ASTM A213 TP321 U-Tube for Heat Exchangers

GNEE, as a professional supplier of stainless steel U-bend tubes, provides TP321 (UNS S32100) titanium-stabilized austenitic stainless steel U-tube heat exchanger tubes in compliance with ASTM A213 / SA213M and ASME SA213 standards.The product is manufactured from high-quality TP321 seamless tubes, which undergo solution annealing (rapid cooling from 920–1150°C) to ensure optimal corrosion resistance. All U-bend sections are subjected to automatic temperature-controlled stress relief treatment, effectively preventing intergranular corrosion sensitivity caused by heat treatment. The wall thinning rate in the bent area is controlled within ≤10%, and ovality strictly complies with ASME B16.49 requirements.

ASTM A213 TP321 U-Tube Manufacturing Process

Attached is the stress-relieving heat treatment curve for our 321 stainless steel U-bends.

TP321 stainless steel U-tube heat exchangers offer significantly improved high-temperature stress rupture strength and creep resistance compared to 304 stainless steel. They can operate stably in long-term high-temperature environments ranging from 427–816°C (800–1500°F), making them particularly suitable for heat exchange systems with frequent thermal cycling.

 

We supply 321 SS U-bend tubes with an outer diameter range of Φ6 mm to Φ76.2 mm (NPS 1/4" to 3"), and wall thickness from 1.0 mm to 10 mm. The bending radius (R) can be customized according to heat exchanger tube sheet layout requirements. The straight length before bending can reach up to 30 meters, with customized cutting available upon request.

 

Each batch is supplied with an EN 10204 3.1 material certificate. Upon request, we can also provide hydrostatic test reports (typically test pressure ≥ 1.5 times design pressure), as well as eddy current testing (ET) or ultrasonic testing (UT) reports to ensure defect-free delivery. The product fully complies with PED 2014/68/EU and ASME Section VIII pressure vessel codes.

 

ASTM A213 TP321 U-Tube for Heat Exchangers Specification

Feature	Specification
Standard	ASTM A213 / ASME SA213
Grade	TP321 (Titanium Stabilized)
UNS Designation	S32100
Equivalent DIN/EN	1.4541 (X6CrNiTi18-10)
Structure	Seamless Austenitic Stainless Steel
Outer Diameter (OD)	12.7 mm – 38.1 mm (0.5" – 1.5")
Wall Thickness (WT)	1.2 mm – 3.5 mm (Average or Minimum Wall)
Bending Radius (R)	1.5 × OD up to 1250 mm
Leg Length	Up to 12,000 mm (Straight length before bending)
Bending Tolerance	Radius: ±1.5 mm; Leg Length: ±3.0 mm
Wall Thinning	Calculated as per TEMA / ASTM A213 requirements

 

Chemical Composition (ASTM A213)

Element	Carbon (C)	Manganese (Mn)	Phosphorus (P)	Sulfur (S)	Silicon (Si)	Chromium (Cr)	Nickel (Ni)	Titanium (Ti)
Weight %	0.08 max	2.00 max	0.045 max	0.030 max	1.00 max	17.0 - 19.0	9.0 - 12.0	5×(C+N)5×(C+N) min / 0.70 max

 

Mechanical Properties (At Room Temperature)

Property	Metric Value	Imperial Value
Tensile Strength (Rm)	≥ 515 MPa	≥ 75 ksi
Yield Strength (Rp0.2)	≥ 205 MPa	≥ 30 ksi
Elongation (A5)	≥ 35%	≥ 35%
Hardness (Rockwell B)	≤ 90 HRB	≤ 192 HBW

 

Physical Properties

Property	Value
Density	7.92 g/cm³ (0.286 lb/in³)
Melting Point	1398 – 1446 °C
Thermal Conductivity (100°C)	16.1 W/m·K
Modulus of Elasticity	193 GPa
Electrical Resistivity	0.72 μΩ·m

 

BWG Gauge Weight Chart for Tube Wall thickness (Heat Exchanger Tube & Condensers Tube & Boilier Tube)

