CAUSTIC SODA (50%) & PVDF Compatibility

Caustic Soda (50%) (sodium hydroxide, NaOH, CAS 1310-73-2) is the most common form of liquid caustic, a clear, viscous, strongly alkaline solution with a specific gravity of about 1.52. It begins to crystallize near 54°F (12°C), so outdoor tanks are often insulated and heated. 50% caustic soda is used in pulp and paper, alumina refining, soaps, textiles, water treatment pH control and chemical manufacturing. Use the compatibility ratings to choose the right tank resin, fittings and gaskets.

Safety data: Caustic Soda Solution Safety Data Sheet (SDS) – Formosa Plastics USA

Not recommended in PVDF. Arkema, the maker of Kynar®, does not recommend Kynar Flex® 2850 PVDF, the resin we mold, for long-term service with Sodium Hydroxide (strong solutions). Ask us about HDPE or polypropylene for this chemical. Arkema’s limits are for solid resin at atmospheric pressure and do not account for mixtures. Source: Arkema Kynar® PVDF chemical resistance chart. Confirm your application with Bailiff before ordering.

At a glance

Polypropylene is the most economical tank material for Caustic Soda (50%), rated Excellent. Nylon and HDPE are also rated Good or better. Avoid PVDF (Kynar®) tanks, PVDF fittings, Viton® gaskets and aluminum hardware. Rated Fair (contact us before use): Hastelloy hardware.

  • Excellent No or minor effect. Recommended.
  • Good Slight effect. Generally suitable.
  • Fair Moderate effect. Limited or conditional use — contact us.
  • Not Recommended Severe effect. Do not use.
  • No Data Not tested. Contact us before use.

Tank Resins

How Caustic Soda (50%) works with the plastics used to make our storage tanks.

Material Relative cost Rating
HDPE $ Good
Polypropylene $$ Excellent
Nylon $$$ Excellent
PVDF (Kynar®) $$$$ Not Recommended

Fittings

How Caustic Soda (50%) works with the plastics used for tank fittings.

Material Rating
HDPE Good
PVC Excellent
CPVC Excellent
Polypropylene Excellent
PVDF Not Recommended

Gaskets & O-Rings

How Caustic Soda (50%) works with gasket and O-ring materials.

Material Rating
Buna-N Excellent
EPDM Excellent
Viton® Not Recommended

Metals

How Caustic Soda (50%) works with the metals used for fittings and bolts.

Material Rating
316 Stainless Steel Good
Hastelloy Fair
Titanium Good
Aluminum Not Recommended

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Storing this chemical in PVDF?

Tanks & Fittings Built for It

PVDF tanks from 25 to 5,000 gallons with fittings installed. Confirm concentration and temperature with us before you order.

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