Stainless Steel Pipe
Stainless Steel Pipe - industrial steel pipe
Stainless steel seamless pipe is a type of pipe made from stainless steel that does not have any welded joints or seams.
Seamless stainless steel pipe is used in applications where high temperature strength and superior corrosion resistance are critical.
Seamless pipes are thought to be able to withstand higher pressure, higher temperatures, higher mechanical stress and a corrosive atmosphere. It can be found in a wide range of applications such as in oil and gas, refinery, petrochemical, chemical, fertilizer, power, automotive, bearing, mechanical and structural.
Stainless steel is one of the most popular and versatile materials. Seamless stainless steel pipe is used in applications where high temperature strength and superior corrosion resistance are critical. Further, stainless steel is easy to clean and doesn’t tarnish.
Stainless steel is an iron alloy that contains a minimum of 10.5% chromium. Alloying elements such as nickel, molybdenum, titanium, carbon, nitrogen, and copper can boost the strength, formability, and other properties of stainless steel. Different alloys offer different levels of corrosion resistance.
Stainless steel alloys offer greater cryogenic toughness, a higher work hardening rate, increased strength and hardness, greater ductility, and a more attractive appearance compared to carbon steel.
It is the resistance of air, steam, water and other weak corrosive media and acid, alkali, salt and other chemical etching medium corrosion of steel pipes. Also known as acid - resistant stainless steel. It will be more and more engineering use and become increasingly popular, and prospects.
The production of our seamless steel pipes is tightly regulated and all of the pipes we stock have been fully tested to international standards to ensure we only supply the highest quality products.
Stainless steel pipe is resistant to rust and other corrosive attack. It is heat-resistant for high-performance and high-temperature use.
Seamless stainless steel pipe is a hollow steel bar, a large number of pipes used for conveying fluids, such as oil, gas, water, gas, steam,heat exchanger,mechinical machine.
| Product Name | Executive | Dimension | Steel Code / Steel Grade |
|---|---|---|---|
| Seamless Austenitic Stainless Steel Pipes | ASTM A312, A312M ASME SA312 / SA312M | OD: 1/4"-20" WT: SCH5S-SCH80S |
TP304, TP304L, TP304H, TP310, TP310S, TP316, TP316L, TP316Ti, TP317, TP317L, TP321, TP321H, TP347, TP347H |
| Seamless Austenitic Stainless Steel Tubing for General Service | ASTM A269 ASME SA269 | OD: 6.0-50.8mm WT: 0.8-10.0mm |
TP304, TP304L, TP304H, TP310, TP310S, TP316, TP316L, TP316Ti, TP317, TP317L, TP321, TP321H, TP347, TP347H |
| Seamless Austenitic Alloy-Steel Boiler, Super Heater and Heat-Exchanger Tubes | ASTM A213 / A213M ASME SA213 / SA213M | OD: 6.0-50.8mm WT: 0.8-10.0mm |
TP304, TP304L, TP304H, TP310, TP310S, TP316, TP316L, TP316Ti, TP317, TP317L, TP321, TP321H, TP347, TP347H |
| Seamless Duplex Stainless Steel Tubing for General Service | ASTM A789 / A789M | OD: 19.0-60.5mm WT: 1.2-5.0mm |
S31803, S32205, S32750 |
| Seamless Duplex Stainless Steel Pipes | ASTM A790 / A790M | OD: 3/4"-10" WT: SCH5S-SCH80S |
S31803, S32205, S32750 |
| Seamless Stainless Steel Mechanical Tubing | ASTM A511 | OD: 6.0-50.8mm WT: 0.8-10.0mm |
MT304, MT304L, MT304H, MT310, MT310S, MT316, MT316L, MT317, MT317L, MT321, MT321H, MT347 |
| Seamless Stainless Steel Tubes for Pressure Purposes | EN 10216 DIN 17456, 17458 | OD: 6.0-530.0mm WT: 0.8-34.0mm |
1.4301, 1.4307, 1.4541, 1.4401, 1.4404, 1.4571, 1.4878, 1.4432, 1.4462 |
Seamless stainless steel pipe is made from solid stainless steel bar which is called billet. By using different processing techniques such as extruding, gun drilling or piercing, the steel bars are produced to be steel tubes.
A heat exchanger is a piece of equipment designed from one medium to another for efficient heat transfer. The application areas of the Stainless Steel Seamless pipes: Heat Exchanger Tube specifically cover the following: Apparatuses and heat exchangers for piping systems.
The areas of application in the fertiliser industry primarily include the following: Melamine plants high-pressure tubes and piping systems apparatus and heat exchangers of urea synthesis ethylene plants.
The fields of operation in the chemical and petrochemical industries primarily include the following: Melamine plants high-pressure tubes and piping systems apparatus and heat exchangers of urea synthesis ethylene plants.
