Typical application:
Widely used with all types of high pressure hydraulic systems in ordnance, industrial marine, machine tool, farm and road machinery, diesel and gasoline engines, material handling, refinery, drilling and refrigerating industries. 

Three-piece design – Body, nut and sleeve.  Fitting Connection fittings have a wedging action of the sleeve when drawn down by nut, which forms a seal between body and sleeve and at the same time, the sleeve is also making a ring cut or “bite” into the tube forming another positive seal. 
Visible Bite – when a fitting connections fitting is disassembled, the extent of the bite at cutting edge of sleeve is completely visible – an important safety feature. 

Performance data:
Vibration – very good vibration resistance while withstanding severe operating conditions.  Rear bevel of sleeve      grips tube, restraining vibration and preventing stresses from concentrating at line of bite.
Leakproof – precision engineer fittings withstand leakage under the most extreme pressure.  Elbows, tees, and crosses are machined from forging or brazed bar stock –straight parts from bar stock. 
Pressure range – perform within recommended ranges suggested by all the tubing manufacturers.
Temperature – ranges are from -65o F to 400o F at maximum operating pressure
Finish – fittings have a zinc plate with a black chromate dip

S.A.E. Standards
A.S.M.E. Standards

Assembly Instructions

1. Cut tube square and burr inside and outside corner (not excessive).
2. Assemble fitting by sliding nut over tubing with open end out.  Slide ferrule just grips the tubing with cutting edge out, the large head end should be inside of the nut. Lubricate the ferrule and the threads on the body and nut with oil or petrolatum. Insert tube into fitting. 
3. Bottom the tube in the fitting, and tighten the nut until the ferrule just grips the tube. With a little experience, the mechanic can determine this point by feel. If the fittings are bench assembled, the gripping action can be determined by rotating the tube by hand as the nut is drawn down. When the tube can no longer be turned by hand, the ferrule has started to grip the tube.
4. After the ferrule grips the tube, tighten the nut one full turn. This may vary slightly with different tubing materials, but for general practice, it is a good rule for the mechanic to follow. 
5. The fittings can now be disassembled for inspection. The bit or cut into the tube can be readily seen since it is on the lead edge of the ferrule. The bite into the tube should show a definite groove where the ferrule cuts into the tube and peels the metal over the lead edge of the ferrule. The rounded or lead edge should show a good seat in the fittings, and the head or shoulder end should be collapsed tight against the tube. The ferrule should have no end movement; however, the ferrule may be rotated on the tube due to spring back of the material. The performance of the fitting is not affected if the ferrule rotates. 

After disassembly of the fitting joint the flarless fitting can be reassembled by assembling the tube and ferrule into the socket of the fitting and threading the nut onto the fitting.
The operation of assembly up to the point at which the ferrule seats itself in the fitting can usually be accomplished by hand or with the use of a small wrench is required, only low torques are necessary to seat the ferrule.
When the ferrule is seated, an increase in the torque will be quite evident. When this point is reached, draw the nut up approximately 1/6 of a turn minimum, but not more than 1/3 of a turn, to complete the tightening operation.