Yuhong Group Co., Ltd. engineers and fabricates custom shell-and-tube heat exchangers, pressure vessels, and air coolers for thermal processing industries worldwide. Our product range includes fixed tubesheet, U-tube, and floating head exchangers, along with replacement tube bundles, U-bend tubes, finned tubes, and exchanger components such as tubesheets, baffles, channels, and floating head assemblies. With ASME U Stamp certification, TEMA Class R/B/C capabilities, and third-party approvals including PED, API, ABS, DNV, GL, BV, KR, TS, and CCS, we supply pressure equipment engineered for severe service and regulatory compliance.
The ASME U Stamp Floating Head Shell and Tube Heat Exchanger is designed and fabricated in accordance with ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, and meets TEMA (Tubular Exchanger Manufacturers Association) Standards for mechanical design, construction, and tolerances. The floating head configuration—available in TEMA types AES, AET, BET, BEP, and AEP—features one tubesheet fixed at the channel end and a floating tubesheet at the rear head that is not rigidly connected to the shell. This allows the tube bundle to expand and contract independently of the shell, accommodating differential thermal expansion without requiring expansion joints or inducing stress on tubesheet joints.
The removable bundle design provides full access to external tube surfaces for mechanical cleaning, inspection, and tube replacement, making this exchanger type the preferred choice for fouling services and processes requiring frequent maintenance.
| Component | Typical Material Standards | Design Function |
|---|---|---|
| Shell & Shell Cover | ASME SA516 Gr.70 (carbon steel) or SA240 316L (stainless) | Contains shell-side fluid; material selected based on process corrosivity and temperature |
| Channel & Channel Cover | ASME SA516 Gr.70 or SA240 316L | Houses tube-side inlet/outlet; removable for tube end access |
| Stationary Tubesheet | ASME SA182 F316L or SA266 Gr.2 | Fixed-end tube support; welded or bolted to channel |
| Floating Tubesheet | ASME SA266 Gr.2 or SA182 F316L | Free to move axially; not welded to shell, enabling thermal expansion |
| Heat Exchanger Tubes | ASME SA213 TP304L / TP316L (seamless) | Primary heat transfer surface; plain or low-finned tubes available |
| Baffles | ASME SA516 Gr.70 or SA240 316L | Support tubes and direct shell-side flow for optimal heat transfer |
| Floating Head Assembly | Cover, gaskets, bolting (per ASME B16.5) | Seals the floating tubesheet; removable for bundle extraction |
| Nozzles & Flanges | ASME SA350 LF2 or SA182 F304L/F316L forgings | Process connections per ASME B16.5 |
| Tie Rods & Spacers | ASME SA193 / SA194 bolting | Secure baffle stack and maintain tube support spacing |
Additional materials available upon agreement: duplex stainless steels (S31803, S32205, S32750), nickel alloys (Inconel, Monel, Incoloy), titanium, and high-alloy grades for extreme corrosion resistance.
| Parameter / Test | Standard / Requirement | Specification |
|---|---|---|
| Design Code | ASME Section VIII Div. 1 | Full U Stamp certification; National Board registered |
| TEMA Class | R (refinery), C (chemical), or B (general) | Per service severity; Class R for severe duty |
| Design Pressure | ASME VIII-1 | Up to 30 bar (shell) / per calculation; customer-specified |
| Design Temperature | ASME VIII-1 | Per material allowable stress tables; up to 450°C+ |
| Hydrostatic Test | ASME VIII-1 UG-99 | 1.3 × design pressure (minimum) |
| Pneumatic Test | ASME VIII-1 UG-100 | Optional; per customer requirement |
| Radiographic Examination (RT) | ASME VIII-1 UW-51 | On critical circumferential and longitudinal welds |
| Dye Penetrant Test (PT) | ASME VIII-1 Appendix 8 | Surface examination of welds and critical areas |
| PMI (Positive Material Identification) | — | 100% grade verification on pressure-retaining components |
| Tube-to-Tubesheet Joint | ASME VIII-1 Appendix A | Expanded, seal-welded, or strength-welded per design |
| Bundle Pulling Clearance | TEMA RCB | Engineered per maintenance access requirements |
Each exchanger is supplied with ASME Form U-1 Manufacturer's Data Report, signed by an ASME Authorized Inspector, and registered with the National Board of Boiler and Pressure Vessel Inspectors.
