Type 316/316L Stainless Steel is a molybdenum steel possessing improved resistance to pitting by solutions containing chlorides and other halides.
Type 316 is a molybdenum steel possessing improved resistance to pitting by solutions containing chlorides and other halides. In addition, it provides excellent tensile, creep and stress-rupture strengths at elevated temperatures. Type 316 is available in low carbon (316L) and high carbon (316H) alloys.
Alloy 316/316L is an austenitic alloy and similar to 304/304L is used in a wide range of applications. It is an important alloy when it comes to chloride environments and many other chemical process industries. The addition of Molybdenum significantly increases general corrosion resistance as compared to 304/304L and more importantly, increases the chloride pitting resistance.
316/316L has excellent forming and welding characteristics. Due to its superior chloride pitting resistance, it is commonly used in applications involving chlorides or halides. That property is also useful in marine environments.
It also has an excellent resistance to intergranular corrosion in as-welded condition. Dual grade becomes important if heavy gauge welding is performed. This is where intergranular corrosion comes into picture and having a lower carbon version makes it difficult for Chromium Carbide to precipitate in the 797 to 1580 degF (425 to 860 degC) range when the welding is going on for a long time due to the heavy gauge.
It has excellent creep and rupture strength at higher temperatures compared to 304/304L. Finally, it has excellent strength and toughness at cryogenic temperatures.
ASTM A269 TP316L stainless tube refers to a specific type of stainless steel tubing that conforms to the ASTM A269 standard and is made from grade TP316L stainless steel.
The ASTM A269 TP316 stainless tubes undergo a comprehensive quality assurance process, including underwater ultrasonic testing, eddy current testing, borescope inspection, spectroscopy, and roughness testing.
The terms AP, MP, BA, and EP refer to different surface finishes or treatments applied to the stainless steel.
These finishes are essential in various industries where the appearance, corrosion resistance, and cleanliness of the stainless steel are critical. Here's an explanation of each term:
EP (Electropolished): EP stands for electropolished, a process where the stainless steel tube, after annealing and acid pickling, undergoes electropolishing using electrodes and acid in a tank, creating a chemical reaction to achieve a clean surface through electrochemical polishing. EP tubes are used in pipeline projects with high cleanliness requirements for the stainless steel tube surface.
AP (Annealed and Pickled): AP refers to the condition where the surface of the stainless steel tube is treated after annealing through acid pickling to remove the oxide layer. Stainless steel industrial pipes sold in the market, known for their wide applications, are extensively used in the chemical industry for pipeline needs.
MP (Mechanical Polished): MP denotes a stainless steel seamless tube that undergoes mechanical polishing after annealing and acid pickling to achieve a bright and clean surface. This finish is primarily utilized in the pharmaceutical and food industries.
BA (Bright Annealed): BA is specific to precision-rolled stainless steel tubes. Also known as precision tubes, BA tubes skip the regular annealing and acid pickling process after semi-finished rolling. Instead, they use argon gas in a vacuum annealing furnace to remove surface oil stains generated during the rolling process, preserving the brightness of the surface without leaving an oxide layer.
These surface finishes cater to various industry requirements, offering different levels of brightness, cleanliness, and corrosion resistance based on specific applications.
The versatility of ASTM A269 lends itself to a wide array of applications across various industries:
1. Chemical and Petrochemical
In aggressive chemical environments, where corrosion resistance is paramount, ASTM A269 stainless steel tubes find applications in transporting and containing corrosive fluids and gases.
2. Pharmaceutical
Pharmaceutical industries demand hygienic and sterile environments. Stainless steel tubes complying with ASTM A269 are utilized in processes involving high-purity fluids and gases.
3. Food and Beverage
For the safe transport of food and beverages, ASTM A269 tubing ensures that no contaminants leach into consumable products.
Alloy 316/316L is an austenitic alloy and similar to 304/304L is used in a wide range of applications. It is an important alloy when it comes to chloride environments and many other chemical process industries. The addition of Molybdenum significantly increases general corrosion resistance as compared to 304/304L and more importantly, increases the chloride pitting resistance.
316/316L has excellent forming and welding characteristics. Due to its superior chloride pitting resistance, it is commonly used in applications involving chlorides or halides. That property is also useful in marine environments.
It also has an excellent resistance to intergranular corrosion in as-welded condition. Dual grade becomes important if heavy gauge welding is performed. This is where intergranular corrosion comes into picture and having a lower carbon version makes it difficult for Chromium Carbide to precipitate in the 797 to 1580 degF (425 to 860 degC) range when the welding is going on for a long time due to the heavy gauge.
It has excellent creep and rupture strength at higher temperatures compared to 304/304L. Finally, it has excellent strength and toughness at cryogenic temperatures.
