Soldering Lead-Free Valves Takes Added Practice

December 1, 2017

Plumbing manufacturers have made great efforts to remove as much lead as possible to comply with regulations established under the Safe Drinking Water Act. In order to meet these requirements, most manufacturers have used brass alloys containing small amounts of silicon or bismuth to improve machability. In the following years, most plumbers learned how to effectively make joints with the new alloys, but sometimes it is not apparent how complete the fill is in joints unless they are tested.

A recently released NCPWB technical bulletin demonstrated how joints that appear to be correctly soldered could often be frayed. The bulletin’s author, Walt Sperko, provided examples of incorrect joints and guidance. Pre-heating the tube more than the casting is critical for no lead copper alloys. This is because casting’s thermal conductivity is much lower than copper.

Incomplete fill from under-heating

When the plumber does not spend enough time on heating the tube, the solder has a tendency to only partially fill the joint. While silicon-based alloys were found to be more difficult to wet properly, both proved insufficient with poor technique.

NCPWB members can also download the Soldering Procedure Specification resource SPS-107-1 to better understand the welding procedures for brass and lead-free alloys.

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