Spacing element for spacing an inner pipe from an outer pipe

A spacing element for spacing a pipe from a protective pipe outwardly surrounding the latter, has an annular body including a plurality of segments adapted to be placed on an outer surface of the pipe and each having a plurality of projections provided with sliding surfaces and adapted to abut against the protective pipe. The spacing element further includes a plurality of electrically insulating wedge-shaped connecting portions for connecting the segments with one another. The connecting portions may be formed as trough-shaped members embracing trough-shaped flanges of the segments. The connecting portions may also be formed as wedge members insertable into bores of a projection of one of the segments engaging a recess of an adjacent segment, or fixable to an outer surface of such projection. Additional connecting members such as electrically insulating pins, straps and strings may be provided for connecting the segments with one another.

BACKGROUND OF THE INVENTION 
The present invention relates to a spacing element for spacing an inner 
pipe from a protective pipe outwardly surrounding said inner pipe. 
Spacing elements for spacing pipes from outer protective pipes have been 
proposed in the art. Such spacing elements have a plurality of segments of 
a synthetic plastic material which are placed on an outer surface of the 
inner pipe and each has a plurality of projections abutting against an 
inner surface of the outer pipe and having slide surfaces. The segments of 
the known spacing elements are connected with one another by metallic 
bolts. The bolts generally are not brought in contact with either the 
outer protective pipe or with the inner pipe extending through the latter, 
so that an electrical path is not established between the pipe and the 
protective pipe in order to assure unobjectionable corrosion protection. 
However, when the spacing element is accidentally broken, a danger will 
occur that the metallic connecting bolts will establish the electrical 
path between the pipe and the protective pipe and thereby will break 
cathodic protection of the former. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a spacing 
element for spacing a pipe from an outer protective pipe, which avoids the 
disadvantages of the prior art. 
More particularly, it is an object of the present invention to provide a 
spacing element for spacing a pipe from an outer protective pipe, which 
eliminates a danger of establishing an electrical path between the pipes 
and thereby breaking a cathodic protection of the inner pipe. 
Another feature of the present invention is to provide such a spacing 
element for spacing a pipe from an outer protective pipe in which 
connecting means for connecting segments of an annular body of the spacing 
elements do not include electrically conducting parts. 
In keeping with these objects, and with others which will become apparent 
hereinafter, one feature of the present invention, briefly stated, resides 
in a spacing element which has a body portion including a plurality of 
segments adapted to be placed on an outer surface of an inner pipe and 
having a plurality of projections adapted to abut against an inner surface 
of a protective pipe, and means for connecting the segments with one 
another including a plurality of electrically insulating wedge-shaped 
connecting portions. The segments are constituted of an electrically 
insulating material. The connecting portions are constituted of a 
non-metallic preferably synthetic resin material. 
In the spacing element in accordance with the present invention the 
connecting portions are electrically insulating, and therefore even in the 
case when the spacing element is broken the thus-constructed connecting 
portions will not establish an electrical path and, therefore, there will 
not be a danger that a cathodic protection of the pipe will be broken. 
Another feature of the present invention is that each of the segments may 
be provided with two flange portions each located at a respective end of 
the segment and having a wedge surface. The connecting portions may be 
formed as clamping members each having an opposite wedge surface 
cooperable with the wedge surface of a respective flange portion so as to 
connect the adjacent segments with one another. 
A further feature of the present invention is that the flange portions of 
the segments and the clamping members are trough-shaped, and the flange 
portion has an inclined free edge defining the wedge surface, whereas the 
clamping member has a further surface defining the opposite wedge surface. 
The trough-shaped clamping members engage the flange portions of two 
adjacent segments and connect the latter with one another. 
Each of the flange portions may have two inclined free edges each extending 
from a respective end towards one another and up to a central plane of the 
flange portion so that two such trough-shaped clamping members may be 
shifted over the two free edges from the opposite ends of the flanges. The 
thus-formed free edges of the flange portions may be inclined relative to 
a longitudinal axis of the segments at identical angles. When the 
trough-shaped clamping members are shifted over the trough-shaped flange 
portions from the opposite ends and move towards one another in the 
direction of the longitudinal axis, for instance by hammer impacts, the 
segments of the annular body will tightly embrace the pipe to be protected 
with pressure fit. The clamping members have great contact surfaces and 
therefore provide for good force distribution in the connected position. 
