Seamless Alloy Steel P921 ASTM A335 Pipe For Petrochemical Plants
ASTM A335 P921 Seamless Alloy Steel Pipe For Petrochemical Plants
Specification
ASTM A335 P921 Alloy Steel Pipe is a seamless ferritic alloy steel pipe designed for high-temperature service, featuring significant Chromium (Cr) and Molybdenum (Mo) for enhanced strength, creep resistance, and corrosion protection, commonly used in power plants and refineries.
| American Standard | Standard Name |
| A335 / A335M | Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service |
ASTM A335 P921 Alloy Steel Pipe Chemical Composition
Sources American Standard A335 / A335M TABLE 1 Chemical Requirements
| ASTM A335 Grades |
UNS Designation |
C | Mn | P | S | Si | Cr | Mo | Others |
| P921 | K91201 | 0.08-0.12 | 0.5-0.7 | 0.03 | 0.02 | 1.6-2.2 | 8.0-9.5 | 0.8-1.1 | Ni 0.8-1.4 N 0.02-0.05 Al 0.04 max Cu 0.8-1.4 |
| A New designation established in accordance with Practice E527 and SAE J1086, Practice for Numbering Metals and Alloys (UNS). B Grade P5c shall have a titanium content of not less than 4 times the carbon content and not more than 0.70 %; or a niobium content of 8 to 10 times the carbon content. C Alternatively, in lieu of this ratio minimum, the material shall have a minimum hardness of 275 HV in the hardened condition, defined as after austenitizing and cooling to room temperature but prior to tempering. Hardness testing shall be performed at mid-thickness of the product. Hardness test frequency shall be two samples of product per heat treatment lot and the hardness testing results shall be reported on the material test report. D Applies to both heat and product analyses. E Chromium-Nickel Balance is defined as CNB = (Cr + 6Si + 4Mo + 1.5W + 11V + 5Nb + 9Ti + 12Al) – (40C + 30N + 4Ni + 2Mn + 1CU). F The terms Niobium (Nb) and Columbium (Cb) are alternate names for the same element. |
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ASTM A335 P921 Alloy Steel Pipe Mechanical Properties
Sources American Standard A335 / A335M TABLE 3 Tensile Requirements
| ASTM A335 Grade |
UNS Designation |
Yield strength, Min:ksi/MPa |
Tensile strength, Min:ksi/MPa |
Elongation Requirements % (Min) | Hardness Requirements (Max) | ||
| Brinell | Vickers | Rockwell | |||||
| P921 | K91201 | 84/580 | 109/750 | 30 | 276 HBW | 290 HV | 26 HRC |
ASTM A335 P921 Alloy Steel Pipe Heat Treatment
Sources American Standard A335 / A335M TABLE 2 Heat Treatment Requirements A
| ASTM A335 Grade | Heat Treatment Type | Normalizing Temperature Range F [C] | Cooling Media | Subcritical Annealing or Tempering Temperature,min or range“F[°C] |
| P921 | normalize and temper | 1670-1740[910-950] | air | 1350-1420[730-770] |
| A Where ellipses (_) appear in this table there is no requirement. B Alternatively, Grade P36, Class 2 shalbe cooled from the austenitizing temperature by accelerated cooling in air or by liquid quenching. C Except when Supplementary Requirement S7 is specified by the purchaser. D Accelerated cooling from the normalizing temperature shall be permited for section thicknesses greater than 3 in. [75 mm). |
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ASTM A335 P921 Alloy Steel Pipe Permissible Variations in Outside Diameter
Sources American Standard A335 / A335M TABLE 7 Permissible Variations in Outside Diameter
| NPS [DN] Designator | Over | Under | ||
| in. | mm | in. | mm | |
| 1/8 to 1 1/2 [6 to 40], incl. | 1/64 (0.015) | 0.4 | 1/64 (0.015) | 0.4 |
| Over 1 1/2 to 4 [40 to 100], incl. | 1/32 (0.031) | 0.79 | 1/32 (0.031) | 0.79 |
| Over 4 to 8 [100 to 200], incl. | 1/16 (0.062) | 1.59 | 1/32 (0.031) | 0.79 |
| Over 8 to 12 [200 to 300], incl. | 3/32 (0.093) | 2.38 | 1/32 (0.031) | 0.79 |
| Over 12 [300] | +/- 1% of the specified outside diameter | |||
ASTM A335 P921 Alloy Steel Pipe Permitted Variations in Wall Thickness
Sources American Standard A335 / A335M TABLE 8 Permitted Variations in Wall Thickness
| NPS [DN] Designator | Tolerance, % from Specified | |
| Over | Under | |
| 1/8 to 2 1/2 [6 to 65] incl., all t/D ratios | 20.00% | 12.50% |
| Above 2 1/2 [65], t/D < or = 5% | 22.50% | 12.50% |
| Above 2 1/2 [65], t/D > 5% | 15.00% | 12.50% |
| (t = Specified Wall Thickness; D = Specified Outside Diameter) | ||
ASTM A335 P921 Alloy Steel Pipe Manufacturing Proces
ASTM A335 P921 Alloy Steel Pipe Application
- Power plants
- Refineries
- Petrochemical plants
- Boiler systems
- Heat exchanger tubing
- Main steam and hot reheat piping
- High-temperature headers and manifolds
- Thermal and waste-to-energy plants
- High-pressure fluid transfer lines
- Retrofit and upgrade projects for high-temperature piping
ASTM A335 P921 Alloy Steel Pipe Packing & Loading
a. 1/2"-2"Plain end with black oil paint, caps both ends, bundles with loading belt.
b. 2"-4"Beveled end with black oil paint, caps both ends, bundles with loading belt.
c. 10"-20"Beveled end with black oil paint, caps both ends, loose packed in to container.
→Alloy Steel Pipes is transported in containers
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