US3126918A - Slip ring spacer for insulated conduit systems - Google Patents

Description

B. E. EATON March 31, 1964 SLIP RING SPACER FOR INSULATED CONDUIT SYSTEMS Filed March 5, 1962 uvmvrom ATTORNEYS. I

United States Patent 3,126,918 SLIP RING SPACER FOR TNSULATED CONDUIT SYSTEMS Burton E. Eaton, Deerfield, 111., assignor to Midwesco, Inc., a corporation of lliinois Filed Mar. 5, 1962, Ser. No. 177,675 5 Claims. ((31. 138-113) This invention relates to conduit and, more particularly, to conduit for connecting hot or cold fluids such as steam or refrigerant mixtures, such conduit comprising an insulated inner pipe about which is disposed an outer conduit casing, and means for uniformly spacing the insulated inner pipe from the outer casing.

Heretofore, conduit of the type described has been constructed such that the inner pipe was spaced from the outer casing by spacer members which were rigidly secured to the inner pipe. The construction resulted in undesirable heat exchange between the inner pipe and the outer casing. Further, as a result of rigidly securing the spacer members or supports to the inner pipe, as the inner pipe expanded and contracted there was wearing movement between the supports and the inner wall of the outer casing, eventual-1y resulting in the effecting of an opening or break Wall of the outer casing. While the use of rollers to overcome the wear problem between the inner pipe and the outer casing has been proposed, such construction is not altogether successful from the standpoint of cost and maintenance.

Previous supports or spacer members between the inner pipe and the outer casing provided only one or two points of contact between the spacer member and outer casing, resulting in undesirably high shear loadings beyond acceptable design values and occasionally causing the support to punch through the wall of the outer casing. In addition, previous supports often unduly restricted the proper air fiow and drainage in the space between the inner pipe and outer casing.

An object of the present invention is to provide a conduit wherein the deficiencies and disadvantages of prior constructions are obviated.

Another object of the present invention is to provide a conduit comprising an inner pipe and an outer casing uniformly spaced therefrom by novel support and spacer means which permit the inner pipe to be insulated substantially continuously along its entire length.

Still another object of the present invention is to provide a conduit comprising an inner pipe and a protective casing thereabout with spacing means between the inner pipe and the outer casing constructed and arranged to obviate wearing movement between the spacing means and the outer casing.

Yet another object of this invention is to provide a prefabricated conduit comprising an insulated inner pipe disposed within an outer casing and provided with annular support members, of corrugated or nodal sheet metal, disposed between the inner pipe and outer casing to uniformly space the inner pipe from the outer casing and to permit substantially unrestricted air movement and drainage in the annular space between the inner pipe and the outer casing.

These and other objects of the present invention will become more apparent hereinafter.

Broadly stated, this invention relates to a conduit comprising an elongated inner pipe for carrying a fluid, substantially continuous annular insulation surrounding said inner pipe, a plurality of sheet metal lagging pieces on the insulation and having substantially no movement relative thereto, an elongated outer casing disposed about and surrounding the inner pipe, and spacer means for spacing the inner pipe from the outer casing comprising a sup- 3,126,913 Patented Mar. 31, 1964 port ring formed from nodalor corrugated sheet metal, the support ring being disposed between the lagging piece and the outer casing, the lagging pieces being slidable within and relative to the nodal support ring in response to expansion and contraction of the inner pipe, the insulation electrically and thermally isolating the inner pipe from the outer casing.

The invention will be better understood from the following description of a presently preferred embodiment of the invention, which is illustrated in the accompanying drawings wherein like parts are identified by like reference numerals in each of the views and wherein:

FIG. 1 is a fragmentary sectional view illustrating a conduit embodying the present invention;

FIG. 2 is a perspective view on an enlarged scale illustrating the spacing means of the present invention;

FIG. 3 is an enlarged cross-sectional view taken along the line 3-3 of FIG. 1; and

FIG. 4 is an enlarged sectional view illustrating a portion of a conduit embodying the present invention.

Referring to FIG. 1, there is illustrated a preferred embodiment of the present invention. The conduit, generally indicated at It is adapted to be positioned in a trench in the ground and comprises an outer conduit, or casing, 11 and an inner conduit, or pipe, 12 disposed substantially coaxially therein. Provided about the inner pipe 12 is suitable insulation 14, which may be formed from annular mats of fiber glass, asbestos, calcium silicate or the like. At'fixed about the insulation 14 as spaced locations are liners or lagging pieces 16.