A still further feature of the present invention is that means are provided 
for preliminary mounting of the segments before their clamping on the 
pipe. Such means include bores provided in the flange portions adjacent to 
one or both ends thereof and in the clamping members, which bores are 
alignable with one another, and also include shearing pins insertable in 
the bores in aligned condition of the latter so as to preliminarily 
connect the segments and the clamping members with each other. The 
shearing pins are constituted of an electrically insulating material such 
as wood. An additional means for preliminarily connecting the segments may 
be provided, including a plurality of bores formed in the projections of 
the segments and aligning with one another, and a cored insertable into 
the bores of the projections of the segments so as to preliminarily 
connect the latter with one another. The thus-connected segments cannot be 
removed from the pipe during mounting of the spacing element on the 
latter. 
Still another feature of the present invention is that respective surfaces 
of the flange portions of the segments and the clamping members may be 
provided with teeth meshing with one another so as to further improve the 
fitting of the clamping members onto the flange portions. The teeth may 
extend substantially parallel to those surfaces of the segments which abut 
against the outer surface of the pipe to be protected. Such construction 
is advantageous inasmuch as in this case all the segments may be made 
completely symmetrical and may have the identical flange portion, and 
furthermore inasmuch as the clamping members for connecting the 
thus-constructed segments may also be identical with one another. 
Finally, end sections of the segments may be differently formed so that for 
instance one end section of the segment has a connecting projection and 
the other end section of the segment has a connecting recess engaging the 
connecting recess and the connecting projection, respectively, of an 
adjacent segment. The connecting projection may have a through bore for 
inserting a wedge member into the bore or an outer surface for shifting a 
wedge member over the latter. The projection and/or the recess and/or the 
wedge member may be provided with teeth on respective surfaces facing 
towards one another. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a pipe 10, for instance of an oil circuit, which extends 
through a protective pipe and is spaced from the latter by means of a 
spacing element. The protective pipe is known per se in the art and for 
this reason is not shown in the drawing. The spacing element has an 
annular body 11 including a plurality of segments of an electrically 
insulating material such as a synthetic plastic material. Each of the 
segments has a plurality of rib-shaped projections 12. The annular body 11 
of the spacing elements serves also as a slide member for slidable 
insertion of the pipe 10 in the not shown protective pipe. The projections 
12 in this case serve as slide skids. For insertion of the pipe 10 in the 
protective pipe, a front opening of the former is closed with a cover 13. 
The annular body 11 of the spacing element may include a varying number of 
segments, and the segments may have different dimensions as shown in FIG. 
1, where two segments 14 and 15 are of different lengths in the 
circumferential direction. It is understood that the segments may also 
have identical dimensions. The segments 14 and 15 are tightly fitted by 
their inner surfaces on an outer surface of the pipe 10 and are connected 
with one another and with adjacent segments at their ends. For this 
purpose trough-shaped flanges 16 are provided at the ends of the segments 
14 and 15. Each of the flanges 16 has free edges each extending from an 
end of a respective flange and forming a wedge surface 17. As shown in 
FIG. 1, each of the flanges has two such free edges 17 extending up to a 
central plane of the flange which plane is normal to a longitudinal axis 
of the latter. However, it is understood that each of the flanges also may 
have only one such free edge forming only one such wedge surface. 
Two clamping members 18 and 19 are further provided, each formed with a 
wedge surface opposite to the wedge surface 17 of the flanges of the 
segments 14 and 15. The clamping members 18 and 19 can be shifted over the 
flanges 16 of the adjacent segments 14 and 15 by their movement in two 
opposite directions which are identified by arrows 20 and 21 in FIG. 1. 
The clamping members are constituted of an electrically insulating 
material, such as a non-metallic material, and preferably of a synthetic 
plastic material. 
As shown in FIG. 1, the rib-shaped projections 12 of the segments are 
provided with a through bore 22 formed in a central region of each 
projection. All of the thus-formed bores 22 are in alignment with one 
another as considered in a circumferential direction of the annular body 
11. A cord 23 or the like member extends through the bores 22 of the 
projections 12 and serves as an auxiliary mounting member so that all the 
segments can be held together and thereby prevented from removal from the 
pipe 10. The bores 22 and therefore the cord 23 are located at a height 
exceeding the height of the flanges 16 plus the thickness of the clamping 
members. The flanges 16 of the segments have through bores 24, and the 
clamping members 18 and 19 have through bores 25 which can be aligned with 
the bores 24 of the flanges 16. A member of an electrically insulated 
material such as a wooden shearing pin 26 is inserted into the aligned 
bores 24 and 25 so as to further serve as auxiliary means for mounting. As 
shown in FIG. 3 the shearing pin 26 inserted in the bores 24 and 25 
provides for firm initial connection of the clamping members 18 and 19 
with the segments 14 and 15 for a preliminary mounting. During a final 
mounting of the segments, the latter are tightly fitted on the outer 
surface of the pipe 10 by further shifting of the clamping members 18 and 
19 over the flange portions 16 of the segments with shearing off of the 
shearing pins 26. A height of the projections 12 must be greater than the 
height of the flanges 16 plus the thickness of the clamping member. 
