Development, Specifications, and Application Experience with 80 ksi (552 MPa) Linepipe by J. Malcolm Gray Paper presented at the ABM Annual Congress Vitoria, Brasil 23 July 2007

Overview Introduction Application Metallurgical Approaches Chemical Compositions Specifications Weldability Fracture Control

Figure 1. Development periods for high strength linepipe

Figure 2. Increase in North American natural gas pipeline operating pressures 1)

Macro Trends Higher Pressures Thicker Wall Higher Toughness Lower Carbon Higher Alloy Contents Need for updated specifications. Cost pressures due to steel prices. Globalization of manufacture.

Figure 3. Progress in adopting X-80 Steel.

TypeCMnNbVTiMoCrOther Nb – V 0.05/ / Nb – Ti / Nb - Mo Cu + Ni Nb – Cr 0.03/ Cu + Ni Table III

Figure 4. Comparison of HAZ hardnesses for mechanized welds in Nb-Mo, Nb-Cr & Nb-V Steel.

Steel Type CMnSiNbVTiCrMoCuNiNPcm Nb-V Nb-Cr Nb-Mo Table IV Chemical Compositions of X-80 Pipe Use For Recent Projects

(a)No prior use of X-70/80 acicular ferrite steels. (b)Lack of knowledge or confidence. (c)Isolation. (d)Committee squabbling. (e)Copy and paste mentality at Engineering companies. (f)No platform for change. (g)Bureaucratic inertia. (h)Long term bad habits.

Table V Summary of EWI Microalloying Recommend Chemical Composition Limits

Figure 5. Comparison of limits for vanadium and niobium for different pipe grades.

Figure 6. HAZ hardness as a function of heat input and Pcm.

Figure 7. Comparison of mean hot rolling flow stress – X70 and X80 steels 8)

Development of Blended Approach to Defect Acceptance Criteria (Shaded area was adopted by the project) Figure 15. Defect acceptance levels for Cheyenne Plains X-80 Girth Welds.

Figure 16. Fracture Arrest Predictions: Recent Analyses for X-100

ProjectYearCompanyCountryProductGradeWall thickness (mm) Tons TCPL1972- Present IpscoCanadaCoil and Pipe X-70/ TCPL, Hearst Ontario 1982Algoma Steel Canadian Phoenix CanadaPlate Pipe Iroquois Project1990StelcoCanadaPipeX Cantarell1998Mittal Steel PMT MexicoSlab, Plate, Pipe X70 sour gas Cameron Highway, offshore 2003Azov Stal SteelUkrainePlateX WelspunIndiaPipeX Cheyenne Plains2004Oregon Steel Mills/Napa Pipe USAPlate, Coil, Pipe X st West-East Gas Pipeline 2004Bao SteelChinaPlate and Coil X70 Anshan SteelChinaPlateX70 Julong PipeChinaPipeX70 EuropipeGermanyPipeX Independence Trail, offshore 2005Azov Stal Welspun Ukraine India PlateX TCPL2005Azov Stal Welspun Ukraine India Plate Pipe X-75 (X- 80) Gulf South2006Nanjing SteelChinaPlate and Coil X-80 Rockies Express Oregon SteelUSACoilX70/X8014.3/15.9 Production History 0.10% Niobium HTP Steel

Figure 17

Figure 18. Relationship between maximum thinning strain e f and Charpy energy