ASTM A335 P11 & P22 Pipes
Giriraj Impex stocks, supplies and exports ASTM A335 P11 pipe and P22 pipe – seamless ferritic alloy steel pipe to ASTM A335 / ASME SA335 grades P11 (1¼Cr-½Mo) and P22 (2¼Cr-1Mo) for high-temperature service. We supply A335 P11 and P22 pipes from approved mills, normalised and tempered, in schedules to ASME B36.10M or specified minimum wall, with IBR certification when the order requires it, and with mill test certificates.
P11 and P22 pipes are used for steam, hydrogen and hot hydrocarbon lines in power plants, refineries and petrochemical plants, where carbon steel would lose strength or suffer high-temperature hydrogen attack.
Specifications
| Item | Details |
|---|---|
| Standard | ASTM A335 / ASME SA335 |
| Grades | P11 (UNS K11597), P22 (UNS K21590); P5, P9, P91 on request |
| Production | Seamless, hot finished or cold drawn |
| Heat treatment | Normalised and tempered (or annealed, as the standard permits) |
| Dimensions | ASME B36.10M schedules, or minimum wall and ID |
| Ends | Plain, bevelled to ASME B16.25 |
| Options | IBR certification, hardness test, PMI, ultrasonic test – on request |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Chemical composition and mechanical properties
P11 and P22 are shown with the other A335 grades.
| Grade | UNS | C | Mn | P | S | Si | Cr | Mo |
|---|---|---|---|---|---|---|---|---|
| P5 | K41545 | 0.15 | 0.30–0.60 | 0.025 | 0.025 | 0.50 | 4.00–6.00 | 0.45–0.65 |
| P9 | S50400 | 0.15 | 0.30–0.60 | 0.025 | 0.025 | 0.25–1.00 | 8.00–10.00 | 0.90–1.10 |
| P11 | K11597 | 0.05–0.15 | 0.30–0.60 | 0.025 | 0.025 | 0.50–1.00 | 1.00–1.50 | 0.44–0.65 |
| P22 | K21590 | 0.05–0.15 | 0.30–0.60 | 0.025 | 0.025 | 0.50 | 1.90–2.60 | 0.87–1.13 |
| P91 | K90901 | 0.08–0.12 | 0.30–0.60 | 0.020 | 0.010 | 0.20–0.50 | 8.00–9.50 | 0.85–1.05 |
P91 also has limits on V, Nb, N, Ni, Al and other elements, as given in the standard.
| Grade | Tensile strength, MPa (ksi) | Yield strength, MPa (ksi) |
|---|---|---|
| P5, P9, P11, P22 | 415 (60) | 205 (30) |
| P91 | 585 (85) | 415 (60) |
Elongation and P91 hardness requirements as given in the standard.
Background on chrome-moly steels is on the alloy steel page.
P11 or P22?
P11 (1¼Cr-½Mo) is used for steam lines, headers and refinery process lines up to around 550 °C, and in moderate hydrogen service. P22 (2¼Cr-1Mo) has higher creep strength and better resistance to high-temperature hydrogen attack, and is used for higher temperatures and hydrogen partial pressures – main steam and reheat lines in older and smaller power plants, and hydroprocessing and reformer lines in refineries. For the highest steam temperatures in modern plants, ASTM A335 P91 pipes are used.
IBR certification
For steam piping in India subject to the Indian Boiler Regulations, P11 and P22 pipes are supplied with IBR certification when the order requires it, with the mill documents and inspection arranged accordingly. Please state the IBR requirement in the enquiry.
Welding and heat treatment
Chrome-moly pipes need qualified welding procedures with preheat, controlled interpass temperature and low-hydrogen consumables of matching composition (for example ER80S-B2 for P11 and ER90S-B3 for P22). Post-weld heat treatment is required by the piping codes above certain thicknesses, to temper the heat-affected zone and relieve stresses. Hardness testing of welds is commonly used to confirm PWHT. Hot bending may require re-heat treatment of the bend.
Positive material identification
P11, P22 and carbon steel pipes look the same, and mixing them up in a hot line can cause failure. Positive material identification of every length is widely specified by refineries and power plants, and can be carried out before dispatch. Every pipe is marked with grade, size, schedule and heat number and supplied with its mill test certificate.
Ordering A335 P11 and P22 pipes
Please give the grade, size, schedule or minimum wall, length, end finish, quantity and any IBR, PMI, hardness, ultrasonic or third-party inspection requirement. Pipes are supplied with end caps and bundled or boxed for transport.
Hydrogen service
At high temperatures and hydrogen partial pressures, hydrogen can react with carbides in carbon steel, causing internal cracking and loss of strength – high-temperature hydrogen attack. Chromium and molybdenum stabilise the carbides, so P11 and P22 are chosen for hot hydrogen lines in hydrotreaters, hydrocrackers and reformers according to the industry operating-limit curves. P22 also suffers temper embrittlement in long service between about 350 °C and 575 °C, so refinery P22 may be ordered with controlled impurity levels.
Applications and related products
A335 P11 and P22 pipes are used for main steam, reheat and header piping, refinery heater and hydroprocessing lines, petrochemical high-temperature lines and boiler components. Matching flanges (A182 F11, F22) and fittings (A234 WP11, WP22) are supplied. Other alloy steel pipes are on the alloy steel pipes and tubes page, and all materials on the seamless pipes and tubes page.
Frequently Asked Questions
ASTM A335 P11 is a seamless 1¼Cr-½Mo alloy steel pipe for high-temperature service.
P22 (2¼Cr-1Mo) has higher creep strength and hydrogen resistance than P11 (1¼Cr-½Mo), and is used at higher temperatures.
Yes. They can be supplied with IBR certification when the order requires it.
Yes, above thicknesses set by the piping code, to temper the heat-affected zone and relieve stresses.
P11, P22 and carbon steel look identical, and PMI prevents mix-ups that could cause failure in hot service.
Matching low-hydrogen consumables such as ER90S-B3 are used for P22.
Request a Quote for ASTM A335 P11 & P22 Pipes
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