Request for Proposal
Status: RFP is Closed

Environmentally-Friendly Approaches for Prevention of Carbon Steel Corrosion in Open Recirculating Cooling Water Systems

Request Number
Due Date
Nov 28, 2018
Program Manager


Licensing, product acquisition, contract research, proof of concept leading to scale-up to manufacturing, joint development.


Review and evaluation of proposed approaches: 3 – 6 months

Proposal selection and further evaluation under NDA: early 2019


A realized solution would impact a $1 Billion per year market.

RFP was closed on
Dec 2018

RFP Title


Environmentally-Friendly Approaches for Prevention of Carbon Steel Corrosion in Open Recirculating Cooling Water Systems
RFP Description

NineSigma, representing a leading company in water treatment and processing, invites proposals for technologies that enable a non-phosphorus (non-P), non-metal (no Zn, Sn, or Mo) solution for prevention of carbon steel corrosion in open-loop water cooling systems. The proposed system must perform as well as current benchmark chemical programs containing phosphorus and zinc for corrosion control. The focus of this RFP is on breakthrough technology to match growing market needs in environmentally friendly treatment approaches for corrosive waters that require improved localized corrosion control. 


In recirculating cooling water systems, plant owners want their assets, such as heat exchange equipment, pumps, and piping, to have lifetimes greater than 20 years.  Many of these assets are mild steel, which is attacked by high levels of aggressive anions, i.e. chloride and sulfate, in the cooling water.  Component failures typically occur due to localized corrosion rather than general corrosion.  Further, plant owners need to increase their re-use of water.  This re-use typically results in increased concentrations of ions in the water and further challenges for cooling water treatment programs.  Control of (localized) corrosion in these challenging systems without the use of phosphorous-containing compounds and additionally without the use of zinc, tin, or molybdate is the subject of this RFP.


Limitations of Phosphorous-Based Programs

Today’s phosphate and zinc chemistries perform well under most circumstances. The concentrations of phosphate and zinc must be balanced carefully with calcium, polymeric dispersant, pH, and temperature. If all six factors are not always kept well-balanced in the system, either corrosion or fouling can occur. This is particularly problematic in the chemical and refining industries due to the presence of high temperature, low flow heat exchangers. Apart from challenging program control requirements such as tight pH operating windows, phosphate/zinc programs have some additional weaknesses, including:


  1. Low hardness, i.e. “soft”, water require much higher levels of phosphate and zinc to achieve good performance
  2. Little or no beneficial effect on copper or aluminum corrosion


Recently, US regulations have begun to restrict the industrial discharge of zinc as a primary pollutant to aquatic life species and phosphorus as an undesirable aquatic nutrient for cyanobacteria and algae in the environment. Molybdate suffers from being both very expensive and often regulated in discharges as well.  The Chinese government has released a series of regulations to limit the discharge of phosphorous. The discharging limit, 0.5 ppm as elemental phosphorus, is too low for the current phosphorus containing cooling water treatment programs.


Desired Performance Criteria of New Non-P, Non-Metal Program

As in the late 1970’s when chromate was banned, the cooling water treatment paradigm is shifting again. The new goal is to find a corrosion inhibition approach for open recirculating cooling water systems that is free of regulated metals (Zn, Sn, and Mo) and phosphorous species, while maintaining most of the operational and economic benchmarks that the zinc phosphate approach provided.  Some “typical” water system chemistries where program performance would need to be proven are shown below in Table 1.  The two most challenging waters from a corrosion treatment perspective are Water 1 and Water 3.



Key program stability criteria and performance expectations are shown in Table 2.  The cooling water environment is obviously oxygen saturated, which the program must be able to tolerate.  Likewise, most cooling towers are now treated with upward of 0.5 ppm free residual chlorine (FRC) resulting from bleach or chlorine gas feed, so at least this level of oxidant must be tolerated on a continuous basis.  Ability to withstand periodic excursions to a maximum of 2 ppm FRC is desired.  Metal surface temperatures and flow velocity refer to typical shell and tube heat exchanger conditions with cooling water on the tube side.  Within these specified conditions, the program should be able to perform for a minimum of 150 hours with minimal loss of potency, which could occur for example by halogen degradation of treatment chemistries.  Corrosion performance expectations for AISI C1010 corrosion test specimen are shown in the last 5 rows of the table.


Key Success Criteria

The technology must:

  • Enable system owners to discharge cooling tower blowdown directly to environments without further treatment expense
  • Assist system owners to maintain reliable production and preserve assets with robust corrosion control without seriously compromising simultaneous control of both mineral scaling and microbial growth.
  • Help system owners comply with corporate environmental objectives by selecting green cooling water treatment solutions (e.g. without phosphorus compounds and proscribed metals such Zn, Sn, and Mo)
Possible Approaches

The RFP sponsor is interested in very specific technology approaches. A WATER TREATMENT PROGRAM is the ultimate goal of this Technology Search. Possible approaches might include, but are not limited to:


  • Cathodic corrosion inhibitors that are non-P, non-metal and that mimic the action of Zn
  • Filming: Approaches that create a uniform protective layer on carbon steel surfaces
  • Other innovative approaches, including those with non-chemical components
Approaches not of Interest

The RFP client has extensive expertise in current anti-corrosion mechanisms for water cooling, and is not interested in the following approaches or outcomes:


  • Any system that does not meet the basic premise of this RFP
  • Chemistries with extreme toxicity or very poor biodegradation properties
  • Materials-based options such as coatings or materials substitutions for carbon steel.  The approach MUST act on the water system itself, and not require direct changes to the equipment assets.
  • Corrosion Inhibitors that act solely or primarily anodically
  • Scale inhibitors unless they are integral to stabilizing the new corrosion control approach
  • Biocides or agents that specifically target microbially-influenced corrosion
  • Chemical approaches likely to generate excessive foam as water falls into the cooling tower basin
Items to be Submitted

Your response should address the following:

  • Non-confidential description of proposed technology and working principle
  • Availability of technical data
  • Technical maturity of the approach (concept, reduced to practice, prototype, ready to commercialize, ready to implement, commercialized)
  • Pathway to commercial scale including timing, estimated budget, and capacity for manufacture
  • Position on intellectual property including patent references
  • Desired relationship with sponsor
  • Team description and related experience
Preferred Collaboration Types
Area of Interest