ASTM A790 Stainless Steel Pipe

ASTM A790 is a standard specification for seamless and welded ferritic/austenitic stainless steel pipe, also known as duplex stainless steel pipe. This specification is designed for general corrosive service and high-temperature applications. ASTM A790 pipes offer excellent mechanical properties and corrosion resistance, particularly in chloride-containing environments.

ASTM A790 Steel Pipe Range

• Type: Seamless and Welded
• Material: Ferritic/Austenitic (Duplex) Stainless Steel
• Service: General Corrosive Service, High-Temperature Applications

ASTM A790 Steel Pipe Size Range

 

Nominal Pipe Size (NPS)	Outside Diameter (OD) (inches)	Schedule (Wall Thickness)
1/8	0.405	Sch 5s to XXH
1/4	0.54	Sch 5s to XXH
3/8	0.675	Sch 5s to XXH
1/2	0.84	Sch 5s to XXH
3/4	1.05	Sch 5s to XXH
1	1.315	Sch 5s to XXH
1 1/2	1.9	Sch 5s to XXH
2	2.375	Sch 5s to XXH
3	3.5	Sch 5s to XXH
4	4.5	Sch 5s to XXH
6	6.625	Sch 5s to XXH
8	8.625	Sch 5s to XXH
10	10.75	Sch 5s to XXH
12	12.75	Sch 5s to XXH
14	14	Sch 5s to XXH
16	16	Sch 5s to XXH
18	18	Sch 5s to XXH
20	20	Sch 5s to XXH
24	24	Sch 5s to XXH

ASTM A790 Steel Pipe Material Grade

Grade	Description
UNS S31803	Standard duplex stainless steel with 22% Cr, 5.5% Ni, 3% Mo
UNS S32205	Enhanced version of S31803 with improved corrosion resistance
UNS S32750	Super duplex stainless steel with 25% Cr, 7% Ni, 4% Mo, higher strength
UNS S32760	Super duplex stainless steel with 25% Cr, 7% Ni, 3.5% Mo, higher strength and pitting resistance

ASTM A790 Steel Pipe Mechanical Properties

Grade	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation (%)
UNS S31803	≥ 620	≥ 450	≥ 25
UNS S32205	≥ 655	≥ 450	≥ 25
UNS S32750	≥ 795	≥ 550	≥ 25
UNS S32760	≥ 750	≥ 550	≥ 25

Comparison with Other Stainless Steel Pipes

Property	ASTM A790 (Duplex)	ASTM A312 (Austenitic)	ASTM A358 (Austenitic)
Corrosion Resistance	Excellent, especially in chloride environments	Good, but less than duplex	Good, but less than duplex
Strength	Higher	Moderate	Moderate
Cost	Moderate to High	Moderate	Moderate
Applications	Chemical processing, oil and gas, marine	General piping, food processing, pharmaceuticals	High-temperature, general corrosive service
Common Grades	S31803, S32205, S32750	304, 316, 321	304, 316, 321
Temperature Resistance	High	High	High
Weldability	Good, requires skilled techniques	Excellent

 

When comparing ASTM A790 stainless steel pipes with other stainless steel pipes made of different materials, it’s important to consider various factors such as composition, properties, and intended use. ASTM A790 stainless steel pipes are specifically designed as duplex stainless steel pipes, which offer a combination of both ferritic and austenitic microstructures. This results in pipes that have higher strength and better corrosion resistance compared to traditional austenitic stainless steel pipes like 304 or 316 stainless steel.

In terms of corrosion resistance, ASTM A790 stainless steel pipes are known for their excellent resistance to pitting and crevice corrosion, making them suitable for use in harsh environments such as chemical processing, oil and gas, and marine applications. They also exhibit good mechanical properties, including high tensile strength and impact resistance.

On the other hand, when compared to other types of stainless steel pipes made of different materials, ASTM A790 stainless steel pipes may be more expensive due to their alloy composition. However, their superior properties make them a preferred choice for applications where both strength and corrosion resistance are critical.

In summary, ASTM A790 stainless steel pipes offer a unique combination of properties that set them apart from other stainless steel pipes made of different materials.