Floating head exchangers are specified for process conditions where fixed tubesheet or U-tube designs are unsuitable due to large temperature differentials, high fouling tendencies, or the need for frequent bundle removal. Primary applications include:
Petroleum Refining – crude oil preheat trains, atmospheric/vacuum distillation overhead condensers, reboilers, product coolers, and amine regenerator reboilers
Chemical Processing – reactor effluent cooling, distillation column reboilers and condensers, corrosive fluid heat exchange (acids, alkalis, solvents)
Petrochemical Plants – ethylene plant quench coolers, ammonia plant exchangers, syngas coolers
Power Generation – feedwater heaters, steam surface condensers, lube oil coolers
Oil & Gas Upstream – produced water coolers, glycol dehydration reboilers, crude oil heaters
Fouling Services – polymer melts, slurry streams, coke-forming hydrocarbons, and other fluids that deposit on heat transfer surfaces
Thermal Expansion Accommodation: The floating tubesheet is not welded to the shell, allowing unrestricted axial movement of the tube bundle relative to the shell. This eliminates thermal stress at tubesheet joints—a common failure mode in fixed tubesheet designs—and is critical for applications with temperature differences exceeding 50°C between shell-side and tube-side fluids.
Complete Bundle Removability: After removing the floating head cover and shell cover, the entire tube bundle can be withdrawn from the shell. This provides full access to:
External tube surfaces for mechanical or high-pressure water cleaning
Individual tubes for plugging, replacement, or retubing
Baffles and tie rods for inspection and repair
Internal shell surfaces for scale or deposit removal
Vibration Mitigation: The floating head configuration, combined with optimized baffle spacing and segmental cut design, reduces flow-induced tube vibration—a primary cause of tube failure in high-velocity shell-side services. Baffle spacing is calculated per TEMA guidelines to maintain tube natural frequencies above the vortex shedding excitation frequency.
Impingement Protection: Inlet nozzles are equipped with impingement plates or distribution baffles to deflect high-velocity inlet streams, preventing erosion of the first row of tubes and extending bundle life.
Custom Engineering: Each exchanger is designed to customer process specifications, including:
Shell and tube pass arrangements (1-pass, 2-pass, or multi-pass)
Baffle types: segmental, disc-and-doughnut, or orifice
Tube layouts: triangular (clean fluids), square (mechanical cleaning), or rotated square (high turbulence)
Nozzle sizes, orientations, and flange ratings per ASME B16.5
Corrosion allowance tailored to process corrosivity
Q: What is the difference between TEMA AES, AET, and BET floating head types?
A: TEMA three-letter codes describe front head, shell, and rear head configurations. AES features a removable channel cover (A), single-pass shell (E), and floating head with split backing ring (S). AET has the same front head and shell but a pull-through floating head (T). BET uses a bonnet-type front head (B). Selection depends on maintenance access, pressure rating, and tube bundle removal requirements.
Q: When should a floating head exchanger be specified instead of a fixed tubesheet or U-tube design?
A: Specify floating head when: (1) temperature difference between shell and tube sides exceeds approximately 50°C (making expansion joints impractical); (2) shell-side fluid is highly fouling and requires frequent mechanical cleaning; (3) straight tubes are required (U-tubes cannot be mechanically cleaned internally); and (4) the tube bundle must be removable for inspection or replacement.
Q: What is the maximum design pressure and temperature for ASME U Stamp floating head exchangers?
A: Design pressure and temperature limits are determined by ASME Section VIII Division 1 based on material allowable stress at design temperature. For carbon steel SA516 Gr.70, typical limits are up to 30 bar at 300°C; for stainless steels and alloys, higher temperatures and pressures are achievable. Each exchanger is designed per the specific process conditions and Code calculations.
Q: How is tube-to-tubesheet joint integrity ensured in floating head designs?
A: Tube-to-tubesheet joints are expanded using hydraulic or mechanical roller expansion, with optional seal welding or strength welding per ASME VIII-1 Appendix A requirements. Joints are tested via hydrostatic test and, where specified, helium leak testing to ensure leak-tightness under operating conditions.
Q: What documentation is provided with an ASME U Stamp exchanger?
A: Each exchanger includes ASME Form U-1 Manufacturer's Data Report, material test certificates (EN 10204 Type 3.1 or 3.2), NDE reports, hydrostatic test certificates, dimensional inspection reports, and as-built drawings. Third-party inspection by authorized agencies (ABS, DNV, BV, Lloyds) is available upon request.
For detailed specifications, custom designs, or third-party inspection arrangements, please contact Yuhong Group Co., Ltd. at vladimir@steelseamlesspipe.com.