Our tubes and pipes are used mainly for heat exchangers in power plants and the energy sector. Environmental systems and waste incineration plants also have the same field of application: reheater superheaters.
In the fields of discovery, manufacturing and processing, we develop tubes for shipbuilding. Stainless Steel 304 Pipes for use in ship construction.
SS Seamless steel pipes for oil casing and tubing for offshore and onshore Oil & Gas applications in the domains of Production, Exploration and Processing.
Our pipes are primarily used in mechanical and plant engineering and construction in the following areas: food manufacturing, automobile technology, measurement and control technology, pumps, hydraulic cylinders, etc. Stainless Steel Seamless pipes is known as a half-finished product for fittings and tubes and pipes of flange output as a half-finished product for radially machined parts.
In the automotive field, DMV products are used especially in the following areas: Other important areas of use are hydraulic braking systems.
The SS Seamless pipes are used in petroleum, Connecting water, gas and other common fluids. Seamless steel pipes are common and can be found in residential walls, labs, and commercial and industrial structures underground and inside them.
Stainless Steel Seamless pipes for high temperature and pressure service
For high temperature and pressure operation, we sell a comprehensive range of Seamless steel pipes. The SS Seamless pipes are also used in the applications like containers, heating pipelines, and high temperature reheaters.
| Grade | Description |
|---|---|
| TP304 | General-purpose stainless steel with good corrosion resistance for most applications. Used for: Bar rails, Boat railings, Canopy supports, Chemical processing equipment, Chemical tubing, Column covers, Duct works, Feed-water tubes, Food preparation equipment, Food processing equipment, Heat exchanger tubes, Hypodermic needles, Ladders, Mechanical & structural components, Pharmaceutical processing equipment, Piping systems, Railings (architectural), Traffic barriers, Water pipes. |
| TP304H | Higher carbon content than 304L, for increased strength, particularly at elevated temperatures. |
| TP304L | Chemical plant and food processing equipment, where freedom from sensitization is required in plate thicknesses TP316/316L |
| TP316/316L | Used where higher corrosion resistance is required. Boat railings, Canopy supports, Chemical tubing, Column covers, Duct works, Feed-water tubes, Food preparation equipment, Food processing equipment, Heat exchanger tubes, Hypodermic needles, Ladders, Mechanical & structural components, Pharmaceutical processing equipment, Piping systems, Railings, Street (urban) furniture, Textile tubing, Traffic barriers, Water pipes. |
| TP316H | Similar oxidation resistance to TP 316. Main areas of application: Heat exchangers, furnaces, chemical and petrochemical plant. |
| TP321 | Heat exchanger tubing, Chemical processing tubing, Pressure tank tubing. Suitable for heat resisting applications to 800°C. |
| TP321H | This is the high carbon version of TP 321 which ensures greater creep resistance. Behaves much the same as TP 321 in oxidation resistance. Main applications: Heat exchangers, furnaces, boilers in chemical and petrochemical plant |
| TP316Ti | A titanium stabilized version of 316 used where good resistance to intergranular corrosion and high temperature strength is required. |
| TP317 | Chemical processing tubing, Dyeing equipment, Ink manufacturing equipment, Pulp & paper manufacturing equipment |
| TP347HFG | Mainly used for boilers in the termal power plant, reheaters and superheaters |
| Grade | Description |
|---|---|
| TP904L | High resistance to general corrosion in e.g. sulphuric and acetic acids, crevice corrosion, stress corrosion cracking, pitting in chloride bearing solutions. |
| Grade | Description |
|---|---|
| TP405 | Used for applications where hardening upon cooling from high temperatures must be avoided. Has excellent long-time stability up to 1200°F. |
| TP410 | General purpose grade for use in mildly corrosive environments |
| TP430 | Mechanical & structural tubing, Architectural tubing, Heat exchanger tubing, Condensers, Re-heaters, Evaporators. |
| Grade | Description |
|---|---|
| S31803 |
Typically used in heat exchangers, gas scrubbers, fans, chemical tanks, flowlines, marine and refinery applications. |
| S32750 |
Used in oil & gas, chemical process, power industries. At that heat-exchangers are main application. |
| S31254 |
With high levels of chromium, molybdenum, and nitrogen is especially suited for high-chloride environments such as brackish water, seawater and other high-chloride process streams. |
When welding seamless stainless steel pipes, in order to reduce the tendency of hot cracking, the weld structure design generally contains a small amount of ferrite, and the control of the ferrite content is mainly realized by the alloy composition. Austenitic stainless steel welds contain more than 3% ferrite, which can effectively avoid solidification cracks, but too much ferrite will adversely affect performance.
