In an ever-changing world, it is hard to ignore the increasing amount of foreign threaded connections in the hydraulic industry. Whether it is in a port connection, to a hydraulic hose, even lubrication and grease fittings, they seem to be in all areas of a hydraulic application. Understanding foreign threaded connections can be very cumbersome, and confusing! But being able to understand, and more importantly identify foreign threads can make the difference on whether a customer purchases from you again or goes to the competition.
With the increased amount of goods purchased from over-seas manufacturers, it only makes sense that those goods will have foreign threaded connections. Essentially, there are only three countries that still use the Imperial System; The United States of America, Liberia, and Myanmar (formerly known as Burma). So, it’s no wonder why foreign threads are more prevalent than ever in the hydraulic industry. Here is a list of the most common Foreign threads in the Hydraulic Industry.
The two types of British Threads are, Parallel (BSPP) and Tapered (BSPT). British Parallel threads are commonly referred to as a “G” thread, whereas British Tapered threads are referred to as “R” thread. They are measured in Nominal Sizes, and the threads are measured in Threads per Inch.
There are three sealing methods to a BSPP thread. This thread can seal using the BS 5200 60° Cone-Seat, which is like how a NPSM thread will seal, with an external Gasket, or the ISO 1179 O-Ring. These gaskets can include Bonded Seals, O-Ring and Washer combination, and Elastomeric Seals. The O-Ring Only Style is exclusive and will only seal with the correct size O-Ring, like the SAE J514 Straight Thread O-Ring Boss.
The British Tapered threads are only intended to seal on the flanks of the threads, like how a NPT thread seals, and are generally seen on lower pressure, or schedule pipe, applications.
Metric (DIN) Threads
There are also two styles of Metric Threads, Parallel or Tapered. Metric threads are measured, in millimeters, on the outside diameter and pitch of the threads. Generally, there are 3 thread pitches in metric fittings, pertaining to the hydraulic industry; 1.0, 1.5, and 2.0.
Just like the British Parallel threads, Metric Parallel threads can seal in one of three ways. Either, it can seal on the 24° Tube Seat, like an Ermeto® fitting, it can seal with an external gasket, or with the ISO 6149 O-Ring. The external gaskets are alike to the British Parallel style Bonded Seals, O-Ring and Washer combination, and Elastomeric Seals, ignoring the true size of the seal. The ISO 6149 O-Ring Only style is exclusive and will only seal using the correct O-Ring, like the SAE O-Ring Boss style previously explained.
Metric Tapered threads are generally seen in low pressure, and lubrication applications. They are intended to seal on the flanks of the threads, like NPT threads.
Japanese (JIS) Threads
Japanese threads, or JIS, are easy to understand. They are nominally sized, and the threads are measured in Threads per Inch. JIS threads are the exact same size, pitch, and thread count as British threads. The only difference is that JIS has a 30° outward flare, similar to the 37° flare that we see on JIC fittings. There are more Japanese threads that exist in hydraulic systems, but to keep things as “easy” as possible, we will not go over those at this point.
If this isn’t confusing enough, Komatsu threads tie in Metric thread pitch along with the JIS 30° flare. Komatsu threads are only ever used on Komatsu made machinery. Which is why when identifying threads, it never hurts to ask what kind of machine that the thread originates from.
TCH Industries: Hose, Fitting, & Sealing Experts
The highly trained sales staff at TCH Industries has been dealing with foreign threads for over three and a half decades. By partnering with world-class suppliers of fittings and adapters of every type, TCH has developed a top reputation for quality, reliability, exceptional service, and professionalism.
If you wish to receive a quote from TCH Industries for foreign accessories, please complete the easy-to-use online form that requests information about your needs in a simple questionnaire.
Best yet, for easy-to-understand answers from the hose and fitting pros at TCH, the solution is to visit in person the TCH Hose Center at 2307 East Aurora Road, Twinsburg OH, only 25 miles from the heart of Cleveland.