A48Y Series Spring Full Lift Safety Valve | Steam & Pressure Vessel Overpressure Protection
The A48Y Spring Full Lift Safety Valve offers reliable overpressure protection for boilers, pressure vessels, and steam systems handling non-corrosive media. Available in PN16/PN25 ratings with DN32–DN150 sizes and working temperatures up to 300°C.
- Full lift design for high-capacity overpressure discharge
- WCB cast steel or ductile cast iron body with Stellite seal face
- Models: A48Y-16C, A48Y-16Q, A48Y-25
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Product Details
The A48Y spring full-lift safety valve is the high-capacity flanged relief valve for boilers, pressure vessels and steam systems to 300°C: the disc opens to full travel for maximum discharge, with a Stellite hard-faced seat that survives repeated high-energy actuation. PN16/PN25, DN32–DN150.
- Flanged spring-loaded safety valve, full-lift for maximum discharge
- Open bonnet — direct atmospheric vent
- Stellite hard-faced disc and seat for long cycle life
- PN16/PN25, DN32–DN150, to 300°C
- WCB cast steel or QT450-10 ductile iron body; 50CrVA calibrated spring
- CE-marked; China Safety Valve Manufacturing License; designed & tested to GB/T 12243
Product Overview
The A48Y is a flanged spring-loaded safety valve for steam and air at temperatures to 300°C. When system pressure exceeds the set point the spring-loaded disc lifts to full travel for maximum discharge capacity, and reseats automatically when pressure normalizes — no manual reset.
The open-bonnet design vents directly to atmosphere — the simple, economical choice for steam and water where the discharge is safe to release at the valve.
Body material follows the duty: WCB cast steel for higher temperature and pressure, QT450-10 ductile iron as the cost-effective option for standard service. The Stellite sealing surfaces and 2Cr13 internals hold a tight seal through thousands of cycles, and the 50CrVA spring is calibrated to the set pressure and sealed before dispatch.
Key Advantages
Maximum Discharge (Full Lift)
The disc opens to full travel, giving the largest flow area for rapid relief — essential on boilers and large vessels where a fast overpressure must be vented quickly.
Simple Atmospheric Vent
Open-bonnet venting is the economical, maintenance-light choice where the discharge is safe to release at the valve.
Stellite Sealing for Cycle Life
Stellite hard-facing gives exceptional wear, corrosion and erosion resistance under repeated actuation.
Calibrated 50CrVA Spring
The alloy spring holds the set pressure consistently and reseats tightly; adjustable screw allows on-site calibration within the rated range.
Two Body Materials
WCB cast steel for strength and temperature; QT450-10 ductile iron for cost-effective standard duty.
Fine Pressure Gradation
Multiple working-pressure steps within PN16/PN25 ensure an exact match to the system set pressure, without compromising safety margin.
Pressure Test Data & Set Pressure Range
| Nominal Pressure PN | Shell Test (MPa) | Working Pressure Range (MPa) |
|---|---|---|
| PN16 | 2.4 | 0.1 ∼ 0.13 / 0.13 ∼ 0.16 / 0.16 ∼ 0.2 / 0.2 ∼ 0.25 |
| PN16 | 2.4 | 0.25 ∼ 0.3 / 0.3 ∼ 0.4 / 0.4 ∼ 0.5 / 0.5 ∼ 0.6 |
| PN16 | 2.4 | 0.6 ∼ 0.8 / 0.8 ∼ 1.0 / 1.0 ∼ 1.3 / 1.3 ∼ 1.6 |
| PN16 | 2.4 | Total: 12 pressure stages from 0.1 to 1.6 MPa |
| PN16 | 2.4 | |
| PN25 | 3.8 | 1.6 ∼ 2.0 |
| PN25 | 3.8 | 2.0 ∼ 2.5 |
| Working Temperature: ≤ 300°C | Applicable Medium: Steam, Air, Non-Corrosive Media | Working Temperature: ≤ 300°C | Applicable Medium: Steam, Air, Non-Corrosive Media | Working Temperature: ≤ 300°C | Applicable Medium: Steam, Air, Non-Corrosive Media |
Materials for Main Parts
| Part Name | Material |
|---|---|
| Body | WCB Carbon Steel / QT450-10 Ductile Cast Iron |
| Disc, Seat Ring, Adjusting Ring, Valve Guide, Stem | 2Cr13 Stainless Steel |
| Bonnet Cap of Valve, Wrench | WCB / Ductile Cast Iron |
| Spring | 50CrVA Alloy Spring Steel |
| Disc, Seat Ring Sealing Face | Stellite (Cobalt-Based Hard Alloy) |
Dimensions & Weight
| DN (mm) | d0 (mm) | L (mm) | D (mm) | K (mm) | g (mm) | b (mm) | Z-φd | D1 (mm) | K1 (mm) | g1 (mm) | b1 (mm) | D1′ (mm) | Z’-φd’ | H (mm) | H1 (mm) | Weight (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 32 | 20 | 115 | 140 | 100 | 78 | 18 | 4-φ18 | 150 | 110 | 88 | 18 | 40 | 4-φ18 | 282 | 100 | 16 |
| 40 | 25 | 120 | 150 | 110 | 88 | 18 | 4-φ18 | 165 | 125 | 102 | 18 | 50 | 4-φ18 | 358 | 110 | 18 |
| 50 | 32 | 135 | 165 | 125 | 102 | 18 20▴ | 4-φ18 | 185 | 145 | 122 | 18 | 65 | 4-φ18 | 365 | 120 | 22 |
| 65 | 40 | 150 | 185 | 145 | 122 | 18 22▴ | 4-φ18 8-φ18▴ | 200 | 160 | 138 | 20 | 80 | 8-φ18 | 366 | 130 | 32 |
| 80 | 50 | 170 | 200 | 160 | 138 | 20 24▴ | 8-φ18 | 220 | 180 | 158 | 20 | 100 | 8-φ18 | 385 | 135 | 42 |
| 100 | 65 | 205 | 220 235▴ | 180 190▴ | 158 162▴ | 20 24▴ | 8-φ22▴ 8-φ18 | 250 | 210 | 188 | 22 | 125 | 8-φ18 | 632 | 180 | 70 |
| 125 | 80 | 210 | 250 270▴ | 210 220▴ | 188 | 22 26▴ | 8-φ18 8-φ26▴ | 285 | 240 | 212 | 22 | 150 | 8-φ22 | 626 | 190 | 87 |
| 150 | 100 | 250 | 285 300▴ | 240 250▴ | 212 218▴ | 22 28▴ | 8-φ22 8-φ26▴ | 340 | 295 | 268 | 24 | 200 | 12-φ22 | 652 | 210 | 92 |
Inlet flange columns D/K/g/b/Z-φd; outlet flange columns D1/K1/g1/b1/D1′/Z′-φd. Marked values differ for PN25. Certified drawings issued with the quotation; state set pressure when enquiring.
