Fire-rated modular duct assembly suitable for exhausting flammable or hazardous gases, vapours and other materials

1. A modular fire-rated exhaust duct assembly comprising:

two or more exhaust duct modules;

each of said exhaust duct modules having an inner duct liner and an outer casing, and a void being formed between at least a portion of space between said inner duct liner and said outer casing, said void being configured for receiving an insulation material, and including one or more insulation encapsulation sections configured to connect to said inner duct liner and said outer casing to contain said insulation material in said void;

a first exterior flange connector, and one end of each of said exhaust duct modules being configured for receiving said first exterior flange connector;

a second exterior flange connector, and another end of each of said exhaust duct modules being configured for receiving said second exterior flange connector;

said first and said second exterior flange connectors being configured to form a field assembly junction for coupling respective ends of said exhaust duct modules to form a single exhaust duct run, and said field assembly junction comprising a plurality of holes in each of said first and said exterior flanges, said plurality of holes being in alignment on said first and said exterior flanges, and being configured to receive a detachable fastener; and

a joint encasement section configured to be field connectable to each of said exhaust duct modules and encase said junction.

2. The modular fire-rated exhaust duct assembly as claimed in claim 1 , wherein said exhaust duct modules have a generally rectangular cross-section.

3. The modular fire-rated exhaust duct assembly as claimed in claim 2 , wherein said inner duct liner comprises a flange configured to be affixed to said first and said second exterior flange connectors.

4. The modular fire-rated exhaust duct assembly as claimed in claim 1 , wherein said inner duct liner and said outer casing are formed from a metallic material, and each having a thickness to provide a specified fire rating.

5. The modular fire-rated exhaust duct assembly as claimed in claim 1 , wherein said insulation capsulation sections have a profile comprising one of a flat profile, a step profile, a sawtooth profile and an accordion profile.

6. The modular fire-rated exhaust duct assembly as claimed in claim 1 , wherein said joint encasement section comprises a plurality of joint encasement sections, each of said joint encasement sections comprising an outer layer and an inner layer, and said outer layer having a flange on each longitudinal edge for affixing said encasement section to respective ends of said adjacent exhaust duct modules.

7. The modular fire-rated exhaust duct assembly as claimed in claim 6 , wherein said outer casing is formed from a metallic material having a thickness sufficient to provide a specified fire rating and said outer layer of said joint encasement section comprises the same metallic material.

8. The modular fire-rated exhaust duct assembly as claimed in claim 7 , wherein said joint encasement sections are configured to be field attachable to said respective surfaces of the said exhaust duct modules.

9. An exhaust duct module configured to be assembled in the field to form a fire-rated exhaust duct assembly, said exhaust duct module comprising:

an inner duct liner formed with a generally rectangular cross-section;

an outer casing formed with a generally rectangular cross-section and being sized to substantially surround said inner duct liner;

a first flange connector configured to be attached to one end of said inner duct liner and one end of said outer casing, and couple said inner duct liner to said outer casing;

a second flange connector configured to be attached to one end of said inner duct liner and one end of said outer casing, and couple said inner duct liner to said outer casing; and

said first flange connector and said second flange connector being configured to be field attachable to couple another exhaust duct assembly comprising a first exterior flange connector and a second exterior flange connector, wherein said first flange connector comprises a plurality of holes configured to be aligned with a plurality of holes on said first exterior flange connector, and said second flange connector comprises a plurality of holes configured to be aligned with a plurality of holes on said second exterior flange connector, and being configured to receive a detachable fastener.

10. The exhaust duct module as claimed in claim 9 , wherein said inner duct liner comprises a flange configured to be affixed to said first and said second flange connectors.

11. The exhaust duct module as claimed in claim 9 , wherein a void is formed in at least a portion of a space separating said inner duct liner from said outer casing.

12. The exhaust duct module as claimed in claim 11 , further including a plurality of insulation encapsulation sections configured to connect to said inner duct liner and said outer casing to close in said void space.

13. The exhaust duct module as claimed in claim 12 , further including a thermal insulation material substantially filling said void space between said inner duct liner and said outer casing.

14. The exhaust duct module as claimed in claim 13 , wherein said inner duct liner and said outer casing are formed from a metallic material, and each having a thickness to provide a specified fire rating.