Basic diameter - no chart in the register measures this size
The visual tell
What the end of the fitting looks like
Schematic cross-section of the male half, upper side only, with the centre line dashed and the open end on the left. Cone angles are drawn at their true angle from the axis; nothing else is to scale and no dimension should be measured off it. Thread shown: M18 x 1.5.
A deep, narrow cone - noticeably more pointed than a 37 degree flare. Common on Japanese equipment, usually with a loose female swivel nut.
Where it seals: Metal to metal, a 30 degree female seat against a 30 degree male cone.
Dimensions
Thread size, pitch and diameters for M18 x 1.5 Komatsu 30.
Designation
M18 x 1.5 Komatsu 30
Thread
M18 x 1.5
Threads per inch / pitch
1.5 mm pitch
Basic major diameter (male)
18 mm / 0.709 in
Measured across the male crests
Not published - fewer than two identification charts in the source register carry this size
Basic minor diameter (mating female)
16.38 mm / 0.645 in - computed from the 60 degree thread profile, not measured
Thread form
60 degree flank angle, parallel
Seat
30 degree flare cone or seat
How the size is named
Sized by metric thread designation rather than by tube size.
The two charts give different tube sizes for this thread, so none is published here. The thread and the seat are agreed.
Working pressure
No working pressure is published for this connection. Ratings for it vary by manufacturer, body material, port form and seal, and no two independent sources in the register give the same figure under conditions they both state. A generic number here would be a decoration, not a rating. Read the pressure from the catalogue of the fitting you are actually installing.
A fitting with two different ends is only ever as strong as the weaker end, and any rating assumes the fitting is undamaged, correctly assembled and within its temperature range. Pressure ratings are safety-relevant: confirm them against the manufacturer specification before the system is charged.
What it mates with
A female M18 x 1.5 swivel nut with a 30 degree cone seat. The thread is metric, so it will not start on a JIS 30 degree BSPP fitting despite the identical seat.
Mating two different cone angles is the classic way to make a joint that holds pressure on the bench and weeps in service: the two cones touch on a line instead of a face, and tightening harder cold-flows the softer of the two rather than sealing it.
Do not mix these up
Fittings that measure like a M18 x 1.5 Komatsu 30
Every size below sits within 0.9 mm of this one across the male thread crests, which is inside what a worn or plated fitting and a hurried measurement produce together. Those marked same thread will screw together with this fitting.
Fittings in other standards whose male thread diameter is close to M18 x 1.5 Komatsu 30.
No - 0.85 mm apart on diameter, and a different pitch
This list is computed from the published diameters in the database rather than kept as a hand-written list, so a correction to a table can never leave a stale warning behind.
Answers
Common questions about M18 x 1.5 Komatsu 30
What thread is a M18 x 1.5 Komatsu 30 fitting?
M18 x 1.5 Komatsu 30 runs a M18 x 1.5 thread: 1.5 mm pitch, basic major diameter 18 mm / 0.709 in. No two identification charts in the source register measure this size, so no caliper figure is published for it.
How do I tell a M18 x 1.5 Komatsu 30 apart from a fitting that measures the same?
Look at the sealing surface. A deep, narrow cone - noticeably more pointed than a 37 degree flare. Common on Japanese equipment, usually with a loose female swivel nut. Metal to metal, a 30 degree female seat against a 30 degree male cone. The thread is parallel (straight) and the flank angle is 60 degrees.
What does a M18 x 1.5 Komatsu 30 screw into?
A female M18 x 1.5 swivel nut with a 30 degree cone seat. The thread is metric, so it will not start on a JIS 30 degree BSPP fitting despite the identical seat.
What pressure is a M18 x 1.5 Komatsu 30 rated for?
No working pressure is published here for this connection. Ratings vary by manufacturer, body material and seal, and no two independent sources in the register give the same figure under stated conditions for it. Read the rating from the catalogue of the fitting you are installing.
Dimensions are as defined by ISO 261, manufacturer catalogue dimensions. FittingKey is an independent reference and is not affiliated with, endorsed by or approved by any standards body or fitting manufacturer.
Every value on this page was checked against 2 independent published sources:
Which published source supplied each column, and what it gave.
Column
Sources
What they gave
Dash and trade size
gates-idchart, mcgill-id
Two identification guides agree on seven threads. One carries an M14 x 1.5 the other does not, and it is recorded as a gap.
Basic major diameter
gates-idchart, mcgill-id
The basic major diameter is the M number, and both charts print exactly that.
Tube outside diameter
gates-idchart, mcgill-id
The two disagree on the tube diameter for M18 x 1.5 and M22 x 1.5, so no tube size is published for those two threads.
Sources disagree: Komatsu tube diameter at M18 x 1.5 and M22 x 1.5.
9.5 mm and 13.0 mm (gates-idchart)
9 mm and 12 mm (mcgill-id)
One chart appears to be giving the inch tube sizes these threads serve converted to millimetres (3/8 in and 1/2 in), the other the nearest metric tube. No tube size is published for those two threads. The thread and the seat are agreed and are what identifies the fitting.