A trunnion-mounted ball valve primarily consists of a valve body, bonnet, ball, seat, stem, and operating mechanism. The valve body serves as the main structural component; typically manufactured from cast iron or stainless steel, it exhibits excellent corrosion resistance. The bonnet connects to the valve body and functions to secure the ball and seats in place. The ball is the critical component of the trunnion-mounted ball valve; usually made of stainless steel, it ensures superior sealing performance.
The valve seat is the component that interfaces with the ball; typically constructed from resilient materials, it ensures the valve's sealing integrity. The valve stem connects the bonnet to the ball, serving to transmit the operating force. The operating mechanism may be either a manual device or an automated control unit, utilized to regulate the opening and closing of the valve.
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Components of API Trunnion ball valve
| Part Name | Primary Function | Common Materials |
| Body | Contains pressure and internals | A105, WCB, LF2, F316 |
| Ball | Controls flow (Open/Close) | A105+ENP, F316, F51 |
| Trunnion | Fixes the ball on a vertical axis | 4140, 17-4PH, SS316 |
| Seats | Provides primary sealing | PTFE, PEEK, Devlon, Metal |
| O-Rings | Prevents external & internal leaks | Viton, NBR, HNBR (AED) |
| Drain Valve | Venting the body cavity (DBB) | Stainless Steel |
API Trunnion ball valve Specifications Table
| Category | Technical Specs / Range | Remarks |
| Nominal Size Range | 2" – 60" (NPS 50 – NPS 1500) | Large bores typically require trunnion design |
| Pressure Class | Class 150, 300, 600, 900, 1500, 2500 | Equivalent to PN20 – PN420 |
| Bore Type | Full Bore (FB) / Reduced Bore (RB) | Full Bore is "Piggable" for pipeline cleaning |
| End Connection | Flanged (RF, RTJ), Butt-weld (BW) | RTJ is standard for Class 600 and above |
| Body Design | 2-Piece / 3-Piece Bolted Body | Available in Side Entry or Top Entry |
| Operation / Actuation | Lever, Gear, Pneumatic, Hydraulic, Electric | Selected based on torque requirements |
Materials of API Trunnion ball valve Construction (Typical Trim Chart)
| Part Name | Common Materials (ASTM) | Trim / Coating |
| Body | A105, WCB, LCC, LF2, F316, F51 | Selected based on corrosion and temp |
| Ball | A105+ENP, F316, F51, F53 | Hard seated typically uses Stellite/TC coating |
| Seat Ring | PTFE, RPTFE, Nylon, Devlon, PEEK | Metal-to-Metal for abrasive/high-temp service |
| Stem | 4140+ENP, 17-4PH, F316, XM-19 | Must feature Anti-blowout design |
| Seals / O-Rings | Viton (FKM), NBR, HNBR, AED | AED (Anti-Explosive Decompression) for high-pressure gas |
| Seat Springs | Inconel X-750, SS316, SS17-7PH | Provides initial seat pre-load |
API Trunnion ball valve Design & Testing Standards Reference
| Item | Reference Standard | Description |
| Design & Manufacturing | API 6D / ISO 14313, ASME B16.34 | Primary standard for pipeline valves |
| Face-to-Face (F-F) | ASME B16.10 / API 6D | Ensures interchangeability in pipelines |
| Flange Dimensions | ASME B16.5 / ASME B16.47 | B16.47 Series A/B for sizes > 24" |
| Fire Safe Testing | API 607 / API 6FA | Ensures integrity during high-temp fire events |
| Pressure Testing | API 6D / API 598 | High-pressure hydrostatic and low-pressure gas tests |
| Sour Service (NACE) | NACE MR0175 / ISO 15156 | For H2S-containing acidic environments |
API Trunnion ball valve Key Features & Functional Characteristics
| Feature / Function | Technical Description | Procurement Value |
| DBB (Double Block & Bleed) | Double sealing with a bleed function | Allows cavity venting to verify seat integrity |
| DIB (Double Isolation) | Double Isolation (DIB-1 or DIB-2) | Enhanced safety with two independent seals |
| Anti-Static Device | Electrical continuity spring/ball | Prevents static build-up and spark risks |
| Sealant Injection | Emergency grease/sealant fittings | Provides a temporary seal if the seat is damaged |
| Self-Relieving Seat | Automatic cavity pressure relief | Prevents body burst due to thermal expansion |
| Anti-Blowout Stem | Integral stem shoulder design | Prevents stem ejection under high line pressure |
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FAQ
What are Trunnion mounted ball valve applications
Trunnion-mounted ball valves are widely utilized across various industries, including petroleum, chemical, metallurgy, electric power, and pharmaceuticals. They serve to control the opening and closing of fluid lines, as well as to regulate flow rates and pressure. In petroleum pipeline systems, trunnion-mounted ball valves are frequently employed to control the flow of oil and gas, thereby ensuring the safe and secure operation of the pipeline infrastructure. In chemical manufacturing, these valves are used to control the flow of various chemical substances, facilitating the smooth and efficient execution of production processes.