(i) Literally, to cave in or give way. (ii) The sudden and dangerous distortion of any part of a boiler or pressure plant by bending or crushing caused by steam, gas or fluid pressure whether attended by rupture or not. It shall not mean any slowly developing deformation due to any cause.
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UK: 1. An insured risk under boiler and pressure plant insurance. It means ‘the sudden and dangerous distortion (whether or not attended by rupture) of any part of the plant caused by crushing stress by force of steam or other fluid pressure (other than pressure of chemical action, or chemical action or ignition of the contents of ignited flue gases)’. 2. Under a buildings policy, collapse has been held to mean: ‘falling, shrinking together with breaking down or giving way through external pressure, or loss of rigidity or support’. It is commonly the outcome of subsidence. Collapse does not cover intentional demolition unless necessary in the course of remedial work consequent upon an insured event such as subsidence.
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A property insurance peril, subject to its own specific agreement in property policies, that otherwise insure on an open perils basis.