A tube sheet is the primary pressure-containing component of a shell and tube heat exchanger that separates the tube-side fluid from the shell-side fluid and provides structural support for the tube bundle. It is a flat circular plate drilled with a pattern of holes to accept tubes, which are then expanded, welded, or both to form the tube-to-tubesheet joint.
The tube sheet functions as:
A pressure boundary between tube side and shell side (must withstand the higher of the two pressures or the differential pressure)
A structural support for the tube bundle (transmits tube loads to the shell flange)
A flow distributor (inlet/outlet nozzles direct fluid to specific tube rows)
This product is designed and manufactured per ASME Section VIII Division 1 or Division 2, TEMA Class R (refinery), B (chemical), or C (commercial), and GB/T 151 for domestic applications. Tube sheets are supplied as standalone forged or rolled plates, or as part of a complete tube bundle assembly.
Tube sheet is welded or bolted directly to the shell on both ends
Tubes are fixed at both tube sheets; shell is integral with tube sheets
Thermal expansion compensation: Requires expansion joint on shell when ΔT between tube and shell exceeds allowable (typically > 60°C for carbon steel; > 40°C for stainless steel)
Application: Clean shell-side fluids, small temperature differential, non-fouling service
Limitation: Shell-side cleaning is not possible without removing entire bundle; no mechanical cleaning access on shell side
One tube sheet is fixed (stationary) to the shell flange; the other is free to move (floating) to accommodate thermal expansion
Floating tube sheet is not welded to shell – allows axial movement of the bundle
Application: Large temperature differential (ΔT > 60°C), fouling service requiring bundle removal
Limitation: Requires additional sealing arrangement (floating head cover) which increases cost and maintenance complexity
Single tube sheet supports both ends of U-shaped tubes
All tubes are bent into a U-shape and both tube ends are rolled/welded into the same tube sheet
No differential thermal expansion between tubes and shell – each tube expands independently
Application: High thermal differential (ΔT up to 200°C), high-pressure gas service, hydrogen service, thermal shock
Limitation: Tubes cannot be mechanically cleaned (only chemical cleaning); minimum U-bend radius limits tube OD selection
| Parameter | Range | Standard / Note |
|---|---|---|
| Diameter (OD) | 200mm – 4,000mm | Limited by forging/rolling capability and transport |
| Thickness | 15mm – 350mm | Determined by ASME VIII-1 UG-34 / TEMA RCB-4.3 |
| Bolt circle diameter | Matches shell flange or channel flange | Per ASME B16.5 / B16.47 |
| Number of bolt holes | Matches flange standard | Per ASME / TEMA |
| Bolt hole diameter | Bolt diameter + 1.5mm – 3.0mm clearance | Per flange standard |
| Gasket seating surface | Raised face (RF) or ring-type joint (RTJ) | Per ASME B16.5 |
| Parameter | Range | Standard / Note |
|---|---|---|
| Hole diameter | Tube OD + 0.2mm – 0.5mm (for expanded joints) | Per TEMA RCB-4.3 / GB/T 151 |
| Hole diameter tolerance | H11 (e.g., Ø25.2mm +0.13/0) | Per ISO 286 / TEMA standard |
| Hole finish (Ra) | ≤ 1.6μm (expanded) / ≤ 3.2μm (welded) | For expansion: finer finish ensures pull-out strength |
| Ligament (bridge) width | Minimum 0.8* hole diameter | Per ASME VIII-1 Appendix A – prevents ligament rupture |
| Ligament deviation from drawing | ≤ ±0.2mm | Per TEMA RCB-4.3 |
| Hole perpendicularity to surface | ≤ 0.5° | Prevents tube misalignment during insertion |
| Pattern | Description | Application |
|---|---|---|
| Triangular (30° or 60°) | Tubes arranged in equilateral triangles | Maximum tube density; highest heat transfer surface area per shell cross-section |
| Square (90°) | Tubes arranged in straight rows, perpendicular | Allows mechanical cleaning (rod/brush) access through tube lanes |
| Rotated square (45°) | Square pattern rotated 45° | Higher tube density than square; moderate cleaning access |
