ASME U-Stamp & TEMA Class "C" HP-LT Shell-and-Tube Preheater | Geothermal ORC Duty | n-Butane / Brine Service
Product Overview
This HP-LT Preheater is engineered for the 28 MW Mahanagdong Geothermal Power Plant Project (GEX 2810-28) of Energy Development Corporation, and manufactured in full compliance with ASME Boiler & Pressure Vessel Code Section VIII, Division 1 and TEMA Class "C" standards. Designed as a critical component in Organic Rankine Cycle (ORC) geothermal power generation, the unit transfers heat from corrosive geothermal brine to organic working fluid (n-Butane) under high-pressure, moderate-temperature conditions.
With ASME U-Stamp certification, 100% radiographic examination on all pressure boundary welds, and a duplex stainless steel tube bundle (UNS S31803/2205), this preheater delivers long-term reliability in aggressive geothermal service.
Key Features & Advantages
Engineered for Aggressive Geothermal Service
- Tube Bundle: UNS S31803 / 2205 duplex stainless steel – exceptional resistance to chloride stress corrosion cracking (SCC) from high-salinity brine
- Shell & Channel: SA-516 Gr.70 carbon steel with SS 316L cladding (minimum 3 mm) – combining structural strength with superior corrosion protection
- Tubesheet: SA-266 Gr.2N forgings with SS 316L weld overlay (0.10 mm min) – ensures leak-tight tube-to-tubesheet joints
International Code Compliance
- Design Code: ASME VIII Div.1 + TEMA "C"
- ASME U-Stamp: Yes
- Joint Efficiency: 1.0 (both shell and tube sides)
- Radiographic Examination: 100% on all pressure welds
- NDE Suite: Ultrasonic Testing (UT), Magnetic Particle Testing (MT), Penetrant Testing (PT) – all performed per applicable code and contractual documents
Robust Mechanical Design
- TEMA Type: NEN (channel-integral front head + one-pass shell + channel-integral rear head with removable cover) – provides direct access to tubesheet for inspection and maintenance without dismantling the unit from the pipeline
- Baffle Type: NTIW-Segmental, 1060 mm spacing (center-to-center) – optimized for thermal performance
- Expansion Joint: Designed for N = 5000 cycles – absorbs thermal expansion between shell and tube sides
- Gaskets: Kammprofile 316L / Graphite – premium sealing performance under high pressure
- Bypass Seal: 2 pairs of sealing strips – minimizes shell-side bypass flow
Precision Fabrication & Testing
- Tube-to-Tubesheet Joint: Strength welding + leak test + hydrostatic test
- Stress Relief: Performed per code requirements
- Surface Finish: Flange facings machined to comply with ASME B16.5 or ASME B16.47
- Hydrostatic Test: Performed at 1.3 × design pressure per ASME VIII-1
Technical Specifications
| Item |
Specification |
| Equipment Name |
HP-LT Preheater |
| Tag No. |
PH1001A/B |
| Project |
GEX 2810-28 MW Mahanagdong Geothermal Power Plant |
| Client |
Energy Development Corporation |
| Drawing No. |
P063-E-ORC-M-DWG-1021 (Rev. 1) |
| TEMA Type |
NEN |
| Design Code |
ASME VIII Div.1 + TEMA "C" |
| ASME U-Stamp |
Yes |
| Number Required |
1 |
Materials of Construction
| Component |
Material |
| Shell & Cover |
SA-516 Gr.70 |
| Channel |
SA-516 Gr.70 + SS 316L cladding (3 mm min) |
| Tube Bundle |
UNS S31803 / 2205 (Duplex SS) |
| Tubesheet |
SA-266 Gr.2N + SS 316L weld overlay (0.10 mm min) |
| Bolting |
SA-193 B8/B8M / SA-194 Gr.8M |
| Gaskets |
Kammprofile 316L / Graphite |
| Baffles & Supports |
Carbon Steel (C.S.) |
Tube Bundle Details
| Parameter |
Value |
| Number of Tubes |
2759 |
| Tube Length |
16000 mm |
| Tube Outer Diameter |
19.05 mm |
| Tube Wall Thickness |
0.889 mm (BWG) |
| Tube Pitch |
25.4 mm |
| Tube Pattern |
30° triangular |
| Passes (Shell / Tube) |
1 / 1 |
Design Conditions
| Parameter |
Shell Side |
Tube Side |
| Fluid |
n-Butane |
Brine |
| Design Pressure |
42 Bar |
32 Bar |
| Design Temperature |
200 °C |
220 °C |
| Operating Temperature |
85 °C |
95 °C |
| Metal Temperature (Tubesheet) |
165 °C |
15 °C |
| Corrosion Allowance |
1.587 mm |
1.587 mm |
Nozzle Schedule (PH1001A)
| Nozzle Tag |
Size |
Rating / Type |
Service |
| N1A |
24" |
N/A BW |
Inlet Shell |
| N1A |
24" |
N/A |
Outlet Shell |
| N3A |
16" |
300# WN |
Inlet Tube |
| N5A |
16" |
N/A WN |
Outlet Tube |
| N7A |
2" |
N/A BW |
Drain Shell |
| N7A |
2" |
N/A BW |
Vent Shell |
| N8DA/B |
2" |
300# WN |
Drain Tube |
| N8A |
2" |
300# WN |
Vent Tube |
| N51 |
1/2" |
N/A NPT F |
Temp. Instrument Shell |
| N61 |
1/2" |
N/A NPT F |
Temp. Instrument Tube |
Weight Data
| Condition |
Weight (kg) |
| Empty Weight |
55,800 |
| Operating Weight |
85,800 |
| Full of Water |
90,000 |
| Bundle Weight |
21,500 |
Inspection & Testing
| Test |
Standard / Method |
| Hydrostatic Test |
Per ASME VIII-1 (Vendor) |
| Radiographic Examination (RT) |
100% on pressure boundary welds |
| Ultrasonic Test (UT) |
Per code & contractual documents |
| Magnetic Particle Test (MT) |
Per code & contractual documents |
| Penetrant Test (PT) |
Per code & contractual documents |
| PWHT |
Per code (Shell & Tube sides) |
Miscellaneous
| Item |
Shell Side |
Tube Side |
| Painting |
Per Specification |
Per Specification |
| Electrical Tracing |
N/A |
N/A |
| Internal Coating |
-- |
-- |
| Fireproofing |
-- |
-- |
| Impregnation Device |
-- |
-- |
| Bypass Seal |
2 pairs sealing strips |
2 pairs sealing strips |
| Expansion Joint |
N = 5000 cycles |
N = 5000 cycles |
Applications
Geothermal Power Plants – ORC cycle preheaters for n-Butane, pentane, or similar organic working fluids
Oil & Gas – Crude preheat trains, lean/rich amine exchangers
Petrochemical & Refining – Feed preheaters, reactor effluent coolers
Power Generation – Feedwater heaters, waste heat recovery economizers
Chemical Processing – Heat recovery from corrosive process streams