Product Overview
The THINKTANK TT-A41H Series is a direct spring-loaded, low-lift enclosed safety valve designed for automatic overpressure protection of industrial equipment and process piping.
Unlike the smaller threaded A21/A27/A28 Series, the TT-A41H uses flanged inlet and outlet connections and is available in sizes up to DN250, making it suitable for a broader range of industrial piping and equipment applications.
The series covers nominal pressure ratings from PN16 to PN100, depending on valve size and configuration.
Standard TT-A41H configurations are suitable for petroleum, air, water and similar compatible media at operating temperatures up to 300°C. TT-A41H-P/R configurations are intended for corrosive service at temperatures up to 200°C.
Model Selection
TT-A41H
The TT-A41H is suitable for equipment and pipelines handling:
- Petroleum-related media
- Air
- Water
- Similar compatible media
Operating temperature: ≤300°C
TT-A41H-P/R
The TT-A41H-P/R is designed for equipment and pipelines handling:
- Corrosive media
Operating temperature: ≤200°C
Actual material compatibility should be confirmed according to the process medium, concentration, operating pressure and temperature.
Quick Specifications
| Parameter | Specification |
|---|---|
| Model | TT-A41H / TT-A41H-P/R |
| Product Type | Spring-Loaded Low-Lift Safety Valve |
| Construction | Enclosed Type |
| Connection | Flanged |
| Size Range | DN20–DN250 depending on pressure rating |
| Pressure Rating | PN16 / PN25 / PN40 / PN64 / PN100 |
| Design | Direct Spring-Loaded |
| Lift Type | Low Lift |
| TT-A41H Media | Petroleum, air, water and similar media |
| TT-A41H Temperature | ≤300°C |
| TT-A41H-P/R Service | Corrosive media |
| TT-A41H-P/R Temperature | ≤200°C |
| Function | Automatic Overpressure Protection |
| Manufacturer | THINKTANK |
How It Works
The TT-A41H is a direct spring-loaded safety valve.
During normal operation, the compression force of the spring keeps the valve disc seated against the nozzle or valve seat.
When the pressure in the protected system reaches the specified set pressure, the upward pressure force acting on the disc overcomes the spring force and the valve begins to open.
The process medium is discharged through the valve outlet, reducing pressure within the protected equipment or pipeline.
As system pressure decreases into the reseating range, spring force pushes the disc back toward the seat and the valve recloses.
This automatic opening and reclosing action protects pressure-containing equipment from excessive internal pressure.
Low-Lift Design
The TT-A41H is a low-lift safety valve.
Under the general performance criteria applicable to this safety valve family:
Lift H ≥ 1/20 d₀
where:
- H = Valve lift
- d₀ = Orifice diameter
Because valve lift and effective flow area directly influence relieving capacity, the TT-A41H should not be selected only by nominal flange size.
The required relieving load must be checked against the actual capacity of the selected valve configuration.
Typical Applications
The TT-A41H Series can be considered for:
- Petroleum process systems
- Compressed air systems
- Industrial water systems
- Process piping
- Pressure vessels
- Packaged process equipment
- Utility systems
- Skid-mounted equipment
- General industrial overpressure protection
- Corrosive process applications with the appropriate TT-A41H-P/R configuration
Final selection should be based on the process medium, set pressure, 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 testing and performance requirements shall be confirmed according to the selected valve model, project specification and applicable standard.
For the TT-A41H Series, the low-lift criterion applies: H ≥ 1/20 d₀.
Dimensions – PN16 / PN25 / PN40
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 15 | 20 | 100 | 85 | 275 |
| 25 | 20 | 25 | 100 | 85 | 275 |
| 32 | 25 | 32 | 115 | 100 | 285 |
| 40 | 32 | 40 | 120 | 110 | 285 |
| 50 | 40 | 50 | 135 | 120 | 355 |
| 65 | 50 | 65 | 140 | 130 | 390 |
| 80 | 65 | 80 | 160 | 135 | 394 |
| 100 | 80 | 100 | 170 | 160 | 500 |
| 125 | 100 | 125 | 190 | 190 | 570 |
| 150 | 125 | 150 | 205 | 195 | 585 |
| 200 | 150 | 200 | 240 | 230 | 710 |
| 250 | 200 | 250 | 350 | 320 | 905 |
Dimensions – PN64 / PN100
| DN | Orifice d₀ (mm) | Outlet DN′ | L (mm) | L1 (mm) | H Approx. (mm) |
| 20 | 15 | 20 | 100 | 95 | 268 |
| 25 | 20 | 25 | 100 | 95 | 268 |
| 32 | 25 | 32 | 115 | 105 | 279 |
| 40 | 32 | 40 | 135 | 115 | 330 |
| 50 | 40 | 50 | 160 | 130 | 365 |
| 65 | 50 | 65 | 175 | 160 | 503 |
| 80 | 65 | 80 | 175 | 160 | 498 |
| 100 | 80 | 100 | 190 | 180 | 530 |
| 150 | 100 | 150 | 280 | 260 | 657 |
Dimensions are for preliminary engineering and layout reference. Final approved drawings should be confirmed before piping fabrication or installation.
Pressure Rating and Size Selection
The available nominal size depends on the required pressure class.
PN16 / PN25 / PN40:
DN20 to DN250
PN64 / PN100:
DN20 to DN150
The pressure rating alone does not define the allowable set pressure or relieving performance of the valve. Final selection must consider the actual valve configuration, process conditions and applicable project requirements.
Safety Valve Sizing and Selection
For correct selection of the TT-A41H Series, please provide:
- Process medium
- Set pressure
- Operating pressure
- Design pressure
- Operating / relieving temperature
- Required relieving capacity
- Back pressure
- Required inlet DN
- Required outlet DN
- Nominal pressure / flange rating
- Required body and trim materials
- Applicable standards and certification requirements
- Installation and discharge arrangement
Depending on whether the relieving medium is a gas, vapor or liquid, additional process properties may be required for capacity calculation.
Engineering Support
THINKTANK supports EPC contractors, process equipment manufacturers, system integrators 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 datasheets and documentation
With more than 30 years of industrial valve application experience, THINKTANK can also evaluate replacements for existing safety valve brands and provide technically suitable, cost-effective alternatives.