Gaoshan Safety Valve Series — Which Model
| Model | Lift | Bonnet | Seal | DN Range | Best For |
|---|---|---|---|---|---|
| A47H | Low lift | Open | 2Cr13 | DN32–DN150 | General steam / water relief |
| A48Y | Full lift | Open | Stellite | DN32–DN150 | Boilers, large vessels — high capacity |
| A41H | Low lift | Sealed | 2Cr13 | DN40–DN100 | Water / air / oil — piped discharge |
| A42Y | Full lift | Sealed | Stellite | DN40–DN100 | Gas / petroleum — max safety + capacity |
This page is the A48Y. For the other lift/bonnet/seal combinations see the series table and the safety valve series.
Structure Drawing
Design, Testing and Reference Standards
- CE-marked and manufactured under the China Safety Valve Manufacturing License; designed and tested to GB/T 12243.
- EN ISO 4126 and, for US codes, ASME BPVC Section VIII compliance available on request — state the code your project is inspected against.
- Material certificates to EN 10204 3.1 and a set-pressure certificate supplied with each calibrated valve.
Installation & Maintenance Guidelines
- Mount vertical at the top of the protected volume: no isolating valve upstream; the valve must see system pressure directly.
- Keep the vent clear: ensure the open-bonnet discharge path is unobstructed and directed away from personnel.
- Never adjust in service: the set pressure is factory-calibrated and sealed; recalibrate at the interval your code requires.
- Test periodically: bench-test or raise to set at the inspection interval to confirm lift and reseat.
- Protect from condensate on steam: allow drainage so the valve is not waterlogged.
Application Fields
The A48Y protects steam boilers; pressure vessels; steam and hot water lines; power and process plant. Anywhere a trapped volume can exceed its rated pressure, the spring safety valve is the last line of defence.
What We Need to Quote Your A48Y Valves
- Size and pressure class: DN32–DN150, PN16/PN25.
- Set pressure (MPa): the key parameter — state it exactly.
- Medium and temperature: steam and air, to 300°C.
- Body material: WCB cast steel or QT450-10 ductile iron.
- Bonnet: open bonnet; sealed version = A41H/A42Y.
- Code: GB/T 12243 standard; EN ISO 4126 / ASME on request.
- Documentation: EN 10204 3.1 + set-pressure certificate.
Frequently Asked Questions
Sealed (enclosed) bonnet or open bonnet – which do I need?
A sealed bonnet (A41H/A42Y) routes the discharge through a pipe to a safe point – required for hazardous, toxic or valuable media and indoor plant. An open bonnet (A47H/A48Y) vents to atmosphere – the economical choice for steam and water where that is safe. This page is the open-bonnet A48Y.
Full lift or low lift – which do I need?
Full lift (A48Y/A42Y) opens to full travel for maximum discharge – choose it for boilers and large vessels where a rapid overpressure must be vented. Low lift (A47H/A41H) opens proportionally in a smaller envelope for modest relief needs. The A48Y is full-lift.
What does the Stellite seat buy me?
Stellite (cobalt-based) hard-facing gives far better wear, erosion and corrosion resistance than plain 2Cr13 under repeated high-energy actuation – the choice for steam boilers and cycling service. 2Cr13 is fine for general steam/water.
How is the set pressure calibrated?
Each valve is calibrated to your stated set pressure and sealed before dispatch, with a set-pressure certificate. The adjusting screw allows on-site calibration within the rated range, but never adjust it in service.
Can it be used on corrosive media?
The A48Y covers steam and air. For acids and aggressive fluids use the stainless A28Y/A27Y threaded series or a stainless flanged variant – tell us the medium.
What standards does it meet?
CE-marked and manufactured under the China Safety Valve Manufacturing License, designed and tested to GB/T 12243, with EN ISO 4126 and ASME BPVC Section VIII compliance available on request. State your code and we will confirm.
Get a Quote & Technical Support
Gaoshan Valve has manufactured industrial valves since 1975 and holds ISO 9001/14001/45001, is CE-marked and holds the China Safety Valve Manufacturing License, exporting to more than 30 countries. Reply within 24 hours. Contact us with your size, pressure class and exact set pressure for a calibrated A48Y quotation.
