A335 Pipe Specifications

A/SA335
NPS 1/4″ – 24″
Schedules 40 through 160, STD, XH and XXH

Scope

This specification covers nominal wall and minimum wall seamless ferritic alloy-steel pipe intended for high-temperature service. ASTM A335 pipe ordered to this specification shall be suitable for fusion welding, bending, flanging (vanstoning), and similar forming operations.


Material & Manufacture

Pipe may be either hot finished or cold drawn with the finishing heat treatment noted below.


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, or
Normalize and Temper*****1250 [675]
Subcritical Anneal (P5c only)*****1325 – 1375 [715 – 745]
P9Full or Isothermal Anneal, or
Normalize and Temper*****1250 [675]
P11Full or Isothermal Anneal, or
Normalize and Temper*****1200 [650]
P22Full or Isothermal Anneal, or
Normalize and Temper*****1250 [675]
P91 (type 1 and 2)Normalize and Temper, or1900-1975 [1040 – 1080]1350-1470 [730 – 800]
Quench and Temper1900-1975 [1040 – 1080]1350-1470 [730 – 800]

Chemical Requirements

GradeP5P9P11P22P91 (type 1)P91 type 1 shall also include the following:P91 (type 2)P91 type 2 shall also include the followingP91 type 2 continued
ElementUNSK41545K90941K11597K21590K91560K91560
Carbon0.15 max0.15 max0.05 – 0.150.05 – 0.150.08 – 0.12V at 0.18 – 0.25Heat: 0.08 – 0.12
Product: 0.07 – 0.13
V (heat) at 0.18 – 0.25
V (product) at 0.16 – 0.27
N / Al ration ≥ 4.0
Manganese0.30 – 0.600.30 – 0.600.30 – 0.600.30 – 0.600.30 – 0.60N at 0.030 – 0.0700.30 – 0.50DN at 0.035 – 0.070DSn at 0.01 maxD
Phosphorous, max0.0250.0250.0250.0250.020Ni at 0.40 max0.20DNi at 0.02 maxDSb at 0.003 maxD
Sulfur, max0.0250.0250.0250.0250.010Al at 0.02 max0.005DAl at 0.02 maxDAs at 0.010 maxD
Silicon0.50 max0.25 – 1.000.50 – 1.000.50 max0.20 -0.50Cb at 0.06 – 0.100.20 – 0.40DCb (heat) at 0.06 – 0.1
Cb (product) at 0.05 – 0.11
B at 0.001 maxD
Chromium4.00 – 6.008.00 – 10.001.00 – 1.501.90 – 2.608.00 – 9.50Ti at 0.01 max8.00 – 9.50DTi at 0.01 maxDW at 0.05 maxD
Molybdenum0.45 -0.650.90 – 1.100.44 – 0.650.87 – 1.130.85 – 1.05Zr at 0.01 maxHeat: 0.85 – 1.05
Product: 0.80 – 1.05
Zr at 0.01 maxDCu at 0.10 maxD
DApplies to both heat and product analyses.

Tensile Requirements

Seamless  
  P5P9P11P22P91 (1, 2)P91 type 1 and 2 shall have a hardness within the range of 190 to 250 [HBW] or 196 to 265 [HV] or 91 HRBW to 25 HRC.
Tensile Strength, min., psi
ksi6060606085
MPa415415415415585
Yield Strength, min., psi
ksi3030303060
MPa205205205205415

Permissible Variation in Wall Thickness

NPS [DN] DesignatorTolerance, % from Specified
OverUnder
1/8 to 2 1/2 [6 to 65] incl., all t/D ratios20.0%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 ThicknessP5, P9, P11, P22 P91 (type 1 and 2)
in.mmLongitudinalTransverse Longitudinal
5/16 (0.312)8302020
9/32 (0.281)7.2281919
1/4 (0.250)6.4271818
7/32 (0.219)5.62617
3/16 (0.188)4.82416
5/32 (0.156)42215
7/8 (0.125)3.22114
3/32 (0.094)2.42013
1/18 (0.062)1.61812

Permissible Variations in Outside Diameter

Outside Diameter at any point shall not vary from standard specified more than:

NPS [DN] DesignatorOverUnder
in.mmin.mm
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

Mechanical Tests Specified

Transverse or Longitudinal Tension Test, Hardness Test, and Flattening 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.
Unless otherwise specified, the flattening test or bend test shall be chosen at the manufacturer’s option.

See our full list of pipe testing services.


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)
HydrostaticNondestructiveMarking
YESNOTest Pressure
NOYESNDE
NONONH
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 (type 1 and 2)

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

Ordering Information

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 (type 1 or 2)
ManufacturerHot-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
End Finish

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