MXPA99011345A - Pipeline distribution network systems for transportation of liquefied natural gas - Google Patents

Abstract

Pipeline distribution network systems are provided for transporting pressurized liquefied natural gas at a pressure of about 1035 kPa (150 psia) to about 7590 kPa (1100 psia) and at a temperature of about -123°C (-190°F) to about -62°C (-80°F). Pipes and other components of the pipeline distribution network systems are constructed from an ultra-high strength, low alloy steel containing less than 9 wt.%nickel and having a tensile strength greater than 830 MPa (120 ksi) and a DBTT lower than about -73°C (-100°F) environ.

Description

SYSTEM. OF DISTRIBUTION NETWORK OF PIPE FOR TRANSPORTATION OF LIQUEFIED NATURAL GAS DESCRIPTION OF THE INVENTION The present invention relates to pipe distribution network systems for transportation of liquefied and pressurized natural gas (PLNG), and more particularly to systems that have pipes and other components that are constructed to from an extremely high strength low alloy steel containing less than 9% nickel weight and having a tensile strength greater than 830 -MPa (120 ksi) and a lower DBTT of approximately -73 ° C (-100 ° F). Several terms are defined in the following specification. For convenience a Glossary of terms is provided in the same as before the claims. Many sources of natural gas are located in remote areas, far from any commercial gas market. Sometimes a pipeline is available to transport the produced natural gas to commercial markets. When pipeline transportation to a shopping center is not feasible, the natural gas produced is frequently processed in LNG for transport to the market. The LNG is commonly transported by specially constructed tankers and then stored and revaporized in a major terminal near the market. The equipment used to liquefy, transport, store and revaporize natural gas is usually very expensive; and a common conventional LNG project can cost from $ 5 thousand to $ 10 billion dollars, including field development costs. A "fundamental common" LNG project requires a minimum natural gas resource of approximately 280 Gm3 (10 TCF) (trillion cubic feet) and LNG customers are generally large facilities. Frequently, natural gas resources discovered in remote areas are less than 280 Gm3 (10 TCF). Even for natural gas resource bases that meet the minimum of 280 Gm3 (10 TCF), the very long-term commitments of 20 years or more of all those involved, ie the LNG provider, the LNG carrier, and the Major installation as a customer is required to economically process, store and transport natural gas as LNG. When potential LNG customers have an alternative source of gas, such as piped gas, the conventional LNG supply chain is often not economically competitive. An LNG plant produces LNG at temperatures of approximately -162 ° C (-260 ° F) and at atmospheric pressure. A common natural gas stream enters a conventional LNG plant at approximately 4830 kPa (700 psia) to approximately 7600 kPa (1100 psia) and temperatures from approximately 21 ° C (70 ° F) to approximately 38 ° C (-100 ° C) F). Up to approximately 350,000 horsepower cooling is required to reduce the temperature of natural gas to the low output temperature of approximately -162 ° C (-260 ° F) in a conventional two-way LNG plant. Water, carbon dioxide, sulfur-containing compounds, such as hydrogen sulfide, other acid gases, n-pentane, and heavier hydrocarbons, including benzene, must be substantially eliminated from natural gas during conventional LNG processing, reduce at levels of parts per million (ppm), or these compounds will freeze, causing clogging problems in the process equipment. In a conventional LNG plant, gas treatment equipment is required to remove carbon dioxide and acid gases. The gas treatment equipment typically uses a regenerative process of chemical and / or physical solvent and requires a significant capital investment. Likewise, operating costs are high in relation to those for other equipment in the plant. Dry-bed dehydrators, such as molecular sieves, are required to remove water vapor. The washing tower and the fractionating equipment are used to remove the hydrocarbons that tend to cause clogging problems. Mercury is also removed in a conventional LNG plant as it can cause faults in the aluminum constructed equipment. further, a large part of the nitrogen that may be present in the natural gas is eliminated after processing since the nitrogen does not remain in the liquid phase during the transport of conventional LNG and that has nitrogen