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For copper boilers which are silver soldered/brazed the copper grade most specified and acceptable to the boiler inspectors is: -C106 CopperPhosphorus deoxidised copper is the grade of copper where oxygen is removed by the controlled addition of phosphorus during the melting cycle. A slight excess of phosphorus ensures complete removal of oxide. The residual phosphorus remains alloyed with the copper within the specified range 0.013-0.050%. The copper content is 99.85% minimum and the grade conforms to the compositional requirements of British Standard alloy designation C106.C106 is superior to the electrolytic tough pitch copper electrical grade (C101) and should be specified for all non-electrical applications, especially those involving assembly by welding or brazing. Phosphorus deoxidised copper is not susceptible to hydrogen embrittlement which is a serious risk with non-deoxidised grades.Related SpecificationsBS2871.Cu-DHP.DIN 1787.
What about C122? C106 is almost unobtanium around here.ThanksTony
I think the worms are wriggling out of the can here. It seems to me that, in the UK, for a home constructed copper boiler made using silver soldered joints, a boiler inspector will not expect to see material certification. This therefore implies that any nominally pure copper is adequate for the purpose, as has been demonstrated by every amateur boiler maker since records began. The requirements for welded copper boilers are entirely different since the construction method involves melting the copper with a consequent drastic change to the metallurgy. I suspect there is confusion between the 2 requirements. I may be entirely wrong but until some body can show me chapter and verse I shall continue to offer boilers constructed from copper bought, without tracability, from the ME trade, to my club inspector.Cheers,Rod
Even if the boiler was being built to a published design, he would still be within his rights to ask for these in order to verify that the materials used are as specified on the design drawings. Sandy.