Disposed between the lagging pieces 16 and the inner wall of the outer casing 11 are spacer means 18 for substantially uniformly spacing the inner pipe from the outer casing,

As is more clearly seen in FIGS. 2 and 3, each lagging piece 16 comprises a generally circular piece of sheet metal which is drawn up and tightly clamped to the insulation. Beneath the lagging pieces, the insulation may be formed from semicylindrical members 14a and 14b. The overlapping ends of the lagging piece may then be suitably connected, as, for example, by spot welding.

The spacing means 18 are formed from an annulus of sheet metal that has been preformed with nodes, of corrugations 19. The annular arrangement provides that the outermost ridges of corrugations 19' are adapted to engage the outer casing 11 while the innermost ridges engage lagging piece 16 at circumferentially spaced lines. It is apparent from FIG. 2 that in the preferred embodiment of the invention the corrugations extend longitudinally parallel to the axis of the inner pipe and outer casing. However, it is within the scope of the present invention and will be apparent to one skilled in the art that the corrugations may be formed helically and thus extend at an angle to the longitudinal axis of the inner pipe.

Secured to the lagging piece 16 on opposite sides of the annular spacer ring 18 and spaced axially from the edges of ring 18 are a pair of arrestors or stop members 21. These stop members assure that in operation each lagging piece 16 will always be located within its associated support ring 18.

The conduit illustrated in FIG. I normally will be constructed or prefabricated in sections in a factory or shop. When installed in the field it is intended that the usual anchors and expansion joints will be provided. Adjacent sections will be joined together, as in the past, with circumferential Welds of the inner pipe 12 and outer casing 11. The inner pipe 12 normally is not assembled complete with insulation, so as to permit access in the field for effecting the circumferential butt weld 12a between adjacent pipe sections. Then, the semicylindrical insulation sections 14a and 1411, cut to the precise axial length to give complete insulation of pipe 12, are applied. The sheet metal lagging piece 16 may be applied around insulation sections 14a and 14b, thereby holding those sections assembled. Then the sheet metal spacer it; is assembled on lagging piece 16 and the entire assembly is slid into a casing section 11.

:In use, upon the first passage of fluid through the inner pipe, the inner pipe will expand or contract. The lagging pieces 16, which are clamped onto and thereby fixed relative to the insulation, will also move. When either stop member 20 or 21 abuts the end of annular spacer ring 18, the ring will be moved within the outer casing 11 to its final position. In subsequent operation each lagging piece 16 will slide relative to and Within its associated ring 18. Thus, it is apparent that after the first heat-up of the system there is no wearing movement between spacer ring 18 and the outer casing 11. Since the inner pipe is spaced from spacer ring 18, there is no sliding wear on the inner pipe. As a consequence, the operating life of both the inner pipe and of the outer casing is increased.

By virtue of the corrugations 19 defining the annular spacer ring 18, the inner pipe 12 is substantially uniformly spaced from the inner wall of the outer casing.

It is apparent from FIGS. 3 and 4 that there are a relatively large plurality of contact points (axial lines) between the lagging piece 16 and the spacer ring 18, and between the ring 18 and the outer casing 11, as provided by the corrugations 19 of the ring 1-8. In a presently preferred embodiment of my invention, there are at least three lines of contact between the lagging piece 16 and spacer ring 1 8 and between the spacer ring 18 and the outer casing 11. The existence of a large number of points of contact eifects a distribution of the spear loading on the casing 11, thereby reducing possibility of punching a hole in the casing 11, as when previous spacers provided only one or two points of contact which developed very high shear loadings. Thus, the possibility of the spacing means punching through the wall of the outer casing 11, which has occurred in previous designs, is virtually obviated for the individual ring corrugations are yieldable and all deflection takes place within the ring 18. Further, by virtue of the construction'of support ring 18, maximum utilization is made of the annular space between the insulation 14 surrounding the inner pipe 12 and the inner wall of outer casing 11 to provide increased space for air movement and for drainage, inasmuch as approximately 95 percent of the annular space is unrestricted. The passages defined between the corrugations 19 and the lagging pieces 16 and between the corrugations 19 and the support ring 18 are uniformly defined about the annular space such that air flow and drainage are substantially unrestricted in any radial position of the conduit. Thus in field installation, the straight sections of conduit may be installed in any radial position.

It will be apparent that changes can be made in the construction and arrangement of the parts while accomplishing the objects and falling within the scope of the invention. The inner pipe may be made from black pipe, galvanized pipe, or wrought iron pipe, depending upon the use and fluid (liquid or gas) to be conducted within the inner pipe. In one presently preferred form of the invention, the outer casing is spiral welded steel made of 8, or 14 gauge black steel. Other suitable material will be apparent to those having ordinary skill in the art.

