Line Stopping: University of Chester

LINE STOPPING CASE STUDY

Client: All universities demand high quality of work and safe procedures, University of Chester trusted Ormond Pipework Services Ltd to fulfil these standards when working on their commercial gas installations.

The problem:

University of Chester had a commercial gas leak coming from a 6” steel pipe located underground.

The leak was caused by corrosion which is common on underground pipework installations, when the corrosion protection has been damaged or not installed correctly.

To avoid shutting off their gas supply and subsequently purging and tightness testing the whole site, it was decided that line stopping the gas supply was the best time and cost-effective solution.

Our solution:

First, an ultrasonic thickness test was undertaken to check if welding onto the 6” steel pipe would be safe.

After the successful test, custom made 6” on 6” saddles were welded on. To check the integrity of the welds, a pressure test of 2bar was performed.

Upon finding no leaks, Ormond under pressure drilled the existing pipework to form purge points and to insert the line stopping paddles.

Upon establishing the stops were not letting-by, we purged out the segment between the two gas flow stopping paddles.

This made it safe to cut the existing pipework and weld a positional flange to replace the damaged section with a spool piece. 

Tasks involved:

• Ultrasonic thickness test
• Welding
• Pressure test   
• Hot tapping/Under pressure drilling
• Line Stopping
• Gas Bagging Off
• Indirect Purge 
• Direct Purge 
• Underground gas pipework installation