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A crack arresting device for limiting crack propagation in welded sheet structures, is made in the form of a multi-layer section of the structure, integrally interposed therein. At least in one layer of the section there is provided at least one slot located at an angle to a probable crack propagati

A crack arresting device for limiting crack propagation in welded sheet structures, is made in the form of a multi-layer section of the structure, integrally interposed therein. At least in one layer of the section there is provided at least one slot located at an angle to a probable crack propagation path.

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1. A crack arresting device for limiting propagation of cracks in a welded construction fabricated of a plurality of interconnected sections formed of sheets, said crack arresting device being made in the form of a multi-layer section integrally interposed between confronting edges of adjacent ones

1. A crack arresting device for limiting propagation of cracks in a welded construction fabricated of a plurality of interconnected sections formed of sheets, said crack arresting device being made in the form of a multi-layer section integrally interposed between confronting edges of adjacent ones of the interconnected sections formed of sheets, wherein at least in one layer of said multi-layer section there is provided at least one slot, spaced from the edges of the layer connected to the confronting edges of the adjacent ones of the sections formed of sheets and located at an angle to a probable direction of propagation of cracks from a first of the adjacent ones of the sections formed of sheets, the slot defining an open space within the at least one layer for stopping propagation of cracks from the first to a second of the adjacent ones of the sections formed of sheets, at both sides of a slot in an outer layer of said multi-layer section there are formed melted-through weld joints spaced from the confronting edges of the adjacent ones of the sections formed of sheets, with the fusion penetration exceeding the thickness of the layer containing the slot to thereby ensure tightness of the crack arresting device. 2. A crack arresting device according to claim 1, wherein slots are provided at least in two said layers of said multilayer section, said slots being brought in coincidence. 3. A crack arresting device according to claim 1, wherein said welded construction is a pipeline and said multi-layer section is a pipe in said pipeline, wherein at least two closely spaced apart slots are provided in the same layer, a first of said slots extending around a first portion of the circumference of the pipe and having spaced apart ends, a second of said slots extending around a second portion of the circumference of the pipe that includes the space between the ends of the first slot so that the first and the second slots together extend around the entire circumference of the pipe. 4. A crack arresting device according to claim 1, wherein in the case of said welded construction fabricated of sheets being a pipeline, said multi-layer section is made in the form of a pipe whose layers are arranged along a spiral normal to the longitudinal axis of the pipe. 5. A crack arresting device according to claim 4, wherein slots are provided at least in two layers of said multilayer section, said slots coinciding at least in two layers of said multilayer section. 6. A crack arresting device according to claim 4, wherein at both sides of a slot provided in an outer layer of said multi-layer section there are formed melted-through weld joints spaced from the confronting edges of the adjacent ones of the sections formed of sheets, with the fusion penetration exceeding the thickness of said slot to thereby ensure thightness of the crack arresting device. 7. A crack arresting device according to claim 4, wherein at least two slots are provided in said multi-layer section, said slots being located parallel to each other. 8. A crack arresting device according to claim 4, wherein at least one layer of said multi-layer section is made continuous. 9. A crack arresting device according to claim 1, wherein the length of each said slot is equal at least to one perimeter of said multi-layer section.