WO1989008178A1

WO1989008178A1 - Container element

Info

Publication number: WO1989008178A1
Application number: PCT/FI1989/000032
Authority: WO
Inventors: Antero Salakari
Original assignee: Antero Salakari
Priority date: 1988-02-26
Filing date: 1989-02-17
Publication date: 1989-09-08
Also published as: FI880914A0; AU3185189A; FI880914A

Abstract

The invention concerns a container element, which is bent to a desired radius of curvature, for producing a container with, e.g., a circular cross section. According to the invention, the element is comprised of an inner part (1, 1') forming the inner lining of the container and fabricated from a sheet-like, hard, pliable material; an outer part (3, 3') forming the outer lining of the container and fabricated from a sheet-like, hard, pliable material; and an intermediate part (2), arranged between the inner part (1, 1') and the outer part (3, 3') and fabricated from a heat-insulating material; and recesses are arranged to those rims of the element to be mated with the other elements, which recesses are situated both between the inner part (1) and the intermediate part (2) as well as between the outer part (3) and the intermediate part (2) and extend over the entire length of the element rim, whereby each pair of rims in the two adjacently abutting elements form contiguous inner (4) and outer (5) cavities in order to simplify mounting and inspection operations.

Description

Container element

The present invention relates to a container element in accordance with the preamble of claim 1.

The conventional method for constructing a container requires that when the shell section of the container is being manufactured, its sections are fabricated from steel plate, whose thickness is determined according to dimensioning rules of containers. In the conventional method, the manufacturing of the shell sections is handled in the heavy workshop industry, where the sheet is trimmed to correct dimensions by shearing or torch cutting, after which the edges are bevelled for welding and the sheets are rolled to correct radius of curvature. In the installation stage the sections are lifted by a crane to their correct places, where generally several welders locate the section appropriately by welding tacks. This operation requires sturdy supports both inside and outside the container. After the container is ready assembled, it is sand-blasted and coated with an corrosion-protection paint on both sides. The sections may be primer-coated, whereby only touch-up treatments are required after the assembly weldings, if the container requires a heat-insulation, the insulation must be mounted on attachments fixed by welding. The outer lining sheets are fixed to the same attachments.

If the container is made for food or process industry, it must usually be fabricated from stainless or acid-proof steel, whose dimensioning is performed using the general design rules applicable to containers.

Disadvantages of the conventional technology are appreciated as follows:

- dimensions of sections usable in assembly are limited by their weight and the relatively low stiffness of a bent steel sheet, - production costs are high,

- transportation costs are high due to the great weight of the sheets, and

- maintenance costs are high (due to the recurring need for recoating treatment) .

The aim of this invention is to overcome the disadvantages associated with the prior art technology described above and to achieve a totally new kind of a container element for containers with a circular cross section.

The invention is based on manufacturing the element in a layered fashion (sandwich structure) and adapting recesses in the insulation layer at the rims of the elements for welding and inspection.

More specifically, the container element in accordance with the invention is characterized by what is stated in the characterizing part of claim 1.

The invention provides outstanding benefits.

Sheet thickness in the inner lining is decreased as the strength properties of a sandwich structure can fully be utilized. As a rule, the sheet thickness used is decreased to an order of about 2 mm, while sheet thicknesses up to 20 mm are used in conventional container constructions.

A corollary from the above is that corrosion-protection treatment of the inner lining can be omitted as the reduced material quantity makes it feasible to use stainless and acid-proof steels as materials for the inner lining. If for reasons of cost, the use of steel sheet in combination with a separate corrosion-protection treatment is considered desirable, this naturally is also possible. Work performed on the construction site is reduced essentially. The prefabrication of the elements can be carried out so that part of the joints are completed prior to transportation to the construction site, and the container construction is transported in the form of large elements to the construction site. With the increased stiffness of sandwich structures, the dimensions of large elements can be selected to be as large as possible (e.g., 3.0 x 12.0 m) , which requires only a minimum of joints to be made on the construction site. Further, this reduces the total delivery time and allows control over the generally uncontrollable installation costs. In addition, transportation costs are reduced in comparison with those of the conventional technology. Scaffold operations are significantly reduced, because the separate heat insulation and outer lining installations become unnecessary.

Installation of large-volume containers is simplified, when installation work is performed outdoors in the wintertime, the container can be assembled in such a sequence that the majority of weldings are performed only after the preassembly of the container, which allows the heating of the container interior. The weld seams can be x-ray inspected after the welding of the inner lining in a single operation.

The required welding work is significantly reduced. When thin sheets are used, no two-sided welding is required.

Element fabrication can be performed using straight, unbent and standard size sheets, which conform in the laminating press to a desired shape. Equally, welding bevelling becomes unnecessary.

The elements in accordance with the invention achieve a container construction, in which the loads computed according to the theory of strength conventionally applied to container constructions, with the exception of tensile stress placed on the inner lining, are met by the aggregate stiffness of the sandwich construction (i.e., buckling and the effect of wind loading) . The element construction facilitates the welding of the inner lining in a container construction with sandwich-element structure as well as the integrity inspection of the weld seam by X-ray photography.

