5 Design 5.1 General 5.1.1 The desi

5 Design 5.1 General 5.1.1 The design shall incorporate guiding arrangements necessary to ensure consistent operation and seat tightness. 5.1.2 The seat of a safety valve, other than when it is an integral part of the valve shell, shall be fastened securely to prevent the seat becoming loose in service. 5.1.3 In the case of valves where the lift can be reduced to conform to the required discharge capacity, restriction of the lift shall not interfere with the operation of the valve. The lift restricting device shall be designed so that, if adjustable, the adjustable feature can be mechanically locked and access sealed. The lift restricting device shall be installed and sealed in accordance with the design of the manufacturer. Valve lift shall not be restricted to a value less than 30 % of unrestricted lift or 1 mm, whichever is the greater. 5.1.4 Means shall be provided to lock and/or to seal all external adjustments in such a manner so as to prevent or reveal unauthorized adjustments of the safety valve. 5.1.5 Safety valves for toxic or flammable fluids shall be of the closed bonnet type to prevent leakage to atmosphere, or if vented, it shall be disposed of in a safe place. 5.1.6 Provision shall be made to prevent liquid collecting on the discharge side of the safety valve shell.