Flareless Bite Type Fittings

A bite type fitting cuts its own seal into the tube. Drawing the nut up drives a hardened cutting ring along the tapered bore of the body, and its leading edge bites into the tube OD, ploughing up a collar of material ahead of it. That one feature grips against pull-out and seals.

What sells it is what it does not require: the tube needs only a square cut and a deburred end, so runs are built and altered from plain stock with hand tools. DIN 2353, carried forward as ISO 8434-1, splits the range into a light (L) series for moderate pressures and a heavy (S) series for thicker-walled tube. Quality is created at assembly rather than in a factory, and a bad bite is a leak no retightening will close.

Where it's specified

• Tube runs made up on site — cut, deburr, pre-assemble and fit — no flaring or welding gear
• Machinery built to metric practice — matches the tube sizes and port threads of European designs
• Many diameters at one pressure class — L or S selection matches wall thickness to duty
• Repairs to existing DIN plumbing — same-series rings and nuts drop into bodies already fitted

Range and materials. Straights, elbows, tees, bulkheads and male stud ends in BSPP with bonded seal, SAE ORB, NPT or metric threads, plus loose rings and nuts, covering 6 mm to 42 mm tube in L and 6 mm to 38 mm in S. Carbon steel with zinc plating and 316 stainless carry the range.

Ordering notes. Pre-assemble in a setting tool or hardened body, not in the finished fitting, whose softer bore would be scored forming the bite. Match wall thickness to the series and use tube softer than the ring, or the edge skates. Withdraw the ring and check for an even collar of displaced metal before final make-up; that collar, not a torque figure, proves the bite.