For the problem found grime inside of coper tube. which, as you want to know the composition of grimes. What’s it ? I have contacted to SGS (Thailand) Ltd. They can’t analyze.
So, I have contact to others institute as follow ;
1. Institute for Scientific and Technological Research and Services (ISTRS)
2. National Metal and Materials Technology Center (MTEC)
then, I sent the picture and your requirement to them already. They will feedback within this week.