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Publication numberUS925317 A
Publication typeGrant
Publication dateJun 15, 1909
Filing dateJan 7, 1908
Priority dateJan 7, 1908
Publication numberUS 925317 A, US 925317A, US-A-925317, US925317 A, US925317A
InventorsByron E Eldred
Original AssigneeDuplex Metals Company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Flexible metallic tubing.
US 925317 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)




Patented June 15, 1909.


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925,317. Patented June 15, 1909.

5 2 sums-sum 2.

Inventor: fli miwwg Attys UNITED sTA'r sfATEnT OFFICE.




Application filed. January 7, 190a. Seral No. 400,021.

To all whom it may concern:

Be it known that I, BYRON E. ELDRED, a citizen of the United States, residing at Bronxville, in the county of Westchester and State of New York, have invented certain new and useful Im rovements in Flexible Metallic Tubing; an I do hereby declare the following to be a full, clear, and exact description of the same, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to flexible metallic tubing, and particularly to flexible tubing adapted to withsand considerable internal or external pressure, and which therefore must have tight joints.

Flexible metallic tubes such as those to which my invention relates are usually composed of one or morespiral strips of metal, the adjacent turns of which are locked together by crimping or otherwise so as to form a tight oint, (packing being sometimes introduced into this joint) or-of a pair of interwound spiral wires. In either case it is obvious that overlapping or abutting surfaces must iit together quite accurately and must be smooth and free to move on each other to afford the desired flexibility of the tube. Furthermore,

since such tubing when conveying steam,

hot water etc. is or may be subjected to great changes of tem ierature, it is necessary that the joint shall e one which will permit expansion or contraction without development of leaks. Heretofore such tubing has customarily been made either of steel or of co per. Copper, even when hard drawn, has the objections that owing to its well-known weakness and small elasticity, when any considerable pressure is to be resisted the 00 per walls of the tube must be of considerab e thickness, thereby makin the tube less flexible than if the walls were t inner. opper has, however, the important advantage that it is substantially unaffected by oxygen,

' steam, water of condensation, fatty acids such as may be present in lubricating oils con- I tained in steam or water of condensation,

and other li uids and gases or vapors which such tubing is usually called upon to carry. Steel is much stronger than co per, and therefore can be used in mucli thinner gages; but its well-known susceptibility to oxidation, pitting, etc, steel tubing impracticable in most cases.

According to the present invention,

Specification of Letters Patent.

changes of temperature.

the l maria June 15, 1909.

tubin is formed of steel, but 1a ers of copper, sllver or other less oxidizab e metal are attached to and interposed between adjacent or overlapping layers of steel, such copper, silver etc., because of its relative softness, and relatively high rate of expansion, forming an efficient packing and a superior rubbin or friction surface which is not liable to oxi ation, corrosion or pitting; and such layers of copper, silver etc. also protect the steel from oxidation, corrosion or pitting. The cop er etc. is preferably weld-united to the steel being thereby confined as to expansion longitudinally-or in a direction parallel to the weld, substantially to the rate of expansion of the steel, but being free to expand in a direction at right angles to the Weld, at its own rate. Since this rate is, as stated, much greater than that of steel, as the temperature of the tube rises the joint automatically becomes tighter. This advantage can be attained with weld-clad steel and the copper strip or layer still be very thin. Owing to the copper etc. being Welded to the steel, the expansion of the copper etc. at right angles to the Weld is greater proportionately than would .be the caseexce t for the weld, owing to the limitation oft e expansion of the copper in other directions by the weld-union to another metal (steel having a lower rate of expansion.

In some cases the steel used is one the rate of expansion of which has been regulated, by i the use of regulated amounts of an alloying ingredient such as nickel or cobalt, so that it has a )artieular desired rate of expansion or even oes not expand or contract at all with In such case the copper, sliver etc. has, of course, a stall greater efficiency as a means for insur ng tight joints. In forms of tubing comprising two interwound spirals, one of the spirals may he of ordinary steel coated with copper etc., and the other of steel having a less rate of expansion than ordinary steel, and like- 100 W180 coated with copper etc.; the different rates of expansion tern ing to make the joints tighter as temperature rises. And in the forms of tubing in which the oints between adjacent turns are formed by crimping or 105 interlocking adjacent edges, a layer of packmg material, preferably copper, silver etc.,

makes the use ol may be included in the joint.

