominal Trim | Seat | Disc | Stem / Backseat | Typical Service |
|---|---|---|---|---|---|
| 1 | 13Cr | 410 SS (CA15 / F6) | 410 SS | 410 SS | General service |
| 2 | 304 | 304 SS | 304 SS | 304 SS | Mild corrosion |
| 3 | 310 | 310 SS | 310 SS | 310 SS | High temperature |
| 4 | Hard 13Cr | Case-hardened 410 | Case-hardened 410 | 410 SS | Abrasion resistance |
| 5 | FHF (13Cr) | Hardfaced (Stellite) | Hardfaced (Stellite) | 410 SS | Severe wear, steam |
| 6 | 13Cr + Cu-Ni | 410 / Cu-Ni | 410 / Cu-Ni | 410 SS | Mixed corrosion |
| 7 | Hardened 13Cr | Case-hardened 410 | Case-hardened 410 | 410 SS | Wear + pressure |
| 8 | 13Cr + HF | Hardfaced (Stellite) | 410 SS | 410 SS | Hard seat, moderate erosion |
| 9 | Monel | Monel | Monel | Monel | Marine / HF service |
| 10 | 316 | 316 SS | 316 SS | 316 SS | Corrosive service |
| 11 | Monel + HF | Hardfaced (Stellite) | Monel | Monel | Marine + erosion |
| 12 | 316 + HF | Hardfaced (Stellite) | 316 SS | 316 SS | Corrosive + erosion |
| 13 | Alloy 20 | Alloy 20 | Alloy 20 | Alloy 20 | Acid service |
| 14 | Alloy 20 + HF | Hardfaced (Stellite) | Alloy 20 | Alloy 20 | Acid + erosion |
| 15 | FHF (304) | Hardfaced (Stellite) | Hardfaced (Stellite) | 304 SS | High wear, mild corrosion |
| 16 | FHF (316) | Hardfaced (Stellite) | Hardfaced (Stellite) | 316 SS | Severe corrosive / erosive |
| 17 | FHF (347) | Hardfaced (Stellite) | Hardfaced (Stellite) | 347 SS | High temp + erosion |
| 18 | FHF (A20) | Hardfaced (Stellite) | Hardfaced (Stellite) | Alloy 20 | Severe acid |
The same trim number can be supplied in cast, forged, or weld-overlay construction depending on valve body type. This matrix shows the material specification for each construction method by trim family.
| Trim # | Nominal | Seat (Cast) | Seat (Forged) | Seat (Welded) | Disc (Cast) | Disc (Forged) | Disc (Welded) | Stem / Backseat |
|---|---|---|---|---|---|---|---|---|
| 1 | F6 (13Cr) | CA15 (A217) | F6a (A182) | ER410 | CA15 (A217) | F6a (A182) | β | 410 (A276) |
| 2 | 304 | CF8 (A351) | F304 (A182) | ER308 | CF8 (A351) | F304 (A182) | β | 304 (A276) |
| 3 | 310 | β | F310 (A182) | ER310 | β | F310 (A182) | β | 310 (A276) |
| 4 | Hard F6 | Case Hardened F6 | Case Hardened F6 | β | Case Hardened F6 | Case Hardened F6 | β | 410 (A276) |
| 5 | FHF (F6) | β | β | Hardfaced | β | β | Hardfaced | 410 (A276) |
| 6 | F6 + Cu-Ni | CA15 | F6a | β | CA15 | F6a | β | 410 (A276) |
| 7 | F6 + HF + Cu-Ni | β | β | Hardfaced | β | β | Hardfaced | 410 (A276) |
| 8 | F6 + HF | CA15 (A217) | F6a (A182) | Hardfaced | CA15 (A217) | F6a (A182) | Hardfaced | 410 (A276) |
| 9 | Monel | β | MFG Standard | β | β | MFG Standard | β | MFG Standard |
| 10 | 316 | CF8M (A351) | F316 (A182) | ER316 | CF8M (A351) | F316 (A182) | β | 316 (A276) |
| 11 | Monel + HF | β | MFG Standard | Hardfaced | β | MFG Standard | Hardfaced | MFG Standard |
| 12 | 316 + HF | CF8M (A351) | F316 (A182) | Hardfaced | CF8M (A351) | F316 (A182) | Hardfaced | 316 (A276) |
| 13 | Alloy 20 | CN7M (A351) | Alloy 20 (B473) | ER320 | CN7M (A351) | Alloy 20 (B473) | β | Alloy 20 (B473) |
| 14 | Alloy 20 + HF | CN7M (A351) | Alloy 20 (B473) | Hardfaced | CN7M (A351) | Alloy 20 (B473) | Hardfaced | Alloy 20 (B473) |
| 15 | FHF (304) | β | β | Hardfaced | β | β | Hardfaced | 304 (A276) |
| 16 | FHF (316) | β | β | Hardfaced | β | β | Hardfaced | 316 (A276) |
| 17 | FHF (347) | β | β | Hardfaced | β | β | Hardfaced | 347 (A276) |
