ASTM A335 PIPE
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 strenght 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.
1.1 This specification2 covers nominal wall and minimum wall seamless ferritic alloy-steel pipe intended for high-temperature service. Pipe ordered to this specification shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. Selection will depend upon design, service conditions, mechanical properties, and high-temperature characteristics.
1.2 Several grades of ferritic steels (see Note 1) are covered. Their compositions are given in Table 1. NOTE 1: Ferritic steels in this specification are defined as low- and intermediate-alloy steels containing up to and including 10 % chromium. (A) New designation established in accordance with Practice E527 and SAE J1086, Practice for Numbering Metals and Alloys (UNS). (B) Grade P 5c shall have a titanium content of not less than 4 times the carbon content and not more than 0.70 %; or a columbium content of 8 to 10 times the carbon content. (C) Alternatively, in lieu of this ratio minimum, the material shall have a minimum hardness of 275 HV in the hardened condition, defined as after austenitizing and cooling to room temperature but prior to tempering. Hardness testing shall be performed at mid-thickness of the product. Hardness test frequency shall be two samples of product per heat treatment lot and the hardness testing results shall be reported on the material test report.
1.3 Supplementary requirements (S1 to S8) of an optional nature are provided. Supplementary requirements S1 through S6 call for additional tests to be made, and when desired, shall be so stated in the order together with the number of such tests required.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order. NOTE 2: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.”
ASTM A335 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 gr. P5 and P9 are more common for application in the petrochemical industry.
|A335 Pipe Grade||
|NPS / DN||Over||Under|
|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|
|NPS / DN||Tolerance, % from Specified|
|1/8 to 2 1/2 [6 to 65] incl., all t/D ratios||20.00%||12.50%|
|Above 2 1/2 , t/D < or = 5%||22.50%||12.50%|
|Above 2 1/2 , t/D > 5%||15.00%||12.50%|
|(t = Specified Wall Thickness; D = Specified Outside Diameter)|
TENSILE / YIELD STRENGHT
|Grade||Tensile Strength, min., psi||Yield Strength, min., psi|
|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|
TESTING REQUIREMENTS A335
- Transverse / logitudinal: 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 minumum has to be tested
- ASTM A335 Gr. P91 shall have a hardness above 250 HB / 265 HV (25 HRC)
- Hydro testing: shall be applied on every lenght of pipe
- Non destructive electric test is optional
MANUFACTURERS OF A335 PIPES
|Jiangu Chengde Steel Tube Co Ltd. Ltd||China|
|Vallourec Tubes||Germany, France, & Brazil|
|Tenaris||Italy, Mexico, & Argentina|