Alloy Steel Seamless Pipe

QS Pipe: Xiamen Alloy Steel Seamless Pipe

Alloy steel seamless pipe in ASTM A335 chrome-moly grades, from P5 and P9 through P11, P22 and P91, for refinery and power piping.

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One-Minute Overview

Seamless alloy steel pipe in chrome-moly grades P5, P9, P11, P22 and P91.
Sizes 1/2 to 24 inch, schedules Sch 40 to XXS, hot finished or cold drawn.
Plain or bevelled ends, with mill test reports traceable to each heat.
Used where temperature, creep or oxidation rules carbon steel out of the line.

Alloy steel seamless pipe covers a family of chrome-moly grades — P5, P9, P11, P22 and P91 among them — each blended for a different corner of the temperature and corrosion map. Chromium buys oxidation resistance, molybdenum adds creep strength, and grades like P91 add vanadium and niobium for the highest duties. Because the pipe is rolled or drawn without a weld seam, the wall is uniform around the circumference and burst and fatigue behaviour stays predictable. Typical users are refineries, petrochemical plants and power stations running hot process lines, heater tubes and steam.

Name: Alloy Steel Seamless Pipe
Type: Seamless, hot finished or cold drawn
Size: 1/2-24 Inch
Schedule: Sch 40-XXS
Material: Chrome-moly grades P5, P9, P11, P22, P91
Standard: ASTM A335 / ASME SA335
End: Plain End or Bevel End
Feature: Alloy grades matched to temperature and creep duty
Sizes, wall thicknesses and schedules are confirmed per inquiry, and a detailed specification sheet is available on request.

The production route shapes the pipe as much as the chemistry does. Hot finished tubes are worked above recrystallisation temperature, so the grain is uniform and the pipe suits larger diameters and heavier walls. Cold drawn pipe starts from a hot finished shell, is drawn through a die at room temperature, and comes out with tighter dimensional tolerance and a smoother bore — useful for heat exchanger tubes and lines where pressure drop matters. Both routes are heat treated before they leave the mill; the certificate will tell you which one you are buying.

Selection starts with the design temperature and the fluid. Wet hydrogen and naphthenic acid service change the corrosion picture and may push you toward a specific grade or a stainless overlay; pure thermal duty is usually solved by climbing the P-grade ladder. Confirm the wall schedule against the pressure class, order the cut lengths your spool drawing needs, and state the non-destructive examination level up front — hydrostatic test is baseline, ultrasonic or radiographic adds cost and certainty. Welding alloy grades takes matching consumables and, for most of the family, preheat and post-weld heat treatment.

FAQ

Q1. How do I choose between P5, P9, P11, P22 and P91?

Match the grade to the design metal temperature and the corrosion environment. P5 and P9 bring more chromium for oxidation and sulphur resistance, P11 covers moderate creep duty, P22 handles hotter steam, and P91 serves the highest pressure and temperature. The fluid chemistry can rule a grade in or out before temperature even enters the discussion.

Q2. Hot finished or cold drawn — does anyone actually care?

You will, if tolerance or bore finish matters. Cold drawn pipe holds tighter dimensions and a smoother inside surface; hot finished pipe suits larger sizes and heavy walls and costs less. Heat exchanger and high-flow lines lean cold drawn; big utility headers usually lean hot finished.

Q3. Is alloy steel one grade, or a family that needs a spreadsheet?

A family with a spreadsheet, honestly. Alloy steel seamless pipe spans several P-grades, each with its own limits. Send the temperature, the fluid and the code, and we narrow the list to one grade instead of quoting you a pile of maybes.

Q4. What payment terms do you accept?

T/T, L/C at sight and other internationally accepted terms. The exact terms are agreed with you before production starts, because the payment schedule has to match the order value, the shipping method and the delivery schedule you need — which is also why we confirm them up front rather than after shipment.

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