Gas & Watertight Access Covers
Gas-tight manhole covers and frames are often used to prevent odours from emitting from the services below. However, gas-tight access covers are also watertight covers and can prevent water ingress into the services also.
There are a number of international standards relating to Access Covers… and whilst most of the world looks to the European Standard EN124, it is the Australian Standard, AS3996 which provides the industry and manufacturers a method of testing covers for gas-tightness and water-tightness. AS3996 was updated in 2019 and continues to lead the way globally for in-depth testing methodology for access covers.
Please note the product standard (AS3996) underwent a significant overhaul in 2019 resulting in the new standard which we follow. The previous edition was dated 2006 and the industry has adopted the 2019 edition as the standard to follow. Please ensure your products are meeting the requirements and tested to the correct AS3996:2019.
Details of the load ratings for AS3996:2019 and EN124 can be found here.
Mascot Engineering have been manufacturing gas and airtight covers since the 1970’s. Our first significant project was for the NSW Parliament House, which also included our largest multipart cover assembly to date… a 100 part multipart with multiple beams which is still in place today.
Given the design of our gastight and watertight covers and frames are similar through the load ratings and sizes, we don’t do third party accredited tests for every cover we manufacture, instead choose specific products to ensure our methodology of design and the parameters we work to in manufacture and machining are correct.
Clause 2.3.4 of AS3996:2019 defines Watertightness:
“When covers are tested in accordance with Appendix E, there shall be no visible leakage under a 150mm head of water for 10 minutes.”
Details of test methodology for Appendix E are below.
Clause 4.2.5 of AS3996:2019 defines Gas-Tightness:
“When covers are tested in accordance with Appendix F, there shall be no drop in pressure for 10 minutes, when the unit is subjected to the test pressure. The test pressure shall be 0.5 kPa unless otherwise specified by the purchaser.”
Details of test methodology for Appendix F are below.
AS3996:2019
Appendix E – Method of testing covers for watertightness
Refer to AS3996:2019 for the scope, principle, apparatus and procedure details. Illustration for reference.
Appendix F – Method of testing covers for gas-tightness
Refer to AS3996:2019 for the scope, principle, apparatus and procedure details. Illustration for reference.
Figure F1 Typical testing assembly for gas-tightness test
Contact our technical team on +61 2 9828 2600 for more information.
As with our installation and maintenance instructions and details, these tests also require the use of a sealant between the cover and the frame. Mascot Engineering use and recommend Manhole Cover Sealing Grease manufactured by Denso or similar.