Thanks Glenn,
Unfortunately the compressors have now been discarded of with the engineering company who assessed the failure cause.
In my opinion the photos I have uploaded clearly show that the welds had not correctly penetrated the outer shell of the compressor. However I have been in contact with Danfoss Australia, they directed blame towards Liquid Flood-back although for the last 3 years I am positive the systems have never seen these conditions. Not to mention the report from assessment engineer shows the bearing surfaces to be immaculate.

Under general operation the compressors are smooth and very normal vibration. As soon as the weld lets go the compressor turns into a bucking bull, this intense vibration has caused pipework to fail releasing 70kg of refrigerant to atmosphere on both compressor failures. It is a worrying issue, not knowing how many compressors are going to fail, no symptoms until its to late and no preventative measures available.

report.jpg