Factories Act 1961

31 Precautions with respect to explosive or inflammable dust, gas, vapour or substance. E+W+S

(1) Where, in connection with any grinding, sieving, or other process giving rise to dust, there may escape dust of such a character and to such an extent as to be liable to explode on ignition, all practicable steps shall be taken to prevent such an explosion by enclosure of the plant used in the process, and by removal or prevention of accumulation of any dust that may escape in spite of the enclosure, and by exclusion or effective enclosure of possible sources of ignition.

(2) Where there is present in any plant used in any such process as aforesaid dust of such a character and to such an extent as to be liable to explode on ignition, then, unless the plant is so constructed as to withstand the pressure likely to be produced by any such explosion, all practicable steps shall be taken to restrict the spread and effects of such an explosion by the provision, in connection with the plant, of chokes, baffles and vents, or other equally effective appliances.

(3) Where any part of a plant contains any explosive or inflammable gas or vapour under pressure greater than atmospheric pressure, that part shall not be opened, except in accordance with the following provisions:—

(a) before the fastening of any joint of any pipe connected with the part of the plant or the fastening of the cover of any opening into the part is loosened, any flow of the gas or vapour into the part or into any such pipe shall be effectively stopped by a stop-valve or otherwise;

(b) before any such fastening is removed, all practicable steps shall be taken to reduce the pressure of the gas or vapour in the pipe or part of the plant to atmospheric pressure;

and if any such fastening has been loosened or removed, no explosive or inflammable gas or vapour shall be allowed to enter the pipe or part of the plant until the fastening has been secured or, as the case may be, securely replaced; but nothing in this subsection applies to a plant installed in the open air.

(4) No plant, tank or vessel which contains or has contained any explosive or inflammable substance shall be subjected—

(a) to any welding, brazing or soldering operation;

(b) to any cutting operation which involves the application of heat; or

(c) to any operation involving the application of heat for the purpose of taking apart or removing the plant, tank or vessel or any part of it;

until all practicable steps have been taken to remove the substance and any fumes arising from it, or to render them non-explosive or non-inflammable; and if any plant, tank or vessel has been subjected to any such operation, no explosive or inflammable substance shall be allowed to enter the plant, tank or vessel until the metal has cooled sufficiently to prevent any risk of igniting the substance.

(5) The chief inspector may by certificate grant, subject to any conditions specified in the certificate, exemption from compliance with any of the requirements of subsections (3) and (4) of this section in any case where he is satisfied that compliance with the requirement is unnecessary or impracticable.