The insulation may be formed from a tube or cylinders of insulating material slipped over the inner pipe, irom contiguous annular segments, or from half-cylinders suitably interconnected. The latter arrangement is preferred where adjacent conduits have to be welded together in the field. After welding, half-cylinders of insulation may be installed about the joint. Then the lagging piece is affixed about the split insulation and the overlapping ends thereof are secured together. In each usage, the inner pipe is thermally and electrically isolated from the outer i casing substantially along its length. The spacers are constructed to allow drainage and free flow of air within the annular space between the inner pipe and outer casing and will permit the expansion and contraction of the inner pipe without damage to the insulation.

While there has been shown and described a particular embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new, and desire to secure by Letters Patent of the United States is:

1. Improved spacer means for conduits of the type having an inner pipe for carrying a fluid and an outer casing through which said inner pipe extends in spaced relation with the outer casing; said spacer means including a ringlike axially elongated sheet metal lagging piece operatively secured to the inner pipe so as to move axially with the inner pipe in response to expansion or contraction of the inner pipe, and a sheet metal nodal-type spacer ring slidably arranged on said lagging piece and adapted to engage the inner surface of an outer casing to space the inner pipe from the outer casing, whereby the inner pipe and the lagging piece operatively secured thereto are slidable within the spacer ring when the inner pipe extends or contracts.

2. Improved spacer means as in claim 1 wherein the axial length of the ring-like lagging piece is greater than the 'axial length of the spacer ring, to atford relative sliding movement of the lagging piece within the spacer ring.

3. Improved spacer means as in claim 2. including a stop element on the lagging piece adjacent an end thereof positioned to engage and move the spacer ring with the lagging piece, in the event the expansion or contraction of the inner pipe would tend to move the end of the lagging piece wholly or partly through the spacer ring.

4. A conduit comprising an elongated inner pipe for carrying a fluid, substantially continuous annular insulation surrounding said inner pipe, an elongated outer casing disposed about and surrounding said inner pipe and its insulation, and a plurality of axially spaced spacer means for spacing the inner pipe from the outer casing, each spacer means comprising a sheet metal annular lagging piece secured to the insulation, a nodal-type annular spacer ring of sheet metal of lesser width than the width of a lagging piece disposed between the lagging piece and the outer casing to providea plurality of axially extending lines of support, said lagging pieces being slidable within and relative to said spacer rings in response to expansion and contraction of the inner pipe, said insulation electrically and thermally isolating said inner pipe from the outer casing, and stop members secured to each lagging piece on opposite sides of said nodal-type spacer ring to assure that the spacing between adjacent spacer rings will be maintained 'in use.

5. In combination with a conduit casing and an insulated inner pipe in and disposed longitudinally thereof, lagging pieces afiixed to said insulated inner pipe at spaced locations and movable therewith in response to expansion and contraction of the inner pipe, and corrugated support members disposed between the lagging pieces and the outer casing to provide a plurality of lines of support for spacing the inner pipe from the outer casing, said lagging pieces being slidable within and with respect to said support members in response to expansion and contraction of the inner pipe, and including stop members on each lagging piece disposed on opposite sides of an associated support member.

References Elitcrl in the file of this patent UNITED STATES PATENTS 2,903,017 Cotman Sept. 8, 1959 2,914,090 Isenberg Nov. 24, 1959 2,938,569 Goodrich May 31, 1960

Claims (1)

1. IMPROVED SPACER MEANS FOR CONDUITS OF THE TYPE HAVING AN INNER PIPE FOR CARRYING A FLUID AND AN OUTER CASING THROUGH WHICH SAID INNER PIPE EXTENDS IN SPACED RELATION WITH THE OUTER CASING; SAID SPACER MEANS INCLUDING A RINGLIKE AXIALLY ELONGATED SHEET METAL LAGGING PIECE OPERATIVELY SECURED TO THE INNER PIPE SO AS TO MOVE AXIALLY WITH THE INNER PIPE IN RESPONSE TO EXPANSION OR CONTRACTION OF THE INNER PIPE, AND A SHEET METAL NODAL-TYPE SPACER RING SLIDABLY ARRANGED ON SAID LAGGING PIECE AND ADAPTED TO ENGAGE THE INNER SURFACE OF AN OUTER CASING TO SPACE THE INNER PIPE FROM THE OUTER CASING, WHEREBY THE INNER PIPE AND THE LAGGING PIECE OPERATIVELY SECURED THERETO ARE SLIDABLE WITHIN THE SPACER RING WHEN THE INNER PIPE EXTENDS OR CONTRACTS.

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