Dear sirs,

We have a 36" dia CS piping with insulation + steam tracing. The piping is internally aluminized. Following is the details:

MoC: A672 C60 Cl 12, internally aluminized

Size: 36" x 7.92 mm thk

Service: Acid gases (sulfur rich)

Operating Conditions: Pressure- 0.6 kg/cm2, Temp- cyclic - 130 to 343 deg C.

Insulatuion: Yes - 115 mm thk

Steam Tracing: Yes LP steam - through 4 nos of 0.5" dia SS tubing at 90 degrees apart.

Minimum temp to be maintained: 120 deg C.

Now, because of severe blistering in aluminized coating due to cyclic temp and acid gases, it has been proposed to change this piping from CS to SS304L.

It has been decided to use the same steam tracing tubings for new SS lines.

My question is:

since heat conductivity of SS is almost half than that of CS,

(1) can the same nos (04) of steam tracing lines will be enough? or
(2) no of steam tracing lines have to be increased?

I have read somewhere that the steam tracings are provided just to compensate for any heat loss occurs because of any damage in insulation. Hence, as far as insulation is wrapped and mounted properly and there is no damage, then there is no need to redesign the steam tracing system while we are upgrading MoC of parent pipe with same size.

Request to do the needful,

Thanks and Regards,

....quote
I have read somewhere that the steam tracings are provided just to compensate for any heat loss occurs because of any damage in insulation. Hence, as far as insulation is wrapped and mounted properly and there is no damage, then there is no need to redesign the steam tracing system while we are upgrading MoC of parent pipe with same size.
unquote

I can tell you my experience: I have always seen steam tracing made to keep the fluid inside the pipe warm not to warm it.
Mauro