Obudowa membranowa ze stali nierdzewnej klasy spożywczej: Spawanie, higieniczna konstrukcja i zgodność z przepisami

Food grade membrane housing is a sanitary, food-contact pressure vessel designed for hygienic service in dairy, beverage, flavors and nutraceuticals. It combines 316L construction, ASME BPE finishes (SF1/SF4), orbital TIG with verified purge, and FDA/EU-compliant gaskets to ensure cleanability across CIP/SIP cycles.

1) Regulatory & Standards Map (What “Food-Grade” Really Means)

• Food-contact framework — EU 1935/2004; US FDA food-contact rules (gaskets/elastomers under 21 CFR 177.2600).
• Hygienic design — 3-A Sanitary Standards / EHEDG hygienic design principles for crevice-free, drainable, cleanable construction.
• Surface & fabrication — ASME BPE finish classes (e.g., SF1/SF4) and orbital-weld best practices for smooth, fully penetrated, purge-protected welds.
• Materials & documents — ASTM A270 (sanitary tube), ASTM A967 (passivation), EN 10204 3.1 MTR traceability, pressure test & QA dossier on shipment.

2) Food Grade Membrane Housing Materials & Surface Finish (Cleanability First)

• Base metal: default SS 316L (Mo-alloyed, better chloride resistance) with low-carbon grade to reduce sensitization risk; SS 304 available for low-chloride utilities.
• Internal finish options:
  • SF1: Ra ≤ 0.51 μm (mechanically polished), economical for standard food service.
  • SF4: Ra ≤ 0.38 μm (electropolished), preferred for stringent hygiene and reduced biofilm risk.
• Post-weld treatment: heat-tint removal + chemical passivation (ASTM A967) to restore the chromium-rich passive layer.
• Gaskets & seals: FDA-compliant EPDM/FKM/PTFE/Silicone as specified by media, temperature, and CIP/SIP chemistry; lubricants use NSF H1-grade only.

3) Welding for Sanitary Service (Orbital GTAW + Verified Purge)

1. Process: orbital GTAW/TIG with internal purge to protect root; weld maps maintained against serial numbers.
2. Welder qualification: per ISO 9606-1; WPS/PQR on file and available in the documentation pack.
3. Inspection: borescope images for every circumferential weld; dye-penetrant where applicable; ferrite checks on welds if specified.
4. Finishing: mechanical blend where needed without undercut; electropolish option to reach SF4.

4) Hygienic Geometry & Connections (Drainable, Crevice-Free)

• No dead legs: “dead-leg length ≤ 2× branch diameter” design rule for ports and gauges.
• Full drainability: housing oriented with slope ≥ 1% toward sanitary drain; end caps designed to avoid product traps.
• Connections: sanitary tri-clamp ferrules as default; dairy ends, DIN/ISO clamp, or RJT on request.
• Cleanability: rib-free seals, uniform compression, and gasket intrusion control to ensure repeatable CIP.

5) QA/QC & Validation Dossier (What You Receive)

• Material traceability: EN 10204 3.1 MTR for major wetted components.
• Surface verification: Ra test records (critical areas), electropolish certificate if SF4 specified.
• Weld quality: welder quals, WPS/PQR, weld map + borescope photo log.
• Pressure integrity: hydrostatic test report at 1.5× design pressure; leak test before shipment.
• Compliance pack: FDA/EU compliance declarations for gaskets/seals, passivation certificate (ASTM A967), and cleaning recommendations (CIP/SIP).

6) CIP/SIP Compatibility (Typical Ranges)

Compatible with alkaline/acid CIP (e.g., NaOH 0.5–2.0%, HNO₃/H₃PO₄ 0.5–1.0%) and SIP up to 121–135 °C depending on gasket selection. We provide media-specific limits and elastomer compatibility tables in the QA pack.

) Standard Food-Grade Membrane Housing Specs

*Final limits depend on selected elastomer (EPDM/FKM/PTFE/Silicone) and cleaning chemistry.

8) RFQ Checklist (Copy & Paste to Your Inquiry)

• Process media & target product (e.g., dairy permeate, juice concentrate, flavors)
• Max temperature / pressure, cyclic profile, and design code requirements
• Surface finish target: SF1 or SF4 (internal); external cosmetic grade if needed
• Connection type & size: tri-clamp / DIN / ISO / RJT; drain orientation
• Gasket choice: EPDM / FKM / PTFE / Silicone + required compliance (FDA/EU)
• CIP/SIP regime & chemicals; required cleanability tests (e.g., riboflavin optional)
• Documentation pack: 3.1 MTR, Ra map, hydrotest, weld dossier, passivation cert
• Packaging & labels: cleanroom poly-bagging / desiccant / palletization spec

Send the checklist to Stark Water and we’ll return a design + quote within one business day.