1. Boiler tube process flow
Tube billet heating – inspection – skin – – – perforation, pickling, grinding, dry lubrication, welding head, cold drawing, solid solution treatment, pickling, pickling passivation – inspection – cold rolled – oil – cutting head – dry – polishing, polishing, inspection, identification, finished product packaging
GB3087 boiler tube
1. Manufacturing methods
According to different production methods can be divided into hot – rolled tube, cold – rolled tube, cold – drawn tube, extrusion tube and so on.
1.1 hot rolled seamless tubes are generally produced on automatic tube rolling sets.After inspection and removal of surface defects, the solid tube billet is cut into the required length, and then the tube billet is centered on the perforated end face, and then sent to the heating furnace for heating, and perforated on the puncher.In the perforation at the same time continuously rotating and forward, in the role of the roller and the head, the tube blank internal cavity gradually formed, called capillary.Send to the automatic rolling machine to continue rolling.At last, the whole machine has the same wall thickness, and the diameter is determined by the sizing machine to meet the specification requirements.It is a more advanced method to produce hot – rolled seamless steel tube by continuous tube mill.
1.2 if seamless tubes of smaller size and better quality are to be obtained, they must be cold-rolled, cold-drawn or a combination of the two.Cold rolling is usually carried out on a two-high rolling mill. The steel tube is rolled in a circular pass formed by a circular groove with a variable section and a stationary tapered top.Cold drawing is usually carried out on 0.5~100T single chain or double chain cold drawing machine.
1.3. The extrusion method puts the heated tube billet in a closed extrusion cylinder, and the perforating rod and the extrusion rod move together to make the extrusion part extrude from the smaller die hole.This method can produce small diameter steel tube.
GB3087 boiler tube size and allowable deviation
Deviation level standardized outside diameter allowable deviation
D1 ±1.5%, minimum ± 0.75mm
D2 plus or minus 1.0%.Minimum + / – 0.50 mm
D3 ±0.75%. Minimum ± 0.30mm
D4 + / – 0.50%.Minimum + / – 0.10 mm
Boiler tube weight formula :[(outside diameter – wall thickness)* wall thickness]*0.02466=kg/ m (weight per meter)