About FittingKey

You have a hydraulic or pneumatic fitting in your hand and no part number. FittingKey asks for what calipers and a thread gauge can tell you, narrows the candidates, and shows the port dimensions it matched against. It is written for maintenance fitters, hose shops, buyers and anyone else who has to order the mating part.

Where the numbers come from

The 110 sizes across 10 standards each list the references they were checked against, drawn from a register of 23 documents by 18 publishers, standards bodies and fitting makers among them. That register, along with the figures that could not be confirmed and were left blank, is on sources and known gaps.

The 5 guides sit on top of that table, and each one links out to the size pages it discusses.

Who runs it

One independent developer builds and maintains FittingKey and a handful of other reference sites, ThreadRef, EngiRef, SpanRef and AmpSizer among them. The guides go out under the FittingKey name with no individual byline, and in the structured data their author is the FittingKey organization. No engineering credential is claimed for anyone.

A guide's visible date marks the last time its text changed.

Limits worth knowing

Identification gets you to a standard and a size. It does not certify a part. Pressure ratings belong to a specific component in a specific material, so check the rating and the assembly torque against the maker's data for the exact part before a line is pressurised. FittingKey has no affiliation with SAE International, ISO, ASME, JIS, DIN or any fitting manufacturer, and none of them endorse it.

Contact

Corrections, a size you could not identify, or a source that disagrees with a figure here: [email protected].

Start with the fitting identifier, the size reference or the guides. See also privacy and terms.