GB/T 3091 Low Pressure Liquid Delivery Galvanized Welded Steel Tube , ERW SAWL SAWH Steel Tubes
product name:
GB/T 3091 Low Pressure Liquid Delivery Welded ERW SAWL SAWH Steel Tubes
sizes:
O.D : 5mm-420mm W.T : 0.5mm-50mm Length:3000mm-12000mm
Steel material:
Q195,Q215,Q215B,Q235A,Q235B,Q235,Q345,Q345B
Zinc coating:
100-500g if galvanized
Application:
Carbon steel pipe use for construction ,building filed , low pressure liquid, water, gas, oil, line pipe
Surface Treatment:
Galvanized,Oiled,Black Painted (varnish coating),corrosion resistant coating, Anti corrosion coating
Technique:
Electronic Resistance Welded (ERW ) SAW Submerged-arc Welded Helical(SAWH) Submerged-arc Welded Longitudinal(SAWL)
Material: Fully killed steel, Fine grain steel with a ferritic grain size.
Apperance and General:
The weld areas are free from cracks, lack of fusion and lack of penetration
The tubes are free from external surface defects that can be detected by visual examination.
Straightness:
The deviation from straightness, of any tube length L, shall not exceed 0.0015L.
Deviations from Straightness over any one meter length shall not exeed 3mm.
Tube Manufacturing Process, route and delivery condition:
| Rounte No. | Manufacturing Process | Manufacturing routes | Delivery condition | Applicable for quality | |||
| Process | Symbol | Starting material | Forming operation | TR1 | TR1 | ||
| 1a | Electric welded | EW | As(hot) rolled strip | Cold formed(+welding) | As welded | X | - |
| 1b | NW | X | - | ||||
| 1c | NP | X | X | ||||
| 2a | Normalized rolled strip | As welded | X | - | |||
| 2b | NW | X | X | ||||
| 2c | NP | X | X | ||||
| 3 | As(hot)rolled or normalising rolled strip | Cold formed(+welded)+hot stretch reduced at a controlled temperature to give a normailsed condition | NR | X | X | ||
| 4 | Cold Rolled + streass relieved | Cold formed(+welded) | NP | X | X | ||
| 11a | Submerged arc-welded -Longitudinal seam or -helical seam | SAW: -SAWL -SAWH | As(hot) rolled plate or strip | Cold formed(+welded) | As welded | X | - |
| 11b | NW | X | - | ||||
| 11c | NP | X | X | ||||
| 12a | Normaliseing rolled plate or strip | Cold formed(+welded) | As welded | X | X | ||
| 12b | NW | X | X | ||||
| 12c | NP | X | X | ||||
| 13a | As in lines 11 or 12 | Normalising formed(+welded) | As welded | X | X | ||
| 13b | NW | X | X | ||||
| 13c | NP | X | X | ||||
| 21 | Continous welded, only for steel grades P195 and P235 with D ≤114.3mm | BW | As(hot) rolled strip | Hot formed(+welded) | As welded | X | - |
| a As wekded = no heat treatment. NP=Full pipe normalsed. NW= Normalised weld zone. NR=Normaised rolled b For tubes of quqality TR2, only high-frequency welding, minimum frequency 100kHz,(symbol=HFW) is permited | |||||||
QUALITY CONTROL
1~ Incoming Raw Material Inspection
2~ Raw Material Segregation to avoid steel grade mix-up
3~ Heating and Hammering End for Cold Drawing
4~ Cold Drawing and Cold Rolling, on line inspection
5~ Heat Treatment, +A, +SRA, +LC, +N, Q+T
6~ Straightening-Cutting to specified length-Finished Measuring Inspection
7~ Machanical Testing in own labs with Tensile Strength, Yield Strength, Elongation, Hardness, Impact, Mictrostruture etc
8~ Packing and Stocking.
100% of our steel tubes are dimensionally checked
100% of our steel tubes are visually checked to assure they have a perfect surface condition and no surface defects.
100% eddy current test and ultrosonic test to eliminate longitudinal and transversal defects.
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