| Applies when | sulfuric acid, h2so4, 98% sulfuric, oleum, sulfur trioxide |
|---|---|
| Avoid | PVDF threaded, Noryl body, threaded PTFE (Valve) |
| Recommend instead | Griffco Valve Back Pressure Valves / Pressure Relief Valves (Valve) |
| Rationale | Griffco Valve's technical bulletin (TIB2010-001, 'Sulfuric Acid Options') documents a real field failure pattern: at 98.3%+ concentration, sulfuric acid carries a natural sulfur trioxide (SO3) contaminant - commonly termed '98+% sulfuric acid' - that attacks and causes stress fractures in both PVDF and Noryl, materials that are otherwise fine at lower concentrations. Quantified material options: Noryl (to 95%, 200F), PVDF (to 95%, 175F), Halar/ECTFE (to 100%, 200F), PTFE in flanged one-piece construction only (to 100%, 200F - threaded PTFE fails from cold-flow leakage at the joint, not chemical attack), and Alloy 20 (to 100%, 300F, most expensive/most robust option). The PTFE cold-flow-at-threaded-joints failure mode is cross-vendor consistent with JCS Tool's molded-vs-threaded-liner findings (see jcs-tool-ptfe-lined-fittings.md) - treat 'PTFE must be one-piece/flanged, not threaded' as a general rule for any concentrated-acid threaded connection, not just sulfuric acid. |
| Confidence | single-vendor |
| Source | data/vendor-sources/griffco-valve.md |
This is a general engineering rule derived from real field/case-study evidence, not a substitute for a project-specific specification review — confirm against your exact process conditions before ordering equipment.
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Source: Liberty Chemical Equipment & Supply, Inc. (LibertyCES) — engineering data compiled from real vendor and field-verified sources. For a free spec review, call James Riggins at (559) 395-5500 or email [email protected] / [email protected]. Website: libertyces.com.