Construction technology of galvanized seamless pipe

The construction of galvanized seamless pipes differs from ordinary galvanized pipes, mainly because extra care is needed to protect the zinc layer. Although seamless pipes have no welds, their galvanized coating is soft and easily damaged during cutting, threading, or handling.

Key Considerations of Connecting Galvanized Seamless Pipe

Protect the galvanized layer – Avoid scratches or abrasion during transport and installation.

Avoid welding – Welding burns the zinc layer, reduces corrosion resistance, and produces toxic fumes.

Cutting & repair – Pipe ends and damaged areas must undergo secondary anti-corrosion treatment (zinc-rich paint, epoxy primer, or repair agent).

Main Connection Methods of Galvanized Seamless Pipe

1. Threaded Connection

Process: Thread both ends → clean burrs → apply anti-corrosion coating → use PTFE tape/sealant → tighten with pipe wrench.

Pros: Simple, fast, easy disassembly.

Cons: Damages coating at threads, requires repair; limited strength.

2. Grooved Coupling Connection

Process: Groove both pipe ends → coat damaged parts → place sealing ring → install clamp and tighten bolts.

Pros: Quick, flexible, good sealing, suitable for medium/large diameters.

Cons: Needs grooving equipment; groove area must be re-protected.

3. Flange Connection

Process: Use pre-threaded or slip-on flanges → insert gasket → align and bolt.

Pros: Strong, reliable, easy disassembly and maintenance.

Cons: Higher cost, more complex installation, requires precision.

Additional Precautions

Cutting: Use saws/cutters (not gas cutting) to protect the zinc layer.

Secondary protection: Every cut, thread, or groove must be re-coated.

Handling/storage: Avoid dragging, impacts, and moisture.

Supports/hangers: Use insulating pads to prevent electrochemical corrosion.

Pressure test: Conduct water/air test after installation to check sealing.

By choosing the right connection method and ensuring secondary corrosion protection, galvanized seamless pipes can retain their durability and corrosion resistance throughout service life.

Read more: Wholesale guide of galvanized seamless pipes