Pipe Treatment
Careful control of the treatment process results in tension and burst properties equivalent to 95,000 psi circumferential yield.
Strength can be imparted to tubular goods in several ways. Insofar as most steels are relatively mild (0.30% carbon), small amounts of manganese are added to them and the material is merely normalized. When higher-strength materials are required, they are normalized and tempered. Additional physical strength may be obtained by quenching and tempering (QT) a mild or low-strength steel. This QT process improves fracture toughness, reduces the metal’s sensitivity to notches.
Uncoiling Leveling Sheoring Side Coil Edge Forming Welding
Trimming UST (Welding Conditi on Monitoring)
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Sizing Full Body UST |
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Cutting |
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Stroightening |
Outside it Ultrasonic Seom Cooling
Inside Test (No. 1) Normoli2ing
Weld Bead Removing
Fig. 1.4: Nippon’s Electric Welding Method of manufacturing casing. (Courtesy of Nippon Steel Corporation.)
lowers the brittle fracture temperature and decreases the cost of manufacturing. Thus, many of the tubulars manufactured today are made by the low cost QT process, which has replaced many of the alloy steel (normalized and tempered) processes.
Similarly, some products, which are known as ‘warm worked’, may be strengthened or changed in size at a temperature below the critical temperature. This may also change the physical properties just as cold-working does.