Product Overview
The THINKTANK TT-A42Y Series is a direct spring-loaded, full-lift enclosed flanged safety valve designed to protect industrial equipment and piping systems against excessive pressure.
The series is available in sizes up to DN400 for PN16 / PN25 / PN40 configurations and up to DN150 for PN64 / PN100 configurations.
Its full-lift design provides a larger opening relative to the valve orifice than a low-lift safety valve, making the TT-A42Y suitable for applications where greater relieving capacity is required.
Different configurations are available for general gas and liquid service as well as corrosive media.
Model Selection
TT-A42Y-C
The TT-A42Y-C is suitable for equipment and piping systems handling:
- Air
- Petroleum gas
- Liquids
- Similar compatible media
Maximum operating temperature: ≤300°C
TT-A42Y-P/R
The TT-A42Y-P/R is designed for equipment and piping systems handling:
- Corrosive media
Maximum operating temperature: ≤200°C
Material compatibility should be verified according to the actual medium, concentration, operating pressure and temperature.
Quick Specifications
| Parameter | Specification |
|---|---|
| Model | TT-A42Y-C / TT-A42Y-P/R |
| Product Type | Spring-Loaded Full-Lift Safety Valve |
| Construction | Enclosed Type |
| Connection | Flanged |
| Size Range | DN20–DN400 depending on pressure rating |
| Pressure Rating | PN16 / PN25 / PN40 / PN64 / PN100 |
| Design | Direct Spring-Loaded |
| Lift Type | Full Lift |
| TT-A42Y-C Media | Air, petroleum gas, liquids and similar media |
| TT-A42Y-C Temperature | ≤300°C |
| TT-A42Y-P/R Service | Corrosive media |
| TT-A42Y-P/R Temperature | ≤200°C |
| Function | Automatic Overpressure Protection |
| Manufacturer | THINKTANK |
How It Works
The TT-A42Y operates as a direct spring-loaded safety valve.
During normal operation, spring force keeps the valve disc seated and the valve closed.
When pressure in the protected equipment or piping system reaches the specified set pressure, the upward force generated by the process pressure overcomes the spring force and causes the valve to open.
The process medium is then discharged through the valve outlet, reducing pressure in the protected system.
As the system pressure decreases to the reseating range, the spring pushes the disc back toward the seat and the valve recloses automatically.
Full-Lift Design
The TT-A42Y is a full-lift safety valve.
Under the general performance criteria applicable to this safety valve family:
Lift H ≥ 1/4 d₀
where:
- H = Valve lift
- d₀ = Orifice diameter
The full-lift configuration provides a larger available discharge area than a low-lift design and is therefore better suited to applications requiring greater relieving capacity.
The actual valve size must still be selected according to the required relieving load and process conditions rather than nominal flange size alone.
Typical Applications
The TT-A42Y Series can be considered for:
- Compressed air systems
- Petroleum gas systems
- Gas process equipment
- Liquid process systems
- Pressure vessels
- Process piping
- Packaged process equipment
- Skid-mounted systems
- General industrial overpressure protection
- Corrosive process service with the appropriate TT-A42Y-P/R configuration
Final valve selection should consider the process medium, set pressure, operating and relieving temperature, required relieving capacity, back pressure, pressure rating and material compatibility.
General Performance Requirements
| Applicable Medium | Shell Test Pressure Ps | Seal Test Pressure Pm | Blowdown ΔP | Discharge Pressure Pp | Lift Height H |
| Steam | — | 90% Pk or the minimum reseating pressure, whichever is lower | When Pk ≤ 0.4 MPa: ΔP ≤ 0.04 MPa; when Pk > 0.4 MPa: ΔP ≤ 10% Pk | ≤ 1.03 Pk | Full-lift: ≥ 1/4 d₀; Low-lift: ≥ 1/20 d₀ |
| Air or other gases | 1.5 PN | When Pk ≤ 0.3 MPa: Pm = Pk − 0.03 MPa; when Pk > 0.3 MPa: Pm = 90% Pk | When Pk ≤ 0.2 MPa: ΔP ≤ 0.03 MPa; when Pk > 0.2 MPa: ΔP ≤ 15% Pk | ≤ 1.1 Pk | Full-lift: ≥ 1/4 d₀; Low-lift: ≥ 1/20 d₀ |
| Water or other liquids | — | When Pk ≤ 0.3 MPa: Pm = Pk − 0.06 MPa; when Pk > 0.3 MPa: Pm = 80% Pk | When Pk ≤ 0.3 MPa: ΔP ≤ 0.06 MPa; when Pk > 0.3 MPa: ΔP ≤ 20% Pk | ≤ 1.2 Pk | Full-lift: ≥ 1/4 d₀; Low-lift: ≥ 1/20 d₀ |
Notes:
- Pk = Set pressure
- d₀ = Orifice diameter
- PN = Nominal pressure
- Actual test and performance requirements shall be confirmed according to the selected valve model, project specification and applicable standard.
