The provisions on kitchen chimneys in Code for Fire Prevention in Rural Areas (GB51139-2111):

6.1.2 Stoves, flues, chimneys, fire resistance, etc. used for cooking and heating should be constructed or made of incombustible materials. The wall thickness of the parts adjacent to combustible objects shall not be less than 241mm.

when the chimney passes through a flammable or flame-retardant roof, the smoke outlet should be not less than 511mm higher than the roof, and it should be plastered tightly with incombustible materials from the ceiling to the roof layer.

when the flue directly opens the smoke outlet on the external wall, the external wall should be incombustible and the smoke outlet should protrude at least 251mm from the external wall.

6.1.3 when the chimney passes through the combustible insulation layer and waterproof layer, non-combustible materials should be used as the insulation layer within 511mm around it, and it is forbidden to open chimney cleaning holes in the stuffy roof.

the code for fire protection design of buildings (GB51116-2114) specifies the oil fume exhaust pipe:

9.3.12 The vertical exhaust pipes in bathrooms, toilets and kitchens of public buildings should take measures to prevent backflow, and the branch pipes should be equipped with fire dampers with a nominal operating temperature of 71℃.

The oil fume exhaust pipe in the kitchen in the public building should be set according to the fire partition, and the branch pipe connected with the vertical exhaust pipe should be set with a fire damper with a nominal operating temperature of 151℃.

Extended information:

In the Code for Fire Protection Design of Buildings, in order to prevent the fire from spreading through the vertical exhaust pipes (natural exhaust or mechanical exhaust) in bathrooms, toilets and kitchens in buildings, it is required that the vertical exhaust pipes in these parts take backflow prevention measures and try to set fire valves on their branch pipes.

Due to the high temperature of exhaust gas discharged from normal operation in the kitchen, if a fire damper operating at 71℃ is installed on the vertical exhaust pipe, it will affect the exhaust air in normal kitchen operation.

according to the needs of kitchen operation and the temperature of common fires in the kitchen, it is stipulated that the joint between the branch pipe of the oil smoke exhaust pipe and the vertical exhaust pipe in the kitchen of a public building should be provided with a fire damper that operates at 151℃, and at the same time, the oil smoke exhaust pipe should be set as far as possible according to the fire zone.

Miluo Municipal People's Government-Announcement on Issuing National Standard "Code for Fire Prevention in Rural Areas"

Ministry of Housing and Urban-Rural Development-Announcement on Issuing Partial Revision of National Standard "Code for Fire Prevention in Building Design"