ASME PTC 10-2022: The Rulebook for "Does the Machine Meet Its Guarantee" Was Rebuilt After 25 Years

When a compressor's guarantee is on the table, the argument is settled by a test — and the test is settled by a code. For axial and centrifugal compressors that code is ASME PTC 10, and in 2022 it received its first major revision since 1997. Four years on, the industry is still digesting it: the code committee's chair published an overview of the changes, and the 2026 LNG conference in Doha carried a dedicated presentation on what the revision means for testing the big liquefaction machines. This article records what changed, why it matters to anyone who reads a compressor test report, and where the public record stops. It is not a compliance determination.

What does PTC 10 actually govern?

The procedures that turn instrument readings into a verdict on thermodynamic performance.

The code's scope, per ASME's catalogue: test procedures to determine the thermodynamic performance of an axial or centrifugal compressor working on a gas of known or measurable properties under specified conditions — the arrangement and instrumentation, the procedure, and the evaluation and reporting of results. The quantities it defines include the pressure rise, the volume reduction ratio, polytropic work, shaft power, polytropic efficiency, surge point and choke point, corrected as necessary to specified conditions. It does not cover rotor dynamics or mechanical performance.

In plain terms: the number on a test certificate — the polytropic efficiency the machine is guaranteed against — is a computed quantity, and PTC 10 is the computation.

What did the 2022 revision change?

The committee chair's published overview lists fifteen updates; four of them change the computation at its core.

The ideal-gas model is out: the code now uses real-gas relationships, matching the code to the machines it actually tests — high-pressure process and LNG compressors working where ideal-gas assumptions visibly fail. The polytropic process is applied consistently throughout, with new methods for computing polytropic work and polytropic efficiency, and a re-based definition of the process itself — constant polytropic efficiency along the path. The Reynolds-number regime got an updated allowable range and a new correction method for its effect. And uncertainty got a chapter of its own — test uncertainty is now a documented output, not an appendix habit.

Around those, the overview lists further changes: leakage-ratio-based flow corrections, multi-point test requirements to verify performance curves, test-stabilization rules, updated instrument and data-treatment requirements, new methods for test total pressure and temperature, casing heat-transfer updates for power measurement, a non-mandatory appendix for back-to-back compressor arrangements, and the addition of metric units.

What does it mean for a test report's reader?

The same machine can yield a different number under the two codes — and the code named in the contract decides which one is true.

The committee's own framing is that the revision makes the evaluation more accurate and more applicable to current duties; the practical corollary is that efficiency figures computed to the 1997 code and to the 2022 code are not interchangeable. A field-testing paper by two senior practitioners makes the adjacent point plainly: field tests, unlike factory tests, run at whatever conditions the site presents, and the revised code's method for computing polytropic work directly affects data reduction on site as well. For anyone comparing test reports across years or vendors, the first question is no longer "what was the efficiency" but "computed to which code".

Where does the public record stop?

At three places — the code's text is paid, site testing keeps its own constraints, and no article re-computes anyone's machine.

The code's text is a paid document. The fifteen changes are recorded here as listed in the committee chair's published overview and in ASME's public scope; the clauses themselves are in the document.

Site versus factory remains its own problem. The code governs the test as specified; field performance verification operates under site constraints the code does not pretend to remove.

Nothing here re-computes any machine's result. Whether a given test meets its guarantee is determined per contract, per test, against the invoked edition.

What does the trend add up to?

The revision closed a twenty-five-year gap between the machines being tested and the model they were tested against — real gas for real duties, one polytropic frame throughout, and uncertainty as a first-class output. The digestion now visible at conferences is the industry re-basing its numbers: test codes do not change what a compressor does, but they change what its performance is called, and guarantees are written in that language.

What this article does not cover

Note that this article does not reproduce the code's equations or procedures, does not evaluate any test or machine, does not advise which edition a contract should invoke, and gives no prices. It records the public record of a revised test code. It is not a compliance determination.

Where the next constraint sits

The machines the code tests — how the compressor families divide the duty before testing ever starts — is mapped in Diaphragm vs Piston vs Screw Compressors: A Comparison Table.

And a duty where the test conditions are set by the storage cycle itself — compressed-air energy storage — is covered in Compressed-Air Energy Storage: What the Compressor Train Has to Do.

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