Specifications

Chemical composition and mechanical properties

Other elements and footnotes as given in the standard. Dual-certified material meets both grades.

Transverse elongation and other requirements as given in the standard.

Background, equivalents and physical properties of the grade are on the SS 316 / 316L page.

Where SS 316 pipe outperforms 304

The molybdenum in TP316 and TP316L raises resistance to pitting and crevice corrosion, so 316 is chosen for coastal and offshore utility lines, brackish cooling water, chloride-bearing process streams, dilute sulphuric and phosphoric acids, organic acids, and pharmaceutical and food lines cleaned with chlorinated or acidic chemicals. In warm seawater, concentrated brine and hot chloride solutions, 316L still has limits – pitting, crevice corrosion and, above about 60 °C under stress, chloride stress corrosion cracking – and duplex or super duplex pipe is then used.

Seamless or welded SS 316 pipe

Seamless 316 pipe – see stainless steel seamless pipes – is used for high-pressure and critical process lines. Welded 316 pipe – see stainless steel welded pipes – is widely used in thin walls and larger diameters for water, utility and hygienic lines, and for large headers made by EFW to ASTM A358. Both are heat treated and meet the same A312 grade requirements.

For pharmaceutical and food lines, welded 316L tube and pipe with polished bores are often used instead of standard pipe, and orbital welding gives smooth, crevice-free joints.

Equivalent designations

Equivalent grades are similar but not identical; composition and property limits differ between standards. Order to the standard you need.

Testing, marking and ordering

Each length is hydrostatically or electrically tested, with flattening and tensile tests on samples, and marked with grade, size, schedule, heat number and SMLS or WLD. Pharmaceutical and chemical projects often add an intergranular corrosion test to ASTM A262 Practice E and require pickled and passivated surfaces. Please give the grade, seamless or welded, size, schedule, length, end finish, surface finish, quantity and any supplementary tests or inspection.

Applications and related products

SS 316 pipes are used in chemical and petrochemical plants, pharmaceutical and biotech facilities, dairy, brewery and food processing, desalination pre-treatment, marine and offshore utilities, pulp and paper, and coastal architecture. Matching products in the same grade include SS 316 flanges, SS 316 pipe fittings, SS 316 sheets and plates and SS 316 round bars. Other materials are on the seamless pipes and tubes and welded pipes and tubes pages.