Metal fusion bonding – Including means to apply flux or filler to work or applicator – Gaseous flux
Patent
1987-09-16
1989-05-09
Godici, Nicholas P.
Metal fusion bonding
Including means to apply flux or filler to work or applicator
Gaseous flux
219 591, 21913763, 269 481, 269 43, 269 22, B23K 916
Patent
active
048281603
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an apparatus to be used when welding pipes together, which apparatus comprises a bellows structure for shielding the weld joint area by internal contact with the pipe ends on both sides of the weld joint, and means for leading a compressed gas into and out of the bellows structure and for leading a protective gas into and out of the area shielded by the bellows.
It is generally known that the quality of a weld joint, especially at its so-called root, will be better, if the welding area on the root side is arranged in a protective gas, e.g. nitrogen. This implies that the inside of the pipes should be filled with a protective gas when pipe ends are welded together.
The general practice has been to fill the whole pipe line, which can be very long, with a protective gas, the consumption of which thus will be big, causing high costs. For centering the pipe ends and keeping them stationary, separate mechanical devices have been used.
In apparatuses that use a bellows structure, however the consumption of expensive protective gas can be remarkably reduced. Additionally, the pipe ends can be centered and kept stationary, and welding beads can be prevented from adhering to the inner surface of the pipe ends, from where it is difficult to remove them.
The apparatuses with typical bellows structure have, nevertheless, a serious disadvantage. Most bellows materials do not contract very much after releasing the over-pressure in the bellows, and although it is not difficult in itself to pull out the apparatus, the bellows will drag against the strongly heated weld joint which burns the bellows.
When pipes of relatively small diameter are welded together, as the fact often is in hydraulic and similar piping, a further difficult problem appears. The means for feeding a protective gas and compressed air, generally comprising three flexible hoses, often of a so-called semistiff type, will be situated so near each other that it is extremely difficult to carry out a tightening of screw connections. There is simply not enough room for usual tightening tools.
The object of the present invention is primarily to develop further a pipe welding apparatus using a bellows structure so as to eliminate the above-described drawbacks associated with the use of a typical bellows structure.
The object is achieved by means of the apparatus of the invention which is mainly characterized in that both bellows of the bellows structure are provided with radial supports for contact with the inner surface of the pipes, when the apparatus is arranged in its place and removed from there, respectively, and that the bellows are arranged to contract radially in the absence of inner pressure within the radial supports mentioned above.
Preferred embodiments are stated in more detail in the claims 2 to 10, and appear likewise from the following description with reference to enclosed drawing.
FIG. 1 shows an apparatus according to the invention in position for welding.
FIG. 2 shows a part of the bellows structure with the bellows contracted.
FIG. 3 shows the use of the apparatus when a pipe bend is welded.
FIGS. 4 and 5 show an embodiment to be used when welding a flange, with the apparatus loosely inserted and in position for welding, respectively.
FIG. 6 shows an embodiment for welding a flange at a pipe bend.
FIG. 7 is a sectional perspective view of the apparatus according to the FIGS. 4-6, at the flange.
FIGS. 8-12 show a preferred embodiment for connection of the means for compressed air and a protective gas, respectively, with the bellows structure of the apparatus.
FIGS. 13-15 show an alternative embodiment for the same connection.
FIG. 16 shows a cotter pin included in the embodiment according to the FIGS. 8-12.
In FIG. 1, the pipes to be welded together are indicated by numerals 1 and 2, the weld joint is indicated by 3. The numerals 4 and 5 refer to bellows fastened on holders and arranged within the pipe 1 and 2, respectively, on both sides of the weld joint 3, which bellows in an inflated state, according to F
REFERENCES:
patent: 3095844 (1963-07-01), Thielsch
patent: 3194466 (1965-07-01), Davis
patent: 3292254 (1966-12-01), Sloan
patent: 3387761 (1968-06-01), Pickard
patent: 4465220 (1984-08-01), Ledlow et al.
patent: 4529861 (1985-07-01), Blanton
patent: 4685662 (1987-08-01), Vaughn
Godici Nicholas P.
Heinrich Samuel M.
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