vapors in LNG containers at a point of supply that It is undesirable. The containers, pipe, and other equipment used in another conventional LNG plant are typically constructed, at least in part, from aluminum or steel containing nickel (eg, 9% by weight nickel), to provide the toughness of the necessary fracture at extremely low processing temperatures. Expensive materials with excellent fracture toughness at low temperatures, including aluminum and steel containing commercial nickel (for example 9% by weight nickel), are typically used to contain the LNG in LNG ships and import terminals, in addition to its use in the conventional plant. A typical conventional LNG boat uses large spherical containers, known as Moss spheres, to store the LNG during transport. These boats in a common way have a cost of more than approximately $ 230 million dollars each. A typical conventional project to produce LNG in the Middle East and transport it to the Far East may require 7 to 8 of these vessels for a total cost of approximately $ 1.6 to $ 2.0 billion. As can be determined from the above discussion, there is a need for a more economical system to process, store and transport LNG to commercial markets to allow remote gas resources to compete more effectively with alternative energy supplies. In addition, a system is needed to market smaller remote natural gas resources that otherwise would not be economical to develop. In addition, a more economical gasification and distribution system is needed so that LNG can be made economically attractive to smaller consumers. Accordingly, the main objects of the present invention are to provide a more economical system for processing, storing and transporting LNG from remote sources to commercial markets and to substantially reduce the threshold size of both the reservation and the market required to make an LNG project. economically viable One way to achieve these objects would be to process the LNG at higher pressures and temperatures than what is done in a conventional LNG plant, that is, at pressures above atmospheric pressure and temperatures above -162 ° C (-260 ° F). . While the general concept of processing, storage and transport of LNG at increased pressures and temperatures has been discussed in industrial publications, these publications generally discuss the construction of transport containers from nickel-containing steel (for example, 9% by weight). nickel weight) or aluminum, both of which can cover design requirements even though they are very expensive materials. For example, on pages 162-164 of his book NATURAL GAS BY SEA The Development of a New Technology, published by itherby & Co. Ltd., first edition 1979, second edition 1993, Roger Ffooks discusses the conversion of the Sigalpha boat to transport either MLG (medium condition liquefied gas) to 1380 kPa (200 psig) and -115 ° C (-175 ° F), or CNG (compressed natural gas) processed at 7935 kPa (1150 psig) and -60 ° C (-75 ° F). Mr. Ffooks indicates that although technically proven neither of the two concepts found buyers "due" to a large extent to the high cost of storage. According to a document on the subject referred to by Mr. Ffooks, for the CNG service, that is, at -60 ° C (-75 ° F), the design objective was a tempered and tempered steel, which can be welded, low alloy, with good strength (760 MPa) (110 ksi) and good fracture toughness under operating conditions (see "A new process for the transportation of natural gas" by RJ Broeker, International LNG Conference, Chicago, 1968 ). This document also indicates that an aluminum alloy was the lowest cost alloy for the MLG service, that is, at the much lower temperature of -115 ° C (-175 ° F). Likewise, Mr. Ffooks describes on page 164, the Ocean Phoenix Transport design, which operates at a much lower pressure of approximately 414 kPa (60 psig), with tanks that could be built with 9 percent nickel or alloy steel. of aluminum; and indicates that, again, the concept does not seem to offer sufficient technical or financial advantages to be marketed. See also: (i) US Patent 3,298, 8O5, which discloses the use of a steel with 9% nickel content or a high strength aluminum alloy to make containers for transportation of a compressed natural gas; and (ii) U.S. Patent 4,182,254, which describes 9% nickel or similar steel tanks for the transport of LNG at temperatures from -100 ° C (-148 ° F) to -140 ° C (-220 ° F) and pressures from 4 to 10 atmospheres (ie from 407 kPa (59 psia) to 1014 kPa (147 psia)); (iii) US Patent 3,232,725, which describes the transportation