The present invention relates to an insulation element for thermal insulation of piping and similar objects.

The invention also concerns an apparatus to be used in the installation of the elements according to the invention.

Elements for thermal insulation on piping and similar objects such as containers are known in the art, which elements consist of a thermal insulation layer of mineral wool and a sheath bonded to one side of said layer. The sheath is made from a material of high tensile strength selected according to the intended application. Thin sheet metal is employed particularly for the sheath of an insulation element for outdoors mounted pipes. Such ther¬ mal insulation elements are conventionally manufactured in planar sheet form and also transported to the instal¬ lation site as stacked and bundled planar elements.

The elements are dimensioned according to the installati¬ on site requirements so that the element is designed to be bent in one direction that permits wrapping the element about the object to be insulated such as a pipe so as enclose the object, whereby the abutting ends of the element can be joined to form an insulating jacket around the pipe or similar object. Such jacket elements are then mounted end-to-end in succession to achieve a continuous insulating jacket, whose longitudinal seams are made using certain joining structures to be described later in detail.

Such elements are primarily used in thermal insulation of large-diameter pipes (with diameters in the range of ap- prox. 0.3 - 1.5 m and insulation thicknesses in the range of approx. 50 - 250 mm) , whereby insulation element al¬ ready becomes so large and heavy as to have an impact on

the stress dimensioning of the insulation element. The installed element will impose its weight on the top of the pipe with the mineral wool layer of the element res¬ ting against the pipe, whereby the rigidity of the ine- ral wool layer must be dimensioned sufficiently stiff to take the element weight without compressing. A method of fulfilling this requirement is to produce the insulation layer from a mineral wool grade having sufficient compressive strength to sustain the weight of the thermal insulation element.

However, the above approach gives rise to a flexibility problem of the mineral wool. A wool possessing sufficient compressive strength becomes so stiff as not to permit bending of the insulation about the pipe any more. Con¬ ventionally, this disadvantage has been overcome by pro¬ viding the insulation layer with tapering grooves which are cut perpendicular to the bending direction so as to extend over the entire width of the insulation element. These grooves provide void spaces which facilitate bend¬ ing the insulation about the object to be insulated. How¬ ever, the fabrication of such grooves is a demanding work phase and their dimensioning must be separately preci¬ sion-tailored according to the diameter of each object to assure full closure of the grooves in an assembled element.

Another approach to providing sufficient compressive strength is based on using a mineral wool grade of higher compressive strength only for those areas of the insula¬ tion element that, when assembled remain facing the top of the object being insulated. Then, an insulation material of lower compressive strength can be used for the rest of the element. This arrangement solves the problem of insufficient compressive strength of the insu¬ lation with the penalty of requiring extra work phases during the manufacture of the element in order to provide

the insulation areas of different compressive strength. Further, correct alignment of such an insulation element on the object being insulated is a prerequisite during the installation of the element.

The above-mentioned problems associated with conventional thermal insulation elements are essentially overcome by virtue of an insulation element according to the inven¬ tion, which in a manner analogous to conventional thermal insulation elements is comprised of a mineral wool blan¬ ket and a sheath layer such as sheet metal covering the blanket one-sidedly and bonded thereto, whereby at least one linear dimension of said element is essentially equal to perimeter length of the object to be insulated, said element being characterized in that said insulation blan¬ ket is comprised of mineral wool which during the manu¬ facturing phase is compressed in one linear dimension and that said insulation blanket is placed in the thermal insulation element so that its compressed dimension is aligned essentially parallel to intended bending direc¬ tion of the element during its installation.

The manufacture of the mineral wool blanket in a manner comprising compressing the blanket in one linear dimen- sion during the manufacturing process is known in the art. Detailed description of such manufacturing techniques are to be found in, e.g., publication WO 91/14816. Using such compressing or folding-by- collapsing steps, the fiber orientation of the fiber blanket is modified such that makes the dominating fiber orientations formed in the blanket to resemble a fluted pattern in which the flutes are oriented crosswise per¬ pendicular to said folding direction. A manufacturing technique known in the art is based on folding by collapsing, that is, subjecting the blanket being formed to longitudinal compression in the machine direction of the blanket web. Then, the flutes are formed perpendicu-

lar to the machine direction of the blanket under forma¬ tion. The flutes are made to have in the finished blanket a high crest amplitude extending essentially across the entire thickness of the blanket.

