Insulation device for application to an uninsulated portion of a preinsulated pipe

An insulation device for surrounding the uninsulated, adjoining end portions of a preinsulated pipe comprising a plurality of axially extending cylinder segments adapted to be circumferentially joined to form a cylindrical insulating jacket around the uninsulated end portions. The cylinder segments in their undeformed states have a length slightly greater than the combined length of the uninsulated adjoining end portions. The cylindrical insulating jacket has an inside diameter generally conforming to the outside diameter of the uninsulated end portions and an outside diameter generally conforming to the outside diameter of the preinsulated pipe. Each cylinder segment has at least a first pair of rigid arcuate sections and a first resilient arcuate section sandwiched therebetween. The first resilient arcuate sections of all of the cylinder segments are longitudinally positioned in the cylindrical jacket to fall substantially in the same transverse plane.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to insulation devices for pipes; more particularly, 
to an insulation device for surrounding the uninsulated, adjoining end 
portions of preinsulated pipe. 
2. Description of the Prior Art 
Above-ground and undersea pipeline systems have assumed increased 
importance, particularly in the oil and gas industry where it is necessary 
to transport fluids from well-heads located in remote, extremely cold 
regions, such as Alaska, to seaports or processing facilities. Often sea 
water likewise is transported by pipeline to a well-head to replace 
extracted oil and gas, and thereby maintain pressure. In these 
circumstances, a buried pipeline is impractical because the pipeline must 
traverse the earth's permafrost layer which remains frozen. The fact that 
a pipeline is above-ground often means that the fluid being transported is 
at a temperature substantially higher than ambient temperature; therefore, 
the pipeline must be insulated to prevent undue heat loss from the fluid 
during transport and consequence viscosity increase. Furthermore, if the 
pipeline were not insulated, the heat generated by the transported fluid 
would melt the permafrost layer. 
A common technique for insulating pipelines is to apply rigid polyurethane 
foam to the exterior of steel pipe sections before they are delivered to 
the field for installation. Typically, such pipe sections are fabricated 
in lengths of twenty or forty feet with about nine inches of bare pipe 
exposed at each end to permit the welding of adjoining ends without 
melting any preapplied polyurethane foam adjacent the ends. This means 
that after installation, a short length of the pipeline, say about 
eighteen inches, spanning the weldment joining the pipe sections remains 
uninsulated. 
In ordinary climates, the uninsulated portion of the pipeline left after 
installation would be insulated by pouring polyurethane foam into a mold 
surrounding the uninsulated portion or by spraying such foam onto that 
portion. These application methods require, however, ambient temperatures 
of +40.degree. F. or above and such temperatures exist in many of the cold 
regions in question only for about one month each year. Further, these 
application methods may not be used during conditions of high humidity. At 
the present time, therefore, the adjoining ends of an entire length of 
pipeline may remain uninsulated for an extended period before conditions 
permit the foam application techniques just discussed. There exists, 
therefore, a need for some means of applying insulation to the uninsulated 
joints of a preinsulated pipeline immediately after the pipeline is 
installed and tested, regardless of ambient temperature or humidity. 
SUMMARY OF THE INVENTION 
The present invention provides a convenient, relatively inexpensive means 
for surrounding the uninsulated end portions of preinsulated pipe with 
insulation following the welding of those end portions and the testing of 
the weld. Further, the invention requires no elaborate or costly 
installation procedures or equipment and may be used at any ambient 
temperature and humidity. 
The present invention provides an insulation device for surrounding the 
uninsulated, adjoining end portions of a preinsulated pipe comprising a 
plurality of axially extending cylinder segments adapted to be 
circumferentially joined to form a cylindrical insulating jacket around 
the uninsulated end portions. The cylinder segments in their undeformed 
states have a length slightly greater than the combined length of the 
uninsulated adjoining end portions. The cylindrical insulating jacket has 
an inside diameter generally conforming to the outside diameter of the 
uninsulated end portions and an outside diameter generally conforming to 
the outside diameter of the preinsulated pipe. Each cylinder segment has 
at least a first pair of rigid arcuate sections and a first resilient 
arcuate section sandwiched therebetween. The first resilient arcuate 
sections of all of the cylinder segments are longitudinally positioned in 
the cylindrical jacket to fall substantially in the same transverse plane.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The preferred material for use in the present invention is polyurethane 
foam, a material well known to persons skilled in the art to be moldable 
into useful shapes having a range of densities and a corresponding range 
of insulating ("K") factors. Depending on the particular application of 
the present invention, persons skilled in the art will adjust the density 
of the polyurethane foam to achieve the needed strength and insulating 
parameters. Reference will be made herein to "rigid" material; in the case 
of polyurethane foam, "rigid" means a closed-cell material. Reference also 
will be made to "resilient" material; in the case of polyurethane foam, 
"resilient" means an open-cell material capable of deformation and having 
the tendency after deformation to resume its original shape. 
Referring now to the drawings, particularly to FIG. 1, there is shown two 
lengths 10 and 12 of preinsulated pipe. Typically, pipes 10, 12 are coated 
to within nine inches of each end portion 14, 16 with polyurethane foam 
18, 20; such pipe is well known and will be referred to hereinafter as 
"preinsulated pipe" in that the pipe is delivered to the field in that 
condition. 
To form a pipeline, the uninsulated end portions 14, 16 are joined by a 
weldment 22 at the junction defined by the joinder of end portions 14 and 
16. After installation, there remains, therefore, a section of pipe having 
a length indicated by the letter A that is not insulated and subject to 
the exterior environment. The present invention is intended to be inserted 
into the uninsulated section of pipe across the distance A. 