| 18 | FHF (A20) | β | β | Hardfaced | β | β | Hardfaced | Alloy 20 (B473) |
| Service Condition | Recommended Trim |
|---|---|
| General hydrocarbon | Trim 8 (13Cr + HF) |
| Erosive service | Trim 5 / 10 / 12 |
| Corrosive service | Trim 10 (316) |
| Severe erosion | Trim 16 / 18 (Full Hardface) |
| High temperature | Trim 3 / 17 (310 / FHF 347) |
| Acid / chemical | Trim 13 / 14 (Alloy 20) |
| Marine / HF acid | Trim 9 / 11 (Monel) |
Bolting is often the weakest link in valve reliability. Bolts must match body material, pressure class, temperature, and sour service requirements β get any one wrong and the body-to-bonnet joint leaks or the studs fail under thermal cycling.
| Bolt | Nut | Typical Use |
|---|---|---|
| A193 B7 | A194 2H | Carbon steel valves, standard service |
| A193 B7M | A194 2HM | NACE sour service (hardness-controlled) |
| A320 L7 | A194 7 | Low temperature, impact-rated |
| A193 B16 | A194 4 | High temperature |
| A193 B8 | A194 8 | Stainless valves, general |
| A193 B8M | A194 8M | Stainless + corrosion (316 SS) |
| Valve Body Material | Acceptable Bolting |
|---|---|
| Carbon Steel (WCB / A105) | B7 / 2H |
| LTCS (LCC / LF2) | L7 / 7 |
| Cr-Mo (WC6 / WC9) | B16 / 4 |
| 300-Series Stainless | B8 / B8M |
| Duplex | A453 660 (or per project spec) |
| Nickel Alloys | B8M (or alloy-matched per spec) |
End-connection choice determines installation method, leak risk, and serviceability. Sealing philosophy follows facing type β and mismatched facings between valve and pipe spool create persistent maintenance problems.
| Type | Description | Use Case |
|---|---|---|
| RF | Raised Face | Most common process piping. Default for Class 150β600 flanged valves. |
| FF | Flat Face | Low-pressure utilities. Matches cast iron mating flanges where bending stress is a concern. |
| RTJ | Ring Type Joint | High pressure / high temperature. Class 900 and above; refinery and pipeline service. |
| BW | Butt Weld | Permanent installation. High integrity. Eliminates flange leak paths. |
| SW | Socket Weld | Small bore (typically β€2"). Forged valves in high-pressure utility service. |
| THD | Threaded (NPT) | Non-critical small bore. Utility / instrument service. |
Every industrial valve must be identifiable by size, pressure class, material, trim, manufacturer, and heat number. This is what enables traceability, compliance, and correct replacement during outages.
NPS or DN designation, stamped on the body.
ASME class (150 / 300 / 600 / 900 / 1500 / 2500) or PN designation.
Body grade per ASTM (e.g., WCB, A105, CF8M, F316).
API trim designation (gate / globe / check) or direct material callout (ball / butterfly).
Maker's name or registered mark β required for traceability.
Specific melt of material β links to the CMTR for full chemistry and mechanical properties.
Specify all four explicitly on every datasheet. A valve quoted as "316 stainless ball valve, RF flanged, Class 150" without trim, bolting, and end-prep details is an incomplete specification β and the vendor will fill in the cheapest interpretation by default.
Send the service conditions (media, temperature, pressure class, ΞP), valve type, and any NACE / fugitive emissions / fire-safe requirements. We'll come back with a complete material + trim + bolting spec ready to drop into your datasheet.
For standard valves across body materials and trim options, E4 Industrial supports procurement through our e-commerce arm at Watermain Supply.
Shop at Watermain Supply
