Forged Tube Sheets and Flanges for Heat Exchangers and Pressure Equipment

Role of Tube Sheets and Flanges in Heat Exchangers

Tube sheets are thick, perforated metal plates that hold the tube bundle in position, separate the shell-side fluid from the tube-side fluid and prevent leakage between the two circuits. Flanges are ring-shaped components that connect the exchanger to piping or other equipment, and are often forged integrally with the tube sheet. Baffles are plates positioned inside the shell to direct shell-side flow across the tubes, increasing fluid velocity and improving heat transfer. Forgings are preferred over castings for these parts because forging refines the grain structure and improves strength and toughness under high pressure and temperature.

Material Selection

Material is selected for design temperature, pressure, corrosion and applicable code requirements. The most common material families and designations are listed below.

Material family	Common designations
Carbon steel	ASTM A105, A350 LF2, A266, A694 F52-F70, A765
Low alloy steel	A182 F1, F5, F9, F11, F12, F22, F91, F92
Stainless steel	A182 F304/F304L, F316/F316L, F310, F317L, F321, F347
Duplex stainless steel	A182 F51, F53, F55, F60
Nickel alloys	UNS N04400, N06600, N06625, N08800/N08810/N08811, N08825, N08020, N10276
Titanium	ASME SB381 Gr. 1, 2, 5, 7, 12, 16
Copper alloys	C70600 (Cu-Ni 90/10), C71500 (Cu-Ni 70/30), C63000, C61400, C46400 per ASTM B171/ASME SB171

Standards and Specifications

Forged flanges and fittings for pressure service are commonly supplied to ASTM A182/A182M for alloy and stainless steel, A105/A105M for carbon steel piping components, A350/A350M for low-temperature carbon steel, A266/A266M for carbon steel pressure vessel forgings, A508/A508M for quenched and tempered pressure vessel steels and A694/A694M for high-yield pipeline flanges. European projects commonly reference EN 10222-2/3/4/5 for flanges and EN 10250 for open-die forgings. Tube hole drilling follows TEMA or ASME requirements, and dimensional verification follows the applicable product standard. For European material designations, typical grades include 11CrMo9-10 (W.Nr. 1.7383) and 13CrMo4-5 (W.Nr. 1.7335) per EN 10222-2, X2CrNiMo17-12-2 (W.Nr. 1.4404) and X5CrNi18-10 (W.Nr. 1.4301) per EN 10222-5, and 12Ni14 (W.Nr. 1.5637) per EN 10222-3.

Manufacturing and Quality Control

Forgings are produced from ingot or billet, heat treated in accordance with the product standard, machined on CNC equipment and drilled to the specified tube pattern. Tube sheet drilling is performed to TEMA or ASME requirements with close tolerance hole patterns. Quality control includes material test certificates (EN 10204 3.1 or 3.2), non-destructive examination such as ultrasonic testing, dimensional inspection and full traceability of heat number and batch. For severe chloride service, clad tube sheets are produced by explosion cladding, combining a corrosion-resistant layer of titanium, nickel alloy or stainless steel with a carbon steel or alloy steel base.

Applications

Shell-and-tube heat exchangers, boilers, condensers and reactors in power plants; desalination plants using multi-effect distillation and reverse osmosis; petrochemical refining and gas separation units; nuclear steam generators; marine engine cooling systems; and food and beverage heat exchangers where hygiene and contamination control are critical. Component types include heat exchanger tube sheets, girth flanges, channel covers, baffle plates, forged nozzles, self-reinforced nozzles, nozzle necks and long welding necks.

Frequently Asked Questions

What is a tube sheet in a heat exchanger? A plate with precisely drilled holes through which the tubes pass; it holds the tubes in position and separates shell-side from tube-side fluid.

What is the difference between a tube sheet and a baffle? The tube sheet supports the tube bundle at each end and separates the fluid circuits; baffles are placed along the shell to direct shell-side flow across the tubes for better heat transfer.

Which standard covers forged stainless steel flanges? ASTM A182/A182M is the most common specification for forged or rolled alloy and stainless steel pipe flanges, fittings and valves.

What does TEMA drilling mean? Tube holes are drilled and verified to the hole pattern and tolerance requirements of the TEMA standard for shell-and-tube heat exchangers.

Why use forgings instead of castings or plate? Forging produces a directional, refined grain structure with higher strength and toughness, which is important for high-pressure, high-temperature service.

What materials are used for seawater tube sheets? Copper-nickel C70600 and C71500, titanium per ASME SB381, and duplex stainless steels such as A182 F51 and F53 are typical choices for chloride service.

Frequently Asked Questions

Q1. Which ASTM standards cover forged flanges by material family?
ASTM A182/A182M for alloy and stainless steel, A105/A105M for carbon steel piping components, A350/A350M for low-temperature carbon steel, A508/A508M for quenched and tempered pressure vessel steels and A694/A694M for high-yield pipeline flanges.

Q2. Which European standards are referenced?
EN 10222-2/3/4/5 for flanges and EN 10250 for open-die forgings, with grades such as 1.4404 (X2CrNiMo17-12-2) and 1.4301 (X5CrNi18-10) per EN 10222-5.

Q3. What quality control is applied to forgings?
Material test certificates to EN 10204 3.1 or 3.2, non-destructive examination such as ultrasonic testing, dimensional inspection and full traceability of heat number and batch.

Q4. How are tube holes drilled?
Tube hole drilling follows TEMA or ASME requirements with close-tolerance hole patterns.

Q5. What are clad tube sheets?
Forgings produced by explosion cladding that combine a corrosion-resistant layer of titanium, nickel alloy or stainless steel with a carbon steel or alloy steel base for severe chloride service.