Black and galvanized steel pipes are both made of steel, but galvanized pipes have a zinc coating while black pipes do not. Therefore, galvanized pipes are more expensive and more durable.

EN 10219-Cold formed welded structural sections of non-alloy and fine grain steels.

JIS G3454-Carbon steel pipes for pressure service.

EN 10216-Seamless steel tubes for pressure purposes. Unalloyed steel tubes with specified room temperature properties.

The seamless square tube is a long strip of steel having a hollow section and no seam at the periphery, and is a square tube formed by a seamless tube passing through the four sides of the mold.

ASTM A210 standard covers minimum-wall-thickness, tubing sizes, boiler flues including safe ends, arch and stay tubes.