Large-diameter steel pipes are pickled using an acid solution to remove oxide scale and rust on the surface of steel, called pickling. Acids for pickling include sulfuric acid, hydrochloric acid, phosphoric acid and mixed acids.

Generally speaking, the appropriate petroleum cracking steel pipe should be selected from the three aspects of performance, economy and working conditions.

Small and medium-sized steel, wire rods, steel bars, medium-diameter steel pipes, steel wires and wire ropes, etc., can be stored in a well-ventilated material shed, but must be topped and bottomed.

Most of the water pipelines in urban sewage treatment projects are buried steel pipelines. The corrosion problem is a major problem in sewage treatment projects.

Defects that are easy to produce in the submerged arc welding zone are pores, hot cracks, and undercuts.

Hot rolling is relative to cold rolling. Cold rolling is rolling below the recrystallization temperature, while hot rolling is rolling above the recrystallization temperature.