Sanitary Grade 304L 316L Double Tube Sheet Hairpin Heat Exchangers for Clean Processes

Yuhong Group Co., Ltd. manufactures sanitary-grade hairpin heat exchangers in 304L and 316L stainless steel with a double tubesheet configuration, intended for clean process duties where product integrity and cleanability are governing selection criteria rather than heat transfer alone. The hairpin geometry places product on the tube side in a true counter-current arrangement, which suits viscous, particulate-bearing, or thermally sensitive streams that are difficult to handle in baffled shell-side passages. The double tubesheet is the defining safety feature: two independent tubesheets at each end create a vented air gap, so a tube-to-tubesheet joint failure releases to atmosphere rather than allowing product and utility to mix. In clean-process service, this configuration is typically specified where the utility side cannot be permitted to enter the product stream under any credible failure mode, and where drainability, surface finish, and CIP/SIP compatibility must be demonstrated rather than assumed.

The double tubesheet adds length and tubesheet faces to be polished, and that is a deliberate cost against the consequence of utility ingress into a product stream. It is not a default that every clean-process line needs; it is specified where the utility fluid is not acceptable as a product contaminant and where a leak must be detectable rather than silent.

The product-contact boundary is fabricated to ASME BPE, with the pressure boundary reviewed against TEMA mechanical requirements. Documentation and examination scope:

1. Material certification: mill certificates traceable to each product-contact tube, tubesheet, and wetted fitting, with 304L or 316L grade confirmed against the purchase specification.

2. Surface finish records: Ra measurements on product-side tube IDs and tubesheet faces, reported against the specified target (0.8 / 0.5 / 0.38 / 0.25 µm) rather than a single nominal value.

3. Weld examination: orbital GTAW welds on product-contact joints inspected visually and by borescope where specified; weld log and passivation record issued with the unit.

4. Leak and pressure testing: hydrostatic or pneumatic test of the pressure boundary; double-tubesheet vent gap checked for detectable leakage paths before shipment.

5. Cleanability verification: drainability check on the product side; riboflavin or equivalent coverage test available on request where the cleaning validation requires documented evidence.

6. Compliance documentation: ASME BPE compliance statement, FDA-compliant gasket certificates, and surface finish report supplied with the qualification package.

1. Exchanger body: foam-lined plywood case or iron-frame crate with the hairpin bundle supported to prevent bending stress at the U-return.

2. Product-contact openings: capped with clean, non-shedding covers; hygienic fittings protected against impact and particulate ingress.

3. Surface protection: product-side surfaces wrapped in clean polyethylene; no carbon steel contact on polished stainless surfaces.

4. Documentation: packing list, surface finish report, and material certificates packed in a document holder inside the case; shipping marks reference the purchase order and tag number.

1. Is the double tubesheet necessary for every clean-process hairpin duty?

   • No. A single tubesheet with seal-welded and polished tube joints is often sufficient where the utility is potable and a leak into the product would not create a safety or regulatory event.

   • The double tubesheet is specified where the utility fluid must be prevented from entering the product stream under any credible joint failure, and where a leak must be detectable rather than concealed.

   • In WFI and most aseptic pharmaceutical duty, the double tubesheet is treated as standard rather than optional.

2. What surface finish should be specified for food versus pharmaceutical duty?

   • General food-grade duty commonly targets Ra ≤ 0.8 µm on product-contact surfaces; Ra ≤ 0.5 µm is the usual high-purity pharmaceutical target; stringent biotech or WFI duty may require Ra ≤ 0.25 µm with electropolish.

   • The finish should be chosen against the cleaning validation target and the product’s soil-release behaviour, not against a single “sanitary” label.

   • The utility side can generally be left at a coarser finish unless it is also product-contact.

3. How does the hairpin geometry support CIP and SIP?

   • The product-side flow path is a straight tube with a U-return, with no baffled shell-side dead zones on the product side.

   • A low-point drain and high-point vent, together with the slope shown on the drawing, allow the product channel to drain after CIP.

   • SIP cycles heat and cool the unit; the gasket compound and tube wall are selected against the cycle temperature and chemistry, not just the steady-state design condition.

4. What commercial terms apply?

   • MOQ: 1 set per configuration.

   • Incoterms: FOB, FCA, CIF, or EXW, quoted against the agreed shipment mode and destination.

   • Lead time: approximately 60–150 days after drawing approval, based on the ASME BPE scope, surface finish requirement, and documentation package.

For datasheets, drawings, or an ASME BPE-based quotation, please write to vladimir@steelseamlesspipe.com with the subject line “Sanitary Double Tubesheet Hairpin RFQ.”