Standard:  

      EN_10305_4-2003.zip，EN10305-4(DIN2445/2) , EN10305-1( DIN2391/C) ,GB/T3639, ASTM A179 

Steel Grade:

 E235 (ST35 ST37.4 10# ) ,E255(ST45 20#) E355 ,(ST52 ST52.4 16Mn)

Size:

OD: 4-120mm,  WT: 0.5-10mm, Length:Fixed 6m or as your requirement

Surface treatment: 

1.Bright--polishing and do corrosion protection after NBK 

2.galvanized--this tubes with a zinc coating of 8 to 12μm and subsequently chrome VI-free passivated (yellow and silver);

3.Phosphated--internal and external phosphated coating

Heat treatment: 

+N (NBK) normalized

Straightness:

 10μm / meter