Line pipe steel

Recently, attention has been directed to a study of the problem of grooving corrosion in line-pipe steel welded by high frequency induction or electric resistance welding. In sea water, it seems to be related to high sulphur content in the weld zone, the type of environment, its temperature and velocity The importance of sulphur is significant since Drodten and... 

Toughness 30% higher than line pipe steels for comparable natural gas service... 

Figure 19. Dramatic prevention effect introduced by REM additions against disintegration of line pipe steel by hydrogen-induced cracking (HIC)...

Elboujdaini, M., Shehata, M.T., A Review on the Initiation of Environmentally Assisted Cracking in Line Pipe Steel, Proceedings of the Egyptian Corrosion Society, pp. 1-13, December 2004. 

Fig. 7.82 Effects of strain rate upon stress corrosion susceptibility of line pipe steel in 79 °C, 2 N CO3/HCO3 solutions at several potentials relative to SHE. Redrawn from Ref 119...

Fig. 7.119 Fatigue-crack-growth rates as a function of stress-intensity amplitude for X-65 line pipe steel in air. Frequency 0.1-15 Hz, at R = 0.2. Redrawn from Ref 1 69...

Figure 7.123 shows the corrosion-fatigue behavior of the line pipe steel in the 3.5% NaCl solution at the corrosion potential, -440 30 mV (SHE) compared with -800 10 mV (SHE) when cathodically coupled (Ref 169). At the higher free-corrosion potential, the slope of re-... 

Boothby P J, Hart P H M Welding 0.45%V line pipe steels . Metal Constr 13 (9) 1981 560-565. 

To evaluate the hydrogen trapping abftity of API X65 line pipe steels, hydrogen per-meabihty and apparent diffusivity was measured in their various microstructures... 

A. Takahashi, H. Ogawa, Influence of microhardness and inclusion on stress oriented hydrogen induced cracking of line pipe steels, ISIJ Inti. 36 (1996) 334-340. 

W.K. Kim, H.G. Jung, G.T. Park, S.U. Koh, K.Y. Kim, Relationship between hydrogen induced cracking and type I sulfide stress cracking of high-strength line-pipe steel, Scripta Mater. 62 (2010) 195-198. 

G.H. Koch, T.J. Barlo, W.E. Berry, Effect of grit-blasting on the stress corrosion cracking behavior of line pipe steel, Mater. Performance 23 (1984) 20—23. 

Hydrogen-induced blistering Also commonly referred to as hydrogen-induced cracking (HIC), it occurs in lower-strength (unhardened) steels, typically with tensile strengths less than about 550 MPa (80 ksi). Line pipe steels used in sour gas environments are susceptible to HIC. 

Vosikovsky, O. Fatigue-crack growth in an X-65 line-pipe steel at low cyclic frequencies in aqueous environments. Trans. ASME Series H 97, 298-305 (1975)... 

Type A sleeves simply encircle the pipeline and provide structural reinforcement of the defective area. To do this, they do not require sleeve-end fillet welds. Type B sleeves also encircle the pipeline and provide structural reinforcement, but since the ends are fillet welded to the pipeline, they can also contain pressure in the event that the defect is leaking or will eventually leak in subsequent service. The results of work at BatteUe showed that steel sleeve repairs are capable of restoring the strength of a damaged pipeline to a pressure level in excess of a pressure that corresponds to 100% of the specified minimum yield strength of the line pipe steel. The results of this work led to the widespread use of fuU-encirclement steel sleeves for pipeline... 

The early work at Battelle showed that steel sleeves are effective because they restrain bulging, or accumulation of strain, in the defective area. Steel sleeves accomplish this while absorbing only 15—20% of the hoop stress in the carrier pipe. Steel sleeves are effective because the stiffness (elastic modulus) of the sleeve material is equivalent to that of the line pipe steel. 

While Type B sleeves have to be fillet welded to the pipeline (Figure 4.11), they can be used where composite repairs cannot, such as for repair of defects that are 80% deep or greater, circumferentially oriented defects, leaking defects or for defects that will eventually leak (e.g., internal corrosion), and cracks. The raw materials required to make Type B sleeves are significantly less expensive than composite materials, and the stiffness and long-term performance of Type B sleeves are equivalent to that of line pipe steel. 

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