Meaning of the JIC standard for connection fittings

JIC (Joint Industry Council) is a standard for hydraulic fittings developed in 1945 by the Society of Automotive Engineers (SAE) in conjunction with industry associations under SAE J514. Its core feature is the 37° taper seal (compatible with ISO 84342 ferrule fittings), which is used in a wide range of applications such as industrial hydraulics, construction machinery, agricultural equipment and aerospace. Aerospace.

JIC Connection Fittings Model and Size System

JIC fittings are designated by a “number + suffix” which represents 16 times the hose diameter in inches (i.e., “Dash Size”):

Note: Suffix may indicate form (e.g., straight/elbow) or material (e.g., SS = stainless steel).

JIC Connection Fittings Size Chart

Reference: https://en.wikipedia.org/wiki/JIC_fitting

JIC Connection Fittings Core Structural Characteristics

JIC Connecting Fittings Sealing Angle:

37° metal taper (not 45° SAE flange or 30° AN aerial fitting), metal-to-metal sealing by taper extrusion.

JIC Connecting Fittings Material:

Carbon steel: zinc-plated/phosphated surface, economical and universal (suitable for mineral oils).
Stainless steel (304/316): corrosion resistant, food/marine environment
Brass: low pressure, corrosion-resistant occasions

JIC Connection Fittings Pressure Rating

Note: Actual pressures are affected by system design, vibration, and temperature; a safety margin is required.

How to Identify JIC Connection Fittings

Visual inspection:

37° tapered sealing face (as distinguished from SAE 45° or NPT threaded seals)
UN/UNF straight thread (not tapered for NPT)

Marking Identification:

Fitting bodies are often marked with “JIC” or Dash Size (e.g. “8”)
Thread size stamping (e.g. “3/416”)

JIC Connection Fittings Installation Torque Guide

Excessive tightening will result in taper deformation leakage! Reference Values (Dry Mount, Carbon Steel)

Key Tips:
Clean the sealing surface and prohibit the use of sealant!
Stainless steel fittings require 20% more torque (low coefficient of friction)

JIC connection fittings sealing principle

Metal-to-metal wire contact sealing:

When the nut is tightened, it pushes the 37° inner taper and 37° outer taper to extrude, generating plastic deformation at the contact line and forming a high-pressure sealing band.

Advantages: high temperature resistance, impact resistance, long life.

Disadvantages: sensitive to scratches, requires precise machining.

Adaptation options for different forms of JIC connection fittings

Adaptation to other standards:

JIC to NPT: tapered threads require sealant (not an ideal solution)  
JIC to SAE: 45 ° plane sealing need to add O-ring (SAE straight thread)  
JIC to BSPP: G thread through the transition connector to match

Common Problems and Solutions in Different Situations of JIC Connection Accessories

JIC Connection Accessories Selection and Maintenance Recommendations

System compatibility: ensure that the sealing surface angle is the same (do not mix 37 ° and 45 °)
Corrosive environment: prefer 316 stainless steel
Periodic Inspection: Check torque every 500 hours in a vibrating environment.
Leak Response: Use JIC Seal Repair Kits (temporary filling of taper scratches).

SAFETY WARNING: Relieve pressure from hydraulic system before operating! Incorrect installation may result in injury from high pressure oil injection.

Conclusion:

With their reliable metal seals and standardized design, JIC connection fittings have become the universal language of hydraulic systems worldwide. A proper understanding of their technical details is the key to guaranteeing leak-free system operation.

For model specific torque tables or dimensional drawings, provide them to our technical engineers who will answer your queries free of charge.