It is true that many automatic pipes galvanizers use 50° C. and high baume'(density)flux solution for galvanizing medium and small diameter pipes. If the flux solution is hotter, then the last pipes in the bundle will have corrosion lines on the outside and have "black" (bare) spots. (Higher flux temperature causes faster corrosion.) If however, large diameter pipes are galvanized or the "breaking table" is wide enough and slanted such that a single layer of pipes results (for the fluxed pipes), then low baume' and hot flux gives a better result. Better by having a thinner zinc layer on the inside of the pipes and having much less ash (skimmings) at the kettle.
For general galvanizing it is common practice in North America to use either triple salt flux (ACN=1.17) or quadraflux (ACN=1.60) at about 13 to 14 degrees baume' and 71° C. (160° F.). (ACN = weight of ammonium chloride/weight of zinc chloride.) This often gives a percent gross zinc usage between 4% and 5% (%GZU = zinc consumed/steel galvanized all times 100%) (no zinc credits for ash or dross). The correct pH and the proper wetting agent (surfactant) in the flux also help prevent corrosion of the fluxed steel.