SA266 Gr.2 Carbon Steel Forged Tubesheet for Shell & Tube Heat Exchangers

ASME SA266 Gr.2 Carbon Steel Forged Tubesheet for Shell & Tube Heat Exchangers

SA266 Gr.2 Tubesheet is a carbon steel forged component designed for pressure-bearing applications in shell and tube heat exchangers, condensers, boilers and related process equipment.

Manufactured in accordance with ASME SA266 Gr.2, the tubesheet is produced from forged carbon steel and machined with precision tube holes, pass-partition features and sealing surfaces according to equipment drawings.

SA266/A266M covers carbon steel forgings for boilers, pressure vessels and associated equipment, with requirements covering chemical composition, mechanical properties and applicable heat-treatment conditions.

The product can be supplied as a fixed tubesheet, floating-head tubesheet or other project-specific configuration, depending on the heat exchanger design.

SA266 Gr.2 Carbon Steel

SA266 Gr.2 belongs to the carbon steel forging grades covered by ASTM A266/A266M. The specification includes four grades for pressure-vessel-related applications. The current designation system uses Grade 1, Grade 2, Grade 3 and Grade 4, replacing the former Class 1-4 terminology.

For a tubesheet application, the material is selected according to the mechanical design, pressure, temperature, corrosion allowance and compatibility with the shell, tubes and channel materials.

Forged Construction

The forged construction provides a suitable starting form for machining a thick tubesheet with a large number of precisely positioned tube holes.

Typical forging-related controls include:

• Forging Reduction
• Heat Treatment
• Grain Flow Consideration
• Chemical Analysis
• Mechanical Testing
• Ultrasonic Examination

The tubesheet is machined according to the heat exchanger drawing rather than relying only on standard flange dimensions.

Critical machining features include:

• Tube Hole Diameter
• Tube Hole Pitch
• Tube Hole Pattern
• Tube Hole Quantity
• Tube Hole Tolerance
• Tube Hole Perpendicularity
• Pass Partition Grooves
• Gasket Seating Surface
• Outer Diameter
• Overall Thickness
• Concentricity

The tube-hole design can be adapted to the selected tube OD, wall thickness, tube pitch and heat exchanger configuration.

Tube Hole Patterns

Common tube-hole arrangements include:

• Triangular Pitch - Provides a compact tube arrangement and can offer high heat-transfer surface density where cleaning requirements permit.
• Square Pitch - Provides more accessible spacing between tubes and can be considered where mechanical cleaning or maintenance access is important.
• Rotated Square Pitch - Can be used for specific flow and layout requirements.

The final tube-hole pattern should always follow the heat exchanger thermal and mechanical design.

A tubesheet is not simply a drilled steel plate. Its thickness and hole arrangement are determined by the interaction between tube-side pressure, shell-side pressure, differential pressure, temperature, tube loads and gasket sealing requirements.

Important design inputs include:

• Design Pressure
• Design Temperature
• Tube OD
• Tube Wall Thickness
• Tube Material
• Shell ID
• Tube Count
• Tube Pitch
• Pass Arrangement
• Corrosion Allowance
• Differential Pressure
• Gasket Configuration
• Tube-to-Tubesheet Joint

The tube holes can be prepared for different tube attachment methods, depending on the heat exchanger design:

• Expanded Tube Joint
• Strength-Welded Joint
• Seal-Welded Joint
• Expanded & Seal-Welded Joint

Tube-hole surface finish and groove configuration can be manufactured according to the customer's drawing.

Available inspection can include:

• Chemical Composition Analysis
• Tensile Test
• Yield Strength Test
• Elongation Test
• Reduction of Area
• Hardness Test
• Heat Treatment Record
• Ultrasonic Testing
• Magnetic Particle Testing
• Liquid Penetrant Testing
• Dimensional Inspection
• Tube Hole Inspection
• PMI Where Required
• Visual Inspection

Additional inspection requirements can be incorporated when specified by the purchase order or project specification. ASTM A266/A266M also provides supplementary requirements when additional testing or inspection is requested by the purchaser.