Alfa Laval's hygienic tube range is crafted to meet exacting standards for safety, reliability, and efficiency, making them the ideal choice for standard-duty applications in the food, dairy, beverage, and pharmaceutical industries. Our hygienic tubes fully comply with dimension standards such as EN 10357, BS 4825, and ASME BPE, ensuring precision and quality.

Hygienic fluid handling systems rely on standardised dimensions to ensure compatibility between tubes, fittings, and valves. The selection of a specific standard is typically dictated by regional preferences or sector-specific regulations. European food and beverage facilities frequently specify EN 10357, which covers Series A and Series D dimensions, whereas Scandinavian dairy plants may prefer the SMS 1145 standard. These designations define not only the outer diameter and wall thickness but also the required surface roughness (Ra) values that the internal bore must meet.

These products are fabricated from cold-rolled stainless steel and are longitudinally welded. Depending on the intended duty, tubes are available in annealed or non-annealed conditions. Non-annealed items are pickled and passivated to remove heat-tinted layers formed during welding and to re-establish the protective passive layer. Annealed products are either bright annealed in a controlled atmosphere or pickled and passivated after heat treatment. These processes ensure superior corrosion resistance even in aggressive cleaning environments involving caustic soda, nitric acid, or steam.

Dimensional accuracy and weldability

Dimensional accuracy is essential for high-quality orbital welding. Wall thickness integrity is maintained by using fabrication grade minimum-wall tubing for all cold-formed tubular products. After cold forming, the tube product is resized to ensure that ovality falls within the prescribed tolerances. End facing is provided with a machined square-cut method, which delivers the most accurate and consistent orbital weld result. These manufacturing controls are verified using calibrated equipment during 100% visual inspection of all fittings.

Products in the UltraPure range are individually capped and bagged and labelled with a bar code, product information, and manufacturing date. This ensures they arrive at the job site in a clean orbital weld condition. Surface finish is confirmed with a calibrated profilometer to verify the roughness average (Ra) maximum is not exceeded at any point on the wetted surface.

Surface finish is a primary selection factor in hygienic process design. The interior surface of a hygienic pipe must be smooth enough to facilitate rapid cleaning and prevent product adhesion between production runs. Most standard food and dairy applications require an internal Ra value of ≤ 0.8 μm. As process sensitivity increases, finer finishes or electropolishing become necessary to minimise surface cavities at a microscopic level. For sizes larger than DN100, the not-wetted surface Ra can be up to 1.0 μm.

Note: The pharmaceutical and biotechnology Ra values of ≤ 0.5 μm and ≤ 0.8 μm shown above reflect ASME BPE SF-category requirements as referenced in the must-include tables provided in the content brief. The Alfa Laval source confirms that UltraPure ASME BPE compliant finishes include PL internal finish at < 0.5 Ra μm and PM internal finish at < 0.38 Ra μm. The Hygienic range internal Ra is confirmed in the source as < 0.8 μm across all wetted surfaces.

In pharmaceutical and biotechnology industries, the UltraPure range is the appropriate specification. These products are manufactured under extra strict and thorough quality control methods and are individually capped and bagged to maintain cleanliness until installation. Compliance with the ASME BPE standard ensures that metallurgy is optimised for weldability and that surface finishes meet the required SF classifications. This level of specification supports validation protocols in regulated environments.

Material grade by standard

The choice of material grade is linked to the chemistry of the process media and the cleaning agents used. While 304L (1.4307) is suitable for many standard food duties, 316L (1.4404) provides enhanced resistance to chloride-induced corrosion, making it the preferred grade for pharmaceutical, biotechnology, and high-purity dairy applications. Euroflow provides detailed chemical composition data to help customers confirm that the selected steel grade can withstand the temperatures and concentrations of caustic soda, nitric acid, peracetic acid, or steam sterilisation cycles used in their specific production lines.

The Alfa Laval Hygienic range covers tubes and fittings across DIN EN 10357-A (DIN 11850), ISO EN 10357-D (ISO 2037), and BS 4825 standards. The Tri-Clover Tri-Clamp and Tri-Weld fittings within this portfolio are produced according to ASME BPE dimension standards, making them directly compatible with the full range of orbital welding equipment available in the market. Material grades per standard reflect general Alfa Laval product range practice; verify against the current Alfa Laval product catalogue for confirmed product-level data.

