Dyplast is now issuing its latest Technical Bulletin 0620 comparing elastomeric insulation to polyisocyanurate in process applications such as food, beverage, and pharmaceutical. This TB is complementary to Dyplast’s May Technical Bulletin 0520 comparing the same insulants in refrigeration pipe applications. This sister-bulletin was necessary since process applications are different.
For instance, Federal Regulations, such as those from the Food & Drug Administration, may make stainless steel piping an advantage given cleanliness, chemical resistance, and corrosion. And regardless of regulations, the use of stainless steel may be higher due to the process of liquid/gas chemistry, sanitation, or washdown protocols. Temperature ranges in process applications may extend beyond those encountered in refrigeration, yet the majority of processes are under 350°F.
The primary demonstrable conclusion is that polyisocyanurate (ISO-C1 and ISO-HT) have better thermal insulation properties than any elastomeric on the market and at a lower installed cost!
- Although certain beverage processing facilities (beer, wine, liquor, milk, soda, etc.) may exceed 212°F, very few exceed 300°F. Additionally, the majority of food and pharma processing occurs at temperatures under 350°F. Elastomeric suppliers limit their maximum service temperatures to either 220°F or 300°F depending on the formulation, whereas polyiso (specifically Dyplast’s ISO brands) are suitable up to 350°F.
- Elastomeric insulation has 30-47% poorer thermal conductivity when compared to polyiso. When elastomeric insulation is commonly more expensive the essential question is “why use it?” Some elastomeric insulant suppliers argue a debatable advantage that elastomeric is preferable on the small portion of process pipe that is Austenitic Stainless Steel (ASS) since it is less susceptible to Stress Corrosion Cracking (SCC), yet the facts are:
- SCC generally occurs within temperatures from 140°F to 250°F (a temperature range at the higher end of the beverage industry yet encountered in food and pharma).
- SCC is not applicable to cold piping.
- Non-austenitic stainless steel, carbon steel, and copper do not exhibit SCC!
- SCC is a concern only in a narrow set of circumstances, where there is a presence of chlorides, similar halogens, water, or stress over time and above thresholds.
- Polyiso has a Leachable Chloride content comparable to some elastomeric insulation – in some cases less!
- Given the chloride content of some elastomeric insulants, they may not be the appropriate solution to address SCC.
- At least two elastomeric insulant manufacturers published adjusted R-value tables which were adjusted to create an illusion of superior performance when in fact the tables have nothing to do with the actual performance of the insulant and rather on the geometry (e.g. cylindrical pipe vs. flat), which would apply to any insulant.
- ASTM standard conventions measure thermal heat flux using flat specimens to facilitate apples-to-apples comparisons of insulation. Publishing R-values for cylindrical geometries is not necessarily a deceptive practice, yet those R-values cannot be compared to other insulants unless the same geometric adjustments are made. Polyiso always has superior thermal performance! (read more on this in the Technical Bulletin, including indicative tables)
- Elastomeric insulants vary in their chemistries, and thus physical properties (e.g. NBR/PVC, EPDM, etc.). Products may be sheets or tubes, each with different characteristics.
- Polyisocyanurate (polyiso or PIR) insulants have many decades of demonstrably successful performance in food, beverage, pharma, and other process applications (from -297°F to +350°F), across a spectrum of metallurgies and industries.
For more elaborative data, review the Technical Bulletin here.