SA/A335 P91 pipe is a kind of chrome moly pipes (ASME S/A335, Chrome-Moly) listed in ASTM A335, which has become a standard in the power generation industry and the petrochemical industry, not only because of its tensile strength, corrosion resistance and high-temperature strength, but also because of its cost-effectiveness. Chrome Moly Pipes are popular in P-Grades P5, P9, P11, P22, P91 and P92. The most common use of grades P11, P22 and P91 is in the powder industry and petrochemical plants, Grades P5 and P9 are commonly used in refineries.
Table of Content
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We stock a full range of the following A335 Chrome Moly Pipe grades
SA/A335 P91 Pipes Sizes
1/4” Nominal to 24”O.D. Seamless Alloy Pipe
Wall Thickness – Schedule 40 through XXH
Chrome Moly Pipe Specifications & Grades
SA335 & A335 – Grades P5, P9, P11, P22, P91, P92
A691 1-1/4 Chrome through 9 Chrome (Welded Alternative to A335)
SA/A335 P91 Pipe Specifications
A/SA335
NPS 1/4″ – 24″
Schedules 40 through 160, STD, XH and XXH
SA/A335 P91 Pipe Dimensions
SA/A335 P91 Pipe Weight
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 | |||
| Grade | Heat Treatment Type | Normalizing 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] | |
| P9 | Full or Isothermal Anneal | ||
| Normalize and Temper | ***** | 1250 [675] | |
| P11 | Full or Isothermal Anneal | ||
| Normalize and Temper | ***** | 1200 [650] | |
| P22 | Full or Isothermal Anneal | ||
| Normalize and Temper | ***** | 1250 [675] | |
| P91 | Normalize and Temper | 1900-1975 [1040 – 1080] | 1350-1470 [730 – 800] |
| Quench and Temper | 1900-1975 [1040 – 1080] | 1350-1470 [730 – 800] |
SA/A335 P91 Pipe Chemical Requirements
| Grade | P-5 | P-9 | P-11 | P-22 | P-91 | P-91 shall also include the following: | ||
| Element | UNS Designation | K41545 | S50400 | K11597 | K21590 | K91560 | ||
| Carbon | 0.15 max | 0.15 max | 0.05 – 0.15 | 0.05 – 0.15 | 0.08 – 0.12 | V at 0.18 – 0.25 | ||
| Manganese | 0.30 – 0.60 | 0.30 – 0.60 | 0.30 – 0.60 | 0.30 – 0.60 | 0.30 – 0.60 | N at 0.030 – 0.070 | ||
| Phosphorous, max | 0.025 | 0.025 | 0.025 | 0.025 | 0.020 | Ni at 0.40 max | ||
| Sulfur, max | 0.025 | 0.025 | 0.025 | 0.025 | 0.010 | Al at 0.02 max | ||
| Silicon | 0.50 max | 0.25 – 1.00 | 0.50 – 1.00 | 0.50 max | 0.20 -0.50 | Cb at 0.06 – 0.10 | ||
| Chromium | 4.00 – 6.00 | 8.00 – 10.00 | 1.00 – 1.50 | 1.90 – 2.60 | 8.00 – 9.50 | Ti at 0.01 max | ||
| Molybdenum | 0.45 -0.65 | 0.90 – 1.10 | 0.44 – 0.65 | 0.87 – 1.13 | 0.85 – 1.05 | Zr at 0.01 max | ||
SA/A335 P91 Pipe Mechanical Properties
| Seamless | ||||||||
| P-5 | P-9 | P-11 | P-22 | P-91 | P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC]. | |||
| Tensile Strength, min., psi | ||||||||
| 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 | |||
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 | |||
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. | ||||||||
| The inside diameter of the bend shall be 1 inch [25 mm]. | ||||||||
| Hydrostatic Test | Each length of pipe shall be Hydro tested, at option of manufacture, nondestructive electric testing can be used. | |||||||
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