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Controlled rolled X60, X65, and X70 steels, originally developed to meet the stringent requirements of arctic pipelining, have been used in offshore oil and gas pipelines. This paper discusses the technology and application of these acicular-ferrite and pearlite-reduced steels, which have been used successfully in several North Sea submarine pipelines. Introduction The last 10 years have seen a worldwide flurry of alloy design and development activity by manufacturers of large-diameter line pipe. This effort was stimulated by the discovery of large deposits of crude oil and natural gas in hostile environments. The North Sea as well as the arctic regions of North America and the Soviet Union require high-strength, tough, weldable steels, up to X70 quality, to meet severe installation and operating conditions. In the early 1960's, pipe manufacturers commonly offered large-diameter line pipe with only 52-ksi specified minimum yield strength. Wall thicknesses were usually no greater than 0.50 in. However, the new trend in the industry is to higher-strength, thicker-wall pipe. Large pipe, ranging from 30 to 48 in. in diameter and, in the Soviet Union, up to 56 in. in diameter, is being used. High operating pressures of 2,000 psig and above and pipelaying in water to depths well below 400 ft emphasize pipelaying in water to depths well below 400 ft emphasize the need for products with thicker walls. Pipe with wall thicknesses of 0.625.to 0.750 in. is already being used and 1-in.-thick pipe will be needed for future projects. projects. While pipe with 60-ksi yield strength (X60) is now in common use, products with higher strength (X65 and X70 grade) already have been placed in crude and natural gas transmission service. Several major projects planned for construction, including the Canadian Arctic Gas Pipeline in North America and the Stratfjord project in Pipeline in North America and the Stratfjord project in the North Sea, will use these higher-strength grades for technical and economic reasons. Installation and operation of oil or gas pipelines in cold, remote regions have led to an increase in toughness requirements by the pipeline designer. Battelle Research Laboratorie's drop-weight tear test (BDWTT) criteria are used to be sure that the steel will behave in a ductile manner. The operating temperature of the pipeline must be above the ductile-brittle fracture-appearance transition temperature (FATT). Extensive testing is carried out to assure that the pipeline operates above the BDWTT-FATT of the steel. To guard against fast-running ductile fracture, Charpy V-notch requirements, established by correlation with full-scale burst tests that simulate actual pipeline operating conditions, are often specified. Recently, in a program sponsored by the AGA, Battelle established the following empirical equation: Cv = 0.0108 (H)2 (Rt)1/3,......................(1) where Cv is the minimum, full-size Charpy energy in foot-pounds that will produce fracture arrest, H is the operating stress in ksi, and R is the pipe radius and t is the pipe-wall thickness, both expressed in inches. The specified minimum yield strength of the pipe multiplied by a suitable "safety factor" is equal to the operating stress, H. Eq. 1, using a safety factor of 0.72, which applies to natural gas transmission pipelines in the U.S., is shown graphically in Fig. 1. JPT P. 730
- Europe > United Kingdom > North Sea (0.65)
- Europe > Norway > North Sea (0.65)
- Europe > North Sea (0.65)
- (4 more...)
ABSTRACT Controlled rolled X60, X65 and X70 steels, originally developed to meet the stringent requirements of Arctic pipelining, have been used in offshore oil and gas pipelines. The technology and application of these acicular ferrite and pearlite reduced steels, which have been used successfully in several North Sea submarine pipelines, are discussed. Fracture toughness and field weldability of these low carbon steels are highlighted. INTRODUCTION The last ten years have seen a flurry of alloy design and development activity, worldwide, by manufacturers of large diameter line pipe. This effort was stimulated by the discovery of large deposits of crude oil and natural gas in hostile environments. The North Sea, as well as the Arctic regions of North America and the Soviet Union, require high strength, tough and weldable steels, up to X70 quality, to meet severe installation and operating Conditions. In the early sixties, pipe manufacturers commonly offered large diameter line pipe with only 52 ksi specified minimum yield strength (SMYS). Wall thicknesses were usually no greater than .50 inches. The new trend in the industry is, however, to higher strength, heavy wall thickness pipe. Large pipe, ranging in size from 30 inch to 48 inch diameter and, in the Soviet Union up to 56 inch diameter, is being utilized. High operating pressure, up to 2000 psig and above, and pipelaying in water to depths well below 400 feet, emphasize the need for heavier wall thickness product. Pipe with wall thicknesses of.625 to .750 inch is already being used and 1 inch thick pipe will be needed for future projects. While pipe with yield strength of 60 ksi (X60) is now in common use, products with higher strength, X65 and X70 grades, have already been placed into crude and natural gas transmission service. Several major projects planned for construction in the near future including the Canadian Arctic. Gas Pipeline-in North America and the Statfjord Project in the North Sea will make use of these higher strength grades for technical and economic reasons. Installation and operation of oil or gas pipelines in cold, remote regions have led to an increase in toughness requirements by the pipeline designer. Battelle Drop Weight Tear Test (BDWTT) criteria are used as a measure to ensure that the steel will behave in a ductile manner. The operating temperature of the pipe- line must be above the ductile-brittle fracture appearance transition temperature (FATT). Extensive testing is carried out to insure that the pipeline ?operates above the BDWTT-FATT of the steel. To guard against fast running ductile fracture, Charpy V-notch requirements, established by correlation with full scale burst tests which simulate actual pipeline operating conditions, are oftentimes specified. Recently, Battelle, in a program sponsored by the American Gas Association (AGA), had established the following empirical equation:(Mathematical Equation)(Available in full paper) where Cv is the minimum, full size, Charpy energy in foot-pounds that will produce fracture arrest, ?H the operating stress in kai, R the pipe radius and t the pipe wall thickness also expressed in inches.
