BSP, DIN, JIC & O-ring Fittings in UK and European OEM Equipment
The UK and continental European construction equipment market is valued at £5.5 billion and is expected to reach £7.9 billion by 2027, registering a Compound Annual Growth Rate of over 6% during the next five years. As the construction industry grows, so does the hydraulic fitting market.
The most common hydraulic fitting threads styles in much of the world, and particularly in Europe, are BSP and DIN. Each is available with O-ring connections for specific applications. While the JIC fitting is also very popular in Europe, its 37° flare seating surface with straight threads provides optimum metal-to-metal sealing without the need for an O-ring or tapered threads.
While BSPP fittings require a bonded seal ring or O-ring to seal, BSPT and JIC fittings do not due to their tapered threads providing a positive metal-to-metal seal. However, the ORB and Face Seal fittings use O-rings to establish excellent leak-free connections. How and where are these fittings used by heavy equipment OEMs in the UK and Europe?
The five largest UK and European OEMs of construction, agricultural and road equipment are:
- CNH Industrial NV (headquartered in the UK/incorporated in Amsterdam, Netherlands)
- JCB (UK)
- Liebherr Group (Germany-Switzerland)
- Volvo Construction Equipment (Sweden)
- Wirtgen Group (Germany)
It’s no surprise the UK’s JCB primarily uses British Standard Pipe (BSP) fittings in their equipment. Though JCB equipment is popular in the UK, they enjoy sales in 150 countries around the globe. They are widely used in other parts of Europe, plus the U.S., China, India and Brazil, where they have wholly owned manufacturing plants.
German/Swiss OEM Liebherr and Volvo Construction Equipment, based in Sweden, both predominantly use the European metric DIN (Deutsches Institut für Normung) fitting thread style.
These DIN connection styles are the:
- Light Series (DKL/DKOL): DKL “Dicht Kegel Leicht” incorporates a 24° Cone and DKOL has an O-ring seal
- Heavy Series (DKOS): straight thread version of Dicht Kegel has an ozone resistant Nitrile (NBR) O-Ring
Many of the thread sizes in each of these series are the same, yet the Heavy Series tube OD is smaller and has a thicker tube wall, rendering it with a smaller ID. It’s important to note that the light and heavy series are NOT interchangeable due to the different sizes of the tube and sealing cone.
JIC Threads: A U.S. Standard with a European Popularity
Let’s first understand the distinction in applications for Boss O-ring and JIC fittings. SAE O-Ring Boss fittings provide superior leak control and vibration resistance in medium to high pressure applications.
The JIC fitting design specification comes from the American Society of Automotive Engineers (SAE), yet they are the most common American fitting style in Europe. JIC fittings, generally known as the Joint Industry Council SAE JIC 37° flare surface angle with United National Fine straight threads (UNF) give a secure metal to metal seal. JIC fittings provide an excellent sealing capability under high working pressures.
JIC fittings are widely used by Case, a U.S. OEM manufacturer of agricultural machinery owned by CNH Industrial NV, headquartered in the UK.
Depending on the material, such as stainless, JIC fittings are particularly efficient at high pressures of up to 690 bar and temperatures ranging from -254°C to 649°C, in many fluid power and fuel delivery applications in construction and agricultural equipment.
Regardless of the style, fittings with a metal-to-metal sealing surface, (particularly those made of stainless steel,) are typically best for corrosion resistance, high pressures and temperatures. Comparatively, those with O-rings are best for applications experiencing high vibration or shock.
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