Product Overview
The THINKTANK TT-A44Y Series is a direct spring-loaded, full-lift enclosed flanged safety valve with lever designed for automatic overpressure protection of industrial equipment and piping systems.
The series combines a full-lift relieving design with an external lifting lever and is available in sizes up to DN400 for PN16 / PN25 / PN40 configurations and up to DN150 for PN64 / PN100 configurations.
The TT-A44Y-C is intended for air, steam, petroleum and similar compatible media at operating temperatures up to 300°C, while the TT-A44Y-P/R configuration is intended for corrosive service at temperatures up to 200°C.
Model Selection
TT-A44Y-C
The TT-A44Y-C is suitable for equipment and piping systems handling:
- Air
- Steam
- Petroleum
- Similar compatible media
Maximum operating temperature: ≤300°C
TT-A44Y-P/R
The TT-A44Y-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-A44Y-C / TT-A44Y-P/R |
| Product Type | Spring-Loaded Full-Lift Safety Valve |
| Construction | Enclosed Type with Lever |
| 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 |
| Lever | Yes |
| TT-A44Y-C Media | Air, steam, petroleum and similar media |
| TT-A44Y-C Temperature | ≤300°C |
| TT-A44Y-P/R Service | Corrosive media |
| TT-A44Y-P/R Temperature | ≤200°C |
| Manufacturer | THINKTANK |
How It Works
The TT-A44Y 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 pressure force acting on the disc overcomes the spring force and causes the valve to open.
The process medium is then discharged through the outlet, reducing pressure within the protected system.
As the system pressure falls to the reseating range, spring force moves the disc back toward the seat and the valve recloses automatically.
Full-Lift Design
The TT-A44Y uses a full-lift configuration.
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 suitable for applications requiring greater relieving capacity.
Actual relieving capacity must still be verified according to the required relief load, set pressure, relieving conditions and selected valve configuration.
Lever Design
The TT-A44Y is equipped with an external lifting lever mechanism associated with the valve lifting assembly.
This distinguishes the TT-A44Y from enclosed full-lift safety valve configurations without an external lever.
Normal overpressure protection remains automatic and is controlled by the relationship between system pressure and spring force.
Typical Applications
The TT-A44Y Series can be considered for:
- Steam systems
- Compressed air systems
- Petroleum process systems
- Industrial process piping
- Pressure vessels
- Packaged process equipment
- Skid-mounted systems
- Utility systems
- General industrial overpressure protection
- Corrosive process service with the appropriate TT-A44Y-P/R configuration
Final valve selection should consider the actual 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-A44Y 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 | 307 |
| 25 | 16 | 32 | 110 | 95 | 307 |
| 32 | 20 | 40 | 115 | 100 | 311 |
| 40 | 25 | 50 | 120 | 110 | 330 |
| 50 | 32 | 65 | 135 | 120 | 340 |
| 65 | 40 | 80 | 160 | 140 | 426 |
| 80 | 50 | 100 | 170 | 135 | 438 |
| 100 | 65 | 125 | 205 | 160 | 557 |
| 125 | 80 | 150 | 210 | 190 | 641 |
| 150 | 100 | 175 | 255 | 230 | 656 |
| 200 | 125 | 250 | 305 | 260 | 795 |
| 250 | 150 | 300 | 350 | 320 | 995 |
| 300 | 200 | 400 | 370 | 350 | 1263 |
| 350 | 250 | 500 | 375 | 415 | 1711 |
| 400 | 280 | 500 | 395 | 415 | 1780 |
Dimensions – PN64 / PN100
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 12 | 25 | 110 | 100 | 306 |
| 25 | 16 | 32 | 110 | 100 | 306 |
| 32 | 20 | 40 | 130 | 110 | 325 |
| 40 | 25 | 50 | 135 | 120 | 330 |
| 50 | 32 | 65 | 160 | 130 | 421 |
| 65 | 40 | 80 | 175 | 160 | 535 |
| 80 | 50 | 100 | 175 | 160 | 545 |
| 100 | 65 | 125 | 195 | 195 | 626 |
| 150 | 100 | 200 | 285 | 260 | 899 |
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 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 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-A44Y 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 steam and gas service, additional thermodynamic properties may be required for relieving capacity calculations.
For liquid service, density and other relevant process properties may also be required when applicable.
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.
