Inspector 1978 Low melting alloys like Zn, Al should never be applied in high temp service usage for protective applications. Zn forms a complex embrittling inter-metallic phase (known as 475 o embrtillement due to inter-metallic precipitate) which would affect SS or high nickel-Chromium alloys. So also aluminium alloys. Any Al cladding/ wrapping, is usually done - for outlet pigtails-and this should be over the heat insulating high ceramic wool insulation for high temperature service. Ceramic wool can theoretically stand upto 1200 deg cent. That is why it is given as heat /insulation protection in outlet pig tails in hydrogen furnaces. Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Oct 31, 2010 E-mail: nishi@vsnl.com >Dear experts > >We know that normal paint contains Zn and cladding contains >aluminium , which has 420 & 660 Deg C melting point >respectively.What would be the adverse impact on the >integrity of outlet pigtails & why ,in case paint or >aluminium cladding remains in contact with the Inconel >outlet pigtails of Hydrogen reformer, its operating temp.at >the outlet is approx.825 Deg.C.