ASTM A335 Grade P91 pipe is premium grade pipe applied for high pressure boiler.
ASTM A335 P91 alloy steel pipe and high pressure boiler pipes are the two variants available and the range is dependent based on the size, which is solely based on the usage. The length of the pipe will be subject to hydrostatic test and there will also be a non-destructive examination based on the specifications.
ASTM A335 P91 high pressure semaless boiler pipe, The range of ASTM A335 P91 seamless alloy steel pipe sizes that may be examined by each method shall be subjected to the limitations in the scope of the respective practice.
- Steel grade: ASTM A335 P91
- Outer Dimensions: 19.05mm – 114.3mm
- Wall Thickness: 2.0mm – 14 mm
- Length: max 16000mm
Each length of pipe shall be subjected to the hydrostatic test. Also, each pipe shall be examined by a non-destructive examination method in accordance to the required practices.
The different mechanical test requirements for pipes, namely, transverse or longitudinal tension test, flattening test, and hardness or bend test are presented.Both ends of each crate will indicate the order no., heat no., dimensions, weight and bundles or as requested.
Packing:
Bare packing/bundle packing/crate packing/wooden protection at the both sides of tubes and suitably protected for sea-worthly delivery or as requested.Inspection and Test:
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.Surface treatment:
Oil-dip, Varnish, Passivation, Phosphating, Shot Blasting.Both ends of each crate will indicate the order no., heat no., dimensions, weight and bundles or as requested.
ASTM A335 P91 Chemical Compositions(%)
| Compositions | Data |
| UNS Designa-tion | K91560 |
| Carbon(max.) | 0.08-0.12 |
| Manganese | 0.30-0.60 |
| Phosphorus(max.) | 0.025 |
| Silicon(max.) | 0.50 |
| Chromium | 4.00-6.00 |
| Molybdenum | 0.45-0.65 |
| Other Elements | … |
Mechanical properties for ASTM A335 P91
| Properties | Data |
| Tensile strength, min, (MPa) | 415 Mpa |
| Yield strength, min, (MPa) | 205 Mpa |
| Elongation, min, (%), L/T | 30/20 |
Material & Manufacture
Pipe may be either hot finished or cold drawn with the finishing heat treatment noted below.Heat Treatment
- A / N+T
- N+T / Q+T
- N+T
Mechanical Tests Specified
- Transverse or Longitudinal Tension Test and Flattening Test, Hardness Test, or Bend Test
- For material heat treated in a batch-type furnace, tests shall be made on 5% of the pipe from each treated lot. For small lots, at least one pipe shall be tested.
- For material heat treated by the continuous process, tests shall be made on a sufficient number of pipe to constitute 5% of the lot, but in no case less than 2 pipe.
Notes for Bend Test:
- For pipe whose diameter exceeds NPS 25 and whose diameter to wall thickness ratio is 7.0 or less shall be subjected to the bend test instead of the flattening test.
- Other pipe whose diameter equals or exceeds NPS 10 may be given the bend test in place of the flattening test subject to the approval of the purchaser.
- The bend test specimens shall be bent at room temperature through 180 without cracking on the outside of the bent portion.
Advantages of P91
SA 335 P91 or SA 213 T91 is the ultimate Ferrite Alloy steel that meets the extensive condition. Normally, the materials are used in many numbers of successful power plant service. Metal is also called as the 9 Cr 1 Mo steel with more composition. T22 or P22 grade is its predecessor but the Grade 91 mainly exhibits with the higher strength of temperature in the range of about 600 °C. Oxidation temperature mainly limits to higher features so it also effectively allows power plant designers to extensively engineer the components. In fact, it also effectively allows power plant designers for easily engineering the components with superheater coils, steam piping and headers as it mainly has less thickness. The metal also contributes higher thermal fatigue life that is ten times stronger when compared to other metals in much excellence. It also effectively allows to increase operating temperature at the higher level and increased efficiency at the power plant.
Normally, Alloy steel is not tolerant based on variations in the microstructure when compared to the P22 grade and other grades. Alloy steel is available in the difference that mainly contains the amount of carbon and iron. These are like the carbon steel along with it has other elements. Elements used in the Alloy steel mainly add manganese, silicon, chromium, vanadium, boron, and nickel. With more number of value composition about elements that are presented based on different ranges with more properties in the alloy steel. Normally, usage or application of alloy steel is to acquire the well-determined physical properties of the steel. The alloy steel falls into 2 types that include low alloy steels and high alloy steels. The Alloy steel is considered as the high alloy properties with the amount of the included elements belongs to the level of 8%. When these elements are combined with the range that is perforated in the below 8% value then it is called as low alloy steel. Low alloy steel is only used in most of the factories.
Alloy Steel P91 is manufactured based on precision and strict industry standard that mainly follows the heat treatment requirements. It is also reported that the failures of base materials are completely based on the different stages of usage. Alloy Steel P91 mainly used for different application with the extensive precision manufactured that are also complete reinstate with the microstructure to the high excellence. Alloy Steel P91 has properties much lower when compared to the predecessor P22. The effect of variation based on treatment on properties would be quite easier to analyze but it is not in the suitable for P91. Fabrication with construction phase mainly affects microstructure with reversed by precise heat treatment. In fact, it also brings microstructure back to original size and shape to the excellence. Alloy Steel P91 is decided based on tanker linings with complete prevalent consumption protection with high return quality and it also efficiently adds structures. With the variety of welding consumables along other national specifications enabled, P91 materials are widely used across for different aspects.
