Diaphragm Valves for Chemical & Petrochemical Processing
Ball valves, globe valves, PTFE-lined and diaphragm valves in Hastelloy C-276, Alloy 20, SS 316L, and lined designs for acids, solvents, and aggressive chemical process service.
Which diaphragm valves are used for chemical & petrochemical processing?
Chemical and petrochemical plants handle the broadest range of aggressive fluids: concentrated sulphuric acid, hydrochloric acid, nitric acid, caustic soda, chlorine, bromine, organic solvents, and speciality chemicals. Valve material selection requires matching both the chemical resistance of body and trim materials and the operating pressure and temperature to ensure safe, leak-free operation. NACE MR0103 compliance is required for refinery-adjacent chemical plants handling H₂S-bearing streams.
Diaphragm Valve (Chemical-Grade)
Zero stem leakage, PTFE or Viton-over-PTFE diaphragm for corrosive chemical isolation with no packing fugitive emissions
Critical Requirements
- Chemical compatibility verification for every service - pH, temperature, concentration, and mixed chemical effects
- Fugitive emission control: ISO 15848-1 Class A/B for benzene, chlorinated solvents, and toxic chemical services
- PTFE-lined or solid alloy construction for halide (Cl, Br, F) acid service - SS 316 is inadequate for concentrated HCl
- NACE MR0103 for refinery-adjacent chemical plants with H₂S exposure (stricter hardness limits than MR0175)
- IBR certification for steam-traced piping and reactor steam-heated jackets
- Antistatic design and ATEX actuators for flammable solvent services
Service Challenges
- Concentrated sulphuric acid (H₂SO₄ >93%) - use cast iron, Hastelloy B-3, or PTFE-lined; SS 316 passivates at high concentration but fails at dilute concentrations
- Hydrochloric acid (HCl) - one of the most aggressive chemicals; Hastelloy C-276 or PTFE lining required for all concentrations
- Nitric acid (HNO₃) - SS 316L is suitable for dilute service; for concentrated, Hastelloy C-276 or borosilicate-lined
- Chlorine gas (Cl₂, dry) - Hastelloy C-276 or nickel alloy; wet chlorine (Cl₂ dissolved in water) requires titanium or PVDF lining
- Caustic soda (NaOH, 50%) at elevated temperature - SS 316 can suffer SCC; nickel-lined or Alloy 400 recommended above 65°C
Vajra Diaphragm Valves
Elastomer-lined valves for corrosive, abrasive, and sterile applications.
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