The invention is next examined in greater detail with help of the exemplifying embodiment illustrated in the attached drawings.

Figure 1 shows in a perspective view a container fabricated from elements in accordance with the invention.

Figure 2 shows a section A-A for the container illustrated in Fig. 1.

Illustrated in Fig. 2 is a joint of two elements. An inner lining sheet 1 is fabricated from corrosion-resistant metal sheet. A heat insulation 2 is of foamed plastic (polyurethane, phenol formaldehyde, polystyrene or PVC foam), foamed glass or aerated concrete. An outer lining sheet 3 is of metal, reinforced plastic or veneer sheet. A most advantageous selection for the material of the outer lining sheet 3 is generally a plastic-coated steel sheet, whose rims are inwardly bent to a groove 5 as illustrated in Fig. 2. Part of the heat insulation is removed from the rims of the element, whereby the rim grooves of two adjacent elements for an inner cavity 4 and an outer cavity 5, which extend over the entire rim of the element. In the inner cavity 4, on the outer surface of the container inner lining sheet 1, it is possible to weld steel plate guides 6, which aid in the assembly. In all cases, however, the most recommendable alternative is to select metal sheet for the material of both the inner lining sheet 1 and the outer lining sheet 3.

The purpose of the inner cavity 4 is to form a space behind the inner lining sheet that offers the possibility for welding the inner lining sheet l to the adjacent inner lining sheet l¹ without the danger of uncontrolled melting, gasification or burning of the heat insulation, thus causing a possibly irreparable crater in the heat insulation.

The inner cavity 4 forms a continuous space, into which an X-ray film 7 can be inserted when the seam must be inspected by X-ray photography. Film insertion is performed through a hole in the outer lining and heat insulation by means of such a cable, pull wire or cotton line which has been inserted prior to the start of welding operations. When the required X-ray photographs have been taken in an acceptable manner, the inner cavity 4 can be filled with an appropriate foam material, e.g., foamed bitumen.

The dimension of the inner cavity 4 in the direction of the element plane is about 40...60 mm, preferably about 50 mm, and the dimension of the cavity 4 in the direction perpendicular to the element surface is about 10...20 mm, preferably about 15 mm.

Correspondingly, the dimensions of the outer cavity 5 are both in the direction of the element plane as well as in the perpendicular direction about 15...25 mm, preferably about 20 mm.

The outer surface of the outer cavity 5 is formed by outer lining sheets 3 and 3' , whose rims are advantageously bent inwardly when the sheet is fabricated from metal, whereby the rims adhere to the cast plastic during the casting operation of the cavity, thus forming a water-tight joint, capable of transferring stresses. The plastic material preferably used in casting is a polyurethane elastomer due to its good adherence and mechanical properties.

The container is advantageously fabricated from standard- size sheet elements, which can be preassembled at the factory into sections of a convenient size taking into account the requirements set by installation and transportation.

Claims

WHAT IS CLAIMED IS:

1. A container element bent to a desired radius of curvature for producing a container with, e.g., circular cross section, c h a r a c t e r i z e d by

- an inner part (1, 1• ) , which forms the inner lining of the container and is fabricated from a sheet-like, hard, pliable material,

- an outer part (3, 3' ) , which forms the outer lining of the container and is fabricated from a sheet-like, hard, pliable material, and

- an intermediate part (2), which is arranged between the inner part (1, 1• ) and the outer part (3, 3') and is fabricated from a heat-insulating material, wherein recesses are arranged to those rims of the element to be mated with the other elements, which recesses are situated both between the inner part (1) and the intermediate part (2) as well as between the outer part (3) and the intermediate part (2) and extend over the entire length of the element rim, whereby each pair of rims in the two adjacently abutting elements form contiguous inner (4) and outer (5) cavities in order to simplify mounting and inspection operations.

2. A container element in accordance with claim 1, c h a r a c t e r i z e d in that the dimension of the inner cavity (4) in the direction of the element plane is about 40...60 mm, preferably about 50 mm, and the dimension of the cavity (4) in the direction perpendicular to the element surface is about 10...20 mm, preferably about 15 mm.

3. A container element in accordance with claim 1 or 2, c h a r a c t e r i z e d in that the dimensions of the outer cavity (5) are both in the direction of the element plane as well as in the perpendicular direction about 15...25 mm, preferably about 20 mm.

4. A container element in accordance with any of the foregoing claims, c h a r a c t e r i z e d in that the rim of the element's outer part (3) is inwardly bent toward the intermediate part (2) in the outer cavity (5).

5. A container element in accordance with any of the foregoing claims, c h a r a c t e r i z e d in that the inner part (1, 1') is of a corrosion-resistant metal sheet, e.g., stainless steel sheet.

6. A container comprising elements in accordance with claim 1, c h a r a c t e r i z e d in that the cavities (4 and 5) are filled with a heat-insulating material, e.g., a polyurethane elastomer in order to provide heat insulation to the seam between the container elements and to provide a possibly required bonding of the outer parts (3, 3^! ) to each other.