- Europe > United Kingdom > North Sea (0.65)
- Europe > Norway > North Sea (0.65)
- Europe > North Sea (0.65)
- (5 more...)
High Strength Low Alloy Steels in Naval Construction
Montemarano, T. W. (David Taylor Research Center) | Sack, B. P. (David Taylor Research Center) | Gudas, J. P. (David Taylor Research Center) | Vassilaros, M. G. (David Taylor Research Center) | Vanderveldt, H. H. (Naval Sea Systems Command (NAVSEA))
The Naval Sea Systems Command has recently certified a lower-cost alternative steel to the HY-80 steel presently used in construction of naval surface ships. This alternative steel is based on the commercial development of high strength low alloy (HSLA) steels originally directed to the offshore oil exploration platform and gas line transmission industries. The certification is a result of an ongoing research and development program begun in 1980. This paper addresses several aspects of the HSLA steel development effort, including a discussion of the properties and metallurgy of this steel, and the cost savings which are achievable. Finally, the status of the current and planned Navy HSLA usage and the R&D program is described.
- Research Report > New Finding (0.68)
- Research Report > Experimental Study (0.46)
- Materials > Metals & Mining > Steel (1.00)
- Government > Military > Navy (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
- (3 more...)
ABSTRACT The selection of steel compositions for line pipe, unfired pressure vessels, and other applications depends upon choosing an effective combination of mechanical properties and economic considerations. Although strength and resistance to brittle fracture are of major importance, a certain level of weldability is necessary to avoid trouble and excessive costs in fabrication and installation of pipelines. It would be useful of the weld-ability of the steel could be forecast directly from its composition. Weldability is so complex a subject that it is unlikely that this will ever be completely possible. However, if the term weldability is restricted to a single aspect- that, for example, of heat-affected-zone cracking there is a much better prospect of predicting behavior from composition. This is because one of the factor which controls heat-affected-zone cracking is the hardness of the heat-affected zone. Hardness is a function of hardenability of the steel and hardenability itself depends partially upon composition. In this paper, the aspect of weldbility that is considered is cracking in the heat-affected zone of field girth welds in pipe. This is practically the only aspect of weldability of interest to pipeline operators which lends itself to useful correlation with carbon equivalent. INTRODUCTION It is extremely difficult, if not impossible, to relate composition to the weldability characteristic of any steel without reducing the composition to a simple number or index. Several different numbers calculated from the compositions of steels have been proposed as parameters which may be related to various properties and characteristics of the steel. Probably the earliest of these were the hardenability relationships or formulas for calculating hardenability from composition suggested by Grossman' in the early forties. Since first proposed, various formulas for calculating these numbers have been suggested as being useful. They have been used for trying to estimate such things as hardenability, bend ductility, heat-affected-zone hardness, weld-metal hardness, hot-cracking susceptibility, and underbead-cracking susceptibility. Several of the composition equivalents or indices that have been derived have proved to be quite useful. However, it must be remembered that relationships between the numbers and steel properties or characteristics are always empirical relationships. To try to use them in any other than an empirical way quite often lends to unsatisfactory results. Also, to try to apply them outside of the restricted areas where experience has proved then1 useful can result in serious errors. CARBON EQUIVALENT The carbon equivalent is a number which is used to express the composition of a steel in a very simple way. It is made up by adding to the percentage of carbon present in the steel, a factor for each important alloying element present. This factor is arrived at by dividing the percentage of the alloying element present by a number (usually a whole number) which experience has shown to be related to the influence of the alloying element on the characteristic being studied. One of the earliest carbon-equivalent formulas used was CE = C + (Mn/6). Many other formulas have been developed from various types of data.
- Materials > Metals & Mining > Steel (1.00)
- Materials > Metals & Mining > Manganese (1.00)
- Energy > Oil & Gas (1.00)
Significant shipyard fabrication success in the marketplace because of the combined cost savings have already been realized as a consequence of benefits of improved performance and economy. Using low the improved weldability of this grade (that is, preheating carbon and alloy contents in conjunction with specialized is no longer necessary for many applications) [4]. However, thermomechanical processing techniques, a number of new both the HY series and the copper-bearing HSLA-80 grade plate products have evolved which offer improved combinations still require some form of heat treatment after rolling. By of strength, toughness, and weldability, when compared replacing copper/nickel (Cu/Ni) alloying and off-line heat with conventional (and more expensive) heat-treated treating with careful microalloying and thermomechanical grades. Specifically, microalloying [for example, with niobium processing, further cost savings may be possible using an asrolled (Nb), vanadium (V), or titanium (Ti)] is used in combination product, due to (1) reduced alloy costs, and (2) elimination with controlled rolling, contributing to mechanical of the heat treatments after rolling.
- Energy (1.00)
- Materials > Metals & Mining > Steel (0.70)
- Materials > Metals & Mining > Niobium (0.48)