The sensitization tendency of the weld metal is lower than that of the base metal. There is ferrite in the weld, its Cr content is higher than that of austenite, and the diffusion rate of Cr in ferrite is much faster than that of austenite. However, M23C6 carbides tend to precipitate at the pitted ferrite-austenite interface. Instead of precipitation at the relatively flat austenite-austenite interface, the rapid diffusion of chromium in ferrite can overcome the problem of chromium deficiency at grain boundaries. These factors greatly limit the sensitization of austenitic stainless steel welds containing ferrite to prevent intergranular corrosion of stainless steel water pipes.
Austenitic stainless steel weld metals containing a small amount of ferrite are corrosion resistant and contain no ferrite in most corrosive environments, corresponding to the parent metal. However, in organic acids, these media selectively attack ferrite. When the ferrite content in the weld metal is greater than 5FN, corrosion will proceed along the ferrite network, resulting in serious damage to the weld.
Ferrite is formed in the austenitic stainless steel weld metal as a secondary phase strengthening. Compared with the base metal and heat-affected zone, the yield strength is significantly improved, while the ductility is comparable. Increasing the ferrite content in the weld metal can significantly increase the strength at room temperature, but the strength at high temperature is slightly improved. Ferrite is a harmful phase of stainless steel water pipes in high temperature environment.
(1) Creep damage of ferrite
The continuous ferrite network in the weld metal promotes rapid creep damage due to earlier crack initiation than the ferrite-austenite interface. At this point the ferrite content should be below 5FN to prevent the formation of a continuous ferrite network
(2) Ferrite embrittlement at 475°C
Fe-Cr alloys with a Cr content of 15% to 70% will produce severely brittle Cr-rich ferrite and iron-rich ferrite when heated to 425°C to 550°C. The ferrite phase of the austenitic stainless steel weld metal is essentially ferrite embedded in the austenite matrix (Cr20-30%, Ni4%-5%). Therefore, if it stays in the temperature range of 425 ℃ ~ 550 ℃ for a long time (about 5000h), the ferrite phase will become brittle, the hardness will increase, and the plasticity and toughness will be damaged. Short-term heating above 550 °C can eliminate this embrittlement phenomenon, but long-term heating will cause σ-phase embrittlement.
At low temperatures, austenitic stainless steels exhibit good strength, ductility, and toughness; whereas ferritic undergoes a brittle transformation. Therefore, the use of stainless steel water pipes at low temperatures requires a low ferrite content in the weld.
Small amounts of ferrite in austenitic stainless steel welds can reduce low temperature toughness. When the ferrite content in the weld reaches FN=10, the low temperature toughness will decrease by 50%.
The low temperature toughness of stainless steel pipe is not only related to the ferrite content, but also related to the cleanliness of the weld. Tests have shown that the oxygen content of the deposited metal of the basic low-hydrogen electrode is lower than that of the titanium-calcium electrode, and the weld toughness is also better. The oxygen content of the deposited metal in inert gas shielded welding is lower than that of slag shielded welding, and the weld toughness is also better. Ultra-low carbon welding materials have less intergranular precipitation of deposited metal and good welding toughness.
When heat treatment is required after welding or high-temperature service, the ferrite number of weld metal measured before post-weld heat treatment shall not exceed 10FN. When the stainless steel pipe is used in a low temperature environment below -100°C, the low temperature impact test of the weld is carried out in accordance with relevant regulations; when it is used in a low temperature environment below -196°C, the ferrite content of the weld is less than 5FN. When stainless steel pipes are used in non-magnetic or special corrosive environments, they need to be controlled according to design requirements.
To simplify grade identification and align with international designations, China adopted the “Universal Code System for Steel and Alloy Grades” (e.g. 06Cr19Ni10 corresponds to 304). While chemical compositions vary slightly between standards, each grade is governed by its national standard.