The alternatingly varying dominating fiber orientation inside the mineral wool blanket renders the blanket an essentially improved compressive strength in the thick¬ ness dimension of the blanket. Hence, a given compressive strength can be attained by a mineral wool of lower den¬ sity than that of a conventionally manufactured insulat¬ ing material blanket. Such a mutually advantageous combi¬ nation of properties is characteristic in thermal insula¬ tion products to which the present invention is related. The needed self-supporting compressive strength of the insulation is achieved using a mineral wool grade of sub¬ stantially low specific weight, which in turn reduces the compressive strength required from the insulation inner surface area meeting the gravity load imposed by the insulation itself. Another essential characteristic of the present invention is the inherent property of the mineral wool insulation processed through the collapsing step to exhibit easy bending along the flutes. This easy bending is further enhanced by the lower specific weight of the mineral wool.

The utilization of the above-described qualities also results in a thermal insulation element having after installation an insulation layer with an increasing den- sity from its outer perimeter toward its inner perimeter. Due to the bonding of the insulation layer to the outer sheath, the outer perimeter of the fluted insulation will not be stretched during the bending of the element about a circular object, but rather, the bending of the element causes the insulation to become shaped so that the insu¬ lation will be compressed in the tangential bending direction the tighter the closer the considered point of

insulation is to the inner perimeter of the circularly bent insulation layer. This is a most advantageous prop¬ erty for a thermal insulation, because hereby insulation of highest specific density is brought closest to the perimeter of the hot surface to be insulated. Improved compressibility is further enhanced by the fact that the bulk density of the mineral wool can be lighter than that of a mineral wool grade manufactured for use in conven¬ tional insulation products. An insulation element thus manufactured may easily achieve a 50 % compressibility at the inner perimeter of the insulation element bent on site about the object. The initial bulk density of the mineral wool may be varied in the range 50 - 100 kg/m ³ , advantageously in the range 75 - 90 kg/m ³ .

The apparatus according to the invention for installation of the thermal insulation element comprises a lift-mov¬ able and lift-operated dual-gripper assembly having a first, single-piece grip palm member with a radius of curvature equal to the desired radius of bending of the outer perimeter of the element after bending and a sec¬ ond, grip member comprising finger elements extending outward in opposite directions from the edges of the first grip palm member, said finger elements having a radius of curvature equal to the desired radius of bend¬ ing of the outer perimeter of the element after bending and said finger elements further being dimensioned to meet at their distal ends essentially at the longitudinal seam jointing area of the insulation element being installed, and further comprising suction cup elements for grabbing and supporting the insulation element being installed. According to the invention, the structure of the gripper is improved so that the suction cup elements are dimensioned to support the thermal insulation element during the initial bending of the element into an essen¬ tially U-shaped form.

In the following the invention will be examined in greater detail with reference to the appended drawings in which

Figure 1 is a diagrammatic perspective view of a thermal insulation element according to the inven¬ tion still in its planar shape;

Figure 2 is a side view of a preferred embodiment of one edge of the thermal insulation element cross- sectioned along the bending direction;

Figure 3 is a side view of another preferred embodi¬ ment of the corresponding edge;

Figure 4 is a side view of a third preferred embodi¬ ment of the corresponding edge;

Figure 5 is a side view of an installation apparatus according to the invention shown grabbing a thermal insulation element which still is in its planar transportation position;

Figure 6 is a side view of the installation appar- atus holding the thermal insulation element in its initial bending phase; and

Figure 7 is a side view of the installation appar¬ atus in an operating phase in which the thermal insulation element to be installed is bent into its ready-to-mount, essentially U-shaped form.

Referring to Fig. 1, the thermal insulation element in the illustrated embodiment is shown in a horizontal posi- tion, whereby the fluted shape of the mineral insulation wool blanket is visible in an exaggerated form along the front edge of the element. Onto the insulation wool blan-

ket is bonded a sheath plate 2 which advantageously is of sheet metal. The plate may be of any other material hav¬ ing sufficient tensile strength to keep the element outer surface unbroken during the bending of the element onto the object to be insulated. The sheet metal is conventionally of corrosion-coated sheet steel having a thickness of 0.5 - 0.75 mm. The illustrated fluted form of the insulation blanket infers that the insulation wool has during the manufacturing step been collapsed in the direction of the fluted form, that is, in the direction of arrow B in Fig. 1. An important dimension of the ther¬ mal insulation element is dimension A, which must be trimmed according to the diameter of the object being insulated so that the meeting ends of the insulation element mate when the element is completely wrapped about the object being insulated. Preferredly, the edge of the sheath is extended over one edge of the abutting insula¬ tion layer ends so far as to make the sheath layers par¬ tially overlap at the seam area, whereby the seam of the overlapping sheath layers can be easily secured by virtue of the seam lip 2" thus formed. The bending direction C of the insulation element and thus also the direction of dimension A must be selected as shown in Fig. 1.

