AL-6XN Stainless Steel Heat Exchanger Tube

GNEE Stainless Steel, as a professional supplier of stainless steel heat exchanger tubes, can provide ASME SB676 AL-6XN heat exchanger tubes in both ‌seamless‌ and ‌welded‌ forms. These tubes can be manufactured into ‌U tubes, straight tubes, and heat exchanger tube bundles‌ ‌‌. The standard delivery condition is solution annealing at 1105–1175°C followed by water quenching, ensuring uniform microstructure and excellent corrosion resistance. They are particularly suitable for severe corrosive environments such as seawater desalination, chemical heat exchange systems, and flue gas desulfurization, where equipment service life can be 2–3 times longer than that of 316L stainless steel.

 

 

AL-6XN heat exchanger tubes feature a tensile strength of ≥‌690 MPa‌, yield strength of ≥‌310 MPa‌, and elongation of ≥‌35%‌. Their strength is approximately 40% higher than 316L while still maintaining excellent toughness and impact resistance. They are suitable for operating temperatures ranging from -196°C to 427°C and are commonly used in ‌shell-and-tube heat exchangers, air coolers, and economizers‌ ‌‌.

 

AL-6XN stainless steel tubes can be processed and welded using conventional hot and cold working methods. ERNiCrMo-3 filler metal is recommended for welding, making on-site fabrication and maintenance more convenient. Available specifications include outer diameters from Φ6–76 mm and wall thicknesses from 0.5–5 mm, with customized lengths and surface finishes (pickling/polishing) available upon request. Eddy current testing, hydrostatic testing, and complete material test reports are also provided.

 

 

ASME SB 676 UNS N08367 Tubing Chemical Composition

Grade	C	Mn	P	S	Si	Ni	Cr	Fe	N	Cu	Mo
SSC-6MO / AL6XN	.03 max	2.0 max	.04 max	.03 max	1.0 max	23.5 – 25.5	20.0 -22.0	Bal	.18 – .25	.75 max	6.0 – 7.0

 

UNS N08367 Tubes Mechanical Properties

Temp. °F (°C)	Ult. Tensile Strength, psi	.2% Yield Strength, psi	Elongation in 2", percent	Charpy V-Notch Toughness, ft-lb
-450 (-268)	218,000	142,000	36	353*
-320 (-196)	196,000	107,000	49	85
-200 (-129)	–	–	–	100
70 (21)	108,000	53,000	47	140
200 (93)	99,900	49,400	47	–
400 (204)	903,000	40,400	46	–
600 (316)	86,000	36,300	47	–
800 (427)	87,000	36,000	48	–

 

Permissible variation range of outer diameter and wall thickness

Specified Outside Diameter	Permissible Variations
	Outside DiameterB		Wall Thickness, %
	Plus	Minus	Plus	Minus
Inches
1/8 to 5/8, excl	0.005	0.005	15.0	15.0
5/8 to 1 1/2, incl	0.0075	0.0075	10.0	10.0
Over 1 1/2 to 3 1/2, incl	0.010	0.010	10.0	10.0
Over 3 1/2 to 41/2, incl	0.015	0.015	10.0	10.0
Over 4 1/2 to 5 1/2, incl	0.020	0.020	12.5	12.5
Millimetres
3.2 to 15.9, excl	0.13	0.13	12.5	12.5
15.9 to 38.1, incl	0.19	0.19	10.0	10.0
Over 38.1 to 88.9, incl	0.25	0.25	10.0	10.0
Over 88.9 to 114.3, incl	0.38	0.38	10.0	10.0
Over 114.3 to 127, incl	0.51	0.51	12.5	12.5

 

Applications

Seawater Desalination (SWRO) High-Pressure Feed Piping
Heat Exchange and Condensing Systems in Petrochemical Plants and Refineries
Power Plant Steam Condensers and Flue Gas Waste Heat Recovery Systems (e.g., Finned-Tube Heat Exchangers)
Heat Exchange involving Acidic or Chloride-Containing Media under High-Temperature and High-Pressure Conditions

 

In heat exchanger applications, which materials does AL-6XN primarily replace?

Replacing 316L/317L: When high chloride content in the fluid causes pitting and perforation of the original tubing.

Replacing duplex stainless steel 2205: AL-6XN offers superior stability in harsh environments with high temperatures and large pH fluctuations.

Replacing copper-nickel alloy (Cu-Ni 70/30): AL-6XN offers higher resistance to erosion and wear, and eliminates the risk of copper ion contamination.

Replacing titanium tubes: While titanium performs excellently in seawater, AL-6XN offers higher mechanical strength and is easier to weld and expand into tube sheets.

 

What specifications of AL-6XN heat exchanger straight tubes does GNEE offer?

Outer Diameter (OD): Commonly used 15.88mm (5/8"), 19.05mm (3/4"), 25.4mm (1")
Wall Thickness (WT): Commonly used BWG 22 (0.71mm), BWG 20 (0.89mm), BWG 18 (1.24mm)
Length: Up to 25 meters, suitable for large condenser designs.
Surface Finish: Bright annealed (BA) or pickled, ensuring an extremely smooth inner wall to prevent scaling.

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High-quality sea freight packaging

After ultrasonic cleaning and passivation, each pipe must have high-density polyethylene (HDPE) embedded dust plugs installed at both ends. For thin-walled long pipes commonly used in heat exchangers (such as BWG 22/20/18), a thickened ISPM-15 standard fumigated wooden crate is used for packaging. A U-shaped shock-absorbing support frame lined with felt is installed every 1.5 meters inside the crate to effectively prevent the 12-18 meter long pipes from deflecting under their own weight during transportation. The inside of the wooden crate is fully sealed with VCI vapor phase rust-preventive cloth and contains sufficient silica gel desiccant to ensure that the pipes are delivered with zero surface oxidation and zero scratches during 30-45 days of transoceanic transport.