HF welded pipe production line raw material strip choice

For high-frequency welded pipe, the correct choice of strip width dimensional accuracy and weld quality of the finished tube has a very important significance. High-frequency welding raw material width affected by various factors, such as material, welding current frequency, the state of the edge strip, welding margin ,sizing margin and etc.. Generally can be calculated according to the following empirical formula:
(1). B=π (D-t)+Δ1+Δ2+Δ3
B=raw material width, mm
D=finished pipe outer diameter, mm
T=finished pipe thickness, mm
Δ1=forming margin, mm
Δ2=welding margin, mm
Δ3=sizing margin, mm
Δ1, Δ2, Δ3 value selected according to the following table:
Welded pipe equipment forming marginΔ1, mm

Welded pipe equipment welding marginΔ2, mm

Welded pipe equipment sizing marginΔ3, mm

Used range: steel pipe diameter ≤219mm

(2) B=π(DT +ΔDk －t)+kt , mm
DT=the sizing machine last roller diameter, mm. DT =D －（0.2～0.3）
ΔDk= sizing margin, mm
K= coefficient of welding margin
ΔDk decided by finished pipe diameter and sizing machine structure. For sizing machine diameter ≤76mm cantilever type structure, ΔDk advisable 0.25 to 0.50 mm.. For gantry structure sizing mill, ΔDk may be increased to 0.80 mm.. When finished pipe diameter ＞168mm, ΔDk advisable 1.2 to 1.5 mm.. When diameter ＞216mm, ΔDk advisable 2.9 to 3.5 mm.
Coefficient k decided by pipe thickness, but the material and pipe diameter has a certain relationship that the smaller thickness, the bigger diameter, the smaller steel carbon content, the higher the value of k. According to product experience, the k value is 0.5 to 2.75mm, Specific values refer to the table:

The upper Calculation results is the smallest value of strip cutting edge width, upper limited can be increased to about 1 mm. When use hot strip to process, consider of round edge, Oxide and other factors, the smallest size should be plus 0.5mm.
The empirical formula using a wide range, diameter can reach 508 mm.

(3) B=π(D-0.5t), mm
The formula is used to water gas pipe.

(4) B=π(D-t)×1.04～1.05,mm
When D>40mm, 1.040～1.045mm, When D≤40mm, 1.046～1.050mm,
Or  B=π(D-t)+4～5mm
This formula is used to thin thickness pipe.

(5) B=πD-2t+1+z, mm

z is coefficient, choice according to below table:

The formula applies to the width of the double-pipe equipment raw material radius pass design calculation.
These are the five kinds of formulas bandwidth, high-frequency welded pipe equipment due to the different circumstances, according to the calculated results also need to be tested and corrected in the production practice.
If the selected raw material but also trimming in the welded pipe mill, it must also consider the width trimming margin 10 to 15 mm.

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