For the TT-A42Y Series, the full-lift criterion applies: H ≥ 1/4 d₀.
Dimensions – PN16 / PN25 / PN40
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 15 | 25 | 110 | 95 | 281 |
| 25 | 16 | 32 | 110 | 95 | 281 |
| 32 | 20 | 40 | 115 | 100 | 285 |
| 40 | 25 | 50 | 120 | 110 | 295 |
| 50 | 32 | 65 | 135 | 120 | 305 |
| 65 | 40 | 80 | 160 | 140 | 394 |
| 80 | 50 | 100 | 170 | 135 | 406 |
| 100 | 65 | 125 | 205 | 160 | 511 |
| 125 | 80 | 150 | 210 | 190 | 586 |
| 150 | 100 | 175 | 255 | 230 | 601 |
| 200 | 125 | 250 | 305 | 260 | 734 |
| 250 | 150 | 300 | 350 | 320 | 928 |
| 300 | 200 | 400 | 370 | 350 | 1159 |
| 350 | 250 | 500 | 375 | 415 | 1314 |
| 400 | 280 | 500 | 395 | 415 | 1530 |
Dimensions – PN64 / PN100
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 12 | 25 | 110 | 100 | 276 |
| 25 | 16 | 32 | 110 | 100 | 276 |
| 32 | 20 | 40 | 130 | 110 | 287 |
| 40 | 25 | 50 | 135 | 120 | 292 |
| 50 | 32 | 65 | 160 | 130 | 383 |
| 65 | 40 | 80 | 175 | 160 | 497 |
| 80 | 50 | 100 | 175 | 160 | 489 |
| 100 | 65 | 125 | 195 | 195 | 562 |
| 150 | 100 | 200 | 285 | 260 | 832 |
Dimensions are for preliminary engineering and layout reference. Final approved dimensional drawings should be confirmed before piping fabrication or installation.
Pressure Rating and Size Range
Available valve sizes depend on the required nominal pressure class.
PN16 / PN25 / PN40: DN20–DN400
PN64 / PN100: DN20–DN150
The nominal pressure rating and flange size alone do not determine whether a particular safety valve is suitable for an application. Set pressure, relieving conditions and required discharge capacity must also be verified.
Safety Valve Sizing and Selection
For correct selection of the TT-A42Y Series, provide:
- Process medium
- Set pressure
- Operating pressure
- Design pressure
- Operating temperature
- Relieving temperature
- Required relieving capacity
- Back pressure
- Required inlet DN
- Required outlet DN
- Pressure rating
- Required materials
- Applicable standards or certification requirements
- Installation and discharge arrangement
For gas service, additional thermodynamic properties may be required for relieving capacity calculations.
For liquid service, fluid density and other relevant process properties may also be required.
Engineering Support
THINKTANK supports EPC contractors, system integrators, pressure equipment manufacturers and industrial users with:
- Safety valve sizing and selection
- Relieving capacity calculation and review
- Set-pressure configuration
- Pressure class selection
- Material selection
- Dimensional drawings
- 3D models for system integration
- Replacement valve evaluation
- Project-specific technical documentation
With more than 30 years of industrial valve application experience, THINKTANK can evaluate equivalent replacements for existing safety valve brands and provide technically suitable, cost-effective alternatives.
