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Tannins are natural polyphenolic biopolymers extracted from trees that have a long history of use for corrosion and scale control in steam boilers. TGWT’s purified tannin formulations for both steam boilers and closed loops have been successfully used since 1970. These formulations have been found to have excellent compatibility with most common materials used for the storage, pumping, and feed of the neat products to systems.

Neat product vs application levels

At end use levels, the purified tannin products are compatible with most materials of construction used in steam boilers and closed loops. The tannins themselves have little effect on most common materials of construction. It is the formulation at alkaline pH that is the primary consideration for compatibility.


Storage vessels, pumps, hoses, and connectors can be made of any of the following common materials, rated “Excellent” or “Good”:

• Buna N (Nitrile)



• Neoprene

• Nylon

• Polypropylene




• Tygon

N.B. Viton is only rated “Fair” for high pH’s.

For materials that are not listed above, standard databases of compatibility (such as that of Cole-Parmer, can be checked to ascertain that they are compatible with NaOH and/or ammonia.

Yellow Metals

WARNING concerning copper, bronze, or brass elements (fittings, level controls, etc.): As yellow metals are sensitive to high pH, one should ensure that they are not used close to the injection point of the concentrated products. If the components made of these metals cannot be easily changed for proper materials, an alternative injection point can be chosen.

Please contact us should you need additional information about materials compatibility.

Download our Technical Bulletin:

202109 TGWT - BULL-EN-G002 Compatibility of materials with tannin-based products
Download PDF • 315KB

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