Structure for pipe fittings

An improved structure for a metal pipe fittings. Each passage hole of the body of a pipe fitting, such as an elbow, a tee, a cross etc., is provided with a female thread which a male-threaded ring screws in with tightly to press a metal ring and several gaskets abutting against one another around a pipe to be united. The tight screwing of said male-threaded ring in the female thread forces the gaskets to expand between the pipe and the body of the fitting keeping the pipe and the fitting tightly united.

BACKGROUND OF THE INVENTION 
Commonmetal pipe fittings such as an elbow, a tee, a cross, etc., are 
generally provided with female threads for screwing with male threads at 
the ends of metal pipes. This kind of structure for uniting metal pipes is 
quite inconvenient as pipes often have to be cut to a proper length and 
male threads have to be newly made. This takes time and work, especially 
if the pipes should be brought back to a work place from the site for 
thread cutting. Besides, the thickness of the pipe should become thinner 
and the surface may be broken after the male thread is cut on the pipe, so 
the threaded part may easily be corroded and brlken after a period of use. 
In addition, a metal pipe used for high heated liquid can expand, so an 
aperture can be formed at a pipe fitting letting the liquid in the pipe 
leak out. Above all, a stainless steel pipe is widely used for 
transporting hot water, but is has a rather large rate of expansion, so 
its fittings are liable to break and cause leakage after a long period of 
use. 
SUMMARY OF THE INVENTION 
This invention has been made to improve the structure of pipe fittings for 
quickly uniting metal pipes without the necessity of cutting male threads 
on them with said improved pipe fittings. 
Any pipe fitting with this improved structure is provided with passage 
holes cut with a female thread, the first blocking and the second blocking 
edge abutting against one another. Said female thread is for a 
male-threaded ring to screw in with, the first blocking edge for several 
anti-leak gaskets to stay at and the second blocking edge with the 
smallest diameter to block the end of a pipe to be united when said pipe 
is inserted in the passage hole. Besides, there is a metal ring placed 
between said male-threaded ring and said gaskets for pressing said gaskets 
to expand betwen the pipe and the fitting body keeping both of them 
tightly united when said male-threaded ring is tightly screwded in said 
female thread.

DETAILED DESCRIPTION OF THE INVENTION 
First, a pipe fitting having this improved structure shown in FIGS. 1, 2 
and 3 is the first example in this invention, a tee fitting. Its body 1 
has three passage holes for liquid which are provided separately with 
female thread 11, first blocking edge 12 and second blocking edge 13 
abutting against one another; female thread 11 is located at the most 
outer part with a larger diameter than the two blocking edges 12 and 13 
and the diameter of second blocking edge 13 is shorter than that of first 
blocking edge 12. 
Next, anti-leak gaskets 2 shown in FIG. 1 are made of elastic rubber, and 
their inner diameter can just insert around the outer diameter of a pipe 
5. Metal ring 3, as shown in FIGS. 6 and 7, is to be put before several 
anti-leak gaskets 2, and its flat surface can pushevenly anti-leak gaskets 
2. 
Male-threaded ring 4 shown in FIGS. 4 and 5 is provided with a male thread 
for uniting with any passage hole 11 of body 1, and with notches 41 on the 
flat curcumferential surface for a turning tool to insert in so as to turn 
the ring 4. 
As FIGS. 8 and 9 show, when a metal pipe 5 is to be united with body 1, 
anti-leak gaskets 2, metal ring 3 and male-threaded ring are orderly 
inserted around the outer surface of the pipe; the metal pipe should be 
inserted in the passage hole with its end touching and blocked by second 
blocking edge 13; several anti-leak gaskets 2 should be placed at the 
unthreaded part of the hole ith themost inner flat surface touching and 
blocked by first blocking edge 12; then screwing tightly male-threaded 
ring 4 in female thread 11 of body 1 can press metal ring 3, which in 
order presses anti-leak gaskets 2 to expand toward the inner and the outer 
diameter so that there cam be no aperture for leaking between the pipe and 
the pipe fitting. 
After a pipe fitting has been united with a metal pipe and buried in a 
building, the necessity for dismantling them hardly occurs, so anti-leak 
gaskets 2 never wears out nor let the liquid running in the pipe leak out 
because said gaskets never have to turn around. Besides, male-threaded 
ring 4 never has in turning any contact or frictionwith anti-leak gaskets 
owing to their location at the unthreaded part of the passage hole, which 
can never cause any leakage.