| No | China (GB) | Japan (JIS) |
USA | Korea (KS) |
Europe (EN Werkstoff) |
India (IS) |
Australia | Taiwan (CNS) |
||
|---|---|---|---|---|---|---|---|---|---|---|
| Old | New (2007) | SUS | ASTM | UNS | STS | W.-Nr. | IS | Approx. | CNS | |
| Austenitic stainless steel | ||||||||||
| 1 | 1Cr17Mn6Ni5N | 12Cr17Mn6Ni5N | SUS201 | 201 | S20100 | STS201 | 1.4372 | 10Cr17Mn6Ni4N20 | 201-2 | 201 |
| 2 | 1Cr18Mn8Ni5N | 12Cr18Mn9Ni5N | SUS202 | 202 | S20200 | STS202 | 1.4373 | – | – | 202 |
| 3 | 1Cr17Ni7 | 12Cr17Ni7 | SUS301 | 301 | S30100 | STS301 | 1.4319 | 10Cr17Ni7 | 301 | 301 |
| 4 | 0Cr18Ni9 | 06Cr19Ni10 | SUS304 | 304 | S30400 | STS304 | 1.4301 | 07Cr18Ni9 | 304 | 304 |
| 5 | 00Cr19Ni10 | 022Cr19Ni10 | SUS304L | 304L | S30403 | STS304L | 1.4306 | 02Cr18Ni11 | 304L | 304L |
| 6 | 0Cr19Ni9N | 06Cr19Ni10N | SUS304N1 | 304N | S30451 | STS304N1 | 1.4315 | – | 304N1 | 304N1 |
| 7 | 0Cr19Ni10NbN | 06Cr19Ni9NbN | SUS304N2 | XM21 | S30452 | STS304N2 | – | – | 304N2 | 304N2 |
| 8 | 00Cr18Ni10N | 022Cr19Ni10N | SUS304LN | 304LN | S30453 | STS304LN | – | – | 304LN | 304LN |
| 9 | 1Cr18Ni12 | 10Cr18Ni12 | SUS305 | 305 | S30500 | STS305 | 1.4303 | – | 305 | 305 |
| 10 | 0Cr23Ni13 | 06Cr23Ni13 | SUS309S | 309S | S30908 | STS309S | 1.4833 | – | 309S | 309S |
| 11 | 0Cr25Ni20 | 06Cr25Ni20 | SUS310S | 310S | S31008 | STS310S | 1.4845 | – | 310S | 310S |
| 12 | 0Cr17Ni12Mo2 | 06Cr17Ni12Mo2 | SUS316 | 316 | S31600 | STS316 | 1.4401 | 04Cr17Ni12Mo2 | 316 | 316 |
| 13 | 0Cr18Ni12Mo3Ti | 06Cr17Ni12Mo2Ti | SUS316Ti | 316Ti | S31635 | – | 1.4571 | 04Cr17Ni12MoTi20 | 316Ti | 316Ti |
| 14 | 00Cr17Ni14Mo2 | 022Cr17Ni12Mo2 | SUS316L | 316L | S31603 | STS316L | 1.4404 | 02Cr17Ni12Mo2 | 316L | 316L |
| 15 | 0Cr17Ni12Mo2N | 06Cr17Ni12Mo2N | SUS316N | 316N | S31651 | STS316N | – | – | 316N | 316N |
| 16 | 00Cr17Ni13Mo2N | 022Cr17Ni13Mo2N | SUS316LN | 316LN | S31653 | STS316LN | 1.4429 | – | 316LN | 316LN |
| 17 | 0Cr18Ni12Mo2Cu2 | 06Cr18Ni12Mo2Cu2 | SUS316J1 | – | – | STS316J1 | – | – | 316J1 | 316J1 |
| 18 | 00Cr18Ni14Mo2Cu2 | 022Cr18Ni14Mo2Cu2 | SUS316J1L | – | – | STS316J1L | – | – | – | 316J1L |
| 19 | 0Cr19Ni13Mo3 | 06Cr19Ni13Mo3 | SUS317 | 317 | S31700 | STS317 | – | – | 317 | 317 |
| 20 | 00Cr19Ni13Mo3 | 022Cr19Ni13Mo3 | SUS317L | 317L | S31703 | STS317L | 1.4438 | – | 317L | 317L |
| 21 | 0Cr18Ni10Ti | 06Cr18Ni11Ti | SUS321 | 321 | S32100 | STS321 | 1.4541 | 04Cr18Ni10Ti20 | 321 | 321 |
| 22 | 0Cr18Ni11Nb | 06Cr18Ni11Nb | SUS347 | 347 | S34700 | STS347 | 1.4550 | 04Cr18Ni10Nb40 | 347 | 347 |
| Austenitic-ferritic (Duplex) stainless steel | ||||||||||
| 23 | 0Cr26Ni5Mo2 | – | SUS329J1 | 329 | S32900 | STS329J1 | 1.4477 | – | 329J1 | 329J1 |
| 24 | 00Cr18Ni5Mo3Si2 | 022Cr19Ni5Mo3Si2N | SUS329J3L | – | S31803 | STS329J3L | 1.4462 | – | 329J3L | 329J3L |
| Ferritic stainless steel | ||||||||||
| 25 | 0Cr13Al | 06Cr13Al | SUS405 | 405 | S40500 | STS405 | 1.4002 | 04Cr13 | 405 | 405 |
| 26 | – | 022Cr11Ti | SUH409 | 409 | S40900 | STS409 | 1.4512 | – | 409L | 409L |
| 27 | 00Cr12 | 022Cr12 | SUS410L | – | – | STS410L | – | – | 410L | 410L |
| 28 | 1Cr17 | 10Cr17 | SUS430 | 430 | S43000 | STS430 | 1.4016 | 05Cr17 | 430 | 430 |
| 29 | 1Cr17Mo | 10Cr17Mo | SUS434 | 434 | S43400 | STS434 | 1.4113 | – | 434 | 434 |
| 30 | – | 022Cr18NbTi | – | – | S43940 | – | 1.4509 | – | 439 | 439 |
| 31 | 00Cr18Mo2 | 019Cr19Mo2NbTi | SUS444 | 444 | S44400 | STS444 | 1.4521 | – | 444 | 444 |
| Martensitic stainless steel | ||||||||||
| 32 | 1Cr12 | 12Cr12 | SUS403 | 403 | S40300 | STS403 | – | – | 403 | 403 |
| 33 | 1Cr13 | 12Cr13 | SUS410 | 410 | S41000 | STS410 | 1.4006 | 12Cr13 | 410 | 410 |
| 34 | 2Cr13 | 20Cr13 | SUS420J1 | 420 | S42000 | STS420J1 | 1.4021 | 20Cr13 | 420 | 420J1 |
| 35 | 3Cr13 | 30Cr13 | SUS420J2 | – | – | STS420J2 | 1.4028 | 30Cr13 | 420J2 | 420J2 |
| 36 | 7Cr17 | 68Cr17 | SUS440A | 440A | S44002 | STS440A | – | – | 440A | 440A |
During manufacturing, the actual dimensions of stainless steel tubes and pipes often deviate from the nominal sizes. Such deviations are defined as tolerances and have been strictly standardized.
