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Seamless Steel Pipe – ASTM A335 P22 Alloy & A106 Carbon

Hot-rolled and cold-drawn seamless steel pipe for boilers, power plants, refineries, oil & gas lines and mechanical parts. We supply ASTM A335 P22 chrome-moly alloy pipe alongside carbon grades A106 Gr.B, A53 Gr.B and API 5L Gr.B.

ProductSeamless steel pipe – alloy & carbon
Alloy gradesASTM A335 P5, P9, P11, P22, P91
Carbon gradesASTM A106 Gr.B, A53 Gr.B, API 5L Gr.B / X42 / X52, GB/T 8163 20#, Q345B
Outside diameter8 – 610 mm
Wall thickness0.6 – 20 mm+ (SCH10 – XXS)
ProcessHot rolled / cold drawn
Heat treatmentNormalized & tempered / annealed (alloy)
EndsPlain, bevelled
SurfaceVarnish, black paint, anti-rust oil, 3LPE, galvanized
CertificatesEN 10204 3.1 MTC; API, ISO; third-party inspection on request
MOQ1 ton
Trade termsFOB, CFR, CIF, EXW
Payment30% T/T deposit, 70% balance before shipment / against B/L copy

What is ASTM A335 P22?

ASTM A335 covers seamless ferritic alloy steel pipe for high-temperature service. Grade P22 is a 2¼Cr–1Mo steel. The chromium improves oxidation resistance and the molybdenum keeps creep strength at elevated temperatures, which makes P22 a standard choice for steam headers, superheater and reheater piping, and hot hydrogen service in refineries.

A335 P22 chemistry%
Carbon (C)0.05 – 0.15
Manganese (Mn)0.30 – 0.60
Chromium (Cr)1.90 – 2.60
Molybdenum (Mo)0.87 – 1.13
Silicon (Si)≤ 0.50
Phosphorus / Sulphur (P / S)≤ 0.025 / ≤ 0.025

Mechanical properties: tensile strength ≥ 415 MPa, yield strength ≥ 205 MPa. Pipes are delivered normalized and tempered (or annealed), as the standard requires.

Related alloy grades

  • P11 (1¼Cr–½Mo): lower-temperature steam lines; less expensive than P22.
  • P5 (5Cr–½Mo): refinery furnace tubes and sour, high-temperature service.
  • P91 (9Cr–1Mo–V): modern supercritical power plants. It allows thinner walls at higher temperatures but needs strict welding and heat-treatment control.

Carbon seamless pipe

For water, oil, gas and structural use at normal temperatures, carbon seamless pipe is the economical choice:

  • ASTM A106 Gr.B: high-temperature carbon pipe for process plants.
  • ASTM A53 Gr.B (Type S): general pressure piping; black or galvanized.
  • API 5L Gr.B / X42 / X52 (PSL1): line pipe for oil, gas and water transmission.
  • GB/T 8163 / 8162: 20#, Q345B (16Mn) for fluid and structural use.

Sizes, schedules and ends

Outside diameter from 8 mm to 610 mm; wall thickness from 0.6 mm (cold drawn) up to 20 mm and above, to SCH10, SCH40, STD, SCH80, SCH160 and XXS. Ends can be plain or bevelled (30°), and pipes are delivered in random lengths of 5.8–12 m or cut to length. Surfaces can be varnished, black painted, 3LPE coated or galvanized.

Inspection and documents

Every heat is supplied with a mill test certificate to EN 10204 3.1, covering chemical analysis, tensile, flattening and flaring tests, and hydrostatic or eddy-current testing. For power and refinery projects we can arrange third-party witness inspection (SGS, BV, TÜV) and PMI testing of alloy pipes before shipment.

Frequently asked questions

What is the difference between A335 P11 and P22?

P22 contains about 2.25% chromium and 1% molybdenum, while P11 has about 1.25% Cr and 0.5% Mo. P22 keeps its strength at higher temperatures and is used for hotter steam lines; P11 is cheaper and fine for moderate temperatures.

Can A106 Gr.B replace A53 Gr.B?

A106 Gr.B seamless pipe usually meets A53 Gr.B requirements, and many mills certify pipe to both standards. The reverse is not true: A53 pipe cannot be used where A106 is specified for high-temperature service.

Do you do PMI testing on alloy pipe?

Yes. Positive material identification can be carried out on every alloy pipe before shipment, and third-party witnesses can attend.

What is the minimum order for seamless pipe?

1 ton per size for stocked carbon sizes. Alloy grades and non-stock sizes are produced to order; ask us for the current MOQ and lead time.

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