316L – the standard for pharma

316L is the standard material for pharmaceutical process and utility systems: purified water, water for injection, clean steam, process vessels and transfer lines. Its molybdenum content resists the chlorides in cleaning and sanitising agents, and its low carbon keeps welds free from sensitisation. Pharmaceutical specifications often add controlled sulphur – to give good weldability by automatic orbital welding and a smooth electropolished surface – and limits on delta ferrite. See SS 316 pipes and SS 316 pipe fittings.

Surface finish and ASME BPE

In hygienic systems, the internal surface finish affects cleanability and microbial growth. Finishes are specified by maximum surface roughness, Ra, in micrometres – for example Ra ≤ 0.8 µm mechanically polished, or Ra ≤ 0.5 µm or 0.4 µm electropolished for the most critical high-purity lines. The ASME BPE standard (Bioprocessing Equipment) sets dimensions, tolerances, surface finish designations and material requirements for tubing and fittings used in biopharmaceutical plants. Hygienic systems usually use OD tubing and orbital-welded tube fittings, rather than scheduled pipe.

Tubing for hygienic systems

Stainless steel tubes for hygienic service are supplied to ASTM A269 and A270 (sanitary tubing), seamless or welded, with polished or electropolished bores, in OD sizes from ½" upwards, and to ASME BPE where specified. Instrumentation tubes are used for instrument and sample lines. Fittings – elbows, tees, reducers, ferrules and clamps – are matched to the tubing and finish.

Food, dairy and beverages

Dairy, brewery, beverage and food plants use 304L for most process and storage equipment, and 316L where products are salty or acidic or where chlorinated cleaning agents are used. SS 304 pipes, stainless sheets for tanks and vessels, and polished fittings are used throughout. Clean-in-place (CIP) systems with hot caustic and acid washes make corrosion resistance and smooth, crevice-free joints essential.

Traceability and documentation

Pharmaceutical plants must document the material of every product-contact component for validation. We supply each item marked with its heat number and accompanied by its mill test certificate, and can provide surface-roughness reports, ferrite measurements, intergranular corrosion tests and positive material identification on request. Please send the user requirement specification or the BPE requirements with the enquiry.

Welding and passivation

Hygienic stainless systems are joined by automatic orbital TIG welding, which gives smooth, consistent internal weld beads without crevices; welds are inspected with borescopes and documented in weld logs. After installation, systems are cleaned and passivated with nitric or citric acid solutions to restore the chromium-rich passive film and remove free iron. Over time, a reddish film called rouge can form in hot water and clean steam systems; it is managed by periodic derouging and repassivation. Tubing and fittings with controlled sulphur, smooth bores and low ferrite make each of these steps more reliable.

For plants that combine pipe and tube, scheduled 316L pipe to ASTM A312 is normally used for utilities and non-product-contact lines, and OD tubing to ASTM A270 or ASME BPE for product-contact and high-purity lines.

Products for pharma and food

We supply seamless pipes and tubes, welded pipes and tubes, flanges, pipe fittings including stainless steel pipe fittings, plates, sheets, round bars and fasteners in 304L and 316L. All industries we serve are on the industries page.