A42Y Seal Type Spring Full Lift Safety Valve
• A42Y-16C / A42Y-16Q / A42Y-25 seal type spring full lift safety valve
• Enclosed bonnet + full lift design — high discharge capacity with piped exhaust option
• PN16/PN25, DN40–DN100, working temperature ≤300°C
• WCB cast steel or ductile cast iron body, Stellite hard-faced disc & seat ring
• Suitable for air, gas, petroleum, water, and non-corrosive media
Gaoshan Valve — A42Y Seal Type Spring Full Lift Safety Valve
Model: A42Y-16C / A42Y-16Q / A42Y-25 | Pressure: PN16 / PN25 | Connection: Flanged | Medium: Air, Gas, Water, Petroleum
Product Overview
The A42Y Seal Type Spring Full Lift Safety Valve is a premium overpressure protection device designed for boilers, pressure vessels, and piping systems handling air, natural gas, petroleum, water, and non-corrosive media. It combines two critical design advantages: an enclosed (sealed) bonnet that allows discharge to be routed safely to a designated location via connected pipework, and a full-lift opening mechanism that provides maximum discharge capacity when activated. When system pressure exceeds the preset value, the valve opens automatically to release excess medium, then reseals tightly once pressure returns to normal, preventing medium loss during normal operation.
Key Advantages
Enclosed Bonnet + Full Lift Design
Marries the safety benefits of a sealed bonnet (discharge can be piped to a safe remote location) with the rapid pressure relief capacity of a full-lift mechanism. Ideal for applications requiring both controlled environmental venting and high-volume emergency discharge.
Stellite Hard-Faced Sealing
Disc and seat ring sealing surfaces are hard-faced with Stellite alloy, delivering superior wear resistance, outstanding corrosion endurance, and reliable tight shut-off even after thousands of actuation cycles under demanding service conditions.
Automatic Opening & Resealing
When system pressure exceeds the preset threshold, the spring-loaded assembly unseals fully to discharge excess medium. Once pressure drops below the reseat set point, the spring force closes the valve automatically and tightly — no manual reset required.
Dual Body Material Options
Available in WCB cast steel for higher-temperature and higher-pressure applications, or QT450-10 ductile cast iron as a cost-effective choice for standard-duty installations. Both variants feature stainless steel internals for corrosion resistance.
50CrVA Alloy Spring
Equipped with 50CrVA high-grade alloy spring steel, offering precise set-point accuracy, excellent fatigue resistance, and dependable long-term performance even under frequent high-cycle actuation in critical pressure relief applications.
12 Fine Pressure Classes (PN16)
PN16 rating covers 12 precise pressure steps from 0.1 to 1.6 MPa, with PN25 extending coverage to 2.5 MPa. The extensive gradation ensures an exact pressure match to any system requirement, eliminating compromises on safety margin or operational precision.
Pressure Test Data & Working Pressure Classes
| PN | Strength Test (MPa) | Working Pressure Classes (MPa) | |||||
|---|---|---|---|---|---|---|---|
| PN16 | 2.4 | 0.1–0.13 | 0.13–0.16 | 0.16–0.2 | 0.2–0.25 | 0.25–0.3 | 0.3–0.4 |
| 0.4–0.5 | 0.5–0.6 | 0.6–0.8 | 0.8–1.0 | 1.0–1.3 | 1.3–1.6 | ||
| PN25 | 3.8 | 1.6–2.0 | 2.0–2.5 | ||||
| Working Temp | ≤ 300°C | ||||||
| Applicable Media | Air, Natural Gas, Petroleum, Water, Non-Corrosive Media | ||||||
Materials for Main Parts
| Part Name | Material |
|---|---|
| Body | WCB Cast Steel / QT450-10 Ductile Cast Iron |
| Disc, Seat Ring, Adjusting Ring, Guide Sleeve, Adjusting Screw, Stem, Valve Guide | 2Cr13 / Stainless Steel |
| Bonnet, Cap of Valve | WCB Cast Steel / Ductile Cast Iron |
| Spring | 50CrVA Alloy Spring Steel |
| Disc & Seat Ring Seal Surface | Stellite Hard-Facing Alloy |
Dimensions & Weight
Data shown as PN16 / PN25 where values differ (marked ▲ for PN25). Inlet flange on the left, outlet flange on the right side of each row.
| DN (mm) | d0 | L | D | K | g | b | Z-φd | D1 | Kt | gl | bt | Dt | Z′-φd | H | H1 | Wt (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 25 | 120 | 150 | 110 | 88 | 18 | 4-φ18 | 165 | 125 | 102 | 18 | 50 | 4-φ18 | 272 | 110 | 18 |
| 50 | 32 | 135 | 165 | 125 | 102 / 20▲ | 18 / 20▲ | 4-φ18 | 185 | 145 | 122 | 18 | 65 | 4-φ18 | 332 | 130 | 22 |
| 65 | 40 | 150 | 185 | 145 | 122 / 22▲ | 18 / 22▲ | 4-φ18 / 8-φ18▲ | 200 | 160 | 138 | 20 | 80 | 8-φ18▲ | 366 | 130 | 24 |
| 80 | 50 | 170 | 200 | 160 | 138 / 24▲ | 20 / 24▲ | 8-φ18 | 220 | 180 | 158 | 20 | 100 | 8-φ18 | 478 | 150 | 42 |
| 100 | 65 | 205 | 235 / 236▲ | 180 / 190▲ | 158 / 162▲ | 20 / 24▲ | 8-φ18 / 8-φ22▲ | 250 | 210 | 188 | 22 | 125 | 8-φ18 | 627 | 180 | 70 |
∗ Dimension columns D, K, g, b, Z-φd = Inlet flange | D1, Kt, gl, bt, Dt, Z′-φd = Outlet flange. ▲ = PN25 values shown in blue.
Applicable Media
Natural Gas
Petroleum
Water
Steam
Non-Corrosive Media
Gaoshan Safety Valve Series
| Model | Lift Type | Bonnet | Seal Face | DN Range | Best For |
|---|---|---|---|---|---|
| A47H | Low Lift | Open | 2Cr13 | DN32–150 | General steam/water relief |
| A48Y | Full Lift | Open | Stellite | DN32–150 | Boilers, large vessels — high capacity |
| A41H | Low Lift | Sealed | 2Cr13 | DN40–100 | Water/air/oil — piped discharge |
| A42Y ◀ | Full Lift | Sealed | Stellite | DN40–100 | Premium: gas/petroleum — max safety + capacity |
A42Y Seal Type Spring Full Lift Safety Valve — Product Image
A42Y Safety Valve — Structure & Dimension Diagram
Request a Quote for A42Y Safety Valve
Gaoshan Valve manufactures the A42Y seal type spring full lift safety valve specifically for critical overpressure protection in gas, petroleum, air, and water systems. Available in PN16/PN25, DN40–DN100, with WCB cast steel or ductile cast iron body, Stellite hard-faced sealing, and enclosed bonnet design. 12 fine pressure classes ensure precise sizing for your application. Contact us for competitive pricing, technical consultation, and fast delivery.