501F Vendor Spotlight: PAG favored over petroleum-based lubricants by an increasing number of turbine users

American Chemical Technologies Inc

Polyalkylene glycols (PAG) are no longer the “new guy on the block” in the power generation industry. American Chemical Technologies’ (ACT) EcoSafe line has remained unchanged, using PAG base stocks in its formulations since the early 1990s. PAG chemistry has provided lubricant solutions in many different turbine applications for over a decade.

These synthetics are a paradigm shift away from all the obstacles contended when using petroleum-based lubricants—including varnish, electrostatic discharge, failed demulsibility, and hydrolytic instability. The challenges with varnish and solids are here to stay, and might heighten because of the changes forced upon the petroleum industry by OSHA and the EPA.

With more and more turbine users suffering varnish-related issues, the power industry has turned to the non-varnishing PAG to rid their operations of unfavorable variables. In chemistry “likes dissolve likes.”

Petroleum products are non-polar with only hydrogen and carbon in their makeup. As petroleum products oxidize, they produce polar decomposition products that will not solubilize in the base stock. By contrast, PAGs have 28% oxygen, and as they oxidize, produce low-molecular-weight polar byproducts that will always remain soluble in the base stock.

ACT offers the following synthetic non-varnishing PAG formulations in the EcoSafe line for power generators:

  • EcoSafe EHC, a Factory Mutual-approved, fire-retardant hydraulic fluid, was developed for use in servo-operated electrohydraulic control systems. This product, in use since 2004, is now protecting over 220 units, including nine 501F gas turbines.

  • Full-synthetic EcoSafe TF-25 was developed for lube-oil systems. The first user of this fluid just surpassed 11 years of non-varnishing performance with no lubrication-related trips, failed starts, or servo-valve failures. With an anti-oxidant loss of around 2.5% annually, the fluid in the oldest system is tracking to provide an approximate 30-year fluid service life. Today, more than 110 turbine lube systems rely on PAG chemistry.

Oftentimes an end-user plagued by varnish/solids doesn’t have a budget for an oil change, or an outage planned to conduct the work. Some of the newer turbine-oil formulations are yielding reduced service life, with varnish potential lurking after only a few years of service. 

Powerplants are having to proactively investigate alternatives to remove the soluble and insoluble varnish. To provide a chemical solution to the chemical varnish problem, ACT developed and patented an oil-soluble PAG base-oil modifier—EcoSafe Revive—that when added to a varnished petroleum product (patent calls for 2% to 20% treatments), shifts the polarity of the co-mingled lubricant, and solubilizes varnish/solids keeping the system liquid.  All varnish in the system is “dissolved” back into solution with no need to remove it by way of mechanical filtration. EcoSafe Revive has provided varnish solutions in over 170 units, including 18 501F turbines.

Now with over a decade of use and data under its belt in the power generation industry, EcoSafe is one of the oldest formulations on the market. PAGs have proven that no matter the situation, they are a true solution to varnish.