There are a number of reasons why plate and frame heat exchangers (PHEs) are popular as we outlined in this previous post, but what are they made of?
Heat Exchanger Plates:
On average, stainless steel is the most common material used in plate and frame heat exchangers. The two most common grades of stainless steel are 316 and 304.
- Stainless steel earns its value due to its effectiveness at resisting corrosion. It’s anti resistance capabilities are possible due to the ingredient Chromium, which can make up to at minimum, 10.5% of total composition.
- The main difference between 304 and 316SS is the existence of molybdenum (approx. 2-3%), which produces a higher degree of corrosion resistance.
- Although it has high grades in resistance, stainless steel is still susceptible to corrosion over time; the signs of this are pitting and/or holes.
After stainless steel, the next most widely used material for plate and frame heat exchangers is Titanium.
- Titanium is a highly anti-corrosive material, particularly with its immunity to sea/salt water. This makes it a preferred material for the marine industry.
- Another pro to titanium is its density. Titanium can provide weight savings of up to and above 50%.
- The thermal conductivity of titanium plates allows for matching or in some case higher heat transfer, working extremely well for plate and frame heat exchanger applications.
- Titanium is susceptible to cracking if the tensile strength rating is exceeded.
- Hastelloy and Titanium-Palladium plates may be used in more rare and intense applications.
- The standard plate thickness can range from .4mm-1.0mm, the most popular being .5mm and .6mm.
- Plates can come in a variety of patterns depending on the manufacturer. Some of the phrases used to describe these patterns are High/Low Theta, Degrees or Thermal Short/Thermal Long.
Heat Exchanger Gaskets:
Heat exchanger plates are designed with a channel to allow the gasket to create a proper seal and gap between the two plates for the process to flow efficiently. There are several different compounds of gaskets available. The most popular are Nitrile (NBR), EPDM and/or Viton. Others varieties are Hypalon, Neoprene and Hydrogenated NBR. The material used varies on the application and properties of the fluid flowing between each plate.
There are several factors to consider when choosing the proper gasket for your heat exchanger:
- Temperature rating (Viton gaskets have the highest temp rating at approximately 347°F)
- Chemical compatibility of the process; small traces of other chemicals can affect the gasket material.
- Gasket material and plate compatibility.
If you are in the market for new plates or gaskets, or would like to know more about our refurbishment service, please contact us for a custom quote!