Posted on December 12, 2019

International Thread Types: Japanese Pipe Threads

Japanese Threads

As a leading Japanese equipment manufacturer, all of Komatsu® Limited’s equipment uses Japanese couplings with a 30° seat and metric fine Japanese pipe threads.  Most other Japanese heavy equipment manufacturers use fittings with a 30° seat and BSPP (British Standard Pipe Parallel) threads.  This combination is referred to as JIS (Japanese Industrial Standard).  However, they are not interchangeable with standard British couplings because JIC fittings do not have an inverted flare.

Primary Japanese threads include:

  • Japanese Tapered Pipe Thread
  • Japanese 30° Flare Parallel Threads

Japanese 30° flare male threads will only mate with Japanese 30° flare female because the male and female incorporate straight threads with a 30° seat where the seal is made.

Though both Japanese 30° flare and BSPP have a 30° seat and each conform to JIS B 0202 they are not interchangeable due to the British inverted seat.

And like U.S. manufacturer Caterpillar, Komatsu’s fittings are mostly unique to them.

  • Komatsu Style Flange Fittings, Code 61 or Code 62
  • Komatsu Style 30° Flare Parallel Threads

The Komatsu and Japanese 30° flare parallel connectors are identical except for the threads, so are not compatible.  Komatsu uses metric fine threads conforming to JIS B 0207 and Japanese 30° conform to JIS B 0202.

JIS Tapered Pipe


JIS 30 Flare Parallel

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