ASTM A335 Pipe (ASME S/A335, Chorme-Moly) is a seamless ferritic Alloy-Steel Pipe for high temperature service.
Pipe ordered to this specification shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. Sometimes referred to as “P Grade”, chome moly pipe is popular in P-Grades P5, P9, P11, P22, and P91.
General Abbreviations of chrome moly pipe are chrome-moly, cro-moly, CrMo, CRMO, CR-MOLY.
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.
Applications:
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
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Strong resistance to rupturing at high temperatures and high pressures
-
May be used for Hydrogen Sulfide Corrosion Services
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Resistant to cracking from hydrogen attack and embrittlement
-
Resistant to hot sulfide corrosion cracking
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Can be used for NACE Applications where sour environments are under high temp and pressure
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Can be used in NACE-MRO 175 Sour Service
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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:
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Flanges and forged fittings – A/SA 182 F1, F2, F5, F9, F11, F12, F15, F22, F91, F92, F122 Wrought
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Butt-weld Pipe Fittings – A/SA 234 P1, P2, P5, P9, P11, P12, P15, P22, P91, P92, P122
Chemical Composition:
These pipe bear high resistance to rupture at high temperature and pressures. With hydrogen crack resistance and sulfide stress corrosion cracking chrome moly pipe are highly preferred over Carbon pipe.
|
Grade
|
UN
Sequiv.
|
C≤
|
Mn
|
P≤
|
S≤
|
Si≤
|
Cr
|
Mo
|
|
P1
|
K11522
|
0.10~0.20
|
0.30~0.80
|
0.025
|
0.025
|
0.10~0.50
|
–
|
0.44~0.65
|
|
P2
|
K11547
|
0.10~0.20
|
0.30~0.61
|
0.025
|
0.025
|
0.10~0.30
|
0.50~0.81
|
0.44~0.65
|
|
P5
|
K41545
|
0.15
|
0.30~0.60
|
0.025
|
0.025
|
0.5
|
4.00~6.00
|
0.44~0.65
|
|
P5b
|
K51545
|
0.15
|
0.30~0.60
|
0.025
|
0.025
|
1.00~2.00
|
4.00~6.00
|
0.44~0.65
|
|
P5c
|
K41245
|
0.12
|
0.30~0.60
|
0.025
|
0.025
|
0.5
|
4.00~6.00
|
0.44~0.65
|
|
P9
|
S50400
|
0.15
|
0.30~0.60
|
0.025
|
0.025
|
0.50~1.00
|
8.00~10.00
|
0.44~0.65
|
|
P11
|
K11597
|
0.05~0.15
|
0.30~0.61
|
0.025
|
0.025
|
0.50~1.00
|
1.00~1.50
|
0.44~0.65
|
|
P12
|
K11562
|
0.05~0.15
|
0.30~0.60
|
0.025
|
0.025
|
0.5
|
0.80~1.25
|
0.44~0.65
|
|
P15
|
K11578
|
0.05~0.15
|
0.30~0.60
|
0.025
|
0.025
|
1.15~1.65
|
–
|
0.44~0.65
|
|
P21
|
K31545
|
0.05~0.15
|
0.30~0.60
|
0.025
|
0.025
|
0.5
|
2.65~3.35
|
0.80~1.60
|
|
P22
|
K21590
|
0.05~0.15
|
0.30~0.60
|
0.025
|
0.025
|
0.5
|
1.90~2.60
|
0.87~1.13
|
|
P91
|
K91560
|
0.08~0.12
|
0.30~0.60
|
0.02
|
0.01
|
0.20~0.50
|
8.00~9.50
|
0.85~1.05
|
|
P92
|
K92460
|
0.07~0.13
|
0.30~0.60
|
0.02
|
0.01
|
0.5
|
8.50~9.50
|
0.30~0.60
|
Chrome Moly Pipes: Werkstoff vs EN vs ASTM
|
Werkstoff /DIN
|
EN
|
ASTM
|
|
1.5415
|
16Mo3
|
A335 Grade P1
|
|
1.7335
|
13CrMo4-5
|
A335 Grade P11, P12
|
|
1.7380
|
10CrMo9-10
|
A335 Grade P22
|
|
1.7362
|
X11CrMo5
|
A335 Grade P5
|
|
|
|
A335 Grade P9
|
|
1.4903
|
X10CrMoVNb9-1
|
A335 Grade P91
|
Tensile Requirements
|
Tensile Strength, min., psi
|
P-5
|
P-9
|
P-11
|
P-22
|
P-91
|
|
ksi
|
60
|
60
|
60
|
60
|
85
|
|
MPa
|
415
|
415
|
415
|
415
|
585
|
|
Yield Strength, min., psi
|
|
|
|
|
|
|
ksi
|
30
|
30
|
30
|
30
|
60
|
|
MPa
|
205
|
205
|
205
|
205
|
415
|
Note: P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC].
