45 Degree Flare Fine Thread Half Union

Photo of a 45 Degree Flare Fine Thread Half Union
Fitting Connection Part # 173224
Manufacturer Part # 48FT-68
Price $6.57 / each
Condition/Availability New, In-Stock, Most Items Ship Within 24 hours

Category Union - Brass & Pipe Fittings
Sub-Category Half Union
Sub-Sub-Category Male Pipe Thread - Fine Thread Flare Half Union
Item Description 45 Degree Flare Fine Thread Half Union
O.D. Tube 3/8
Male Pipe 1/2
Material Yellow Brass
Manufacturing Process Extruded

Fine Thread

Coarse versus fine for male pipe threads

Coarse threads are those with larger pitch (fewer threads per axial distance), and fine threads are those with smaller pitch (more threads per axial distance). Coarse threads have a larger threadform relative to screw diameter, whereas fine threads have a smaller threadform relative to screw diameter. This distinction is analogous to that between coarse teeth and fine teeth on a saw or file, or between coarse grit and fine grit on sandpaper.
The common V-thread standards (ISO 261 and Unified Thread Standard) include a coarse pitch and a fine pitch for each major diameter. For example, 1⁄2-13 belongs to the UNC series (Unified National Coarse) and 1⁄2-20 belongs to the UNF series (Unified National Fine).
A common misconception among people not familiar with engineering or machining is that the term coarse implies here lower quality and the term fine implies higher quality. The terms when used in reference to screw thread pitch have nothing to do with the tolerances used (degree of precision) or the amount of craftsmanship, quality, or cost. They simply refer to the size of the threads relative to the screw diameter. Coarse threads can be made accurately, or fine threads inaccurately.



Male National Pipe Thread Taper  (NPT) threads are referred to as MPT ('Male Pipe Thread'), MNPT, or NPT(M) for male (external) threads.  An equivalent designation is MIP (Male iron pipe).  NPT is a U.S. standard for tapered threads used on threaded pipes and fittings. In contrast to straight threads that are found on a bolt, a taper thread will pull tight and therefore make a fluid-tight seal.  Threaded pipes can provide an effective seal for pipes transporting liquids, gases, steam, and hydraulic fluid. These threads are now used in materials other than steel and brass, including PTFE,[2] PVC, nylon, bronze and cast iron.

The taper on NPT threads allows them to form a seal when torqued as the flanks of the threads compress against each other, as opposed to parallel/straight thread fittings or compression fittings in which the threads merely hold the pieces together and do not provide the seal. As the thread body is tapered (0.75 in/ft) a larger diameter keeps compressing into a smaller diameter and finally forms a seal (no clearance remains between the crests and roots of the threads because of the taper). This means that NPT fittings should be burr free and lubricated using a lubricating material like lubricating paste or tape. (The use of tape also helps to limit corrosion on the threads, which otherwise can make future disassembly nearly impossible.)


Copper, brass, aluminum, plastic and welded steel hydraulic tubing that can be flared.

Depends on tubing used. Will stand burst pressure of standard tube – up to 5,000 P.S.I. with bundyweld (double flared) and 3,500 P.S.I. with copper tube depending on size.


Good vibration characteristics depending on tubing used.

Approved by Underwriters’ Laboratories No. AU-1344 for hazardous liquid, fuel equipment.
Meets specifications of the Society of Automotive Engineers (S.A.E.) Tube Fittings Standards. 1/8 inch thru 5/8 inch.

Low cost, availability, reusability. Available in long and short nut styles.

Fuel, oil, air, water lines, LP and natural gas lines, hazardous liquids or gaseous chemical not corrosive to tubing material and brass.