In the patent to J. F. itlonuot, No. 853,716,

dated May 14, 1907, a method of inseparably 110 yielding by the comes quite thin or 6-6 my invention a uniting copper,- silver etc. to iron, steel and the like is set forth, the union being produced in the ingot andthe compound 'or clad billets ac produced being extended by rolling, or

- other suitable method of extending, to sheets,

' and the term weld as used herein is used. as

comprising such union. Material such as described in said patent is now available, and is the material which I particularly prefer to use in the construction of my tubing, as it has substantially the strength of steel, and so may be used, even for high pressures, in small gages, and in strips of such material its rate of expansion laterally and longitudinally is substantially that of the steel itself while the copper orlike coating has an increased rate 0 expansion in a direction at right angles to the weld-line or to the surface, for the reason previously stated; and moreover the materla is no more liable to corrosion or other attack than is the coating metal. Moreover such coating metal has a peculiar hardness, due doubtless to support received through substantially molecular union to the stronger metal beneath, which makes it a particularly good bearing metal, for my pres-' ent urpose at least. It is Well known that in earmgs, copper does not work well against copper, or steel against steel. But such objection is not found, in my tubing, to steel-reinforced copper working against steelremforced copper; t'hevcopper being,-in such case, so hard as to make a good bearing metal.

In the manufacture of thin-coated weldclad metal strips or wires ada ted for the present purposes, the compoun metal body is rolled or dravm down to thin gages. In this coextension of the joined metals, the copper, etc., coating, which ultimately be- 7 filmiform, is compressed and compacted-between the tool on the one side and the relatively stiff, hard steel on the other, and, being prevented from lateral asal weld-union to such steel, it assumes throughoutthe film a peculiar hard, dense, compact texture, similar to thesuperficial texture of hard drawn copper, while its surface becomes planished.

"In the accompanying drawings I illustrate plied to certain'of thewellv known types 0 tubing. It will be under- Stood that my invention is independent of any particular joint between adjacent ed es, surfaces, coils or turns, and is not confined to the particular types of tubing shown.

In said drawings: Figure l'shows a fragmentary longitudinal section of one well known type of flexible tubing, having joints between adjacent turns formed by overlapping and-crimping or interlocking adjacent ed es. Figs. 2, 3 and 4 are larger-scale detai sectional views of joints in such tubing, Figs. 2 and 3 showingdifierent arrangements or locations of packing strips. Figs. 5 and 6 are fragmentary longitudinal sections of another type of tubing comprising interwound i spirals of different wires or rods.

Referring to Figs. 1, 2, 3 and 4, at the first, the tubing there shown comprises a spirally: wound or helically-Wound stri or ribbon comprising a core or base 1 oi'one metal, 8 steel for exam le, covered with a protective coating 2 of a ifierent metal, such as cop er, silver, aluminum, gold, platinum, nic el,

cobalt, brass, bronze, aluminum bronze, etc;

such coating 2 preferably weld-united to the 8 base 1, as is the case with material made as described in the Monnot patent previously mentioned. The adjacent edges of adjacent turns of the spiral areoverlap ed and interlooked, as is common in this 0 ass of tubing, 9 and there may be a strip of packing material 3 in the joint, as indicated in Figs. 2 and 3, such acking material bein either the same meta asthe coating or 81105181 metal having a relatively high rate of expansion as com- 9 pared with the base metal 1, and which is suificiently soft and ductile to make a good packingyor the packin may be rubber or asbestos or other suitab e packing material.