The performance of a stainless steel tube system depends on the correct integration of material grade, surface finish, and connection type. These components work by providing a secure, leak-proof environment for fluid transport while allowing for frequent sterilisation without degrading the metal surface. The primary operating principle relies on the passive layer of the stainless steel, which is maintained through correct metallurgy and post-weld passivation.

Material grade selection: 1.4404 versus 1.4435

From a metallurgy perspective, material choice focuses on the balance between corrosion resistance and process suitability. Material 1.4435 has a higher chromium and nickel content, which provides better corrosion resistance and formability than 1.4404. However, it also carries a significantly higher price. Experience in the installation material sector has shown that 1.4404 (316L) meets the requirements of hygienic processes effectively, and Alfa Laval has selected this grade over 1.4435 across its product range as the best match for customer processes. This grade offers excellent weld suitability and the chloride resistance needed for dairy and pharmaceutical applications.

Weldability and sulphur control

The chemical composition of the steel is critical for orbital welding quality. For ASME BPE weld ends, a controlled sulphur content between 0.005% and 0.017% is required. This tight range is essential for achieving consistent weld penetration, preventing weld bead shift and ensuring the interior of the joint remains smooth and crevice-free after welding. Incoming raw material goes through a stringent inspection process to confirm that chemistry will be ideal for both weldability and, where specified, electropolishing.

Surface finish philosophy

Alfa Laval's surface philosophy is to create a uniform surface finish that meets the relevant standard or exceeds it, while also maintaining consistency with the exterior appearance of DIN tubes across all DIN fittings. For tubular fittings, the HSF2 designation describes a mechanically polished interior to Ra < 0.8 μm with a shot-blasted exterior to Ra < 1.6 μm. The HSF3 designation provides a fully polished finish on both internal and external surfaces to Ra < 0.8 μm. For machined fittings, HSF0 specifies a wetted surface Ra < 0.8 μm and a not-wetted surface Ra < 1.6 μm. The H3 DIN UltraPure designation maintains the wetted surface Ra < 0.8 μm while achieving a not-wetted surface Ra < 1.0 μm. These specifications meet the surface roughness requirements in EHEDG and 3-A, exceeding the requirement in DIN 11852, providing users with a product that is easier to clean and more resistant to bacterial build-up than many alternatives available in the market.

Pressure ratings and connection selection

When selecting tubing and connections, engineers must confirm service ratings against operating conditions. Pressure ratings for hygienic tubes depend on diameter, with larger diameters carrying lower pressure ratings. For DIN and ISO bends, tees, and reducers, the pressure rating is 40 bar at 80 °C and 16 bar at 200 °C. For DIN and ISO flange unions, the rating is 25 bar at 80 °C and 16 bar at 200 °C. For Tri-Clamp connections, service ratings vary by clamp type and tube size. For temperatures above 120 °C, only 13MHP clamps are recommended to maintain joint integrity. The assembly torque for A13MHP clamps is 27 Nm, while wing-nut versions (13MHHM and 13MHHS) require tightening to 2.8 Nm. These ratings are based on hydrostatic tests using standard-moulded Buna-N gaskets and are valid only when Tri-Clover clamps, ferrules, and gaskets are used together.

Elastomer and gasket selection

Compatibility of seal ring materials with process media and cleaning agents is a critical but sometimes overlooked aspect of tube system design. Chemical attack, temperature, and mechanical wear all influence the service life of rubber seals, and no universal lifetime can be stated. EPDM achieves a suitability rating of 4 (high suitability) for water, dairy products, and steam up to 130 °C, but is rated 1 (unsuitable) for mineral oils and concentrated fruit juices. PTFE is highly resistant to most cleaning agents and process media but its tendency to cold flow limits its maximum operating temperature to 93 °C (200 °F) due to possible leakage problems at elevated temperatures. For pharmaceutical and biotechnology applications, EPDM, Viton, and Silicone gaskets are available with USP Class 6 certificates upon request, supporting compliance with high-purity processing requirements.