Why Internal Grinding & Polishing Line Matters for High-Performance Steel Pipes?

Why Internal Grinding & Polishing Line Matters for High-Performance Steel Pipes?

Internal grinding and polishing is a critical finishing step in premium steel pipe manufacturing.

This process is designed for pipes serving demanding fluid transport applications: potable water transmission, crude oil & refined oil pipelines, chemical corrosive media, slurry and abrasive fluid conveying.

In these service conditions, the inner bore must stay smooth, defect-free and dimensionally consistent over decades of operation.

As-received hot-rolled or as-welded pipe inner surface carries mill scale, weld bead flash, uneven roughness and residual rust.

Under continuous flow, rough inner surface increases friction loss, boosts pumping energy consumption, and traps scale and sediment that accelerates internal corrosion.

The internal grinding & polishing line solves this core problem.

It uses multiple abrasive wheel stations to machine the inner bore to uniform roughness and concentricity, removing weld flash, mill scale and surface defects in one pass.

A properly ground inner surface reduces flow resistance, improves coating adhesion for internal epoxy / cement mortar lining, and ensures stable hydraulic performance across the entire pipeline.

For large diameter internally ground steel pipes, these critical rules must be followed strictly:

· Precision grinding head alignment — ensure full-contact grinding along the entire bore length, no missed spots or uneven depth.

· Controlled roughness profile — meet project Ra requirement (typically Ra 6.3–12.5 μm for lined pipe, finer for hydraulic/pneumatic service). Too rough causes flow loss; too smooth weakens coating bond.

· Weld bead flushness — internal weld seam must be ground flush to base metal, eliminating flow eddy and stress concentration points.

· Inline dimensional inspection — ultrasonic / laser diameter check after grinding to confirm ovality and wall tolerance remain within spec.

· Post-grinding cleanliness — blow out steel grit and dust immediately, then apply anti-rust oil or wrap for storage to prevent flash rust on freshly ground surface.

Ms.Hazel

Mr.Glen