Mechanical Properties
|
Mechanical properties
|
P1,P2
|
P12
|
P23
|
P91
|
P92,P11
|
P122
|
|
Tensile strength
|
380
|
415
|
510
|
585
|
620
|
620
|
|
Yield strength
|
205
|
220
|
400
|
415
|
440
|
400
|
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.
|
Heat Treatment
|
A / N+T
|
N+T / Q+T
|
N+T
|
Material & Manufacture
Pipe may be either hot finished or cold drawn with the finishing heat treatment noted below.
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 [675]
|
|
|
Subcritical Anneal (P5c only)
|
*****
|
1325 – 1375 [715 - 745]
|
|
A335 P9
|
Full or Isothermal Anneal
|
|
|
|
|
Normalize and Temper
|
*****
|
1250 [675]
|
|
A335 P11
|
Full or Isothermal Anneal
|
|
|
|
|
Normalize and Temper
|
*****
|
1200 [650]
|
|
A335 P22
|
Full or Isothermal Anneal
|
|
|
|
|
Normalize and Temper
|
*****
|
1250 [675]
|
|
A335 P91
|
Normalize and Temper
|
1900-1975 [1040 - 1080]
|
1350-1470 [730 - 800]
|
|
|
Quench and Temper
|
1900-1975 [1040 - 1080]
|
1350-1470 [730 - 800]
|
Permissible Variation 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
|
20.0%
|
12.5%
|
|
Above 2 1/2 [65], t/D < or = 5%
|
22.5%
|
12.5%
|
|
Above 2 1/2 [65], t/D > 5%
|
15.0%
|
12.5%
|
|
(t = Specified Wall Thickness; D = Specified Outside Diameter)
|
Elongation Requirements
|
Calculated Minimum Elongation Values
|
|
Elongation in 2 in. or 50 mm, min %
|
|
Wall Thickness
|
P5, P9, P11, P22
|
|
P91
|
|
in.
|
mm
|
Longitudinal
|
Transverse
|
|
Longitudinal
|
|
5/16 (0.312)
|
8
|
30
|
20
|
|
20
|
|
9/32 (0.281)
|
7.2
|
28
|
19
|
|
19
|
|
1/4 (0.250)
|
6.4
|
27
|
18
|
|
18
|
|
7/32 (0.219)
|
5.6
|
26
|
|
|
17
|
|
3/16 (0.188)
|
4.8
|
24
|
|
|
16
|
|
5/32 (0.156)
|
4
|
22
|
|
|
15
|
|
7/8 (0.125)
|
3.2
|
21
|
|
|
14
|
|
3/32 (0.094)
|
2.4
|
20
|
|
|
13
|
|
1/18 (0.062)
|
1.6
|
18
|
|
|
12
|
Permissible Variations in Outside Diameter
Outside Diameter at any point shall not vary from standard specified more than:
|
NPS [DN] Designator
|
Over
|
Under
|
|
|
in.
|
mm
|
in.
|
mm
|
|
1/8 to 1 1/2 [6 to 40], incl.
|
1/64 (0.015)
|
0.40
|
1/64 (0.015)
|
0.40
|
|
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
|
Ordering Information
Orders for material under this specification should include the following, as required, to describe the desired material adequately:
|
Quantity
|
Feet, meters, or number of lengths
|
|
Name of material
|
Seamless Alloy Steel Pipe
|
|
Grade
|
P5, P9, P11, P22, P91
|
|
Manufacturer
|
Hot-finished or cold-drawn
|
|
Size using one of the following:
|
|
NPS and Schedule Number
|
|
Outside Diameter and Nominal Wall Thickness
|
|
Outside Diameter and Minimum Wall Thickness
|
|
Inside Diameter and Nominal Wall Thickness
|
|
Inside Diameter and Minimum Wall Thickness
|
|
Length
|
Specific or Random
|
|
End Finish
|
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.
Hydrostatic Test
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.
Referenced Documents
-
A999/A999M Specification for General Requirements for Alloy and Stainless Steel Pipe
-
E213 Practice for Ultrasonic Examination of Metal Pipe and Tubing
-
E309 Practice for Eddy-Current Examination of Steel Tubular Products Using Magnetic Saturation
-
E381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings
-
E527 Practice for Numbering Metals and Alloys in the Unified Numbering System (UNS)
-
E570 Practice for Flux Leakage Examination of Ferromagnetic Steel Tubular Products
-
B36.10M Welded and Seamless Wrought Steel Pipe
-
SAE J 1086 Practice for Numbering Metals and Alloys (UNS)
-
SNT-TC-1A Recommended Practice for Nondestructive Personnel Qualification and Certification
