Pipe joints or couplings – With lubrication
Patent
1989-05-23
1990-10-09
Arola, Dave W.
Pipe joints or couplings
With lubrication
285 24, 285286, 285404, F16L 0007
Patent
active
049615980
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a welded pipe joint comprising a sleeve for receiving the end portion of at least one pipe to be joined, said sleeve being, at the respective end thereof, welded to the respective pipe.
Welded joints of this type have been known for a long time, and are still used widely due to their good strength and simple installation.
These pipe joints, however, have a serious drawback; attempts to make the joints sufficiently clean internally have previously been unsuccessful. This is because there is a narrow clearance between the inside of the sleeve and the outside of the pipes and pickling liquid (acid) enters this clearance whereas the neutralizing liquid applied thereafter is not able to flush it off. The remaining acid affects adversely the weld joints in particular. In addition, there is a gap between the end face of the pipe and a respective shoulder formed internally in the sleeve, and this gap gathers impurities both during flushing and regular operation, which impurities eventually come loose and cause serious disturbances.
The object of the present invention is to provide a new welded pipe joint of the type described in the beginning and by means of which the above problems can be solved.
The pipe joint according to the invention is mainly characterized in that in the wall of the sleeve, at the pipe received therein, there is formed a through-going boring for introducing a lubricant, and that a peripheral groove is formed in connection with said boring for distributing the lubricant.
The boring is preferably positioned in the vicinity of the sleeve end and it is threaded, as well as a nipple for the lubricant. The groove may be formed either on the inside of the sleeve or on the outside of the pipe. The latter alternative facilitates correct positioning of the pipe end.
The lubricant, usually oil, forced in prior to the pickling prevents the corrosive pickling acid from entering in between the pipe and the sleeve. Oil impacted during the flushing and regular operation prevents impurities from gathering in the gaps at the end faces of the pipes.
In the following the invention will be described with reference to the the attached drawing.
FIG. 1 is a partial longitudinal section of a first embodiment of a pipe joint according to the invention.
FIG. 2 is a cross-sectional view along the line II--II shown in 1.
FIG. 3 is a partial longitudinal section of a second embodiment of a pipe joint according to the invention.
FIG. 4 is an enlarged longitudinal section of the area A in FIG. 3.
FIGS. 5 and 6 illustrate a preferred method of cutting a pipe, FIG. 6 being a cross-sectional view along the line VI--VI in FIG. 5, for the embodiment of FIG. 3.
In FIGS. 1 and 2, the reference numerals 1 and 2 designate two pipes to be joined. 3 designates a sleeve with a central annular shoulder 4 formed internally therein; 5 and 6 designate weld joints at both ends of the sleeve 3. In a welded pipe joint of this type, there are annular gaps 7 and 8 between the end faces of the pipes 1 and 2 and the shoulder 4, and narrow clearances 9 and 10 between the pipes and the sleeve. The annular gaps 7 and 8 are required in order to permit linear expansion of the pipes 1 and 2 within the sleeve during the welding operation.
When internal cleanness is required, the gaps 7 and 8 as well as the clearances 9 and 10 have caused an insolvable problem. The internal cleaning is carried out by means of a pickling liquid, i.e. acid, whereafter flushing is effected with a neutralizing liquid. The neutralizing liquid is not able to remove the pickling liquid from the clearances 9 and 10 which results in that the weld joints 5 and 6 in particular are gradually corroded internally. In addition the gaps 7 and 8 gather impurities which come loose during the regular operation in more or less large lumps which cause serious disturbances.
The present invention solves the problem by means of lubricant nipples 11, 12 provided in borings formed in the wall of the sleeve 3. Peripheral grooves 15 and 16 are arranged in connectio
REFERENCES:
patent: 1816770 (1931-07-01), Gradl
patent: 2855224 (1958-10-01), Boice
patent: 3600010 (1971-08-01), Downs
patent: 3843170 (1974-10-01), Bagnulo
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