Hot tapping on gas pipework at Plymouth Hospital
Client: Plymouth Hospital
About: Plymouth Hospital required a commercial gas installation to supply new boilers for their heating system.
The problem:
Plymouth Hospital required a 4” branch off their existing underground 150mm MDPE gas installation.
Due to the requirement to keep the hospital at ambient temperatures, the gas supply could not be turned off.
This eliminated the option to purge out the gas and install a new tee whilst the system was off.
In order to keep the gas supply on and the boilers running, specialist hot tapping services, the commercial gas engineers at Ormond Pipework Services, were brought in to perform a live tapping on the gas pipework.
Our solution:
Ormond first prepped the pipework by removing the oxidised outer layer of plastic on the surface of the existing MDPE.
Scraping the outer layer is important to ensure there are no contaminants during the fusion process.
Next, we fused a 4” saddle onto the 150mm MDPE. We provided a full-bore gate valve suitable for gas.
We then tested the integrity of the fittings by pressuring the connection to 3bar.
Upon the successful pressure test, the under-pressure drill was bolted to the valve.
A retaining pilot was utilised during the drilling process to ensure the coupon (the section cut from the existing pipe) was retrieved and not left within the gas pipework which could obstruct the flow of gas.
A specific designed MDPE hole saw was used so the drilling could cut freely as opposed to a bi-metal hole saw which melts MDPE plastic to the teeth.
Once the drilling was complete a safety blank was fitted
By hot tapping the live pipework we were able to avoid any system shutdown.
Hot tapping the connection also saved on time as turning off the gas supply would have involved purging and testing.
Tasks involved:
