The Ultimate Guide to Identify Hydraulic Fittings You Required

The Ultimate Guide to Identify Hydraulic Fittings You Required

Sinopulse Group specializes in fabricating all kinds of rubber hydraulic hoses, supplying a wide range of hydraulic fittings applicable to almost all machinery requiring hydraulic fluid conveying systems. But you may wonder there are a variety of types and dimensions of hydraulic hose fittings in the different regional hydraulic markets, for instance, European markets have their own standards thus American markets prefer to another, moreover, each country has its own traditional usage in thread type, seal type, how can you match them according to client’s requirement, in this article, I will elaborate the details to identify hydraulic fittings you need, and eventually offer you a simple sequence of Number which represent you want. Let’s dive into it.

what are hydraulic fittings made of?

Carbon steel fittings with zinc-plated surfaces are the most popular ones in our stock house, most clients prefer to buy these fittings because of their anti-corrosion, durability, and low-price features, they can meet over 80% of requirements. Anti-salt fog test can witness their durability in some corrosive conditions.

Stainless steel hydraulic fittings have higher corrosion resistance and endure higher pressure, and can be used in some extremely high or low temperatures. But, their price is approximately 10 times steel fittings.

The five dimensions to identify hydraulic fittings

We divide a normal hydraulic fitting into three sections, Head part, Body Part, and Tail part, please refer to the image below:

hydraulic fitting diagram
Hydraulic Fitting Diagram

Our search form on the hydraulic fitting page offers a simple method to help you identify the right one you want to order:

identify hydraulic fittings
In the query form, you should determine each param one by on in sequence.

Tail type

On the tail part, we connect the hydraulic fitting and the end of the hydraulic hose into a tight integration by the methods of crimping the hydraulic ferrule out of the hydraulic hose with a fitting nipple supported inside the hose.

On the hydraulic ferrule, several ring teeth tightly bite the out layer of the hose when they are crimped and pressed on with a hose crimping machine, so, when they are put into use, they can endure a high-pressure pulse.

swaged hydraulic fittings

On the hydraulic fittings nipple, common hydraulic fittings have several ring pagoda shape barbs in order to increase the friction preventing them from dropping out. Here, We name it swaged hydraulic fitting

In some high-pressure occasions, It is not enough to bite the outer layer of the hydraulic hose, we need to peel the inner layer of the hose and introduce interlock hydraulic fitting to cooperate to fasten the hose end with the outer ferrule.

on the interlock fittings, there are Several circular bulges, that have the same functions as the ferrule, and they can supply more friction than the common ring pagoda barbs, So, we call it to interlock hydraulic fitting.

interlock hydraulic fittings
reusable hydraulic fittings

In some other scenarios, we need to replace the worn ones with reusable fittings temporarily for example on-field use, we don’t have hose-making machines, so we can use reusable fittings with a wrench. it is handy but not for permanent use.

Thread type:

In many world regions, especially in developed countries, the industry started early and then formed its own standard system. The main thread types are involved British standards, German Standards, American Standards, and Japanese Standards.

Region ScopeThread Abbr.CompleteNameThread StandardDescription
BritishBSPTBritish Standard Pipe Tapered--British Thread Type
Also adopted by Japanese, used in some Japan made engineering machine.
BSPPBritish Standard Pipe Parallel--BSPPBritish Standards Parallel Pipe Thread.
JIS also adopted this Standard
Germmany (EU)MetricDeutsche Industrial NormeMetricDIN is the German Industrial Standards, they are widely used in German or other European market.
North AmericaJICJoint Industrial CouncilSAE J514The thread was defined by the SAE J514, JIC 37° flare fitting features in flared nose of the fitting and flared tube face in the female connection with metal to metal interface.
NPTNational Pipe TaperedNPTFTapered inner diameter
Tapered outer diameter
NPSMNational Pipe Straight MechanicalNPSM__
SAESociety of Automotive EngineersSAE J512It originate from Society of Automotive Engineers, a very reliable and resuable thread type.
ORFSO-Ring Face SealSAE J1453ORFS is the abbreviations of O-Ring Flat Seal, The thread complies with SAE J1453 Standard.
ORFS connections are commonly manufactured in carbon, nickel plated carbon & Stainless steel and typically use Buna-N or Viton, 90 Durometer O-rings that seat into a groove in the face of the fitting.
4-Bolt Flange--SAE J518 and ISO 6162Connected with flange, with 4 bolt to fix , suitable for both normal duty or heavy duty.
Japan (East Asia)JISJapanese Industrial StandardBSPPLargely used in Japanese or Korean made engineer equipment, They usually have BSP thread.

Through the table above, you can learn the abbreviations of the main thread types in the global, and their location and features.

If you want to replace your old one, you must know how to determine the thread dimension, once you’ve done that, you can look up your dimension in the table below and determine its thread type.

No. Size(Thread Size or O.D.) x (of Threads Per Inch)
NOTE: The dash of metric thread accords with the O.D. of thread.

As long as you carefully study the dimension of your thread in addition to the supported information of the old one, it is not difficult to determine which thread you will choose, once you’ve done it, let’s go to the next step.

