K-STEEL-SEAMLESS STEEL PIPE MANUFACTURE PROCESS SPECIFICATION

SEAMLESS STEEL PIPE MANUFACTURE PROCESS SPECIFICATION

Hebei K-Steel Pipe Industry Co.,Ltd.

Steel Making of Shandong Molong Petroleum Machinery

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 ：

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.

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.