ALLOY STEEL PIPES ASTM A335 PIPE


A335 alloy pipes are widely used in the power generation industry due to their superior mechanical and chemical properties compared to standard carbon steel pipes. A335 pipes are available in multiple grades, from P1 to P5, P9, and P91, which differ by chrome and moly content. P9 and P91 alloy pipes are the most common grades and have a price per ton 3/4 times higher than standard carbon steel pipes.


APPLICATION OF CHROME-MOLY PIPES A335

ASTM A335 P91 alloy steel pipes

The ASTM A335 specification covers chrome moly seamless pipes for the power generation and petrochemical industries. A335 pipes offer remarkable resistance to corrosion, good tensile strength, and resistance at high-temperature service. They are commonly found in power plants, where these features are mandatory requirements.

ASTM A335 (source: ASTM)

This specification covers seamless ferritic alloy-steel pipe for high-temperature service. The pipe shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. Grade P2 and P12 steel pipes shall be made by coarse-grain melting practice. The steel material shall conform to chemical composition, tensile property, and hardness requirements. Each length of pipe shall be subjected to the hydrostatic test. Also, each pipe shall be examined by a non-destructive examination method in accordance to the required practices. The range of pipe sizes that may be examined by each method shall be subjected to the limitations in the scope of the respective practices. The different mechanical test requirements for pipes, namely, transverse or longitudinal tension test, flattening test, and hardness or bend test are presented. This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

 


ASTM A335 PIPES CHEMICAL COMPOSITION (GR. P1 TO P92)

ASTM A335 alloy pipes are available in multiple grades, from P1 to P92 (and beyond). Grades P11/P22 and P91/92 are typically found in power stations, whereas A335 grade P5 and P9 are more common for application in the petrochemical industry.

A335 Alloy Pipe
Grade

UNS

equiv.

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

 


ASTM A335 PIPES TOLERANCES

DIAMETER TOLERANCE CHROME MOLY PIPES A335

NPS / DN Over   Under  
  in. mm in. mm
1/8 to 1 1/2 / DN 6 to 40 1/64 (0.015) 0.4 1/64 (0.015) 0.4
Over 1 1/2 to 4 / DN 40 to 100 1/32 (0.031) 0.79 1/32 (0.031) 0.79
Over 4 to 8 / DN 100 to 200 1/16 (0.062) 1.59 1/32 (0.031) 0.79
Over 8 to 12 / DN 200 to 300 3/32 (0.093) 2.38 1/32 (0.031) 0.79
Over 12 / > DN 300 +/- 1% of the specified outside diameter

WALL THICKNESS TOLERANCE ASTM A335 ALLOY PIPES

NPS / DN 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 PIPES MECHANICAL PROPERTIES

Grade Tensile Strength, min., psi Yield Strength, min., psi  
  ksi MPa ksi MPa
ASTM A335 Gr. P5 60 415 30 205
ASTM A335 Gr. P9 60 415 30 205
ASTM A335 Gr. P11 60 415 30 205
ASTM A335 Gr. P22 60 415 30 205
ASTM A335 Gr. P91 85 585 60 415

 


 

ASTM A335 PIPES TEST REQUIREMENTS

  • Transverse/longitudinal: tension and flattening, hardness, bend tests- for material which has been heat-treated in batch furnaces, these tests shall be made on the 5% of the pipes from each heat lot number. For smaller lots, one pipe at a minimum has to be tested
  • ASTM A335 Gr. P91 shall have a hardness of 250 HB / 265 HV (25 HRC)
  • Hydro testing: shall be applied to every length of pipe
  • The non-destructive electric test is optional

 


MANUFACTURERS OF ALLOY STEEL PIPES SPEC A335

Pipe Mill Country
Jiangu Chengde Steel Tube Co Ltd. Ltd China
Chomutov Czech
Eschweiller(Bentler) Germany
Vallourec Tubes Germany, France, & Brazil
Tenaris Italy, Mexico, & Argentina
Sumitomo Metal Japan
JFE Japan
Productos Tubulares Spain
Tubos Reunidos Spain
Wyman Gordon USA
Michigan Seamless USA
Rockwell Collins USA