Triangular pitch: 1.25* – 1.5* tube OD (minimum)
Square pitch: 1.5* – 2.0* tube OD (minimum)
Pitch tolerance: ±0.5mm (adjacent holes) / ±1.0mm (overall pitch accumulation)
| Grade | Spec | Temp Range | Application |
|---|---|---|---|
| SA-516 Gr.60 / 65 / 70 | ASTM A516 | -20°C to +425°C | General pressure vessel service – non-corrosive tube-side fluids |
| SA-266 Gr.2 / 3 / 4 | ASTM A266 | -20°C to +425°C | Forged tube sheets for high-pressure service |
| Q345R / 16MnR | GB 713 | -20°C to +400°C | Domestic standard equivalent to SA-516 |
| 20# / 16Mn | GB 711 | -20°C to +400°C | Forged or rolled plate tube sheets |
| Grade | Spec | Temp Range | Application |
|---|---|---|---|
| SA-387 Gr.11 (1.25Cr-0.5Mo) | ASTM A387 | -20°C to +540°C | Elevated temperature (hydrocracking, hydrotreating) – chloride/H₂S service |
| SA-387 Gr.22 (2.25Cr-1Mo) | ASTM A387 | -20°C to +540°C | Higher-temperature service (catalytic reforming, ammonia synthesis) |
| SA-336 Gr.F11/F22 | ASTM A336 | -20°C to +540°C | Forged tube sheets for high-temp service |
| Grade | Spec | Temp Range | Chloride Limit | Application |
|---|---|---|---|---|
| 304L / 304 | ASTM A240 / A182 | -196°C to +425°C | ≤ 200ppm | Mildly corrosive, clean steam, food/pharma |
| 316L / 316 | ASTM A240 / A182 | -196°C to +425°C | ≤ 200ppm | Organic acids, salt solutions, chlorides (moderate) |
| 321 / 347H | ASTM A240 / A182 | -196°C to +540°C | ≤ 200ppm | High-temperature service (> 425°C) – stabilized grades |
| Duplex 2205 | ASTM A240 / A182 | -40°C to +280°C | ≤ 300ppm at 80°C | Chloride-containing hydrocarbons, offshore |
| Super Duplex 2507 | ASTM A240 / A182 | -40°C to +250°C | ≤ 500ppm at 60°C | Severe chloride service, seawater |
| Grade | Spec | Temp Range | Application |
|---|---|---|---|
| Titanium Gr.2 | ASTM B265 / B381 | -40°C to +230°C | Seawater, brine, high-chloride service |
| Alloy 625 (Inconel) | ASTM B443 / B564 | -196°C to +540°C | Sour gas, high-temp corrosive, amine units |
| Alloy C276 (Hastelloy) | ASTM B575 / B564 | -196°C to +400°C | Severe acid and chloride service |
| Copper-nickel C70600 | ASTM B171 | -40°C to +200°C | Marine cooling water, brackish water |
For corrosive service, the tube sheet may be supplied with a corrosion-resistant alloy (CRA) layer clad or weld-overlaid on the process-facing surface. Cladding methods include:
Explosion-bonded clad plate: Base material (CS) + CRA layer metallurgically bonded by explosive detonation
Roll-bonded clad plate: Hot-rolled under pressure to form bond between CS and CRA
Weld overlay (strip cladding): CRA material deposited onto CS surface in overlapping strips
Butter welding: CRA layer applied to tube sheet surface by welding, then machined flat
| Parameter | Range / Value | Standard / Note |
|---|---|---|
| Cladding material | 304L / 316L / Duplex / Ti / Alloy 625 / Alloy C276 | Per process fluid corrosivity |
| Cladding thickness | 2mm – 6mm (minimum 3mm per ASME VIII-1 UW-13) | Clad thickness excluded from pressure calculation unless fully bonded |
| Bond shear strength (explosion-bonded) | ≥ 140 MPa | Per ASTM B898 |
| Clad area bond | ≥ 99% bonded area | Individual unbonded patches ≤ 100mm²; total ≤ 1% |
| Weld overlay thickness | 3mm – 6mm minimum | Measured after machining to final surface |
| Surface finish after cladding | Ra ≤ 1.6μm (for expanded joints) / Ra ≤ 3.2μm (for welded joints) | Per TEMA |
The minimum required thickness of a tube sheet is calculated per ASME VIII-1 Appendix A or TEMA RCB-4.3. Simplified formulas for preliminary sizing:
t = F * (P * D) / (2 * S * E – 0.2 * P) * C (correction for tube hole ligament efficiency)
Where: F = design factor (typically 1.0 – 1.5 depending on tube-to-tubesheet joint type), P = design pressure (higher of tube side or shell side, or differential), D = tube sheet diameter, S = allowable stress at design temp, E = ligament efficiency (area of ligament / total pitch area)
