ASTM A335 P128 Seamless Alloy Steel Pipe For Power plants
Specification
ASTM A335 P128 Alloy Steel Pipe is a specification for seamless ferritic alloy steel pipe for high-temperature service, essentially a Chrome-Moly (Chromium-Molybdenum) pipe, offering excellent high-temp strength, oxidation, and corrosion resistance due to chromium and molybdenum, making it ideal for power plants, refineries, and petrochemicals for steam, boiler, and heat exchanger applications.
| American Standard |
Standard Name |
| A335 / A335M |
Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service |
ASTM A335 P128 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 |
| P128 |
K91421 |
0.12-0.17 |
0.3-0.8 |
0.02 |
0.01 |
0.2-0.6 |
10.5-12 |
0.2-0.6 |
V 0.15-0.30 Ni 0.10-0.40 B 0.008-0.015 N 0.002-0.020 Co 1.50-2.20 Al 0.02 max Cu 0.15 max W 1.50-2.20 Nb 0.02-0.06 |
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. |
ASTM A335 P128 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 |
| P128 |
K91421 |
71/490 |
94/650 |
20 |
265 HBW |
280 HV |
27 HRC |
ASTM A335 P128 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] |
| P128 |
normalize and temper |
1975-2140 [1080-1170] |
air |
1350-1470 [730 - 800] |
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). |
ASTM A335 P128 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 P128 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 P128 Alloy Steel Pipe Manufacturing Proces
ASTM A335 P128 Alloy Steel Pipe Application
- Power plants
- Refineries
- Petrochemicals for steam
- Boiler
- Heat exchanger
ASTM A335 P128 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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ASTM A335 P128 Alloy Steel Seamless Pipes 20FT 40FT For Power Plants Images
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