Referring now to FIGS. 2 and 3, there is shown one embodiment of the 
present invention comprising a cylinder which is designated generally by 
the reference numeral 24. Cylinder 24 consists of a plurality of axially 
extending segments of a cylinder (referred to hereinafter and in the 
claims as "cylinder segments"). In the embodiment depicted in FIGS. 2 and 
3, there are two cylinder segments 26, 28, each being a 180.degree. 
section, which are joined in longitudinal abutting relationship as 
indicated by the arrow 30 along the opposing longitudinally extending 
parting lines. Each cylinder segment 26, 28 includes three sections 32, 
34, 36. Sections 32 and 34 of cylinder segment 26 are constructed of rigid 
molded polyurethane foam and are identically reproduced in cylinder 
segment 28 in diametrically opposed relationship. Sandwiched between rigid 
sections 32 and 34 is a resilient section 36 which is constructed of 
resilient polyurethane foam. Sections 32 and 34 are joined to section 36 
by means of a rubber-based adhesive. Resilient sections 36 of cylinder 
segments 26, 28 likewise are diametrically opposed. As best shown in FIG. 
3, resilient sections 36 are positioned to overlie weldment 22 and thereby 
allow for any circumferential deviation of the pipe caused by weldment 22. 
Cylinder segments 26, 28 are constructed to have a length B (see FIG. 2) 
which is slightly greater than length A discussed above. At the time of 
installation, each cylinder segment 26, 28 is longitudinally compressed to 
a length slightly less than length A and inserted into position 
surrounding uninsulated pipe end portions 14, 16. The axial compression of 
each cylinder segment is made possible by the presence of a resilient 
section 36. 
The exterior surface of cylinder 24 is coated with a rubber-based coating 
to protect it against the adverse effects of moisture. This coating is 
necessary to close the exposed open cells of resilient sections 36 against 
moisture penetration. Cylinder 24 also may be fitted with a metal jacket 
to conform with the pipeline. The presence of resilient section 36 also 
supplies outwardly directed spring forces to hold the cylinder segment in 
place prior to completion of the installation of the present invention. 
The end surfaces 42 of cylinder 24 are coated with a polyurethane coating. 
After cylinder 24 is in place, cylinder segments 26, 28 are secured by a 
metal band 38 as shown in FIGS. 3 and 6. 
It may be seen that the resilient means included in cylinder 24 not only 
affords ease of installation, but also allows cylinder 24 to serve in 
effect as an expansion and contraction joint. That is, cylinder 24 can 
take up in an axial direction any cracks formed in the insulation, such 
cracks due to temperature induced expansion or contraction. Because of its 
construction, cylinder 24 also can absorb to a more limited degree radial 
expansion and contraction. Still further, resilient material may be 
attached to the ends of cylinder 24 to accommodate any irregularities on 
the inwardly facing end surfaces 44 of preinsulated pipe segments 10, 12. 
In the embodiment just discussed, it is clear that resilient sections 36 
extend radially from the pipe end portions 14, 16 to the exterior surface 
of cylinder 24. The insulating quality of resilient polyurethane foam is 
less than that of the rigid foam. Thus, the presence of resilient material 
across an entire radius of cylinder 24 affords the possibility of 
excessive heat loss from the fluid being transported. FIGS. 4 and 5 
illustrate a second embodiment of the present invention intended to 
minimize such heat loss. In FIGS. 4 and 5, like parts to parts of the 
first embodiment bear identical reference numerals with a prime affixed. 
As shown in FIGS. 4 and 5, cylinder segments 46, 48 of cylinder 24' are 
constructed in laminar form. The inner layers 50, 52 of cylinder 46, 48 
are constructed (except for dimension) identical to the cylinder segments 
26, 28 of the embodiment described above; that is, each layer is composed 
of three sections 32', 34' and 36'; sections 32', 34' being rigid and 
section 36' being resilient. The outer layers 54, 56 of cylinder segments 
46, 48 are constructed to conform to the outside surfaces of inner layers 
50, 52 and consist of three sections 58, 60, 62. Sections 58 and 60 of 
cylinder segment 46 are constructed of rigid molded polyurethane foam and 
are identically reproduced in cylinder segment 48 in diametrically opposed 
relationship. Sandwiched between rigid sections 58 and 60 of cylinder 
segment 46 is a resilient section 62 which is constructed of resilient 
polyurethane foam. Resilient section 62 is reproduced in cylinder segment 
48 in diametrically opposed relationship. The sections 58 and 60 are 
joined to section 62 by means of a rubber-based adhesive. 
As best shown in FIG. 4, resilient section 62 is offset from resilient 
section 36' in order to minimize the heat loss through the resilient 
polyurethane foam as discussed above. As shown in FIG. 4, resilient 
section 62 is offset to the left, but it will be understood that it may 
also be offset to the right if desired. This offsetting relationship 
eliminates any clear path through resilient (less insulating) material 
from the pipe to the outside environment. 
Outer layer 54, 56 is joined to inner layer 50, 52, respectively, by means 
of a rubber-based adhesive placed outboard of both resilient sections 36', 
62. The location of the adhesive in this manner is essential to permit 
cylinder segments 46, 48 to be longitudinally compressed. 
The manner of installing the laminated embodiment of the present invention 
shown in FIGS. 4-5 on the uninsulated end portions 14, 16 of a 
preinsulated pipeline is identical to that described above.