Connection Port Type:


male connection means that the thread is located on the outer surface of the fitting, normally it can’t be rotated when being fixed, but especially some outer thread is located on the swivel nut. it increases the convenience of being mounted.

Female :

The thread is located on the inner surface of the swivel nut.


Flange connections consist of a flange plate, a couple of flange clamps, and 4 bolts, an annular groove containing an elastic rubber washer on the flange plate is used to seal the interface.

Elbow Angle:

Elbow angle means the bending angle between the fitting head and the fitting tail, commonly types cover straight (0°), 30°, 45°, 60°, and 90°.

Seals type:

The seal type is the most difficult part to understand in the five dimensions, we didn’t make it an option in the query form, but in the query result, all involved seal types are presented based on your defined parameter.

Although there might be hundreds of hydraulic fittings, they all boil down to three basic types of seals type: metal seal, soft seal, and tapered thread seal. the next table elaborates on them in detail.

Seals TypeInstanceImageDescription
Tapered Thread SealNPTThe male thread mates with the female thread and a seal is formed when the two are crushed together i.e. threads deformation.

Teflon and pipe dope are used if needed.

The NPT and BSPT are not interchangeable because of the difference of their thread.
Metal to Metal SealJIC 37° Flare (SAE J514)Both the JIC male and female have straight thread specified in SAE J514 Standards, The two halves have 37° flare (seat).

when they are threaded, a mechanical surface will be formed against leakage.
SAE 45° Flare (SAE J512)The SAE 45° Flare connections are commonly used for low pressure applications such as refrigerant lines, fuel lines, and automotive piping systems.

Both the SAE male and female halves have a 45° flare seat.
The seal is formed on the 45° flare seat.

They have the same thread type with JIC 37° Flare.
SAE 45° Inverted Flare (SAE J512)The inverted flare finds many applications in automotive systems. A machined male connector has a 42° seat.A flared male tubing has a 45° seat. The female end of the inverted flare has a 42° seat that provides a sealing surface. Threads engage to form a mechanically strong connection.
NPSM 60° ConeThe thread of male and female connector is straight, the male has a 30° internal chamfer while the female has an inverted 30° seat.

The metal to metal surface will form leak-resistant when the two parts are threaded together.
Metric 60° ConeThe male of the Metric 60° Cone connection has a 60° recessed cone and a straight thread. The female half has a globeseal seat and a straight thread.

The seal takes place between the 60° recessed cone and the tapered nose of the female. The threads of the two halves engage to form a mechanically strong connection.

This connection finds many applications in hydraulic systems.
BSPP 60° ConeThe BSPP male end has a 30° seat. The tapered nose of the female swivel seals on the 30° seat of the male.

Although the male end is similar to the American National Pipe Straight Mechanical (NPSM) male, the two are not interchangeable because their thread pitches are different.
JIS 30° FlareThe male has a 30° seat and a straight thread.The female half has a 30° seat and a straight thread.

This connection is similar to 37° Flare. Its 30° seat and BSPP-like thread dimensions differentiate it from the American 37° Flare.
KOMATSU 30° Flare (JIS METRIC)The Komatsu 30° Flare has parallel metric threads and a 30° seat.

This connection is widely used on Komatsu equipment. The JIS metric connection is similar to the JIS 30° flare, except that the latter has BSPP-like thread dimensions.
Flareless Compression (SAE J514)The male of the flareless tube has a 24° seat and a straight thread. The female half has a compression sleeve and a straight thread.

In addition to the sleeve, a female nut and a tube form part of the female connection. On the male, the seal takes place between the 24° seat and the compression sleeve.

On the female, the seal takes place between the tubing and the compression sleeve. The threads engage to form a mechanically strong connection.
O-Ring SealSAE straight thread o-ring(o-ring boss)The male connector of the O-Ring Boss has an O-ring and a straight thread. The female port has a sealing face, a chamfer, and a straight thread.

The O-ring is compressed into the chamfer to form a seal. The threads of the two halves engage to form a mechanically strong connection. This connection finds many applications in high pressure hydraulic systems.
O-Ring Face Seal(SAE J1453)This O-Ring Face Seal connection offers an impressive leak resistance and it is suitable for applications that are up to 6000 psi.

The male contact has an O-ring and a straight thread. The female contact has a flat surface and a straight thread.

A seal is formed when the O-ring in the face of the male end is compressed onto the machined flat surface female seat. The swivel female nut mechanically holds the connection.
4-Bolt Flange (SAE J518 AND ISO 6162)The Four-Bolt Flange is suitable for connecting 1/2" to 3" hoses and tubings and it is widely used in fluid power systems.

The O-ring seats on the ring groove of the male. The seal takes place between the O-ring on the male and the smooth face of the female port. Four bolts and two clamp halves hold the connection in place.

Final Thoughts

In this article, we talk about how to identify your hydraulic fitting code from the five dimensions in spite of a variety of hydraulic fittings on the market, First, you should determine the tail type, whether they are swaged for permanent use or temporarily reusable use, Second, determine the thread, it is important to match the other hydraulic component completely, and then, you should determine the connection port type and the elbow angle to meet your mounting need, and finally, the result will present all hydraulic fittings aligning with your requirement in different seal types. Bear in mind, comply with the above step, and one by one, you will get the right one. Don’t hesitate, have a try!


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