Very wide ranging. It is practically used almost everywhere:
In addition, it provides excellent elevated temperature tensile, creep and stress-rupture strengths.
| Grade | 316 | 316L |
|---|---|---|
| UNS Designation | S31600 | S31603 |
| Carbon (C) Max. | 0.08 | 0.030* |
| Manganese (Mn) Max. | 2.00 | 2.00 |
| Phosphorous (P) Max. | 0.045 | 0.045 |
| Sulphur (S) Max. | 0.030 | 0.030 |
| Silicon (Si) Max. | 1.00 | 1.00 |
| Chromium (Cr) | 16.0 – 18.0 | 16.0 – 18.0 |
| Nickel (Ni) | 10.0 – 14.0 | 10.0 – 14.0 |
| Molybdenum (Mo) | 2.0 – 3.0 | 2.0 – 3.0 |
| Nitrogen (N) | — | — |
| Iron (Fe) | Bal. | Bal. |
| Other Elements | — | — |
The main constituents of 316 stainless steel - other than iron - are Chromium and Nickel. However, it is the addition of 2% Molybdenum that provides the increased corrosion resistance.
316 contains 16 - 18% Chromium (Cr). Chromium is the essential chemical in all stainless steel and it is that which forms the thin passive layer that makes the metal "stainless"
316 also contains 10-14% Nickel (Ni). This is added to make the Austenitic structure more stable at normal temperatures.
The nickel also improves high-temperature oxidation resistance makes the steel resistant to stress corrosion cracking.
Where the steel is to be stretched formed a lower percentage (8%) of nickel should be selected. If the steel is to be deep drawn a higher percentage is better (9% or more).
In addition a number of other chemicals may be present but these are expressed as maximum permited levels with the exception of the increased quantity of carbon required in 316H - i.e. a minimum of .04% and a maximum of 0.10%
Electrical Resistivity |
7.2e-005 ohm-cm |
7.2e-005 ohm-cm |
at 20°C (68°F); 1.16E-04 at 650°C (1200°F) |
Magnetic Permeability |
1.008 |
1.008 |
at RT |
| Material | Form | Tensile Strength (ksi) |
Yield Strength (ksi) |
Elongation % |
Hardness HB |
|---|---|---|---|---|---|
| Alloy 316L | 316L Sheet AMS 5507 | 100 max | - | 45 | - |
| Alloy 316 | 316 Sheet AMS 5524 | 75 min | 30 | 45 | 207 max |
| Alloy | UNS Design -ation |
Spec. | Tensile Strength | Yield Strength | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| psi | MPa | ksi | psi | MPa | ksi | Elongation in 2 inches (min.) % | Grain Size Req. | Max. Hardness | Modulus of Elasticity (x106 psi) | Mean Coefficient of Thermal Expansion (IN./IN./°F x 10-6) | Thermal Conductivity (BTU-in/ft2-h-°F) |
|||
| 316 | S31600 | A249, A312 | 75,000 | 515 | 75 | 30,000 | 205 | 30 | 35 | — | 90 Rb | 28.0 | 9.2 | 116 |
| 316L | S31603 | A270, A312 | 70,000 | 485 | 70 | 25,000 | 170 | 25 | — | — | 90 Rb | 28.0 | 9.2 | 116 |
| 316H | S31609 | — | — | — | — | — | — | — | — | 7 or coarser | — | — | — | — |
| Alloy | UNS Designation | Werkstoff NR. | Specifications* |
|---|---|---|---|
| 316 | S31600 | 1.4401 | A269, A/SA249, A/SA312, A1016, A632, A/SA688 |
| 316L** | S31603 | 1.4404 | A269, A/SA249, A/SA312, A1016, A632, A/SA688 |
*Note: The specifications noted including ASTM, ASME, or other applicable authorities are correct at the time of publication. Other specifications may apply for use of these materials in different applications.
Tensile Requirements - Stainless Steel 316/316L
Tensile Strength (KSI): 70
Yield Strength (KSI): 25
KSI can be converted to MPA (Megapascals) by multiplying by 6.895.
Type 316L is the low carbon version of 316 stainless. With the addition of molybdenum, the steel is popular for use in severe corrosion environments due to the materials immunity from boundary carbide precipitation (sensitisation).
The material is widely used in heavy gauge welded components and weld annealing is only required where the material is for use in high stress environments. 316L has an extensive variety of uses especially in marine applications due to the materials high corrosion resistance.
Type 316H is a higher carbon variant of 316 making the steel more suitable for use in applications where elevated temperatures are present.
Stabilised Grade 316Ti offers similar qualities.
The increased carbon content delivers a greater tensile and yield strength. The austenitic structure of the material also gives this grade excellent toughness, even down to cryogenic temperatures.
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.
