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Scope of ASTM A333
This specification covers nominal (average) wall seamless and welded carbon and alloy steel pipe intended for use at low temperatures. Several grades of ferritic steel are included as listed in Table 1. Some product sizes may not be available under this specification because heavier wall thicknesses have an adverse affect on low-temperature impact properties.
Supplementary Requirement S1 of an optional nature is provided. This shall apply only when specified by the purchaser.
The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.
Note 1: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter”, “size”, and “nominal size”.

Strike temperature condition:
CradeThe lowest temperature for strike test
ASTM A333 Grade 1-50-45
ASTM A333 Grade 3-150-100
ASTM A333 Grade 4-150-100
ASTM A333 Grade 6-50-45
ASTM A333 Grade 7-100-75
ASTM A333 Grade 8-320-195
ASTM A333 Grade 9-100-75
ASTM A333 Grade 10-75-60

Mechanical requiremnts of ASTM A333 alloy pipe
StandardGradeTensile Strength (MPa)Yield Point (MPa)Elongation (%)
ASTM A333Grade 1≥380≥205≥35≥25
Grade 3≥450≥240≥30≥20
Grade 4≥415≥240≥30≥16.5
Grade 6≥415≥240≥30≥16.5
Grade 7≥450≥240≥30≥22
Grade 8≥690≥515≥22
Grade 9≥435≥315≥28
Grade 10≥550≥450≥22
Grade 11≥450≥240≥18
Chemical Composition (%) of ASTM A333 steel pipe
StandardGradeChemical Composition (%)
ASTM A333Grade 1≤0.30

Grade 3≤0.190.18-0.370.31-0.64≤0.025≤0.025

Grade 4≤0.120.18-0.370.50-1.05≤0.025≤0.0250.44-1.010.47-0.980.40-0.75

Grade 6≤0.30≥0.100.29-1.06≤0.025≤0.025

Grade 7≤0.190.13-0.32≤0.90≤0.025≤0.025

Grade 8≤0.130.13-0.32≤0.90≤0.025≤0.025

Grade 9≤0.20

Grade 10≤0.200.10-0.351.15-1.50≤0.03≤0.015≤0.15≤0.25≤0.015≤0.50≤0.12≤0.06
Grade 11≤0.10≤0.35≤0.6≤0.025≤0.025≤0.5035.0-37.0

Referenced Documents
  • A370 Test Methods and Definitions for Mechanical Testing of Steel Products
  • A671 Specification for Electric-Fusion-Welded Steel Pipe for Atmospheric and Lower Temperatures
  • A999/A999M Specification for General Requirements for Alloy and Stainless Steel Pipe
  • E23 Test Methods for Notched Bar Impact Testing of Metallic Materials

Heat Treatment Requirements

P5, P9, P11, and P22

GradeHeat Treatment TypeNormalizing Temperature Range F [C]Subcritical Annealing or Tempering
Temperature Range F [C]

P5 (b,c)Full or Isothermal Anneal

Normalize and Temper*****1250 [675]

Subcritical Anneal (P5c only)*****1325 - 1375 [715 - 745]
P9Full or Isothermal Anneal

Normalize and Temper*****1250 [675]
P11Full or Isothermal Anneal

Normalize and Temper*****1200 [650]
P22Full or Isothermal Anneal

Normalize and Temper*****1250 [675]
P91Normalize and Temper1900-1975 [1040 - 1080]1350-1470 [730 - 800]

Quench and Temper1900-1975 [1040 - 1080]1350-1470 [730 - 800]

