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ASTM Pipe Spec Decoder

Read what an ASTM pipe spec actually means: service, seamless vs welded, chemistry, and mechanicals.

The ASTM number on a pipe tells you its intent before you read a single composition value. A106 is seamless carbon for high-temperature pressure service. A53 is general-service carbon that can be welded. A333 is carbon pipe impact-tested for cold. A312 is austenitic stainless. A335 is chrome-moly for creep service. A790 is duplex stainless. This decoder reads the spec and grade and returns the service description, the manufacturing method, the chemistry, and the mechanical minimums, with the field-truth notes that matter most: A106 and A53 are not interchangeable on procurement even when the strength matches, A333 is bought for its low-temperature toughness, and P91 lives or dies on its post-weld heat treatment. Every value is a starting point; verify against the purchased ASTM specification before you design or buy.

Pro Tip: A106 Grade B and A53 Grade B have nearly identical room-temperature strength, which is exactly why people swap them and get burned. A106 is seamless and qualified for high-temperature pressure service; A53 permits a welded seam and is a general-service spec. The code and the drawing call out one or the other for a reason. Order what is specified, not what looks equivalent on a strength chart.

Get the OD, wall, and weight at any schedule with the

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Calculate the required wall thickness for the pressure with the

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For stainless pipe, look up the base alloy and PREN in the

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ASTM Pipe Spec Decoder
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How It Works

  1. Enter the spec and grade

    Type the designation from the drawing or the mill mark (A106 Gr B, A312 TP316L, A335 P22).

  2. Read the spec breakdown

    The decoder shows the specification intent, the grade, the manufacturing method, and the service in plain language.

  3. Check chemistry and mechanicals

    You get the composition ranges and the minimum tensile and yield strength.

  4. Read the field notes

    Notes cover the A106-vs-A53 distinction, A333 low-temperature toughness, chrome-moly PWHT, and duplex temperature limits.

  5. Verify before you buy

    Chemistry and mechanical values are a starting reference. Confirm against the purchased ASTM specification before design or procurement.

Built For

  • A planner confirming whether an A106 Gr B callout can be filled with A53 Gr B stock (it usually cannot).
  • A welder checking that an A335 P91 joint needs strict PWHT before striking an arc.
  • A buyer sourcing low-temperature pipe and confirming A333 Gr 6 impact testing.
  • A fabricator picking stainless pipe and deciding between TP304, TP316L, and duplex.
  • An inspector cross-checking a mill mark against the spec the drawing requires.

Features & Capabilities

Six specs in one tool

A106, A53, A312, A333, A335, and A790, carbon through duplex.

Service intent first

The decoder leads with what the spec is for, not just the chemistry.

Chemistry and mechanicals

Composition ranges plus minimum tensile and yield for each grade.

Procurement caveats

The A106-vs-A53, A333 low-temp, and P91 PWHT cautions are surfaced for every relevant grade.

Comparison

Spec Type Make Service Note
A106 Gr B Carbon Seamless High-temp pressure 60 ksi tensile; boiler/process
A53 Gr B Carbon Seamless or welded General 60 ksi; not the high-temp spec
A333 Gr 6 Carbon Seamless or welded Low-temp Charpy tested ~ -50 F
A312 TP316L Austenitic SS Seamless or welded Corrosive Mo for chlorides; low carbon
A335 P91 Chrome-moly Seamless High-temp creep 9Cr-1Mo-V; strict PWHT
A790 2205 Duplex SS Seamless or welded Chloride/strength High yield; temp ceiling ~600 F

References

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Frequently Asked Questions

A106 is seamless carbon steel pipe intended for high-temperature pressure service (boilers, refineries, process). A53 is general-service carbon pipe that can be welded or seamless and is used for structural, mechanical, and lower-pressure conveyance. A106 Grade B and A53 Grade B have nearly the same room-temperature mechanicals (60 ksi tensile, 35 ksi yield), but they are different specifications and are not freely interchangeable on a code job.
Verified low-temperature toughness. A333 Grade 6 has essentially the same room-temperature strength and chemistry as A106/A53 Grade B, but it is Charpy V-notch impact tested at low temperature (commonly -50 F). For cold-climate and refrigeration service, that impact testing is the whole point; do not substitute a non-impact-tested carbon pipe.
Grade 91 (9Cr-1Mo-V) is a creep-strength-enhanced ferritic steel that gets its high-temperature strength from a controlled normalize-and-temper and a tightly specified post-weld heat treatment. Weld it like a P22, skip the PWHT, or overshoot the tempering temperature and you destroy the creep strength the alloy was chosen for. Follow the qualified WPS exactly.
Use TP316L (or TP316) whenever chlorides are present, such as marine, brine, or many chemical services. The molybdenum in 316 resists pitting that 304 cannot. Use the L grade for welded corrosive service because the low carbon resists sensitization in the heat-affected zone. For very aggressive chloride service, step to duplex (A790).
A790 covers duplex and super-duplex stainless pipe (such as 2205 and 2507). Duplex has roughly twice the yield strength of 316 and far better resistance to chloride stress-corrosion cracking, which makes it the choice for seawater, brine, and sour service. The trade-off is a temperature ceiling (it loses toughness above about 600 F) and a need to control weld heat input to keep the austenite-ferrite balance.
Disclaimer: Chemistry ranges, mechanical minimums, and service descriptions returned by this decoder are reference values compiled from ASTM specifications and vary by grade, size, and standard edition. These specs (A106, A53, A312, A333, A335, A790) are not freely interchangeable even when strengths match, because procurement, code, and welding requirements differ. Use this tool to understand a spec, not to qualify material; always verify against the current purchased ASTM specification before design, procurement, or fabrication. This tool is for educational and reference purposes only and is not a substitute for the governing ASTM standard or a qualified engineer.

Learn More

Shops & Outbuildings

ASTM Pipe Specs Explained

What A106, A53, A312, A333, A335, and A790 actually mean: seamless vs welded, high-temperature vs low-temperature service, and why A106 and A53 are not interchangeable.

Read Guide →

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