Seamless Steel Pipe for Marine Purpose

Marine seamless steel pipe is actually common in marine electrical. Two systems of ship and marine engineering generally need three associated with steel pipes covering steel pipe with the conventional system, construction steel pipe and special steel tube. This steel tube is applicable to Class I and Class II pressure tubing, boiler and superheater that are for manufacturing ships.
Certificates

  • In 1998, our marine seamless steel pipes were certified by China CCS classification society factory.
  • In 1999, JST marine steel tubes passed British LR classification society factory qualification.
  • In 2001, this product gained Norway DNV classification society factory certification.
  • In 2003, JST marine seamless steel pipes received USA ABS classification society factory certification.
  • In 2004, our items are certified Japan NK classification society plant.
  • In 2005, our marine steel tubes obtained France BV classification society factory documentation.
  • In 2007, this product passed Germany GL classification society factory certification.

Specifications of Marine Seamless Steel PipeTable 1 Grade of Seamless Steel Pipe (Pressure Tubing)

Pipe Range I
Designed Pressure(Mpa) Designed Temperature (℃) Designed Pressure (Mpa) Designed Temperature (℃) Designed Pressure (Mpa) Designed Temperature (℃)
>  
Steam and Hot Oil 1.6 300 0.7-1.6 170-300 0.7 170
Fuel Oil 1.6 150 0.7-1.6 60-150 0.7 60
Other Media 4.0 300 1.6-7.0 200-300 1.6 200

Note:

  • When the designed pressure and temperature reach the ones in the above Class I, this steel pipe belongs to Class I pipe. If it meets the pressure and temperature of Class II, it is defined to be the Class II pipe.
  • Other media refer to air, water, lubricating oil and hydraulic oil.
  • Class III seamless steel tubes can be manufactured in accordance with the national standards approved by the ship inspection department.
  • 1) As for the seamless steel pipe for boiler and super heater purpose, the working temperature of wall thickness does not exceed 450℃.
  • 2) The dimension of marine seamless steel pipe should firstly select the general steel pipe size in the first group of GB/T7395-1998 table one. The outside diameter of steel tube should choose the standard outside diameter size in the first series of GB/T7395-1998. We can also produce pipes with other specifications not appear in the GB/T7395-1998 table one.

Table 2 Allowable Deviation of Outside Diameter and Wall Thickness

Type Size (mm) Allowable Deviation
Hot-Rolled Pipe Outside Diameter ≤ 159 ± 1.0%, Min. ± 0.5 mm
> 159 ± 1.25%
Wall Thickness ≤ 20 + 15% + 0.45 mm
-10%, Min. -0.30 mm
> 20 ± 10%
D≥ 351 Hot Expanded Pipe ± 15%
Cold-Drawn Pipe Outside Diameter (D) ≤ 30 ± 0.2 mm
30 < D ≤ 50 < DIV> ± 0.30 mm
> 50 ± 0.8%
1.5 ≤ S ≤3.0 + 12.5% + 10%
> 3.0 ± 10%

Note:

  • The tortuosity of marine seamless steel pipe should not exceed the following value”
  • 1) When nominal wall thickness is equal to or less than 15 mm, the turtuosity should not be more than 1.5 mm/m.
  • 2) When nominal wall thickness is more than 15 mm, the turtuosity should not exceed 2.0 mm/m.
  • 3) For the hot expanded pipe with the outside diameter of not less than 351 mm, it should not be over 3.0 mm/m.
  • If the roundness and wall thickness are not uniform in the same cross section of steel tubes, they should not exceed eighty percent of outside tolerance and wall thickness tolerance respectively. These should be marked out in the contract according to clients' requirements.

Table 3 Grade and Chemical Composition of Marine Seamless Steel Pipe

Type Grade Deoxidation Method Chemical Composition (Mass Fraction) (%)
C Si Mn S P Residual Elements
Cr M0 Ni Cu Total
Carbon Steel and Carbon Manganese Steel 320 Killed or Balanced 0.16 0.35 0.40-0.70 0.035 0.035 0.25 0.1 0.3 0.3 0.7
360 0.17 0.35 0.40-0.80
410 0.21 0.35 0.40-1.20
460 0.22 0.35 0.80-1.40
490 0.23 0.35 0.80-1.50

Note: Grade 490 is only applicable to pressure tubing.

Table 4 Room Temperature Mechanical Properties of Steel Tube

Grade Tensile Strength (MPa) Yield Point (MPa) Elongation (%)
320 320-440 195 25
360 360-480 215 24
410 410-530 235 22
460 460-580 265 21
490 490-610 285 2l

Note: Marine seamless steel pipe is often delivered in normalizing state or normalizing and tempering state. If it is delivered in hot-rolled state, the final rolling temperature should not be below Ar3.

Table 5 High Temperature Mechanical Properties of Steel Tube

Grade High Temperature Yield Point (MPa )
Temperature (°C)
50 100 150 200 250 300 350 400 450
320 172 168 158 147 125 100 9l 88 87
360 192 187 176 165 145 122 111 109 107
410 217 210 199 188 170 149 137 134 132
460 241 234 223 212 195 177 162 159 156
490 256 249 237 226 210 193 177 174 171

 

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