Valves for Chemical & Petrochemical Processing

Hydrochloric acid attacks nearly all common metals including carbon steel, cast iron, and SS 316 at all concentrations. The main options are: Hastelloy C-276 (UNS N10276, ASTM A494 CW6MC in cast form) — the most widely used solid alloy for HCl valve bodies and trim at all concentrations up to ~65°C; PTFE-lined carbon steel or ductile iron ball valves and butterfly valves — cost-effective for lower pressures (PN 10/16) and moderate temperatures; Titanium (Grade 2) — resists HCl at low concentrations. Avoid SS 316, SS 304, and bronze for any HCl service.

Both standards address sour service (H₂S-containing environments) but apply to different industries. NACE MR0175 (ISO 15156) applies to oil and gas field equipment (upstream and midstream) and focuses on naturally occurring H₂S in produced fluids. NACE MR0103 applies to downstream oil refinery and chemical plant equipment and is generally stricter — it sets lower maximum hardness limits for carbon steel components (Rockwell B 90 vs B 92 for MR0175) and includes additional requirements for weld hardness. If a chemical plant valve is used on a stream with H₂S, specify the applicable standard in the purchase order.

ISO 15848-1 classifies the stem packing fugitive emission performance of industrial valves. Class A is the tightest classification (leakage rate ≤ 10 ppm × m of pipe equivalent), Class B is intermediate (≤ 100 ppm), and Class C is lowest (≤ 1000 ppm). For toxic chemicals (benzene, vinyl chloride, H₂S, HCl gas, chlorine), Class A fugitive emission valves are required to meet occupational exposure limits and CPCB / EPA VOC regulations. Low-emission packing designs (graphite-based with live-loading) are used to achieve Class A.

Yes. Vajra Industrial Solutions supplies PTFE-lined butterfly valves (also called fully-lined butterfly valves) with PTFE-lined ductile iron body, PTFE-sleeved disc, and PTFE stem sleeves. These are suitable for dilute and intermediate concentrations of sulphuric acid (up to approximately 70%), hydrochloric acid, hydrofluoric acid (low concentrations), and many other corrosive chemicals. We supply in DN 50 through DN 600, PN 10/16, with pneumatic or electric actuators and can provide chemical compatibility documentation for your specific service conditions.