A positive deviation is called positive tolerance, and a negative deviation is called negative tolerance.
Outside diameter (OD), wall thickness and length are the three fundamental parameters in stainless steel tube & pipe manufacturing and distribution. Among them, OD and wall thickness are critical to structural design, fluid conveyance and downstream processing.
A. Nominal Pipe Size: The idealized dimension specified in standards such as ASME B36.10M and ASME B36.19M. It is the ordered size stated in contracts.
B. Actual Pipe Size: The real dimension obtained after production. Deviation occurs when the actual size is larger or smaller than the nominal size.
European standards define four tolerance classes for OD and wall thickness based on the nominal dimension, expressed either as percentages or absolute values. Larger diameters or heavier walls typically use percentage tolerances, while small-diameter or thin-wall tubes use absolute values.
| Standard | Process & Type | OD Tolerance | Wall Thickness Tolerance | Remarks | |
|---|---|---|---|---|---|
| OD (mm) | Class | ||||
| EN 10216-5 | Hot Finished Seamless | 219.1–610 | D1 | +22.5%T, –15%T | T/D ≤ 0.05 |
| T1 | T/D ≤ 0.09 | ||||
| T2 | T/D > 0.09 | ||||
| 30–219.1 | D2 | T1 | |||
| T2 | |||||
| Cold Finished Seamless | ≤219.1 | D3 | T3 | ||
| D4 | T4 | By agreement | |||
| EN 10297-2 | Hot Finished Seamless | – | D1 | T1 | |
| D2 | T2 | By agreement | |||
| Cold Finished Seamless | – | D3 | T3 | ||
| D4 | T4 | By agreement | |||
| EN 10217-7 | Welded | >168.3 | D2 | T3 | |
| ≤168.3 | D3 | T3 | |||
| D4 | T3 | By agreement | |||
| EN 10296-2 | Welded | >168.3 | D2 | T3 | |
| ≤168.3 | D3 | T3 | |||
| ≤114.3 | D4 | T3 | By agreement | ||
| EN 10312 | Welded | Series 1 | D4 | T3 | T = 0.6–2 mm |
| Series 2 | D3–D4 | T3–T4 | T = 1–3 mm | ||
OD classes D1–D4 and wall thickness classes T1–T4 follow DIN EN ISO 1127: Dimensions, tolerances and conventional masses per unit length.
| Outside Diameter | Wall Thickness | ||
|---|---|---|---|
| Class | Tolerance | Class | Tolerance |
| D1 | ±1.5% or ±0.75 mm min. | T1 | ±15% or ±0.6 mm min. |
| D2 | ±1.0% or ±0.5 mm min. | T2 | ±12.5% or ±0.4 mm min. |
| D3 | ±0.75% or ±0.3 mm min. | T3 | ±10% or ±0.2 mm min. |
| D4 | ±0.50% or ±0.1 mm min. | T4 | ±7.5% or ±0.15 mm min. |
| T5 | ±5.0% or ±0.10 mm min. | ||
Where both percentage and absolute values apply, the greater value shall be used.
