Tubular Heaters Keep Heat On To Get The Lead Out


Almost all metal objects have to be heated up at one time or another in the manufacturing process. This applies to the lead plates used in your car's DC battery. One manufacturer of a machine that molds these plates uses several tubular heaters in their equipment. This machine is found exclusively in battery manufacturing facilities.

Lead has a melting point of around 340°C (650°F), so the tubulars have to keep the process above this temperature.

The lead is initially heated by means other than electric tubulars, then is kept warm in a pipe by tubulars elements until it reaches the mold which is heated by FIREROD® cartridge heaters.

Grooves in the pipe are used for mounting the tubulars heaters.

This machine is very expensive, and down time very costly. A competitive make of tubular heaters was experiencing premature failure.


Since a large part of the tubular surface is in contact with the pipe, Watlow recommended a fairly high watt density, in this case about 37W/in2 (5.7W/cm2). This produced a total of 4000 watts per tubular element. Since this is basically a clamp-on application, an Incoloy® sheath was used.

Watlow received the order from the OEM to correct the many field failures caused by the competitor's product. Watlow has since offered this customer a much lower failure rate and, in cases where a failure does occur, delivery times have been substantially quicker. These reasons have also held true when the end-user calls in and requests replacement elements.

Value Added:

Expert application support


Incoloy® is a registered trademark of Special Metals Corporation.