Outside Diameter		Stainless Steel Tube Weight (kg/m)
		Birmingham wire Gauge Conversion from BWG to mm
		25 BWG	22 BWG	21 BWG	20 BWG	19 BWG	18 BWG	17 BWG	16 BWG	15 BWG	14 BWG	13 BWG	12 BWG	11 BWG	10 BWG
mm	inch	0.51 mm	0.71 mm	0.81 mm	0.89 mm	1.07 mm	1.24 mm	1.47 mm	1.65 mm	1.83 mm	2.11 mm	2.41 mm	2.77 mm	3.05 mm	3.4 mm
6.35	1/4	0.074	0.1	0.112	0.121	0.141	0.158	0.179	0.193	0.206	-	-	-	-	-
9.53	3/8	0.115	0.156	0.176	0.192	0.225	0.256	0.295	0.324	0.351	0.39	0.427	0.466	-	-
12.7	1/2	-	0.212	0.24	0.262	0.31	0.354	0.411	0.454	0.496	0.557	0.618	0.685	0.733	0.788
15.88	5/8	-	0.268	0.304	0.332	0.395	0.452	0.528	0.585	0.64	0.724	0.809	0.905	0.975	1.057
19.05	3/4	-	0.324	0.368	0.403	0.479	0.55	0.644	0.715	0.785	0.89	0.999	1.123	1.216	1.325
25.4	1	-	-	0.496	0.543	0.648	0.746	0.876	0.976	1.074	1.224	1.38	1.561	1.698	1.863
31.75	1 1/4	-	-	-	0.684	0.818	0.942	1.109	1.237	1.364	1.558	1.761	2	2.18	2.401
38.1	1 1/2	-	-	-	-	0.987	1.139	1.341	1.498	1.653	1.892	2.143	2.438	2.663	2.939
44.5	1 3/4	-	-	-	-	1.158	1.336	1.576	1.761	1.945	2.228	2.527	2.879	3.149	3.481
50.8	2	-	-	-	-	1.325	1.531	1.806	2.02	2.232	2.559	2.905	3.314	3.628	4.014
63.5	2 1/2	-	-	-	-	-	-	2.271	2.542	2.811	3.227	3.667	4.19	4.593	5.09
76.2	3	-	-	-	-	-	-	-	3.064	3.39	3.894	4.43	5.067	5.558	6.166
88.9	3 1/2	-	-	-	-	-	-	-	3.586	3.969	4.562	5.192	5.943	6.522	7.241
101.6	4	-	-	-	-	-	-	-	4.108	4.548	5.229	5.955	6.819	7.487	8.317
114.3	4 1/2	-	-	-	-	-	-	-	-	-	5.897	6.717	7.696	8.452	9.393

Please send us your tubesheet layout or design drawings; our engineers will provide you with a detailed technical proposal within 24 hours.

ASTM A213 U bend tube price per meter

 

U bend tube TP321 Applications

Heat Exchangers: Shell and tube heat exchangers in oil refineries.
Power Plants: Superheater tubes and boiler tubes.
Chemical Processing: Equipment for producing nitric acid and volatile chemicals.
Aerospace: Exhaust systems and manifolds.

 

Last quarter, we supplied 500 sets of TP321 U-tubes for the overhaul of heat exchangers at a refinery in the Middle East, successfully passing rigorous third-party inspection.

Click to View Project Materials

 

Heat Treatment & Testing (Quality Control)

Process / Test	Description
Solution Annealing	Straight tubes are solution annealed at 1040°C min, followed by quenching.
Stress Relieving	U-Bend area heat treatment available upon request (Electric Resistance or Furnace).
Hydrostatic Test	100% tested according to ASTM A450/A1016.
Eddy Current Test	100% non-destructive testing (NDT) before bending.
Ball Passing Test	Ensures no internal diameter restriction in the bend area.
Dye Penetrant Test	Performed on the bend area to detect surface cracks.

 

 

Packaging for Export (Gnee Standard)

Bundle Protection: Tubes are bundled with plastic end caps.
Internal Support: U-bends are separated by vertical dividers (wooden or plastic) to prevent vibration damage.
Outer Case: Heavy-duty seaworthy wooden boxes (ISPM15 compliant) or "U" shaped steel frames.