ASTM specifications are primarily governed by ASTM A999/A999M and A1016/A1016M.
| ASTM A999 | ASTM A1016 |
|
|
A511 (seamless mechanical tubing) and A554 (welded mechanical tubing) are exceptions and have independent tolerance tables.
| Standard | Process / Condition | OD (mm) | OD Tolerance (mm) | Wall Thickness T (mm) | Wall Thickness Tolerance | |
|---|---|---|---|---|---|---|
| Minimum | Average | |||||
| ASTM A1016/A1016M | Hot Drawn Seamless | ≤100 | +0.4 / –0.8 | ≤2.4 | +0.4t / 0 | |
| 100–200 | +0.4 / –1.2 | 2.4–3.8 | +0.35t / 0 | |||
| 200–225 | +0.4 / –1.6 | 3.8–4.6 | +0.33t / 0 | |||
| ≥4.6 | +0.28t / 0 | |||||
| Cold Drawn Seamless | <25 | ±0.1 | +0.20t / 0 | ±0.10t | ||
| 25–40 | ±0.1 | +0.20t / 0 | ±0.10t | |||
| 40–50 | ±0.2 | +0.22t / 0 | ±0.10t | |||
| 50–65 | ±0.25 | +0.22t / 0 | ±0.10t | |||
| 65–75 | ±0.3 | +0.22t / 0 | ±0.10t | |||
| 75–100 | ±0.38 | +0.22t / 0 | ±0.10t | |||
| 100–200 | +0.38 / –0.04 | +0.22t / 0 | ±0.10t | |||
| 200–250 | +0.38 / –1.14 | +0.22t / 0 | ±0.10t | |||
| Welded | 40–50 | ±0.2 | +0.18t / 0 | ±0.10t | ||
| 50–65 | ±0.25 | +0.18t / 0 | ±0.10t | |||
| 65–75 | ±0.3 | +0.18t / 0 | ±0.10t | |||
| 75–100 | ±0.38 | +0.18t / 0 | ±0.10t | |||
| 100–200 | +0.38 / –0.04 | +0.18t / 0 | ±0.10t | |||
| 200–250 | +0.38 / –1.14 | +0.18t / 0 | ±0.10t | |||
| ASTM A999 | Seamless & Welded | <48.3 | +0.4 / –0.8 | –0.125t | ||
| ASTM A312 | Seamless & Welded | 48.3–114.3 | ±0.8 | OD=10.3–73 | +0.20t / –0.125t | |
| 168.3–219.1 | +1.6 / –0.8 | t/OD≤5%, OD=88.9–457.2 | +0.225t / –0.125t | |||
| 219.1–457.2 | +2.4 / –0.8 | t/OD>5%, OD=88.9–457.2 | +0.15t / –0.125t | |||
| Welded | 508–660 | +3.2 / –0.8 | OD≥508 | +0.175t / –0.125t | ||
| 711–864 | +4.0 / –0.8 | t/OD≤5%, OD≥508 | +0.225t / –0.125t | |||
| Seamless | 914–1209 | +4.8 / –0.8 | t/OD>5%, OD≥508 | +0.15t / –0.125t | ||
| ASTM A409 | Welded | ±0.2% (t<4.8) ±0.4% (t≥4.8) |
||||
| ASTM A358 | Welded | ±0.50% | ||||
| ASTM A511 | Seamless Mechanical | ≤12.7 | ±0.1 | ±0.15t | ||
| 12.7–38.1 | ±0.2 | ±0.10t | ||||
| 38.1–88.9 | ±0.3 | ±0.10t | ||||
| 88.9–139.7 | ±0.4 | ±0.10t | ||||
| 139.7–203.1 | ±0.8 | ±0.10t | ||||
| 203.1–220 | ±1.1 | ±0.10t | ||||
| 220–325 | ±1.6 | ±0.10t | ||||
U.S. standards predominantly use absolute OD tolerances, often asymmetrical. In many cases, average OD accuracy exceeds D4 class per EN ISO 1127.
Typical wall thickness tolerance: ±10%t or tighter. Pipeline products allow larger tolerances, with hot-finished seamless pipe being the most permissive.
China’s stainless steel tube & pipe standards are broadly aligned with European practice, while incorporating select provisions from U.S. specifications.
| Specification | Process | OD (mm) | OD Tolerance | Wall (mm) | Wall Tolerance | |
|---|---|---|---|---|---|---|
| GB 13296 | Cold Rolled Seamless | 6–30 | ±0.15 / –0.2 | 1–3 | +20% | 0% |
| >30–50 | ±0.3 | >3 | +22% | 0% | ||
| >50 | ±0.75% | Average wall thickness applies | ||||
| GB/T 14976 | Cold Rolled Seamless | 6–10 | ±0.15 | 1–3 | +12.5% | –12.5% |
| 10–30 | ±0.2 | >3 | +12.5% | –10% | ||
| 30–50 | ±0.3 | Average wall: +22% | ||||
| >50 | ±0.8% | |||||
Wall thickness tolerances in Chinese standards are generally comparable to mainstream U.S. and European specifications, though slightly less stringent than the highest EU accuracy classes.
OD tolerances in Chinese standards are typically tighter than U.S. requirements and approach EU levels. U.S. standards place stronger emphasis on tight OD control relative to wall thickness.
Neither Chinese nor European standards prescribe weight tolerances. Seamless tubes may be delivered by actual or theoretical weight; welded tubes are typically delivered by theoretical weight, optionally by actual weight.
