What materials are used for crude preheat exchangers?

Materials used for crude preheat exchangers depend on the crude composition, chloride content, sulfur level, temperature, pressure, and corrosion risk in the service.

Common materials include:

• carbon steel
  Widely used for less corrosive refinery duties and where temperature and chemistry are manageable.

• low alloy steel
  Used when better strength or higher temperature resistance is needed.

• stainless steel
  Often selected when corrosion risk is higher, especially in services involving chlorides, sour components, or water condensation.

• duplex or higher corrosion-resistant alloys
  Used in more severe refinery conditions where standard materials may not provide enough corrosion protection.

• clad materials
  In some cases, exchangers use carbon steel for strength with a corrosion-resistant cladding or overlay on critical wetted surfaces to balance cost and durability.

For shell and tube crude preheat exchangers, different parts may use different materials:

• shell: carbon steel or alloy steel

• tubes: carbon steel, stainless steel, or corrosion-resistant alloy

• tube sheets: carbon steel with cladding, stainless steel, or alloy material

• channel and bonnet: selected based on the process-side corrosion condition

In refinery service, material selection is especially important because crude oil may contain:

• salts

• sulfur compounds

• naphthenic acids

• water

• chlorides

• solids that can promote fouling and corrosion

So, the most common answer is that carbon steel is widely used, but stainless steel, low alloy steel, and corrosion-resistant alloys are also chosen when the operating conditions are more severe.