Astm A335 standard specification for seamless ferritic alloy-steel pipe for high-temperature service. ASTM A335 standard is issued under the fixed designation A 335/A 335M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon ( ュ) indicates an editorial change since the last revision or reapproval.
ASTM A335 standard is issued under the fixed designation A 335/A 335M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision.
The most common use of grades P11, P22, and P91 is in the power industry and petro-chemical plants, Grades P5 and P9 are commonly used in refineries.
ASTM A335 is often called as chrome moly pipe because of the chemical contain of Molybdenum (Mo) and Chromium (Cr). Molybdenum increases the strength of steel and Chromium (or chrome) is the essential constituent of stainless steel.
The composition chrome moly alloy steel pipe make it ideal for use in power plants, refineries, petro chemical plants, and oil field services where fluids and gases are transported at extremely high temperatures and pressures.
Chrome moly pipe under ASTM & ASME specification A/SA 335 P1, P2, P11, P12, P15, P22, P91, P92, P122 are used for power industries whereas ASTM/ASME A/SA 335 P5, P9 are used for petrochemical industries
- Strong resistance to rupturing at high temperatures and high pressures
- May be used for Hydrogen Sulfide Corrosion Services
- Resistant to cracking from hydrogen attack and embrittlement
- Resistant to hot sulfide corrosion cracking
- Can be used for NACE Applications where sour environments are under high temp and pressure
- Can be used in NACE-MRO 175 Sour Service
- Ideal for creep rupture applications
- Can handle high temperatures with very low elasticity
Certitifcation: Chrome Moly pipe are certified as PER DIN 50049 3.1, EN 10204 3.1/3.2 and NACE MR-0175 & NACE MR-0103
Piping Component Specifications:
- Flanges and forged fittings – A/SA 182 F1, F2, F5, F9, F11, F12, F15, F22, F91, F92, F122 Wrought
- Butt-weld Pipe Fittings – A/SA 234 P1, P2, P5, P9, P11, P12, P15, P22, P91, P92, P122
Chemical Composition of ASTM A335 alloy pipes
Chrome Moly Pipes: Werkstoff vs EN vs ASTM
|1.5415||16Mo3||A335 Grade P1|
|1.7335||13CrMo4-5||A335 Grade P11, P12|
|1.738||10CrMo9-10||A335 Grade P22|
|1.7362||X11CrMo5||A335 Grade P5|
|A335 Grade P9|
|1.4903||X10CrMoVNb9-1||A335 Grade P91|
ASTM A335 Steel Pipe Mechanical Properties
|Material||Tensile N/mm2||Strength min N/mm2||Yield %min|
|A335 Grade P1||Min380||205||30|
|A335 Grade P5||Min415||205||30|
|A335 Grade P11||Min415||205||30|
|A335 Grade P12||Min415||205||30|
|A335 Grade P22||Min415||205||30|
ASTM A335 Steel Pipe Elongation Requirements
|Wall Thickness||P5, P9, P11, P22||P91|
A335 is often called chrome moly pipe because of the chemical makeup of Molybdenum (Mo) and Chromium (Cr). Molybdenum increases the strength of steel as well as the elastic limit, resistance to wear, impact qualities, and hardenability. Moly increases the resistance to softening, restrains grain growth and makes chromium steel less susceptible to embrittlement. Moly is the most effective single additive that increases high temperature creep strength.
It also enhances the corrosion resistance of steel, and inhibits pitting. Chromium (or chrome) is the essential constituent of stainless steel. Any steel with 12% or more Chrome is considered stainless. Chrome is virtually irreplaceable in resisting oxidation at elevated temperatures. Chrome raises the tensile, yield, and hardness at room temperatures. The composition chrome moly alloy steel pipe make it ideal for use in power plants, refineries, petro chemical plants, and oil field services where fluids and gases are transported at extremely high temperatures and pressures.
