Food- and Water-Contact-Approved Lubrication and Sealing in SWRO Desalination

Case Study


Desalination typically is accomplished through one of two processes: osmosis or reverse osmosis. The application detailed here was found in the process of seawater reverse osmosis (SWRO), a filtration method that removes many types of large ions by applying pressure when it is on one side of a selective membrane. The process of applying an external pressure to reverse the natural flow of pure solvent is called reverse osmosis. 

Operational parameters (LETS)

  • Load: 1,200 psi (82 atm)
  • Environment: Seawater
  • Temperature: Ambient
  • Process description: Grease applied to O-rings using a swab


During assembly of the membranes, a grease is needed to lubricate the O-ring that connects between the series of membranes and to seal the O-ring and the countersurface from high-pressure water (about 1,200 psi/82 atm). 

The previously used product was a lithium-based grease with EP additives that did not have the appropriate certifications and approvals for food and water contact. The customer was looking for a product that was approved to FDA 21 CFR 175.300, NSF-51, NSF-61 and WRAS.


MOLYKOTE® 111 Compound has the needed food approval and is certified by WRAS.

Read the application story.