K-STEEL STEEL PIPE MANUFACTURE PROCESS SPECIFICATION
Equipments
EAF/BOF, LF
2. Continuous Casting
3. Billet inspection and
cutting
Inspection
item: heat no, length, marking, dimensions, surface quality
4. Rotary
Hearth Furnace
Equipment:Φ28m rotating furnace. According to the procedure
5. Piercing & rolling-Equipment:
ROLL Machine. According to the procedure.
6.Stretch Reducing
Equipment:reducing sizing mill.
7. Normalizing
Equipment:Heat Treatment Furnace, Computer Aid Control System
8. Straightening
pressure straightening machine
pressure straightening
9. Sampling for pipe body
Ladle
Analysis: 1/heat
Product chemical composition：2/ heat
Tensile test：1 PCS/
lot≤100PCS
Traceability
marking (heat and lot number) is applied on the sample and then on the
specimen.
10. Product chemical composition
Laboratory equipment
Spectroanalysis instrument
Product Analysis
Method : Spectrometry analysis
11. Mechanical
testing
Tensile
test 拉伸试验：
Digital universal material test machine
The style and orientation of test pieces
longitudinal strip test pieces& longitudinal rods
gauge length：50mm
width：12.5mm
&38.1&12.7
12. Non Destructive Inspection
The total external and internal surface of
the seamless pipes will be inspected over the entire length to detect
longitudinal defects。The groove’s depth shall be N12.5.
Cibration frequency
At the beginning of production run(change size or change grade)
At the beginning & end of each shift
Every 4 hours of each shift
under continuous production run
13. Visual
Inspection
Illuminance：300Lx
Extent of Inspection：
full length of the pipe
OD, and should include the ID of as much as possible
imperfections treat
a）The surface should be
smooth after repairing and inspected by portable UT
b）cut
off
14. Dimensional Inspection
Measure tool:
vernier calipers、ring gauge、PI-Tape.
壁厚要求WT：(-12.5%~+15.0%)WT。
Straightness：
1、The local
deviation from a straight line in the 1.0m (36 in) portion at each pipe end
shall be ≤4.0mm
2、The total
deviation from a straight line, over the entire pipe length, shall be ≤ 0,2 %
of the pipe length
15. Non Destructive Inspection of Pipe Ends
Both ends of pipe
shall be tested by a MPI. Each length should be inspected for longitudinal of
OD; the cover length should be not less than200mm.
Verification of particle density by
sedimentation.
Verification of magnetism by plate with
cross（A1-30/100 standard test
block）.
Prove up: Removal of imperfection
by grinding smoothly to connect with the coupling surface. OD verification by
micrometer at the lowest point
15.Residual
magnetism Inspection
（1）Four
readings shall be taken ≈ 90° apart
around the circumference of each end of the pipe
（2）The
average shall be ≤3.0 mT (30 Gs), and
maximum 3.5 mT (35 Gs)
（3）Measurements
made on pipe in stacks are not be permited
16. Hydrostatic Test
Hydrostatic test pressure is
showed as follow
Testing hold time
More than 5 seconds
Chart record traceable by Work Order No, heat No, Lot
No, Date, Shift, name of operator, Indication of the graph scale.
17. End
Finish AND Inspection
The angle of the bevel：30°+5°
The width of the root face of the bevel：1.60±0.80mm
Maximum angle of internal taper：7°
The out-of-squareness：≤1.6mm
Pipe ends shall be free from burrs
18.Coating：The
pipe body black paint
19. Measurement of
Length
20. Marking & Painting
Stencil Marking: White stencil marking shall start not
closer than 600mm from the pipe end .
21. Packing
（1）The
inside of the pipes shall be free of any foreign material such as: dirt, chips,
liquid, etc…
（2）Ends
protected with plastic caps approved by customer.
（3）Loose
to be suitable for exportation
（4）Every pipe
of tubes with 1 tag indicating at least num
22. Traceability
1、Traceability by heat and
lot number shall be maintained until the finished product.
2、Heat and lot number shall
be traceable on all the inspection and testing reports/charts.
3、In case of failure of the
calibration of the NDT unit, pipes previously inspected shall be traceable
until the last acceptable calibration.
4、Traceability shall be
maintained on all the manufacturing processes, according to that, any movement
for the pipes between different mills shall be accompanied with tally lists
showing all information concerning traceability.
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