Pipe coupling and method of joining materials

Details Pipe coupling and method of joining materials Pipe coupling and method of joining materials

1994-06-03

1996-01-16

Nicholson, Eric K.

Pipe joints or couplings

Deformed

Both members

29508, 285382, F16L 1314

Patent

active

054841747

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to thin pipe fittings for joining mutually thin stainless steel pipes and the like and a method of joining piping materials using said pipe fittings.


BACKGROUND ART

As a method of joining mutually thin stainless steel pipes and the like, known is a method, as disclosed in Japanese Patent Publication No. 33449/1984 now Japanese Patent No. 1453790, in which a pipe having been processed to have a reduced diameter at an end portion is inserted into a pipe fitting, and then a circumferential surface of the pipe fitting is allowed to undergo plastic deformation using a compressing tool. However, this method suffers problems that it requires an increased number of processing steps since the end portion of the pipe to be joined must be processed to have a reduced diameter at the job site and that a sectional area of the flow path is slightly reduced at the reduced diameter portion to increase flow resistance consequently.
In Japanese Provisional Patent Publication No. 88939/1980 or Japanese Patent Publication No. 39873/1978, there is disclosed a method in which a pipe is directly inserted to an end of a pipe fitting, and a joint is subjected to deformation using a compressing tool to achieve joining of pipes. However, this method suffers a problem that a circumferential surface of the end portion of the pipe which is brought into contact with a liquid flowing therethrough is in close contact with an internal surface of the pipe fitting to cause a phenomenon of crevice corrosion at this portion where an occluded corrosion cell is formed and the corrosion proceeds, so that the joint may be corroded in a relatively short period if said pipe is of stainless steel.


DISCLOSURE OF THE INVENTION

This invention has been accomplished for a purpose of overcoming these conventional problems and providing pipe fittings which allows secured joining of pipes or pipe fittings (hereinafter simply referred to as piping materials) without applying any diameter reducing process to an end portion of the piping materials to be joined thereby and free from a fear of crevice corrosion and also to provide a method of joining the piping materials using the same.
This invention characteristically employs the pipe fittings having an annular expanded portion and a first enlarged diameter portion both formed at least at one end portion of its main body having a substantially equal diameter to that of the piping materials to be joined, and a second enlarged diameter portion which can define a clearance with a circumferential surfaces of the piping materials to be joined, which is of a size large enough to prevent crevice corrosion.
The method of joining the piping materials according to this invention characteristically comprises: expanded portion; the end of said piping materials reach the second enlarged diameter portion; press the annular expanded portion of the pipe fittings at least at a maximum diameter portion and partially at the first enlarged diameter portion, but not at the second enlarged diameter portion to press the sealing material to achieve sealing between the pipe fittings and the piping materials to be joined; and also joined along the circumference of the first enlarged diameter portion.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 and FIG. 2 are side elevational views, partially in section, showing a joint construction in accordance with features of this invention;
FIG. 3 shows a cross-section of joined piping materials and pipe fittings cut along a plane (a cross-section along the line A--A) at a center of the recessed portions; and
FIG. 4 shows another embodiment of this invention in partially cut away front view.


BEST MODE FOR CARRYING OUT THE INVENTION

This invention will be described below in more detail referring to the illustrated embodiments.
In FIG. 1, the reference numeral (1) show pipes to be joined; and (2) a pipe fitting, both of which are made of thin stainless steel pipes. The pipe fitting (2) has first enlarged diameter portions (4), annular expanded portions (

REFERENCES:
patent: 3596939 (1971-08-01), Gibson
patent: 4880260 (1989-11-01), Gotoh et al.
patent: 5007667 (1991-04-01), Unewisse
An extract of Handbook of Piping, Published by Kagakukogyosha Co., Ltd., Japan, Annex 5, pp. 1232-1234.
An extract of Handbook of Anti-Corrosion Technique, Published by Nikkankogyo Shinbunsha, Japan, Annex 4, pp. 36-41.

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