Technical Insights

API 11P covers the packaged, high-speed end of reciprocating compression for oil and gas production: a balanced-opposed machine, its driver, coolers, piping, pressure vessels and auxiliaries on one fabricated base — with responsibilities divided among makers, packager and purchaser.

The reciprocating compressor standard's first revision since 2007 removed the empirical design route entirely — from the sixth edition on, there is no compliance path that skips the acoustic study — and its companion document was upgraded from recommended practice to standard.

Industrial heat pumps already deliver 150 °C steam where 100 °C waste heat is available — but between 150 and 200 °C the IEA's own technology table reads "special refrigerants and compressors, early prototype." The ceiling is a compressor problem.

The performance test code for axial and centrifugal compressors got its first major revision since 1997 — ideal-gas assumptions out, real-gas relationships in, and a new way to compute the number that decides whether the machine passes.

Chlorine compressors answer to water, not pressure: below 100 ppm of moisture, steel survives and a liquid-ring machine running on sulfuric acid does the work; above it, the whole train goes titanium.

Two non-mechanical routes to 90 MPa hydrogen have public track records now: Linde's ionic-liquid compressor reports 2.7 kWh per kilogram in station service, and electrochemical compression holds a 1,000-bar single-stage laboratory record — both aiming at the seal and wear problems of the mechanical incumbent.

ISO's hydrogen refuelling station family is being rebuilt piece by piece — the general requirements document entered revision in January 2026, a first-ever part on high-pressure liquid-hydrogen pumps is in committee draft, and five sibling parts have landed since 2024.

The owner community's procurement overlay for packaged integrally geared air compressors moved to version 2.01 in January 2026 — a four-document system that sits on top of API 672 and decides, item by item, what a purchase file must contain.

API published its first recommended practice for carbon dioxide pipelines in December 2025 — covering supercritical, liquid and gas phases, ductile-fracture control and repurposing of existing lines — and its pressure logic reaches back to the compression train that feeds the pipe.

The compressor between green hydrogen and ammonia synthesis is specified for five years of continuous running and a twenty-year design life — while the plant it serves is fed by wind and sun.

On a platform in the South China Sea the injection route was taken from three compression stages to four, and the reason is the weather rather than the reservoir.

A leached cavity 1,418 m underground holds 1.5 million standard cubic metres of hydrogen, and the machine that fills it is specified at 15 MPa by the rock, not by the customer.

A CO₂ compressor's discharge pressure is not a catalogue choice. It is set by where the gas has to arrive and what phase it must be in when it gets there.

The compressor in a compressed-air store is not a process compressor with a bigger motor. Its discharge pressure is set by a cavern a kilometre underground, and its operating hours are decided by the grid.

An electrolyser delivers hydrogen at a couple of megapascals. Storage, pipelines, furnaces and dispensers need more. The machine in between is chosen by the inlet pressure, not the discharge pressure.

Hydrogen compression is not one problem but five, stacked by pressure. Two of those rungs moved in the last two years: a seal that takes oil and barrier gas out of the machine, and a domestic push past 90 MPa.

The old standard asked when the packing was last replaced. The new one asks what the vent is flowing, in standard cubic feet per minute, measured.

Carbon dioxide stops behaving like a gas at 31 °C and 7.38 MPa. A capture plant has to compress it across that point, and the machine that does it had to be built before it could be bought.

Pressure ratio sets how many stages a duty needs — but it is the temperature at the end of each stage that puts the ceiling on the ratio.

In this category the machine does not choose the duty. The gas composition, the contaminants and the swing in flow do.

In the station reliability data the compressor carries more downtime and more maintenance events than any other component, and the failures concentrate on one part.

Six machine families, one decision order. The column most tables omit is the one that decides the cost.

Above 400 bar only one family remains in our data. Below it, the choice is flow — not pressure.

The gas comes first, the pressure second. Reverse that order and the shortlist is wrong before you start.