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Product Details:
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| Certification: | CE,ISO9001-2000,ISO-9001 | Grade: | A335 P91 T91 |
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| Alloy Or Not: | Is Alloy | Technique: | Hot Rolled,Cold Drawn |
| Thickness: | 2.87 - 13.84 Mm | Standard: | ASTM,DIN,BS |
| Outer Diameter(round): | 13.7 - 1016 Mm | Shape: | Round Shape |
| High Light: | Alloy Seamless Steel Pipe,SCH-160 Seamless Alloy Steel Pipe,ASME B36 Seamless Steel Pipe |
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MITTEL has been a provider of high-quality products and parts since 2012 . No matter your industry or problem, our experienced team will work to provide your company with exactly the solution you need. Though our inventory is already considered one of the best, we are always growing, and we are always evolving to meet the highest standards possible. All of our A335 P91 Type 2 material are of the highest quality from approved international manufacturers. As technology continues to advance, we do, too. ASTM A335 P91 Type 2 evolved from EPRI recommended Code Case 2864.
P91 is a chrome moly alloy metal that contains excellent strength and temperature resistance. It is designed for enhanced creep strength, making it a creep strength enhanced ferritic (CSEF). This metal is made by normalizing at 1050 °C, air cooling to 200 °C, and then tempered through heating to 760 °C. This process is the main reason behind P91’s creep strength and durability. P91 stands for the metal’s composition of 9% chrome and 1% molybdenum plus vanadium. The chrome increases temperature strength and oxidation resistance. The molybdenum increases the elasticity, resistance to wear, and high temperature creep strength. More characteristics to note of ASTM A335 P91 Type 2:
MITTEL can meet your ASTM A335 P91 Type 2 requirements when it comes to fittings,tubing, flanges, valves, and much more. This metal is made and typically usedfor very high heat situations in industries such as chemical processing andpower plants.
Some more common uses of ASTM A335 Type 2include
Contact our experienced and educated team at U.S. Metals today to discuss all your P91 needs. We use only high-quality materials to bring you the best performing products.
Trade Name: P91
Grade: P91
UNS #: K91560
Pipe: A335/SA335
Forged/Bored Pipe: A369/SA369
Length: Specific or random
A335/SA335 P91 is a ferritic alloy steel that has very high strength properties, which do not deteriorate with time, and are creep resistant. It is also called 9 Cr 1 Mo steel, or chrome moly pipe, based on its composition.
Compared to its predecessors, the T22 or P22 grade, grade P91 exhibits high strength, enduring temperatures up to 600 °C. The oxidation temperature limits are also higher allowing elements to be engineered with less thickness. This contributes to an almost 10 times higher thermal fatigue life and allows engineers to increase the operating temperature to a higher level, increasing efficiency.
P91 typically allows a wall thickness reduction by at least a 2-to-1 ratio. A wall that is thinner creates lighter hanger loads, less welding time and uses less filler metal.
These advantages are enabled by this steel’s high amount of chromium. Grade 91 contains 9% chromium and 1% molybdenum compared to 2.5% chromium in the next best P22 grade
Chromium, or chrome, improves high-temperature strength and increases oxidation resistance. It is virtually irreplaceable in resisting oxidation at elevated temperatures. Chrome also raises the tensile, yield and hardness at room temperatures.
Molybdenum increases the strength, elastic limit, resistance to wear, impact qualities and hardenability. It increases the resistance to softening, restrains grain growth and makes chromium steel less susceptible to embrittlement. Moly is also the most effective additive for increasing high temperature creep strength, or creep resistance. It also enhances the corrosion resistance of steel and inhibits pitting.
Also present are smaller quantities of nickel and manganese which increase the hardenability of the steel.
The addition of Vanadium (V) and Columbium/Niobium (Cb/Nb) as well as the control of Nitrogen (N) greatly Improves Creep Strength.
More important than the alloying elements is the formation of this alloy steel. The steel is formed by normalizing at 1050 °C, then air cooling down to 200 °C. It is then tempered by heating to 760 °C. The temperatures and cooling rates produce the microstructure that results in the high creep strength properties.
A335/SA335 P91 is suitable for bending, flanging (vanstoning), and similar forming operations and for fusion welding. P91 is most commonly used in the power industry and petrochemical plants where fluids and gases are transported at extremely high temperatures and pressures.
P91’s strength and high temperature endurance makes it ideally suitable for plants that operate on a cyclic basis - like combined cycle plants. Also, the reduction in thickness suits HRSG designers, in an HRSG the temperature head is limited and locating the coils in the heat transfer path is very critical.
P91 is the correct grade for:
When welding P91, preheating, maintaining inter-pass temperatures and post-weld treatment procedures are essential to maintain the P91 grade. Welding has an important effect on the microstructure and failure to follow the procedures will result in catastrophic failures.
For thick-walled pipes, the use of a modern induction heating system – where the coils do not heat up – is the ideal method. This gives better control, and uniform heating between the inner and outer diameters. Induction heating is ideal for maintaining the inter-pass temperatures and carry out the welding. This is also a more worker-friendly heating process and is ideal for complex shapes like weldolets and tees.
The composition of the welding electrodes used should always be in line with the parent material. The nickel and manganese content of P91, though in smaller percentages, has profound effects on the critical temperatures, which decides the heat treatment temperatures and the cooling rates.
Steel that has not been heat-treated has a great affinity to hydrogen which can cause stress corrosion cracking. Pre-heating must be done properly to remove any moisture. In addition, the post-weld heat treatment must be done as quickly as possible to avoid any contact with moisture from condensation, rainfall, etc. Be sure all joints are post-weld heat treated prior to hydro test.
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