Seamless Tube for boiler and heat exchangers
JIS3461 STB340 Seamless Precision Steel Tube
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Seamless Carbon Steel tubes for boiler and heat exchangers, made according to the Japanese National Standard JIS G3461.
JIS G3461 is a standard applicable for Seamless Carbon Steel pipes which is used for boiler and heat exchangers.
Steel grade of JIS3461 Seamless Boiler Pipe: STB 340, STB 410, STB 510
Applicationof JIS3461 Seamless Boiler Pipe: For boiler and heat exchangers
Chemical composition for JIS3461 Seamless Steel Tube:
| Steel Grade | Chemical composition % |
| C max | Si max | Mn | P max | S max |
| STB 340 | 0.18 | 0.35 | 0.30-0.60 | 0.035 | 0.035 |
| STB 410 | 0.32 | 0.35 | 0.30-0.80 | 0.035 | 0.035 |
| STB 510 | 0.25 | 0.35 | 1.00-1.50 | 0.035 | 0.035 |
Mechanical properties of Seamless Heat Exchanger Tube:
| Steel Grade | Mechanical properties |
| Tensile strength min MPa | Yield strength min MPa | Elongation min % |
| OD＜10mm | 10mm≤OD＜20mm | OD≥20mm |
| STB 340 | 340 | 175 | 27 | 30 | 35 |
| STB 410 | 410 | 255 | 17 | 20 | 25 |
| STB 510 | 510 | 295 | 17 | 20 | 25 |
Heat treatment for JIS3461 Seamless Boiler Pipe:
1. STB 340:
- Hot finished seamless steel tube: As manufactured. However, as required, low temperature annealing or normalizing may be performed.
- Cold finished seamless steel tube: Low temperature annealing, normalizing or full annealing.
- As welded electric resistance Welded Steel Tube: Normalizing.
- Hot finished electric resistance welded steel tube: As manufactured. However, as required, low temperature annealing or normalizing may be performed.
- Cold finished electric resistance welded steel tube: Normalizing.
2. STB 410:
- Hot finished seamless steel tube: As manufactured. However, as required, low temperature annealing or normalizing may be performed.
- Cold finished seamless steel tube: Low temperature annealing, normalizing or full annealing.
- As welded electric resistance welded steel tube: Normalizing.
- Hot finished electric resistance welded steel tube: Low temperature annealing.
- Cold finished electric resistance welded steel tube: Normalizing.
3. STB 510:
Normalizing.
The cold finished electric resistance welded steel tube which has been normalized prior to cold finishing may be finished by low temperature annealing or full annealing.
Appearance for JIS3461 Seamless Steel Tube:
a) The tube shall be practically straight and its both ends shall be at right angles to its axis.
b) The inside and outside surfaces of the tube shall be well-finished and free from defects detrimental to use. In the case of electric resistance welded tube the swelling of inside surface of the welded shall be 0.25 mm or less.
In addition, the purchaser may designate the inside swelling as 0.15 mm or less for the tubes 50.8 mm or under in outside diameter and at the same time 3.5 mm or under in wall thickness.
c) Although when the surface dressing is performed, it may be performed by a grinder or machining, etc., the wall thickness of the product after dressing shall be within the tolerances on wall thickness.
d) The dressed area shall smoothly remain along the shape of the tube.
Tests of Seamless Heat Exchanger Tube:
- Chemical analysis
- Tensile test
- Flattening test
- Flaring test
- Reverse flattening test
- Hydraulic test or non-destructive examination
Production Picture:
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