What is Sendzimir galvanizing?
Sendzimir galvanizing is a continuous process for giving thin steel strip (coil) a zinc coating. The process is named after the Polish engineer Tadeusz Sendzimir, who developed it in the 1930s. The steel strip is first cleaned and annealed in a furnace, then passes in one continuous line through a bath of molten zinc. After the bath, the zinc coating is wiped to the required thickness with air knives. Only then is the galvanized strip cut, bent, pressed or roll-formed into products.
Sendzimir galvanized steel is also known as pre-galvanized steel or strip-galvanized steel. The European standard is EN 10346. The zinc coating is designated by a code, for example Z275: this means 275 grams of zinc per square metre, for both sides combined.
Difference with hot-dip galvanizing of finished parts:
- With Sendzimir, the strip is galvanized before fabrication. The coating is relatively thin, smooth and even. Cut edges and drilled holes created later are not covered with zinc; the surrounding zinc does protect small edges to some extent (cathodic protection).
- With hot-dip galvanizing of finished parts (to EN ISO 1461), the finished product is dipped in zinc as a whole after welding and drilling. All edges and seams are then covered and the coating is usually considerably thicker.
| Sendzimir (strip) galvanizing | Strip galvanized before fabrication; coating relatively thin, smooth and even. Cut edges and drilled holes created later are not covered with zinc, though the surrounding zinc protects small edges to some extent (cathodic protection). |
|---|---|
| Hot-dip galvanizing of finished parts (EN ISO 1461) | Finished product dipped in zinc as a whole after welding and drilling; all edges and seams covered; coating usually considerably thicker. |
Application
Sendzimir galvanized steel is widely used for products made from thin sheet steel, such as metal stud profiles for walls and ceilings, angle brackets and joist hangers, cable trays, ventilation ducts, roof sheets and facade cladding (often with an extra coating), and the support framework of suspended ceilings.
Tips:
- Indoors or outdoors? For dry indoor applications, Sendzimir galvanized steel is usually more than adequate. Outdoors, in damp rooms or in aggressive environments (coast, livestock buildings, swimming pools), a thicker coating, hot-dip galvanizing, an extra coating or stainless steel is often needed. Look at the corrosion class stated by the manufacturer.
- Cut edges: outdoors, treat sawn and cut edges with a zinc-rich paint.
- Fasteners: use screws and nails with comparable or better corrosion protection, otherwise they will rust before the profile does.
- Do not weld without precautions: welding burns off the zinc coating and zinc fumes are harmful. Provide fume extraction and restore the zinc coating afterwards.
Related Terms
- Galvanizing
- Corrosion
- Corrosion class
- Metal stud
- Cold-formed steel
- Cathodic protection
Discover our DIY plans at fredsdiyplans.com