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Table of Content

Duplex Pipes and Tubes Specification
Duplex Stainless Pipe Chemical Composition
Duplex Steel Pipe Mechanical Properties
Duplex Pipe Schedule Chart
Equivalent Grades of Duplex Steel Pipes & Tubes
Duplex Stainless Steel Pipe Weight Chart
Pressure Rating of Duplex SS Pipe
Applications of Duplex Steel Pipes

Kalpataru Piping is a reliable duplex pipe manufacturer and supplier also provide the high-quality of duplex pipes and tubes, which are used in industries. Our products are duplex steel products with well-developed manufacturing facilities and quality control systems We provide duplex steel products that include duplex steel pipe solutions that are made from international quality and fit into the stringent service conditions. We are an experienced supplier of duplex pipes and therefore, we manufacture a broad scope of seamless and welded and ERW duplex steel pipes in both standard and custom-made versions. Our manufacturing capacity has enabled us to have extensive stock of duplex steel pipes and duplex steel tubes, competitive prices, and delivery on time to both the local and global customers.

Our duplex steel pipes are being produced in full compliance with ASTM, ASME, EN, and DIN standards and standards, and high levels of dimensional accuracy, mechanical strength, and performance reliability in high-pressure and corrosive conditions. A list of specific process through which a duplex pipe manufacturing process can be seen through a guide to understand our entire production methodology. Duplex pipes and duplex steel tubes are commonly applied in oil and gas, petrochemical, power generation, marine, chemical processing, and desalination applications as well as offshore applications because of their high strengths, excellent resistance to corrosion and long life.

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Duplex Stainless Steel Pipe Grades & Standards: ASTM A790 / ASME SA790 / ASTM A789

Kalpataru Piping manufactures a premium grade of duplex stainless steel pipes and duplex steel tubes which are of high quality in line with the globally accepted material specifications and ASTM standards of duplex steel. We are experts in the provision of Duplex Steel UNS S31803 and UNS S32205 in seamless and welded market. We manufacture and supply a variety of ASTM A789 and ASTM A790 Duplex Steel Pipes and Tubes that are a global standard of duplex pipe ASTM codes of seamless and welded ferritic-austenitic stainless steel tubing and pipes.

Duplex Steel UNS S32205 Seamless Pipes And Duplex Steel UNS S32205 Tubes

UNS S32205 is one of the most widely used duplex pipe grades in the 2205 family. It maintains a minimum tensile strength of around 620 MPa, yield strength of about 450 MPa, and elongation of 25% making it reliable for pressure piping and structural systems.

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Duplex Steel UNS S31803 Seamless Pipes And Duplex Steel UNS S31803 Tubes

UNS S31803 is the classic 2205 duplex grade historically used for corrosion-resistant piping and tubing. While very similar to S32205, S31803 generally has slightly lower nitrogen content, which can result in marginally lower corrosion resistance and mechanical consistency.

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About Duplex Steel Pipes & Tubes

The duplex stainless steel pipes and tubes are the new corrosion-resistant products, which are produced using a specific alloy composed of a combination of austenitic and ferritic microstructure hence the designation of duplex stainless steel material. This bilateral construction provides all duplex steel pipes and duplex steel tubes with very high strengths, stability, and hostile environment resistance to the usual stainless steels.

The duplex pipe is designed in such a way to provide high quality mechanical properties and at the same time excellent welding capabilities. An average duplex stainless steel pipe has about 22 percent chromium, 5-6.5 percent nickel, 3-3.5 percent molybdenum and regulated nitrogen content with the remaining part being iron, trace elements like manganese and silicon. Duplex stainless steel pipes as well as tubes themselves can be used in the manufacture processes of both seamless welded piping as well as ERW manufacturing and can frequently be left in the as-welded state without affecting their performance. Duplex steel pipes are high tensile and yield strength, good in terms of elongation, and thermal properties and a melting point of approximately 1350 C, are reliable in operation in the service conditions of high pressure and high-temperature and highly corrosive nature. To learn more about material grades, properties, uses and the choice criteria, study our comprehensive guide to duplex steel pipes.