Ovality is the difference between the maximum and minimum OD measured on the same cross-section. It is determined by measuring the high and low points of the tube or pipe.
Eccentricity describes variation in wall thickness around the circumference. High-precision applications require tight concentricity.
EN standards incorporate concentricity within wall thickness tolerances. ASTM A1016/A1016M specifies concentricity for OD ≥ 50 mm and t ≥ 5.6 mm.
Seamless tubes:
WTmax – WTmin ≤ ±10% × (WTmax + WTmin) / 2Welded tubes:
WTmax – WTmin ≤ 5% × (WTmax + WTmin) / 2Standard tubes are supplied straightened to the eye. For special applications, permissible deviation from straightness may be agreed upon. It is expressed per unit length, e.g. 1 mm per 1000 mm.
| OD (mm) ≤ | OD (inches) ≤ | Wall | Commercial Straightness | Achievable (mm/m) |
|---|---|---|---|---|
| 15.9 | 0.625 | All sizes | 1 in 600 | 1 in 2000 |
| 25.4 | 1.00 | ≥2% of OD | 1 in 600 | 1 in 1500 |
| 25.4 | 1.00 | <2% of OD | 1 in 400 | 1 in 1000 |
Delivery length is the length requested by the purchaser and specified in the contract. Standards define several types:
A. Normal / Random Length: Within the standard range, without fixed length requirement. Example: hot-finished pipe 3000–12000 mm; cold-drawn pipe 2000–10500 mm.
B. Fixed Length: A specific length within the normal range. An allowable positive deviation applies.
Fixed-length production yields significantly lower than random length. Price premiums of approximately 10% are common.
C. Multiple Length: Total length is a multiple of a single length, with an additional cutting allowance. Example: 3000 mm × 3 = 9000 mm total.
Cutting allowances: 5–10 mm for OD ≤ 159 mm; 10–15 mm for OD > 159 mm.
D. Range Length: A defined length interval within the normal range. Example: 6000–8000 mm or 8000–10000 mm. Premiums of ~4% are typical.
Density is defined as mass per unit volume. For stainless steels, typical densities range from 7600 kg/m³ to 8000 kg/m³, depending on alloy composition.
Stainless steels contain a minimum of 10.5% chromium, along with alloying elements such as nickel, molybdenum, titanium and copper. These elements enhance strength and corrosion resistance but also influence density.
Even within the same grade, exact density may vary slightly due to compositional tolerances. The values below are theoretical references for engineering calculations.
| Grade Family | Typical Grades | Density (g/cm³) | Density (kg/m³) |
|---|---|---|---|
| Austenitic (Cr-Ni) |
201, 202, 301, 302, 303, 304, 304L, 304LN, 305, 321 |
7.93 | 7930 |
| Austenitic (Mo-bearing) |
309S, 310S, 316, 316L, 316Ti, 316LN, 317, 317L, 347 |
7.98 | 7980 |
| Super Austenitic | 904L | 7.98 | 7980 |
| Duplex | 2205 / S31803 | 7.80 | 7800 |
| Super Duplex | S32750 | 7.85 | 7850 |
| Martensitic | 403, 410, 410S, 416, 431 | 7.75 | 7750 |
| Martensitic (High C) | 440A / 440C | 7.74 / 7.62 | 7740 / 7620 |
| Martensitic | 420 | 7.73 | 7730 |
| Ferritic | 439, 430, 430F | 7.70 | 7700 |
| Ferritic (Mo-bearing) | 434 / 444 | 7.74 / 7.75 | 7740 / 7750 |
| Ferritic | 405 | 7.72 | 7720 |
* Values are given at standard temperature and pressure (STP).
304 and 316 are the most widely used austenitic grades. 304 has a density of 7930 kg/m³, while 316 measures 7980 kg/m³. This difference must be accounted for when calculating theoretical weights for procurement or design.
Density is commonly expressed in g/cm³, kg/m³ or lb/in³. The following conversion applies:
1 kg/m³ = 0.001 g/cm³ = 0.000036127 lb/in³
Stainless steel density varies with environmental conditions. Increasing temperature generally reduces density, while increasing pressure raises density. For precision engineering, these effects should be considered in high-temperature or high-pressure service.
Seamless and welded tubes and pipes are the two primary product forms for stainless steel. For decades, there has been ongoing discussion regarding which type offers superior performance.
With advances in metallurgy and welding technology, the debate now centers on structural integrity and corrosion resistance—particularly within the weld zone of welded products. Fundamentally, the key distinction lies in the manufacturing process.
In certain highly corrosive or high-pressure applications, selecting a higher-performance alloy—rather than simply choosing seamless over welded—may be the most effective solution.
Strip-welded tubes are produced from stainless steel coils or strips. The strip passes through grooved rollers, gradually forming a circular profile. As the edges converge, they are joined by automatic welding.
