Width, material, temperature and magnet requirements for welded steel pipe

Welded steel pipe strip width, material, temperature and magnet requirements
1 the width of the steel belt and tolerance range are carried out according to the requirements of GB/T3091-2001, cutting edges strip should be adopted in principle.
2 the material of steel belt (weldability), according to the request of GB700.
3 welding temperature: 1350-1380℃, the high frequency furnace frequency: 200-400 KHZ, under the condition of the high frequency equipment must have built-in frequency, frequency of high frequency welding changes with the welded steel pipe diameter and wall thickness.
4 bar (impedance) requirements

NPS Bar OD        NPS Bar OD
1/2" Ф13×140 2" Ф35×200
3/4" Ф18×140 3" Ф30×200×4
1" Ф22×140 4" Ф30×200×7
1 1/4" Ф30×200 5" Ф32×200×7
1 1/2" Ф32×200 6" Ф35×200×7

5 water cooling control.
Induction coil, the magnet, and adjacent squeezing roller device generated large heat due to the high frequency effect, which must strengthen the water flow to cooling, after cooling temperature shall below 400℃. Output transformer and induction coil device also should be passed into the circulating cooling water, and ensure the long-term circulating water outlet water in the running process.
6 high frequency electric resistance welded steel pipe appearance judgment:
6.1 when do normal welding operation, look from the squeezing roller center along the direction of equipment operation should be from coarse to fine, from deep to dark red metal extrusion line.
6.2 by scraping scar device, the burr of the steel pipe can not have split ends.
6.3 by scraping scar, the weld of the steel pipe surface should be a continuous blue strip, line width of 1 -- 3 mm.
6.4 weld reinforcement inside the steel pipe should be full and uniform.