Duplex Pipes and Tubes Specification

Duplex stainless steel pipes and tubes are prepared according to the international standards, which provide high strength, great resistance to corrosion, and high performance in hostile environment. Their applications are quite common in oil and gas, chemical processing, marine and power generation.

Size	:	1/2″NB TO 12 “NB IN
Standards	:	ASTM A 790 ASME SA 790
Grades	:	(Duplex UNS S31803), UNS 2UNS S32205 (Duplex UNS S32205)
Length	:	Single Random, Double Random & Cut Length
Type	:	Seamless / ERW / Welded / Fabricated
Form	:	Round, Hydraulic Etc
Schedule	:	SCH20, SCH30, SCH40, STD, SCH80

Duplex Stainless Pipe Chemical Composition

Defines the balanced chromium, nickel, molybdenum, and nitrogen content that gives duplex pipes high strength and excellent corrosion resistance.

Grade	C≤	Mn≤	P≤	S≤	Si≤	Ni	Cr	Mo	N	Cu
S31803	0.03	2.00	0.03	0.02	1.00	4.5–6.5	21.0–23.0	2.5–3.5	0.08–0.20	–
S32205	0.03	2.00	0.03	0.02	1.00	4.5–6.5	22.0–23.0	3.0–3.5	0.14–0.20	–
S32750	0.03	1.20	0.035	0.02	0.80	6.0-8.0	24.0-26.0	3.0-5.0	0.24-0.32	0.5

Duplex Steel Pipe Mechanical Properties

Highlights key properties such as higher yield strength, good ductility, and superior resistance to stress corrosion cracking.

Mechanical properties	Tensile,min,ksi[MPa]	Yield,min,ksi[MPa]	Elongation,%(min)	Hardness,HB(max)
S31803	90 [620]	65 [450]	25	290
S32205	95 [655]	65 [450]	25	290
S32750	116 [800]	80 [550]	15	300

Duplex Pipe Schedule Chart

Provides standard pipe schedules with corresponding wall thicknesses to select the right pipe for pressure and service requirements.

NOMINAL	OD	SCH-5S		SCH-10S		SCH-10		SCH-20		SCH-30		SCH- 40S/STD		SCH-40		SCH-60
PIPE SIZE		THICK	KG/ MTR	THICK	KG/ MTR	THICK	KG/ MTR	THICK	KG/ MTR	THICK	KG/ MTR	THICK	KG/ MTR	THICK	KG/ MTR	THICK	KG/ MTR
1 /8”	10.3			1.24	0.279							1.73	0.386
1/4”	13.7			1.65	0.5							2.24	0.63	2.24	0.63
3/8”	17.1			1.65	0.64							2.31	0.85	2.31	0.85
1/2”	21.3	1.65	0.81	2.11	1.02							2.77	1.27	2.77	1.27
3/4”	26.7	1.65	1.03	2.11	1.3							2.87	1.68	2.87	1.68
1”	33.4	1.65	1.31	2.77	2.13							3.38	2.5	3.38	2.5
1 1/4”	42.2	1.65	1.68	2.77	2.73							3.56	3.39	3.56	3.39
1 1/2”	48.3	1.65	1.93	2.77	3.16							3.67	4.05	3.67	4.05
2”	60.3	1.65	2.42	2.77	3.99							3.91	5.44	3.91	5.44
2 1/2”	73	2.11	3.75	3.05	5.35							5.16	8.63	5.16	8.63
3”	88.9	2.11	4.59	3.05	6.56							5.49	11.29	5.49	11.29
3 1/2”	101.6	2.11	5.26	3.05	7.53							5.74	13.57	5.74	13.57
4”	114.3	2.11	5.93	3.05	8.54							6.02	16.07	6.02	16.07
5”	141.3	2.77	9.61	3.4	11.74							6.55	21.77	6.55	21.77
6”	168.3	2.77	11.48	3.4	14.04							7.11	28.26	7.11	28.26
8”	219.1	2.77	14.9	3.4	20.12			6.35	33.31	7.07	36.81	8.18	42.55	8.18	42.55	10.31	53.08
10”	273	3.4	22.95	4.19	28.2			6.35	41.77	7.8	51.03	9.27	60.3	9.27	60.3	12.7	81.55
12”	323.8	3.96	31.71	4.57	36.53			6.35	49.73	8.38	65.2	9.53	73.88	10.31	79.73	14.28	108.9
14”	355.6	3.96	34.87	4.78	41.99	6.35	54.69	7.92	67.9	9.53	81.33	9.53	81.33	11.13	94.55	15.09	126.7
16”	406.4	4.19	42.2	4.78	48.07	6.35	62.64	7.92	77.83	9.53	93.27	9.53	93.27	12.7	123.3	16.66	160.1
18”	457.2	4.19	47.53	4.78	54.15	6.35	70.57	7.92	87.71	11.13	122.3	9.53	105.1	14.27	155.8	19.05	205.7
20”	508	4.78	60.23	5.54	69.7	6.35	78.55	9.53	117.1	12.7	155.1	9.53	117.1	15.09	183.4	20.62	247.8
22”	558.9	4.78	65.8	5.54	75.75	6.35	85.54	9.53	129.1	12.7	171	9.53	129.1			22.23	234.2
24”	609.6	5.54	83.8	6.35	95.92	6.35	94.53	9.53	141.1	14.27	209.5	9.53	141.1	17.48	255.4	24.61	235.2
26”	660.4					7.92	127.3	12.7	202.7			9.53	152.8
28”	711.2					7.92	137.3	12.7	218.6	15.88	271.2	9.53	164.8
30”	762	6.35	120.15	7.92	149.55	7.92	147.2	12.7	234.6	15.88	291.1	9.53	176.8
32”	812.8					7.92	157.2	12.7	250.6	15.88	312.1	9.53	188.8	17.48	342.9
34”	853.6					7.92	167.2	12.7	266.6	15.88	329.1	9.53	200.3	17.48	364.9
36”	914.4					7.92	176.9	12.7	282.2	15.88	351.7	9.53	212.5	19.05	420.4
38”	965					9.53	226	12.7	301
40”	1016					9.53	238	12.7	317
42”	1067					9.53	251	12.7	333
44”	1118					9.53	263	12.7	349
46”	1168					9.53	275	12.7	365

