ASTM/ASME A/SA 182 F316Ti Corrosion Resistant High-Temperature Stationary

Product Specification

Stationary Tubesheet as Fixed-End Pressure Boundary

A stationary tubesheet (also referred to as a fixed tubesheet) is the pressure‑retaining component at the fixed end of a shell and tube heat exchanger. It acts as the primary barrier between tube‑side and shell‑side fluids, provides structural support for the tube bundle, and transmits tube loads to the shell flange or channel. In a fixed tubesheet design (TEMA Types L, M, or N), both tubesheets are stationary and are welded or bolted directly to the shell, with tubes fixed at both ends.

This product is manufactured from forged stainless steel conforming to ASTM A182 / ASME SA182 – the specification covering forged or rolled austenitic stainless steel pipe flanges, forged fittings, valves, and parts for high‑temperature and corrosive service. The stationary tubesheet is designed and manufactured per ASME Section VIII Division 1 Appendix AA (fixed tubesheet design procedure), TEMA Class R/B/C, and GB/T 151 for domestic applications.

Material Grades – ASTM/ASME A/SA 182 Stainless Steels

The following four austenitic stainless steel grades are available for stationary tubesheet fabrication. Each offers distinct corrosion resistance, temperature capability, and stabilisation characteristics.

ASTM/ASME A/SA 182 F304 (UNS S30400)

• Type: 18Cr‑8Ni austenitic stainless steel (standard carbon)

• Key properties: High strength, good oxidation resistance, general‑purpose corrosion resistance

• Yield strength (min): 205 MPa

• Tensile strength (min): 515 MPa

• Maximum service temperature: Up to 538°C (intermittent), 816°C (continuous)

• Melting point: 1,400 – 1,450°C

• Application: General chemical service, non‑chloride environments, moderate temperatures

• Limitation: Sensitisation risk in welded service above 425°C; not recommended for welded thickness above 16mm without stabilisation

ASTM/ASME A/SA 182 F316L (UNS S31603)

• Type: 16Cr‑10Ni‑2Mo austenitic stainless steel (low carbon – 0.030% max)

• Key properties: Molybdenum addition improves pitting and crevice corrosion resistance; low carbon prevents intergranular corrosion after welding

• Yield strength (min): 170 MPa

• Tensile strength (min): 485 MPa

• Maximum service temperature: Up to 425°C (ASME allowable stress published); continuous service up to 870°C, operating range from -196°C to 450°C

• Hardness: ≤ 200 HB

• Application: Petrochemical, marine, pharmaceutical, food processing – handling acids, alkalis, salts, seawater

• Chloride limit: ≤ 200 ppm for sustained service

• Limitation: Not suitable above 450°C – allowable stresses decrease significantly at higher temperatures

ASTM/ASME A/SA 182 F321 (UNS S32100)

• Type: 18Cr‑10Ni‑Ti titanium‑stabilised austenitic stainless steel

• Key properties: Titanium stabilises carbon (Ti ≥ 5 × (C+N)), preventing chromium carbide precipitation in the heat‑affected zone during welding

• Yield strength (min): 205 MPa

• Tensile strength (min): 515 MPa

• Elongation (min): 30%

• Maximum service temperature: Resist oxidation up to 815°C; higher creep and stress rupture properties than F304 and F304L

• Solution annealing temperature: 950 – 1,120°C, followed by rapid cooling (water quenching)

• Application: Welded heat exchanger components, elevated temperature service (425°C – 540°C), intergranular corrosion resistance after welding

• Limitation: Not suitable above 538°C unless heat treated to minimum 1,095°C

ASTM/ASME A/SA 182 F316Ti (UNS S31635)

• Type: 16Cr‑10Ni‑2Mo‑Ti titanium‑stabilised austenitic stainless steel

• Key properties: Combines the pitting resistance of 316L (Mo content) with titanium stabilisation; resists intergranular corrosion that occurs when standard 316L experiences chromium carbide precipitation during welding or prolonged thermal exposure above 450°C

• Yield strength (min): 205 MPa

• Tensile strength (min): 515 MPa

• Elongation (min): 30%

• Reduction of area (min): 40%

• Operating temperature range: -196°C to 700°C

• Application: High‑temperature heat exchangers, corrosive environments requiring both Mo corrosion resistance and Ti stabilisation

• Limitation: Higher cost than F316L; Ti addition improves high‑temperature strength but may reduce ductility in some conditions

Material Comparison – Key Selection Parameters

Fixed Tubesheet Design – ASME VIII-1 Appendix AA

The stationary tubesheet in a fixed tubesheet heat exchanger (TEMA Types L, M, N) is designed per ASME Section VIII Division 1 Appendix AA – Nonmandatory Tubesheet Design Procedure.

Key Design Parameters

The design thickness accounts for:

• Tube hole ligament efficiency – reduced cross‑sectional area due to drilled holes

• Differential pressure – maximum pressure differential between tube side and shell side

• Temperature derating – allowable stress reduction at elevated temperatures per ASME Section II Part D

• Corrosion allowance – additional thickness for anticipated corrosion over service life

Typical Stationary Tubesheet Dimensions (Forged Stainless Steel)

Manufacturing Process – Forged Stationary Tubesheet

Material Conformance

• Material certified per ASTM A182 / ASME SA182

• Heat number stamping for 100% material traceability

• Positive Material Identification (PMI) verification per XRF spectrometer – 100% of material lots

Forging and Heat Treatment

• Forging: Hot worked from billet or ingot to final forged shape

• Solution annealing:

  • F304 / F321 / F316Ti: 1,040°C – 1,120°C, followed by water quenching

  • F316L: 1,040°C minimum, followed by water quenching

• Cooling: Water quench or rapid air cool after hot working

Machining and Drilling

• CNC drilling for precision hole pattern – tolerance +0.05 / –0.00 mm

• Hole surface finish: Ra ≤ 1.6 μm for expanded joints; Ra ≤ 3.2 μm for welded joints

• Ligament (bridge between holes): Minimum 0.8 × hole diameter per ASME VIII-1

• Deburring: All holes deburred on both faces

Tube-to-Tubesheet Joint Types – Stationary Tubesheet

Inspection and Testing – Stationary Tubesheet

Non-Destructive Examination (NDE)

Dimensional Inspection

Hydrostatic Test (After Assembly)

• Test pressure: 1.3 × design pressure per ASME VIII-1 UG-99

• Test medium: Clean water (chloride ≤ 50 ppm for austenitic SS to prevent SCC)

• Hold time: ≥ 30 minutes

• Acceptance: Zero pressure drop; no visible leakage

Application Profiles – Stationary Tubesheet Material Selection

Petrochemical and Refinery Heat Exchangers

• Service: Hydrocarbon processing, feed/effluent exchangers, condensers

• Recommended material: F316L (sweet service) / F321 or F316Ti (sour service, H₂S present)

• Design considerations: Hydrogen partial pressure; H₂S corrosion (NACE MR0175); chloride content

• Temperature range: 150°C – 400°C

Marine and Offshore Heat Exchangers

• Service: Seawater cooling, platform cooling systems

• Recommended material: F316L or F316Ti (Mo provides pitting resistance in seawater)

• Design considerations: Chloride concentration up to 20,000 ppm; crevice corrosion risk

• Temperature range: 5°C – 150°C

Pharmaceutical and Food Processing

• Service: High‑purity process fluids, clean steam

• Recommended material: F316L (low carbon prevents sensitisation; easy to passivate)

• Design considerations: Surface finish Ra ≤ 0.8 μm (electropolished); FDA compliance

• Temperature range: 20°C – 150°C

High‑Temperature Process Heaters

• Service: Elevated temperature gas cooling, waste heat recovery

• Recommended material: F321 or F316Ti (Ti stabilisation prevents carbide precipitation above 425°C)

• Design considerations: Creep resistance; thermal cycling

• Temperature range: 400°C – 600°C

Thermal Expansion – Fixed Tubesheet Design Constraint

In a fixed tubesheet design, both tubesheets are stationary, and differential thermal expansion between tubes and shell must be accommodated:

• Allowable ΔT without expansion joint: ≤ 60°C (carbon steel tubes) / ≤ 40°C (stainless steel tubes)

• When ΔT exceeds allowable: An expansion joint must be installed on the shell, or a U‑tube / floating head design must be selected

• Thermal stress calculation: Per ASME VIII-1 UG-23(c) – stress must not exceed allowable at design temperature

For stationary tubesheets in high ΔT service, finite element analysis (FEA) is typically required to evaluate expansion joint requirements and tubesheet stress distribution.

Documentation per Shipment

• Material test certificates (EN 10204 3.1 or 3.2) – base material, heat number

• ASME U‑stamp data report (if applicable)

• TEMA datasheet (Class R/B/C)

• Dimensional inspection report (hole diameter, pitch, ligament, flatness, thickness)

• NDE reports – UT (lamination), PT (surface), borescope

• PMI test report (XRF verification)

• Heat treatment chart (solution annealing time‑temperature recording)

• Weld procedure specification (WPS) and qualification record (PQR) – if tube‑to‑tubesheet welds applied

• Tube sheet as‑built drawing – with hole pattern coordinates, pitch, and dimensions

• Hydrostatic test report (if tested as part of assembly)

Selection Checklist – Stationary Tubesheet (ASTM A/SA 182 Grades)

1. Material grade – F304 / F316L / F321 / F316Ti (based on fluid corrosivity and temperature)

2. Tubesheet type – Fixed (stationary) / Floating / U‑tube

3. Shell ID and channel ID – determines tubesheet diameter

4. Tube count and layout pattern – Triangular / Square / Rotated square

5. Tube OD and wall thickness – determines hole diameter

6. Tube pitch – center‑to‑center distance per TEMA RCB-4.3

7. Tube‑to‑tubesheet joint type – Expanded / Welded / Combined

8. Design pressure – tube side and shell side (specify differential)

9. Design temperature – tube side and shell side

10. Corrosion allowance – per service life requirement

11. Chloride concentration – if > 200 ppm, select F316L or F316Ti

12. Welding requirement – if tubes are welded, select low‑carbon or stabilised grades (F316L / F321 / F316Ti)

13. NDE requirement – per ASME VIII-1 or project specification

14. Flange connection type – RF / FF / RTJ

15. PWHT requirement – solution annealing required for all A/SA 182 stainless grades after hot working

Design Limitation Statement – Stationary Tubesheet

The stationary tubesheet is subject to the following limitations:

• It is not rated for internal pressure until assembled with the shell, tubes, and flanges – the complete heat exchanger rating applies.

• F304 is not recommended for welded service above 425°C due to sensitisation risk – use F321 or F316Ti for elevated temperature welded applications.

• F316L has lower allowable stress than F316 at temperatures above 425°C; above 450°C, F316L is not suitable.

• F321 and F316Ti require solution annealing at 950°C – 1,120°C after forging to restore corrosion resistance.

• For chloride service above 200 ppm, F304 is not recommended – select F316L (≤200 ppm) or F316Ti.

• Hydrotest water for austenitic stainless steel tubesheets must have chloride content ≤ 50 ppm to prevent stress corrosion cracking.

• Fixed tubesheet design requires an expansion joint when ΔT between tubes and shell exceeds material‑specific limits.

• For service temperatures above 538°C, F321 and F304 require special heat treatment.