Ligament efficiency η = (p – d) / p (for triangular pitch), where p = pitch, d = hole diameter
t = d * sqrt(C * P / S * E)
Where: d = tube sheet diameter (for circular plates), C = edge constraint factor (0.3 – 0.5 depending on support condition)
For expanded tube joints: Minimum tube sheet thickness ≥ 1.5* tube OD or ≥ tube OD + 20mm (whichever is greater)
For welded tube joints: Minimum thickness ≥ 1.0* tube OD or ≥ 20mm (whichever is greater)
For combined (weld + expand): Minimum thickness ≥ tube OD + 15mm
| Method | Tolerance | Typical Application |
|---|---|---|
| CNC drilling | ±0.05mm – ±0.10mm | High-precision, multi-hole patterns, large tube sheets |
| Radial drilling | ±0.1mm – ±0.2mm | Conventional fabrication, moderate tolerances |
| Gun drilling | ±0.025mm | Deep holes (> 5* diameter), high precision |
| Laser drilling | ±0.02mm | Thin tube sheets (≤ 20mm) |
For expanded joints: Hole surface finish Ra ≤ 1.6μm – ensures adequate friction for mechanical grip
For welded joints: Hole surface finish Ra ≤ 3.2μm – less stringent; weld fusion requires cleanliness
For combined joints: Ra ≤ 1.6μm (expansion portion) / Ra ≤ 3.2μm (weld area)
Deburring: All holes must be deburred on both faces – burrs cause tube insertion difficulty and joint defects
Hole cleaning: Compressed air blow or solvent flush to remove chips and cutting fluid residue
100% of holes checked for diameter with plug gauge (GO/NOGO) – GO gauge must pass; NOGO gauge must not pass
100% of holes checked for ligament (bridge) dimensions – tolerance ±0.2mm
Sample (5%) holes checked for surface finish per comparator – visual comparison to standard
Hole perpendicularity check: Dial indicator on tube sheet face – maximum deviation ≤ 0.5°
| Joint Type | Method | Pull-Out Strength (Min) | Applicable Service | Inspection |
|---|---|---|---|---|
| Expanded only | Hydraulic expansion at 160–220 MPa, hold 5–8s; or roller expansion | ≥ 20 MPa (CS) / ≥ 25 MPa (SS) | Non-toxic, non-cyclic, clean fluids | Hydrotest + first-article pull-out test |
| Welded only (seal weld) | GTAW (TIG) fillet weld, leg 1.5–2.0mm | N/A (mechanical retention from weld only) | High-pressure gas, hydrogen service, toxic fluids | 100% PT per ASME VIII-1 UW-51 |
| Weld + expand (combined) | Seal weld + hydraulic expansion at 160–200 MPa | ≥ 25 MPa | Cyclic thermal (> 500 cycles/year), high pressure, toxic | 100% PT + hydrotest + pull-out test |
| Welded (full penetration) | GTAW full penetration weld, joint complete | ≥ 30 MPa | Extreme pressure (> 15 MPa), hydrogen, high safety factor | 100% PT + 100% RT (spot) |
| Examination | Method | Scope | Acceptance Criteria (Per ASME VIII-1) |
|---|---|---|---|
| Lamination (plate) | UT (straight beam) | 100% of plate area (before drilling) | Laminations ≤ 20mm² per 100cm²; no edge lamination |
| Surface cracks | PT (liquid penetrant) | 100% of drilled face + cladding surface | No cracks; porosity ≤ 0.8mm; no clustered porosity |
| Clad bond integrity (if clad) | UT (shear wave / bond scan) | 100% of clad surface | No delamination > 20mm; no clustered indications |
| Hole wall condition | Borescope (visual) | 5% – 10% of holes (random) | No gouges, scratches > 0.1mm depth |
| Tube sheet-to-shell weld (if welded) | RT / MT / PT | Per UW-51 (full) or UW-52 (spot) | Per ASME VIII-1 UW-51 / UW-52 |
| Parameter | Tolerance | Method |
|---|---|---|
| Hole diameter (ID) | H11 per ISO 286 (e.g., Ø25.2mm +0.13/0) | Plug gauge / bore micrometer |
| Hole ligament (bridge) deviation | ≤ ±0.2mm | Optical comparator / CMM |
| Pitch accumulation (over 1m span) | ≤ ±1.0mm | CMM / optical comparator |
| Flatness of tube sheet face | ≤ 1mm per 1,000mm diameter | Dial indicator / straightedge |
| Surface roughness (clad or CS) | Ra ≤ 1.6μm (expanded) / ≤ 3.2μm (welded) | Surface comparator / profilometer |
| Total thickness variation | ±3% of nominal thickness | Micrometer (at 5 points) |
| Bolt hole circle diameter | Per ASME B16.5 flange standard | Template / CMM |
| Bolt hole alignment | ≤ 1.0mm deviation from drawing | Template / CMM |