ASTM A335 Steel Pipe Heat Treatment Requirements
|Grade||Heat Treatment Type|
P5, P9, P11, and P22
|Normalizing Temperature Range F [C]||Subcritical Annealing or Tempering
Temperature Range F [C]
|A335 P5 (b,c)||Full or Isothermal Anneal|
|Normalize and Temper||*****||1250 |
|Subcritical Anneal (P5c only)||*****||1325 – 1375 [715 - 745]|
|A335 P9||Full or Isothermal Anneal|
|Normalize and Temper||*****||1250 |
|A335 P11||Full or Isothermal Anneal|
|Normalize and Temper||*****||1200 |
|A335 P22||Full or Isothermal Anneal|
|Normalize and Temper||*****||1250 |
|A335 P91||Normalize and Temper||1900-1975 [1040 - 1080]||1350-1470 [730 - 800]|
|Quench and Temper||1900-1975 [1040 - 1080]||1350-1470 [730 - 800]|
ASTM A335 Steel Pipe Permissible Variation in Wall Thickness
|NPS [DN] Designator||Tolerance, % from Specified|
|1/8 to 2 1/2 [6 to 65] incl., all t/D ratios||0.2||0.125|
|Above 2 1/2 , t/D < or = 5%||0.225||0.125|
|Above 2 1/2 , t/D > 5%||0.15||0.125|
ASTM A335 Steel Pipe Permissible Variations in Outside DiameterOutside Diameter at any point shall not vary from standard specified more than:
|NPS [DN] Designator||Over||Under|
|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 ||+/- 1% of the specified outside diameter|
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 Hardness Test:
P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC].
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.
The inside diameter of the bend shall be 1 inch [25 mm].
Each length of pipe shall be Hydro tested, at option of manufacture nondestructive electric testing can be used.
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- SAE J 1086 Practice for Numbering Metals and Alloys (UNS)
- SNT-TC-1A Recommended Practice for Nondestructive Personnel Qualification and Certification
ASTM A335 Steel Pipe Material Comparison Tables
|KS/JIS Symbol||KS/JIS Numbe||Remarks||DIN Type||DIN||Materiral||Remarks||B.S||B.S Grade||Remarks||AFNOR Type||NF Number||Ramarks||UNI Type||UNI Number||Ramarks|
|P1||K11522||SPA 12 / STPA 12||D 3573 / G 3458||-16||16 Mo 5||1.5423||(3a)||-3||TU 15 D 3||A49-213||16 Mo 5||5462|
|P5||K41545||SPA 25 / STPA 25||D 3573 / G 3458||-16||12 CrMo 19 5||1.7362||WBL-590(3b)||3604||FHS 625||CAT.2||TU Z12 CD 5-05||A49-213||Dalmine234(3b)|
|P9||S50400||SPA 26 / STPA 26||D 3573 / G 3458||-16||-3||HFS 629-470||CAT.2||TU Z 10 CD 9||A49-213|
|P11||K11597||SPA 23 / STPA 23||D 3573 / G 3458||-16||13 CrMo 44||17175||1.7335||-8||3604||HFS 621||CAT.2||TU 10 CD 5.05||A49-213||Dalmine227(3b)|
|P12||K44562||SPA 22 / STPA 22||D 3573 / G 3458||-16||13 CrMo 44||17175||1.7335||3604||HFS 620-440||CAT.2||-3||14 CrMo 3||5462||(3b)|
|P22||K21590||SPA 24 / STPA 24||D 3573 / G 3458||-16||10 CrMo 9 10||17175||1.738||3604||HFS 622||CAT.2||TTU 10 CD 9.10||A49-213||12 Cr Mo 9 10||5462||(3b)|
Why ASTM A335 Seamless Steel Pipe is Popular in High Temperature Application?
ASTM A335 Seamless Steel Pipe is generally named chrome moly pipe for the chemical elements- Molybdenum and Chromium. Molybdenum improves steel performances as steel strength, elastic limit, wear resistance, impact and hardenability. While Element Moly increases steel pipe resistance to softening, restrains grain growth and slows down the steel structure embrittlement speed. Through experiment and production test, moly is by now the most effective additive which can increase high temperature creep strength. Seamless Steel pipe with moly added also shows enhanced corrosion resistance and inhibits pitting.
Chromium (or chrome) is one essential element in stainless steel production. Steel product is defined as stainless steel for 12% or more Chrome added. For its outstanding heat resistant feature, chrome is widely used and is irreplaceable in resisting oxidation at elevated temperatures applications. In addition, chrome element raises the steel tensile, yield, and hardness at room temperatures. This is why ASTM A335-chrome moly alloy seamless steel pipe is mostly used for in power plants, refineries, chemical plants, and oil field platforms where fluids and gases are at extremely high temperatures and pressures while transportation.