As shown in FIGS. 2 and 4, the flange portions 16 have upper surfaces 27 
provided with teeth, whereas the clamping members 18 and 19 have opposite 
surfaces 28 also provided with teeth meshing with the teeth of the 
surfaces 27. At the same time, these surfaces are so formed that during 
shifting of the clamping members 18 and 19 over the flange portions 16 of 
the segments the teeth are not subject to breakage, but after the fitting 
prevent the clamping members from withdrawal from the flange portions. A 
strap 29 may be inserted in a central longitudinal groove 30 of the 
clamping members 18 and 19 after completing the mounting of the annular 
body 11 and serves as additional securing means, as shown in FIG. 2. The 
toothed surfaces 27 and 28 are substantially parallel to lower surfaces of 
the segments abutting against the outer surface of the pipe 10. 
FIGS. 5-9 show further embodiments of the spacing element in accordance 
with the present invention. 
FIG. 5 shows a segment 40 having a mating surface 41 and provided with two 
projections 42 serving as slide skids. Two flanges 43 and 44 are formed at 
opposite ends of the segment 40 and have a different shape and a height 
smaller than the height of the projections 42 so that the flanges cannot 
be brought into contact with the protective pipe. The flange 43 has 
several, particularly two, projections 45 extending in the circumferential 
direction, whereas the other flange 44 completely corresponds to not shown 
recess in which the projection 45 of the adjacent segment is inserted. 
FIG. 6 shows two segments 40 and 40' connected with one another. A flange 
43 of the segment 40 has two projections 45 extending in the 
circumferential direction and provided with teeth 46 on the longitudinal 
surfaces thereof. A flange 44 of the adjacent segment 40' has two recesses 
47 whose wall surfaces are also provided with teeth 46, and projections 48 
surrounding the flanges 45. The projections 45 of the flange 43 of the 
segment 40 are inserted into the recesses 47 of the flange 44 of the 
segment 40' and thereby the segments are connected with one another and 
securely prevented from separating under the action of forces applied in 
the circumferential direction. 
FIG. 7 shows a spacing element in accordance with a further embodiment of 
the present invention, having two segments 50 and 50'. The segment 50 has 
a connecting flange 51 at its end, which flange has, in turn, two 
projections 52 and 53. The projections 52 and 53 has head portions 54 and 
55 extending normal to the former. The adjacent segment 50' has a 
connecting flange 56 at its end, which flange has, in turn, two recesses 
57 and 58 shaped in accordance with the projections 52 and 53. As shown in 
the drawing, the recesses 57 and 58 extend substantially radially so that 
the projections 52 and 53 can be inserted from above by movement in the 
radial direction into the recesses 57 and 58. 
After connecting the connecting flanges 51 and 56 with one another an 
intermediate space 59 is formed between the respective surfaces of the 
connecting flange 56 and the head portions 54 and 55 of the projections 52 
and 53 of the flange 51, as shown in FIG. 7. A wedge member 60 having a 
wedge surface 61 provided with teeth is inserted into the thus-formed 
space 59. An opening 61' may further be provided in the projection 53, as 
shown in broken lines of FIG. 7. A not shown wedge member may be similarly 
inserted in the opening 61 by movement in a lateral direction so as to 
assure firm connection between the segments 50 and 50'. 
FIG. 9 shows a still further embodiment of the present invention where the 
spacing element has two segments 62 and 62'. The segment 62 has a 
connecting flange 63 provided with a substantially flat projection 64. 
Teeth 65 are formed on an upper surface of the projection 64. The adjacent 
segment 62' has a connecting flange 67 with a bore 66 through which bore 
the projection 66 of the segment 62 extends. The projection 64 of the 
connecting flange 63 of the segment 62 is inserted into the bore 66 of the 
projection 67 of the segment 62. A withdrawal of the projection 64 from 
the bore 66 is prevented by a wedge member 68 inserted between an upper 
surface of the connecting flange 62' and a lower surface of the projection 
64. In this case the toothed upper surface 65 of the projection 64 engages 
with a lower wall of the bore 66. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
constructions differing from the types described above. 
While the invention has been illustrated and described as embodied in a 
spacing element for spacing a pipe from an outer protective pipe, it is 
not intended to be limited to the details shown, since various 
modifications and structural changes may be made without departing in any 
way from the spirit of the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.