Equivalent Grades of Duplex Steel Pipes & Tubes

Lists international equivalents across ASTM, EN, DIN, and UNS standards for easy material comparison and selection.

STANDARD	WERKSTOFF NR.	UNS
Duplex 2205	1.4462	S31803 / S32205
Super Duplex 2507	1.4410	S32750 / S32760

Duplex Stainless Steel Pipe Weight Chart

Shows accurate weight calculations based on pipe size, schedule, and material density for estimation and project planning.

Outside Dia mm	Wall Thk mm	in.	Schedule	Kg/m
13.72	1.65	1/4	10S	0.50
13.72	2.24	1/4	40S	0.64
13.72	3.02	1/4	80S	0.81
17.15	1.65	3/8	10S	0.64
17.15	2.31	3/8	40S	0.86
17.15	3.20	3/8	80S	1.12
21.34	2.11	1/2	10S	1.02
21.34	2.77	1/2	40S	1.29
21.34	3.73	1/2	80S	1.65
26.67	2.11	3/4	10S	1.30
26.67	2.87	3/4	40S	1.71
26.67	3.91	3/4	80S	2.23
33.40	2.77	1	10S	2.13
33.40	3.38	1	40S	2.54
33.40	4.55	1	80S	3.29
33.40	6.352)	1	160	4.30
42.16	2.77	1¼	10S	2.73
42.16	3.56	1¼	40S	3.44
42.16	4.85	1¼	80S	4.53
42.16	6.352)	1¼	160	5.69
48.26	2.77	1½	10S	3.16
48.26	3.68	1½	40S	4.11
48.26	5.08	1½	80S	5.49
60.33	2.77	2	10S	3.99
60.33	3.91	2	40S	5.52
60.33	5.54	2	80S	7.60
60.33	8.742)	2	160	11.29
73.03	3.05	2½	10S	5.35
73.03	5.16	2½	40S	8.77
73.03	7.01	2½	80S	11.59
88.90	3.05	3	10S	6.56
88.90	5.49	3	40S	11.47
88.90	7.62	3	80S	15.51
88.90	11.132)	3	160	21.67
101.60	3.05	3½	10S	7.53
101.60	5.74	3½	40S	13.78
101.60	8.08	3½	80S	18.92
114.30	3.05	4	10S	8.50
114.30	6.02	4	40S	16.32
114.30	8.56	4	80S	22.67
114.30	13.492)	4	160	34.05
141.30	6.55	5	40S	22.10
141.30	9.53	5	80S	31.44
141.30	15.882)	5	160	49.87
168.28	3.4	6	10S	14.04
168.28	7.11	6	40S	28.69
168.28	10.97	6	80S	43.21
168.28	14.27	6	120	54.75
168.28	18.262)	6	160	68.59
219.08	8.18	8	40S	43.20
219.08	12.7	8	80S	65.63
219.08	18.23	8	120	91.30
219.08	23.012)	8	160	112.97

