Corrosion Resistance Seamless Alloy Steel Pipe ASTM A335 P21 For Heat Exchanger
ASTM A335 P21 Seamless Alloy Steel Pipe For High-Temperature Steam Piping
Specification
ASTM A335 P21 Alloy Steel Pipe is a seamless, ferritic alloy steel pipe designed for high-temperature service, often called a chrome moly pipe due to its Chromium (Cr) and Molybdenum (Mo) content, which enhances high-temp strength and corrosion resistance.
| American Standard | Standard Name |
| A335 / A335M | Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service |
ASTM A335 P21 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 |
| P21 | K31545 | 0.05-0.15 | 0.30-0.60 | 0.025 | 0.025 | 0.5 | 2.65-3.35 | 0.80-1.06 |
ASTM A335 P21 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 | |||||
| P12 | K11562 | 32/220 | 60/415 | 30 | – | - | – |
ASTM A335 P21 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] |
| P21 | full or isothemmal anneal or | - | - | - |
| normalize and temper or | - | - | 1200 [650] | |
| A Where ellipses (_) appear in this table there is no requirement. | ||||
ASTM A335 P21 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 P21 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 P21 Alloy Steel Pipe Manufacturing Proces
ASTM A335 P21 Alloy Steel Pipe Application
- Hydrogen Service in Petroleum Refineries
- High-Temperature Steam Lines
- Petrochemical Process Reactors & Vessels
- Heat Exchanger Tubing for Severe Service
- Transfer Lines in Refinery Units
ASTM A335 P21 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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