Blocking of Tubes

Spreading solder over the crack will not make a permanent watertight repair.

(b) Wire brush or scrape the area around the crack one inch larger

than the patch to be installed. Dig down into the crack itself with a

pointed tool. Tin the cleaned areas and the underside of the patch, wiping

them clean while the solder is in a molten state.

(c) Fit the patch in place as perfectly as possible, following the

contours of the tank. All patches should have rounded corners.

(d) Hold the patch in place with a screwdriver and apply heat. The

proper amount of heat will be indicated when a stick of solder will melt

when touched to the patch.

(e) If proper care has been taken during the tinning operation, the

patch will be strong and watertight. Hold the patch in place until the

solder has set.

(3) Blocking of Tubes Cellular (honeycomb) Radiators. A damaged tube

may not need to be repaired; it can be blocked off. Fifteen percent of the

tubes in a radiator may be blocked off without adverse effects.

(a) Heat face of tube near header plate and spread open with an

improvised tool made from an old hacksaw blade sharpened on one end to the

shape of a chisel.

(b) Thoroughly tin the inside of the tube with tinning compound,

using an acid brush to apply the tinning compound.

(c) Apply flux and fill tube with solder.

(4) Tubular Core.

(a) Heat fins at the header plate and raise fins onehalf of an inch

on each side of the tube to be blocked.

(b) Apply heat to the tube and blow out the solder with an airgun.

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