Pressure Rating of Duplex SS Pipe

OD (In.)	WT (in.)
OD (In.)	.109	.120	.083	.095	.049	.028	.035	.065
–	Pressure (Psig)
1/4	–	–	–	–	7000	3700	4800	9500
1/8	–	–	–	–	–	7900	10100	–
3/8	–	–	–	–	4400	–	3100	6100
5/16	–	–	–	–	5400	–	3700	7300
1/2	–	–	–	–	3200	–	2300	4400
1	3900	4300	2900	3400	–	–	–	2200
3/4	–	–	4000	4600	2200	–	–	3000

Applications of Duplex Steel Pipes

Due to its high levels of strength and corrosion resistance, duplex steel pipes are widely applicable in the chemical processing field, oil and gas exploration and processing equipment, and transport and storage systems. They also suit well in effluent scrubbing systems, food processing equipment, biofuel plants and cargo tanks of ships and road tankers where aggressive media resistance and long service life are of utmost importance.

Duplex Steel Pipe Price

Duplex steel pipes can be of various prices, and their prices depend on the grade, size, schedule, manufacturing type (seamless and welded), the cost of the raw material, and the cost of testing. Duplex pipes are usually more expensive than normal stainless steel since they possess better mechanical qualities, including corrosion resistance. Get the latest duplex steel pipe prices and project-specific quotations.

The approximate price of duplex steel pipes varies based on grade, size, schedule, and manufacturing type. Below is an indicative price range for reference:

Pipe Type	Approximate Price Range (₹/kg)
Duplex Steel Seamless Pipes	₹ 550 – 850 per kg
Duplex Steel Welded / ERW Pipes	₹ 450 – 700 per kg
Duplex Steel EFW Pipes	₹ 480 – 750 per kg

Note: Prices are indicative and may vary based on grade, size, schedule, quantity, testing requirements, and prevailing raw material costs. Contact us for the latest project-specific pricing.

Frequently Asked Questions About Duplex SS Pipes & Tubes

What is a Duplex Steel Pipe?

A duplex steel pipe is a two-phase stainless steel alloy combining austenitic and ferritic structures. It offers higher strength and superior corrosion resistance compared to standard stainless steel pipes, making it ideal for demanding applications.

What is a Duplex Stainless Steel Pipe Used For?

Duplex stainless steel pipes are used in oil & gas, marine, chemical, desalination, and water treatment industries. They are suitable for high-pressure and corrosive environments where durability and reliability are critical.

What is a Duplex Steel Tube?

A duplex steel tube is manufactured in seamless or welded forms, providing excellent corrosion resistance, high strength, and long service life. It is widely used in industrial piping, structural applications, and process systems.

Are Duplex Pipes Heat Treatable?

Yes, duplex pipes and duplex steel tubes are heat treatable through solution annealing to restore corrosion resistance and mechanical properties after fabrication or welding.

What Are the Wall Thicknesses of Duplex Stainless Steel Pipes?

The wall thickness of duplex stainless steel pipes ranges from 0.5 mm to 45 mm, depending on the pipe size, schedule, and application requirements.

Are Duplex Steel Tubes Magnetic?

Yes, duplex steel tubes exhibit magnetic properties due to their ferritic phase, which is common in duplex alloys.