US5234148A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of welding and a system therefor
Assignee: Nuclear Decommissioning Authority
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Filing: 1992-07-28
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Granted: 1993-08-10
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Expires: 2012-07-28
Abstract
Abstract A method of welding in which an inert gaseous shield at a welding zone is provided by a mixture of gases of different densities. The proportions of the individual gases in the mixture are controlled to ensure that the density of the gas mixture is about the same as the density of the surrounding atmospheric air. Cryogenic means may be used to form a condensed gas plug in a pipe or the like to be welded.
Inventors
- 👤 Philip L. Stone
- 👤 David H. Hoskyn
- 👤 Bruce R. Keesing
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:55
CPC Classifications
B; B23; B23K; B23K9/00; B23K9/16; B23K9/164; G; G05; G05D; G05D11/00; G05D11/02; G05D11/035; G05D11/06; Y; Y10; Y10T; Y10T137/00; Y10T137/0318; Y10T137/0391; Y10T137/2496; Y10T137/2499
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
122 words
A system for producing a gas mixture for use in welding and having a density substantially equal to the density of the atmospheric air at a zone,.the system comprising: means for mixing at least two inert gases from a supply of the gases, one said gas being lighter than air and the other said gas being heavier than air; means for comparing the density of the gas mixture with the density of the atmospheric air about the system, and means for varying the proportions of the gases in the gas mixture in response to any imbalance in the densities detected by the comparing means so as to equalise the density of the gas mixture with the density of the said atmospheric air.
Claim 2
Independent Claim
122 words
A system for producing a gas mixture for use in welding and having a density substantially equal to the density of the atmospheric air at a zone,.the system comprising: means for mixing at least two inert gases from a supply of the gases, one said gas being lighter than air and the other said gas being heavier than air; means for comparing the density of the gas mixture with the density of the atmospheric air about the system, and means for varying the proportions of the gases in the gas mixture in response to any imbalance in the densities detected by the comparing means so as to equalise the density of the gas mixture with the density of the said atmospheric air.
Claim 3
Dependent Claim
73 words
A system as claimed in claim 1 wherein the mixing means comprises a hollow cylinder, a plurality of permeable discs disposed substantially diametrally within the hollow cylinder to define a series of chambers between the discs, an inlet for both gases into the first said chamber, and an outlet for mixed said gases from the last said chamber, whereby the gases diffuse progressively from said chamber to said chamber and are mixed thereby.
Claim 4
Dependent Claim
46 words
A system as claimed in claim 2, wherein the varying means is arranged to vary the proportion of the lighter gas in the gas mixture so as to maintain the density of the gas mixture at substantially the same density as that of said atmospheric air.
Claim 5
Dependent Claim
90 words
A system as claimed in claim 1, wherein the comparing means comprises a first tube having an inlet to admit mixed gas from the mixing means, a second tube having at least one inlet to admit said atmospheric air, means for measuring the density of the gas mixture in the first tube, means for measuring the density of the said atmospheric air in the second tube, and computing means for providing a control signal related to any imbalance in the density of the gas mixture and of the atmospheric air.
Claim 6
Dependent Claim
51 words
A system as claimed in claim 4, wherein the density measuring means comprises ultrasonic transmitters respectively located at one end of each of the first and the second tubes and receivers respectively located at the other ends thereof, and the receivers are arranged to provide input signals to the computing means.
Claim 7
Dependent Claim
36 words
A system as claimed in claim 5, wherein the computing means, in response to said input signals, provides a control signal related to any imbalance in the density of the gas mixture and the atmospheric air.
Claim 8
Dependent Claim
74 words
A system as claimed in claim 4, wherein the first and the second tubes are arranged to be of unequal lengths such that the ratio of their lengths is equal to the square root of the ratio of specific heat at constant pressure to specific heat at constant volume for air to the square root of the ratio of specific heat at constant pressure to specific heat at constant volume for the gas mixture.
Claim 9
Dependent Claim
32 words
A system as claimed in claim 4, wherein the varying means comprises valve means which open or close so as to adjust the proportion of the lighter gas in the gas mixture.
Claim 10
Dependent Claim
15 words
A system as claimed in claim 4, wherein the inert gases comprise helium and argon.
Claim 11
Dependent Claim
28 words
A system as claimed in claim 1, including cryogenic means for forming a condensed gas plug in a pipe or the like having a joint to be welded.
Claim 12
Dependent Claim
38 words
A system as claimed in claim 10, wherein said cryogenic means define two adjacent axially displaced annular chambers arranged to be disposed co-axially about the pipe, each said chamber being arranged to be supplied with a cryogenic fluid.
Claim 13
Dependent Claim
20 words
A system as claimed in claim 11, wherein the cryogenic fluid comprises liquid nitrogen, and the gas comprises carbon dioxide.
Claim 14
Dependent Claim
35 words
A system as claimed in claim 10, including means for introducing the gas into the pipe, said means including pressure sensing means for sensing the pressure between the joint and the region for the plug.
Claim 15
Dependent Claim
24 words
A system as claimed in claim 10, including means for heating that portion of the pipe near to the joint to at least ambient.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-09 | 1997-02-08 | 1997-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-09 | 2001-02-08 | 2001-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-09 | 2005-02-08 | 2005-08-10 | $7700.00 | Window Closed / Lapsed |