The most common welding process is TIG (GTAW), which provides excellent protection of the weld seam and consistent metallurgical quality.
After welding, the seam is typically ground flush, followed by solution annealing or stress-relief heat treatment, depending on application requirements. Modern production lines often integrate inline induction annealing, straightening, dimensional calibration, cutting to length, deburring and non-destructive testing.
TIG welding of stainless steel tubing
For large-diameter or heavy-wall pipes, the manufacturing route differs. Production begins with stainless steel plates rather than strips. Plates are plasma-cut to size, edge-prepared, and formed using roller bending machines or hydraulic presses.
Welding methods such as EFW (Electric Fusion Welding) or ERW (Electric Resistance Welding) are commonly applied. For critical services, double-sided welding may be employed to ensure full penetration and structural integrity.
For large-diameter welded pipes, radiographic examination (RT) and hydrostatic testing (HT) are typically mandatory. Double-sided welding is commonly accepted and specified for high-integrity applications.
Chemical composition inspection, mechanical properties test(tensile strength,yield strength, elongation, flaring, flattening, bending, hardness, impact test), surface and dimension test,no-destructive test, hydrostatic test.
identification of the chemical composition of the metal used to manufacture the fitting. Uses PMI sensors, including X-ray fluorescence or optical emission spectrometry.
Common delivery conditions for stainless steel tubes and pipes: cold-hard (BK), cold-soft (BKW), stress-relieved (BKS), annealed (GBK), and normalized (NBK).
| Term | Symbol | Explanation |
|---|---|---|
| Cold-finished / Hard | BK | No heat treatment after final cold-forming. Low deformability. |
| Cold-finished / Soft | BKW | Light finishing pass after heat treatment. Limited cold-formability (bending, expanding). |
| Annealed | GBK | Annealed after final cold-forming in controlled atmosphere or vacuum. |
| Normalized | NBK | Annealed above upper transformation point in controlled atmosphere or vacuum. |
Bare packing / bundle packing / crate packing with wooden protection at both ends, suitable for seaworthy delivery or as requested.
While hundreds of packing methods exist, two principles are mandatory: corrosion prevention and secure sea transport.
Sunny Steel packing can be fully customized to meet customer requirements.
Stainless steel tubes can be beveled at one or both ends to match complementary joints. Beveling simplifies welding preparation, reduces on-site cutting time and lowers installation costs.
Sunny Steel provides heat treatment for selected 400-series stainless steels. Processes include stress relieving, tempering, quenching, normalizing and solution annealing to achieve required mechanical properties and microstructure.
Honing and turning refine the internal surface of tubes and pipes to precise diameters and geometric tolerances. This secondary operation relieves residual stress and improves surface finish after drilling, reaming and heat treatment.
Internal and external polishing is available to meet sanitary, pharmaceutical and high-purity process requirements.
PMI testing verifies alloy composition to ensure compliance with specifications. Sunny Steel performs in-house PMI or coordinates with independent laboratories for critical applications.
UT uses high-frequency sound waves to detect internal flaws, measure wall thickness and verify material integrity. This non-destructive test is routinely applied to seamless and welded stainless steel tubes.
All products are supplied with EN 10204 3.1 Mill Test Certificates. Third-party inspection (SGS, BV, TÜV) is available upon request.
Commonly used alloying elements and their effects are listed in the table given below.
| Alloying Elements | Effect on the Properties |
|---|---|
| Chromium | Increases Resistance to corrosion and oxidation. Increases hardenability and wear resistance. Increases high temperature strength. |
| Nickel | Increases hardenability. Improves toughness. Increases impact strength at low temperatures. |
| Molybdenum | Increases hardenability, high temperature hardness, and wear resistance. Enhances the effects of other alloying elements. Eliminate temper brittleness in steels. Increases high temperature strength. |
| Manganese | Increases hardenability. Combines with sulfur to reduce its adverse effects. |
| Vanadium | Increases hardenability, high temperature hardness, and wear resistance. Improves fatigue resistance. |
| Titanium | Strongest carbide former. Added to stainless steel to prevent precipitation of chromium carbide. |
| Silicon | Removes oxygen in steel making. Improves toughness. Increases hardness ability |
| Boron | Increases hardenability. Produces fine grain size. |
| Aluminum | Forms nitride in nitriding steels. Produces fine grain size in casting. Removes oxygen in steel melting. |
| Cobalt | Increases heat and wear resistance. |
| Tungsten | Increases hardness at elevated temperatures. Refines grain size. |
Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.
Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.
Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.
The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.
Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.
The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.
When you partner with Sunny Steel, you can stop worrying about meeting deadlines thanks to our responsive and timely service. You'll also say goodbye to unnecessary shopping around. Instead, you'll get white glove service from an expert who understands your needs and can get you the materials you need quickly.
