A335 P11 SMLS Pipe

QS Pipe: Zhangzhou A335 P11 SMLS Pipe

ASTM A335 P11 seamless pipe in 1.25Cr-0.5Mo steel for refinery process lines, heater tubes and steam piping at moderate elevated temperature.

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One-Minute Overview

Seamless chrome-moly pipe in ASTM A335 Grade P11 for elevated-temperature process service.
Sizes 1/2 to 24 inch, wall schedules Sch 40 to XXS, cut to length on request.
Hot finished or cold drawn, with plain or bevelled ends and full material certification.
A common choice for refinery piping, heater tubes and moderate steam service.

A335 P11 SMLS pipe sits in the middle of the chrome-moly family: 1.25% chromium and 0.5% molybdenum give it more creep resistance and oxidation tolerance than carbon steel, without the cost and the welding discipline of the heavier grades. Engineers pick P11 for refinery process lines, convection heater tubes, transfer lines and steam piping where the metal temperature stays moderate. The pipe is made seamless to ASTM A335 / ASME SA335, supplied normalized and tempered, and marked with heat number, grade and size so every length can be traced back to its mill test report.

Name: A335 P11 SMLS Pipe
Type: Seamless, hot finished or cold drawn
Size: 1/2-24 Inch
Schedule: Sch 40-XXS
Material: ASTM A335 P11 (1.25Cr-0.5Mo)
Standard: ASTM A335 / ASME SA335
End: Plain End or Bevel End
Feature: Normalized and tempered, traceable heat marking
Sizes, wall thicknesses and schedules are confirmed per inquiry, and a detailed specification sheet is available on request.

Choosing between P11, P22 and carbon steel is mostly a temperature question. Below the creep range, carbon steel does the job; once metal temperatures climb and oxidation starts to eat the wall, P11 earns its place; higher still, P22 or P91 take over. P11 also welds more easily than the heavier chrome grades — preheat and post-weld heat treatment are still part of the procedure, but the window is more forgiving. Send the design temperature, the corrosion allowance and the code, and the grade can be fixed before the first length is cut.

Inspection and handling keep that grade honest. Check the heat number on every length against the mill test report, confirm the wall thickness at both ends, and store the pipe on dunnage with the ends capped so moisture and grit stay out. Bevels should arrive protected and undamaged; a nicked bevel costs more fit-up time than it saves in freight. For lethal or high-pressure services, add the non-destructive examination your code requires — ultrasonic, radiographic or magnetic particle — before fabrication starts.

FAQ

Q1. When is P11 the right grade rather than P22 or carbon steel?

P11 covers the band where carbon steel runs out of oxidation and creep resistance but P22 is more alloy than the job needs. With 1.25% chromium and 0.5% molybdenum, it handles moderate elevated temperature in refinery and heater service, welds more easily than P22, and costs less. If the design keeps metal hot enough for serious creep, move up to P22 or P91.

Q2. Can I weld P11 like carbon steel and skip the paperwork?

Not quite. The weld needs a matching filler, a preheat and usually a post-weld heat treatment, and the paperwork is what proves the heat is really P11. Positive material identification takes minutes on site; sorting out a mixed-up heat after the line is closed in takes a shutdown.

Q3. Will my tubes show up as a mystery pile of steel?

Only if we both fail at our jobs. Each length is marked with heat number, grade, size and schedule, bundled with the mill test report, and capped at the ends. If your project wants a third-party inspection or a specific packing list, tell us with the inquiry and the shipment arrives as a labelled, countable stack.

Q4. What's the minimum I can order?

Standard flange insulation gasket kits start at one set, and standard gaskets, studs, washers and sleeves start at one piece. Kits made to your drawing or for a non-standard bolt pattern are quoted individually, because the minimum really depends on the material and the tooling involved.

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