Chemical Requirements

GradeP-5P-9P-11P-22P-91P-91 shall also include the following:
ElementUNS DesignationK41545S50400K11597K21590K91560
Carbon0.15 max0.15 max0.05 - 0.150.05 - 0.150.08 - 0.12V at 0.18 - 0.25
Manganese0.30 - 0.600.30 - 0.600.30 - 0.600.30 - 0.600.30 - 0.60N at 0.030 - 0.070
Phosphorous, max0.0250.0250.0250.0250.020Ni at 0.40 max
Sulfur, max0.0250.0250.0250.0250.010Al at 0.02 max
Silicon0.50 max0.25 - 1.000.50 - 1.000.50 max0.20 -0.50Cb at 0.06 - 0.10
Chromium4.00 - 6.008.00 - 10.001.00 - 1.501.90 - 2.608.00 - 9.50Ti at 0.01 max
Molybdenum0.45 -0.650.90 - 1.100.44 - 0.650.87 - 1.130.85 - 1.05Zr at 0.01 max

Tensile Requirements


P-5P-9P-11P-22P-91P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC].
Tensile Strength, min., psi



Yield Strength, min., psi



Permissible Variation in Wall Thickness

NPS [DN] DesignatorTolerance, % from Specified

1/8 to 2 1/2 [6 to 65] incl., all t/D ratios
Above 2 1/2 [65], t/D < or = 5%
Above 2 1/2 [65], t/D > 5%
(t = Specified Wall Thickness; D = Specified Outside Diameter)

Elongation Requirements

Calculated Minimum Elongation Values
Elongation in 2 in. or 50 mm, min %
Wall ThicknessP5, P9, P11, P22
5/16 (0.312)83020
9/32 (0.281)7.22819
1/4 (0.250)6.42718
7/32 (0.219)5.626

3/16 (0.188)4.824

5/32 (0.156)422

7/8 (0.125)3.221

3/32 (0.094)2.420

1/18 (0.062)1.618


Permissible Variations in Outside Diameter

Outside Diameter at any point shall not vary from standard specified more than:
NPS [DN] DesignatorOverUnder
1/8 to 1 1/2 [6 to 40], incl.1/64 (0.015)0.401/64 (0.015)0.40
Over 1 1/2 to 4 [40 to 100], incl.1/32 (0.031)0.791/32 (0.031)0.79
Over 4 to 8 [100 to 200], incl.1/16 (0.062)1.591/32 (0.031)0.79
Over 8 to 12 [200 to 300], incl.3/32 (0.093)2.381/32 (0.031)0.79
Over 12 [300]+/- 1% of the specified outside diameter

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].
Hydrostatic TestEach length of pipe shall be Hydro tested, at option of manufacture, nondestructive electric testing can be used.

Required Markings on
Each Length

(On Tags attached to each Bundle in case of Bundled Pipe) Markings will adhere to prescribed specifications in A 999/A999M and be: Rolled, Stamped, or Stenciled (Mfrs. Option)
In addition, markings will include:

Length of pipe
Marking to indicate the test method(s)
YESNOTest Pressure
YESYESTest Pressure/NDE

Schedule Number

Heat Number or Manufacturer's number by which heat can be identified

An Additional Symbol "S" if the pipe conforms to any Supplementary Requirements

S1 - Product Analysis

S2 - Transverse Tension Test

S3 - Flattening Test

S4 - Metal Structure and Etching Tests

S5 - Photomicrographs

S6 - Photomicrographs for Individual Pieces

S7 - Alternative Heat Treatment - Grade P91

Pipe that has been weld repaired shall be marked "WR".

Reference Documents

  • ASTM A999/A 999M Specification for General requirements for Alloy and Stainless Steel Pipe.
  • ASTM E 213 Practice for Ultrasonic Examination of metal Pipe and Tubing
  • ASTM E 309 Practice for Eddy-Current Examination of Steel Tubular Products Using Magnetic Saturation
  • ASTM E 381 Method of Macroetch testing Steel Bars, Billets, Blooms, and Forgings
  • ASTM E 570 Practice for Flux Leakage Examination of Ferromagnetic Steel Tubular Products
  • ASME B26.10M Welded and Seamless Wrought Steel Pipe


Orders for material under this specification should include the following, as required, to describe the desired material adequately:
QuantityFeet, meters, or number of lengths
Name of materialSeamless Alloy Steel Pipe
GradeP5, P9, P11, P22, P91
ManufactureHot-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
LengthSpecific or Random