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Plastic Stoppers for Thermal Pin?The stoppers are using for manufacturing of tubular heating elements .Before filling , plastic stoppers are mounted to the thermal pins. Resistance powder (MgO) , when the pipes filling , prevents the loss of the end of the pipe.Plastic stoppers of sizes , the diameter of the pipe to be used for filling and ?diameter of used thermal pins . These stoppers are removed after the assembly process. Instead of porcelain or fireproof products are assembled.
link:http://www.superbheater.com/materials-and-fitting/tubular-heater-materials-and-fitting-parts/tubular-heaters-heating-element-terminal-plast.html
Tubular Heaters Heating Element Terminal Plastic Plugs Cups