Testing a non-conductive coating for porosity, faults and pinholes.
In July 2018, Lewis Civil Engineering purchased one of our PHD Pro' 1-30kV pinhole detector ― standard/pipeline kits. Buckleys visited Lewis Civil Engineering in Hereford, UK. The pipeline in question is approximately 8 kilometres in length; running between Bewdley Bank Service Reservoir and North Hereford.
The diameter of the pipeline varied between 450mm, 600mm and 700mm. The reason for this visit was to illustrate the effectiveness of Buckleys’ pinhole/holiday detectors in testing for defects, porosity and pinholes on the non-conductive coating of the pipeline.
Over the past 20 years, thousands of kilometres of coated steel pipeline systems from ERCITAS have been laid and remain in operation. If the design life of a water pipeline is 50 years, experience shows that, in most cases, the pipeline will actually be in operation much longer than this. It is therefore essential to design water pipelines for a life in excess of 50 years. According to the AWWA for design life for epoxy coatings is 40-60 years.
To test the non-conductive coating of this pipeline for porosity, faults and defects using the Buckleys PHD Pro' 1-30kV pinhole detector ― standard/pipeline kit.
Type of pipe: The coated and lined spirally welded steel pipe is manufactured in accordance with BS/EN 10224 Standards.
The pipe barrels and socketed ends were fabricated and fitted by UTS. The pipe diameter ranges between 219mm and 3048mm. The outside coating consists of 3 layers polyethylene. Internally, the lining is based on Solvent Free Epoxy EUROKOTE 468 Thixo applied on a minimum thickness of 500 microns which maintains the quality of the potable water throughout its pipe life and provides protection against corrosion.
Pipe length: 12m nominal length
Purpose of pipeline: Potable water mains supply
Thickness of coating: 500 microns
Test equipment used: PHD Pro' 1-30kV pinhole detector ― standard/pipeline kit.
The recommended external field joint coating methods consists either of applying a heat-shrink sleeve around the pipe according to the IFU from the sleeve manufacturer. Before laying, PE coating must be checked visually and by holiday detector at 10kV.
Using a Buckleys PHD Pro’ fitted with a 250mm phosphor bronze brush electrode with 3 extension rods; the pipework’s external coating was inspected at 2kV.
The PHD Pro’30kV was earthed using the Trailing Earth Lead and the sections of pipework were earthed with sections of mild steel placed against them and in contact with the ground. This provided an adequate earth return path for the test to be effective and reliable.
The operator passed the electrode over the entire coating. Every time the PHD Pro’s alarm system triggered, the area around the electrode was thoroughly inspected and retested to ascertain the exact location of the fault. Faults were subsequently clearly marked for remedial work.
Porosity, defects and pinholes can be identified in non-conductive coatings when testing with a PHD Pro' 1-30kV pinhole detector ― standard/pipeline kit using a rolling spring electrode.
ERCIYAS Pipeline Systems, document number TA-04-30, Rev 1 Dcww Civil Engineering Specification, document ID CS501A With special thanks to Mr. George Pickering, LEWIS Civil Engineering Ltd