ndt case study
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fire and sprinkler main installation in large factory

background

In November 2013 a new fire and sprinkler main was installed at a large factory site in north east England. By November 2014, three failures had occurred on the installation. Impact Solutions were contacted by the main contractor for the factory site to conduct failure analysis on the faulty joints. Impact Solutions visited the factory site to discuss the problems and collected three electrofusion coupler joints and three butt fusion joints for destructive testing to WIS 4-32-08 at their lab. All of the joints tested failed the WIS standard test. This was put down to poor welding practice and a lack of QA/QC procedure. As a result the contractor was forced to abandon the failed water main and to install a new one for their client.

 

the solution

Impact Solutions wrote a Quality Control/Quality Assurance procedure for destructive and non-destructive testing (NDT) of the new installation. The contractor stipulated that NDT was to be performed on all electrofusion couplers. In addition to this, the welders were retrained for best practice using impact solution’s external training consultants.

 

challenges

Due to the poor installation of the first main, the contractor for the factory incurred the cost of installing the replacement pipeline. The factory experienced a cost of £20,000 per minute in downtime because of the failed fire main.

During the new pipeline installation NDT was conducted on 42 electrofusion coupler joints challenges across a number of site visits. Two (~5%) of the 42 joints tested on the water main were identified by impact ndt as high risk and the contractor made the decision to replace them.

This is estimated to have the potential to save the client up to £10m assuming a half day of down time per joint failure.

As a result of the new quality assurance procedures, and the use of NDT on all new joints installed, the main contractor for the site can be sure and provide evidence that the fire main handed over to the client is of a very high standard and is not likely to cause extensive future problems during use.

Darryl Roe: M&E coordinator 

Impact have provided us with an invaluable service for both destructive and nondestructive testing. There have been a number of different plastic pipe installation methods used on this project and it has been important to use a testing regime which suits the particular installation method. 

Non-destructive testing has detected faults in electrofusion joints on a number of occasions. These faults were not apparent from visual inspection or from the pipe work pressure tests. When the defective joints were removed it was apparent from internal inspection the pipe and fitting had not welded fully. These faults may not have an immediate impact but would have reduced the longevity of the system and could have caused major disruption to the client. 

Our client has experienced a number of HDPE pipe weld failures in the past and this method of testing has helped us reassure them the new service will be more reliable.

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