The packing may also be introduced at 'va- 1 rious places in the joint, Fig. 2 indicating one location and Fig. 3 anotherglocation. 01',

separate packing may be omitted altogether,

as illustrated in Fig. 4, reliance being placed on the coating 2 to act as a packing, which 1 it will do because of its relatively greater rate of expansion than the base 1, and because, bein limited in expansion longitudinally or para lel to the union between it and the base 1, it will expand the more at right angles to 1 the union, i. e., radially of the tube. In any of these figures 1-4 inclusive, the base 1 may with advantage be of a specialgrade of steel, such as above mentioned, having a very small rate of expansion or having no expan sion whatever with changes of temperature. InFi s. 5 and 6, illustrating another type of. flexi le tubing com rising interwound .spiral'wires or rods, 4 an 5., usually of differ ent sections, as shown, the basewire, 4, is 1 "preferably of coated. or clad metal, asshown; and the packing-wire 5 may-either be composed of a single metal, preferably the same as that of which .the coating of wire 4' is formed, as indicated in Fig. 5-,or it may also 2 be composed of a coated or clad metal, as

shown in Fi 6; in which case the base-wire 4 preferably as a less rate of expansion than the acking-wire 5, though this is not abso- K lute ynecessary. p 2 30 In all of the forins of tubing shown, the

hard, planished, surfaces of the coating metal,

permitting the movement of one surface overanother necessary for flexibilit of the tubing without disturbing the close t necessary to prevent theescape of the fluid being conveyed through the pipe, and without mate rial wear; and as previously explained, with chan es of temperature the said coating meta expands or contracts so as to maintain close fit between the contacting surfaces. The coating metal may in fact, be so thin as to be practically a mere film, and yet serve to make good bearings andgood joints between adjacent turns and to protect the base metal against attack.

I do not regard electro-deposited coatings as the substantial e uivalent, for the purpose of my invention, oi coatings weld-united to the base metal as are, for example, the coatings of clad'metals produced by said Monnot process, for electro-deposited coatings and the like are invariably crystalline, porous, weak, and tend to strip or; readily being merely adherent to the base, and. not coherent. They may indeed be worse than useless, because tending, under conditions of use, to set up local galvanic action between the coating and the metal beneath. Such is not the case with impervious coherent coatings as produced, for example, by said Monnot rocess.

' at I claim is:

1. Flexible metallic tubing comprising s iral coils of one metal having between a utting faces a layer of another kind of metal having a different rateof expansion,

said layer being Welded to one of said abutting faces and said abutting faces being free to move relative to each other.

2. Flexible metallic tubing comprising spiral coils of one metal having between them and united to them layers of another metal having a different rate of ex ansion.

3. Flexible metallic tu ing com rising spiral coils of clad metal comprising a ase of strong metal inse arably united to a coating of a softer meta, the coatings of adjacent turns in substantial contact; and forming bearing-surfaces.

4. Flexible metallic tubing com rising a spirally-wound strip of one metal, a jaeent edges of adjacent turns of such strip interlocked, and a packing consisting of a metal of higher rate of expansion than said strip, included in the joint formed by such int-cl"- lockedjedges, said packing metal in contact with both layers of the metal of the joint.

5. Flexible metallic tubing comprising :2 spirally-wound stri of ferrous. metal having an inseparably-i nited coating of another metal having a higher rate of expansion, the

an inseparably-umted coating of another metal having a higher rateof expansion, the coatings of adjacent turns in substantial c011 tact, and a packing strip of the same metai as said coating between such coatings.

7. Flexible metallic tubing comprising a spirally-wound strip of ferrous metal having an inseparably-united welded-on coating of a softer metal, the coatings of adjacent turns in substantialcontact, and forming bearing surfaces.

In testimony whereof I afiix my signature in the presence of two witnesses.

BYRON E. ELDRED Witnesses:



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US2438146 *Jun 7, 1945Mar 23, 1948American Brass CoFlexible metal hose
US2636083 *Mar 4, 1950Apr 21, 1953Titeflex IncFlexible hollow pipe wave guide
US5228479 *Jun 17, 1991Jul 20, 1993Tru-Flex Metal Hose CorporationMulti-layered flexible piping and method and machine for forming same
US5451718 *Apr 8, 1993Sep 19, 1995Southwire CompanyMechanically bonded metal sheath for power cable
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US5538294 *Nov 1, 1994Jul 23, 1996Tru-Flex Metal Hose CorporationCorrugated flexible metal piping assembly
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US20120103051 *Oct 26, 2011May 3, 2012Sjm Co. Ltd.Method For Manufacturing A Flexible Piping Device For An Exhaust Gas System Of A Motor Vehicle
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Cooperative ClassificationF16L11/16