If the tube sheet is supplied as a standalone component (not assembled to shell), hydrostatic testing is typically performed after assembly of the complete heat exchanger. However, the following intermediate checks are performed:
Tube hole leak test: Apply low-pressure air (0.2 MPa) to each hole (with dummy tube inserted) – soap bubble check for leakage – acceptance: no bubbles
For clad tube sheets: Light hydrotest (0.5 MPa) on clad surface – check for clad blisters or delamination – acceptance: no visible blistering
Bolt hole pressure test (for flange-connected tube sheets): Bolt hole integrity check – no leakage from bolt hole to tube hole under 0.6 MPa air
Material test certificates (EN 10204 3.1 or 3.2) – base plate, cladding material, filler materials
ASME U-stamp data report (if applicable) – including design calculations
TEMA datasheet (Class R/B/C) – if applicable
Dimensional inspection report (hole diameter, pitch, ligament deviation, flatness, thickness)
NDE reports – UT (lamination), UT (clad bond), PT (surface), borescope
Cladding bond shear strength test report (if clad – explosion-bonded or roll-bonded)
Tube hole surface finish report (profilometer records – sample 5% holes)
Weld procedure specification (WPS) and qualification record (PQR) – if clad weld overlay or tube sheet-to-shell welds applied
Post-weld heat treatment (PWHT) chart – if performed (time-temperature recording)
Drawing (as-built) – with hole pattern coordinates, pitch, and dimensions
When ordering a tube sheet (new, replacement, or spare), provide:
Tube sheet type – Fixed / Floating / U-tube
Shell ID and channel ID – determines tube sheet diameter
Tube count and tube layout pattern – Triangular / Square / Rotated square
Tube OD and wall thickness – determines hole diameter and pitch
Tube pitch (center-to-center distance) – per TEMA or GB/T 151
Tube hole diameter – H11 tolerance per ISO 286
Tube-to-tubesheet joint type – Expanded / Welded / Combined / Full penetration
Tube sheet thickness – per ASME VIII-1 Appendix A or TEMA RCB-4.3
Tube sheet material – CS / SS / Duplex / Ti / Alloy (solid or clad)
Cladding requirement (if any) – material, thickness, method (explosion-bonded / roll-bonded / weld overlay)
Design pressure – tube side and shell side (also specify differential pressure)
Design temperature – tube side and shell side
Flange connection type – RF (raised face) or RTJ (ring-type joint) – if tube sheet is flanged
Flange drilling standard – ASME B16.5 / B16.47 or HG/T 20615
PWHT requirement – based on material thickness and service (per UCS-56)
NDE requirement – per ASME VIII-1 or project specification
Surface treatment (if required) – pickling / passivation / coating / electropolish
The tube sheet as a standalone product is subject to the following limitations:
It is not rated for internal pressure until assembled with the shell, tubes, and flanges – the complete vessel rating applies
It must be matched to the shell flange bolt pattern and gasket seating surface; mismatched bolt holes or gasket profile will prevent proper sealing
For clad tube sheets, service temperature is limited by the lowest maximum service temperature of either the base material or the cladding material (e.g., CS base + Ti cladding → max 230°C due to Ti limit)
Not suitable for tube-side or shell-side fluids that exceed the corrosion resistance of the selected material grade – verify with the selection table
Not suitable for thermal cycling exceeding the fatigue limit of the tube-to-tubesheet joint (expanded-only joints are limited to < 500 cycles/year; combined joints recommended for > 500 cycles/year)
For very large diameters (> 3,000mm) or very thick sections (> 300mm), forging or roll-clad plate availability may be limited – consult manufacturer for lead times
Tube sheets with welded cladding require careful PWHT to prevent hydrogen cracking in the base material and sensitization in the cladding (for SS cladding, solution annealing may be required after welding)