The joining of the abutting ends of the element in its bending direction C can be performed using any known joining method such as rivet fasteners or screws. An advantageous method herein is to join the overlapping lips of the sheath 2 along this seaming area of the adjoining element edges by piercing holes through the superimposed sheath lips with a punching tool at constant spacings along the seam. Then, the sheath material is burst inward at the pierced hole making burrs about it, whereby the two superimposed sheath material layers will be fastened to each other. Simultaneously, the thus formed holes provide natural vent holes for the conden¬ sate possibly tending to accumulate in the insulation.

Obviously, the latter joining method necessitates align¬ ing the joining area of the element, that is, the longi¬ tudinal closing seam of the element essentially to the underside of a horizontally mounted heat-insulating pipe jacket.

The opposite element edges running parallel to the bend¬ ing direction of the elements, that is, the circular ends of the bent element must also be designed so that at least one of the element edges has a provision capable of firstly assuring sufficient continuity of the insulation at the adjoining ends of elements successively placed one after another on a pipe or similar object being insulat¬ ed, and secondly, of exhibiting sufficient weather-proof- ness in service under exposure to outdoor conditions.

These kinds of particular details related to the element edge are illustrated in Figs. 2-4. A characterizing prop¬ erty therein is the overlapping of the sheath 2 from one element edge over the end of the insulation layer to the next adjoining element in the same fashion as described above for the abutting bent ends of the insulation element itself. This approach provides one end of the bent element with a seam flange 2• , which in the ready- installed element forms a circular clamp about the end seam area. In a practical installation situation, the sheath extension forming the circular flange is arranged to the downhill end of the bent insulation element to avoid the entry of drip water into the seam.

When placing the elements successively one after another on the object being insulated, also the continuity of insulation must be assured by a design permitting close abutting of the element ends. In the embodiment shown in Fig. 2, this is implemented by leaving the insulation layer 1 unbonded by glue 3 to the sheath 2 at the very end of the element. Thus, the sheath 2 at the edge area 4 of the insulation layer is prevented from hindering the

compressibility of the insulation layer when the element is pushed against the end surface of the preceding element during installation.

Referring to Fig. 3, a corresponding effect is achievable by an arrangement illustrated therein having the end area 4' of the insulation layer made porous by a mechanical treatment resulting in the breaking of fiber bonds in the insulation blanket. Also such a worked end of the insula- tion layer is capable of mating tightly with the end of the opposing element during installation when the elements are pushed abutting end-to-end on the object being insulated.

Referring to Fig. 4, a similar effect mimicking porosity is achievable by means of the illustrated embodiment wherein the insulation layer at that element edge which is to be pushed against the end of the preceding element is processed to contain clefts 5 which run along the direction of the edge and are cut to a defined depth 4" thus improving the compressibility of the edge under com¬ pression when the element edges are pushed abutting.

The installation apparatus according to the invention is based on a conventional dual-gripper design employed in the art having independent finger elements 7 and 8 extending outward in opposite directions from the edges of a common grip palm member 6. The finger members 7 and 8 are attached by pivotal joints to the opposing edges of the palm member 6 and are provided with suitable actuator means to open and close the finger members. In the open position, the distal ends of the finger members and the edges of the palm member are aligned essentially into the same plane, in which position the installation apparatus can be lowered onto an insulation element to be installed in place, onto the sheath of the element still lying flat in its transport package.

The installation apparatus is provided at the joint area of the finger members with high-power suction cups 9. The suction cups are adapted to the ends of jointed arms 10 having the arms attached to the pivotal joints of the finger members so that the suction cups can conform to the shape of the insulation element during its bending. The suction cups 9 are dimensioned to have sufficient holding power to support the insulation element during its bending into its installed shape by closing the fin- ger members of the installation apparatus toward each other. This bending step is carried on until the insula¬ tion element has assumed an essentially U-shaped form. In this form the element can be threaded onto the object to be insulated in the most confined shape of the element thus requiring minimum working space about the installa¬ tion site.

According to a characterizing property of the invention, the fingers of the installation apparatus finger members are adapted so adjustable relative to each other that the distance between the fingers can be varied during instal¬ lation. Such a provision may be desirable in cases where, e.g., a protruding obstacle must be negotiated at the installation site.

According to another characterizing property of the invention, the fingers or at least the ends of some fin¬ ger elements of the installation apparatus are provided with means for securing the longitudinal seam of the insulation element in the installation situation where the element is already bent with the help of the instal¬ lation apparatus about the object to be insulated into a position having the longitudinal seam ends abutting. Such means may comprise, e.g., compressed-air operated punch- ing tools suited to pierce holes at each finger through the superimposed sheath lips of the insulation element thus riveting the sheath lips together.