of a natural gas in a single phase dense fluid state at a temperature as low as -62 ° C (-80 ° F) or in some cases -68 ° C (-90 ° F), and at a pressure of at least 345 kPa (50 psi) above the gas boiling pressure at operating temperatures, using containers constructed from materials such as 1 to 2 percent steel nickel that have been quenched and tempered to ensure a final tensile strength approaching 8436 kg / cm2 (120,000 psi); and (iv) "Marine Transportation of LNG at Intermediate Temperature", CME March 1979, of C. P. Bennett, who describes a case study of LNG transport at a pressure of 3.1 MPa (450 psi) and a temperature of -100 ° C (-140 ° F) using a storage tank constructed of a 9% steel Ni or a tempered and tempered steel 3 1/2% Ni that has walls of 24.13 cm (9? Inches) thick. Although these concepts are described in industrial publications, as far as is known, LNG is currently not stored, processed and transported commercially at pressures substantially higher than atmospheric pressure and temperatures substantially higher than -162 ° C (-260 ° F). This is probably due to the fact that an economic system to process, store, transport and distribute LNG at such pressures and temperatures, both marine and terrestrial, has not been made commercially available so far. Nickel-containing steels conventionally used for cryogenic temperature structural applications, for example steels with nickel contents of more than about 3% by weight, have low DBTTs (a measure of toughness, as defined herein), but also They have low resistance to tension. Typically, commercially available steels with nickel contents of 3.5% by weight, 5.5% by weight, and 9% by weight have DBTTs of about -100 ° C (-150 ° F), -155 ° C (-250 ° F) ), and -175 ° C (-280 ° F), respectively, and tensile strengths of up to approximately 485 MPa (70 ksi, 620 MPa (90 ksi), and 830 MPa (120 ksi), respectively.) These combinations of strength and toughness, these steels generally undergo expensive processing, for example a double annealing treatment.In the case of cryogenic temperature applications, the industry currently uses these steels containing commercial nickel due to its good tenacity at low temperatures Although their relatively low tensile strengths should be designed, these designs generally require excessive steel spouts to support the load in cryogenic temperature applications, therefore, the use of these nickel-containing steels in cryogenic temperature applications Load bearing tend to be expensive due to the high cost of steel combined with the required steel thicknesses. United States provisional provisional co-pending (the "PLNG Patent Applications"), each entitled "Improved System for Processing, Storing, and Transporting Liquefied Natural Gas", describes recent and tankers for storing and transporting liquefied natural gas by sea Pressurized (PLNG) at a pressure in the wide range from about 1035 kPa (150 psia) to about 7590 kPa (110 psia) and at a temperature in the wide range from -123 ° C (-190 ° F) to about -62 ° C (-80 ° F). The most recent of such PLNG Patent Applications has a priority date of May 14, 1998 and is identified by applicants as Document No. 97006P4 and by the United States Patent and Trademark Office ("USPTO") as the Number of Application 60/085467. The first such Patent Application PLNG has a priority date of June 20, 1997 and is identified by the USPTO by Application Number 60/050280. The second of the PLNG Patent Applications has a priority date of July 28, 1997 and is identified by the USPTO as Application Number 60/053966. The third of the PLNG Patent Applications has a priority date of December 19, 1997 and is identified by the USPTO as Application Number 60/068226. The fourth of the PLNG Patent Applications has a priority date of March 30, 1998 and is identified by the USPTO as Application Number 60/079904. However, the PLNG Patent applications do not describe pipeline distribution network systems for PLNG transportation.

LNG and other cryogenic fluids, for example, liquid oxygen, liquid hydrogen and liquid helium, are transported routinely by truck from central processing facilities to the end user sites. Liquid nitrogen is transported through university campuses and facilities, for example, through pipe distribution network systems. The market for LNG in particular has grown in recent years due to the clean burning characteristics of natural gas. Although natural gas is normally supplied through a pipe distribution network system, as far as is known, there are currently no commercial pipe distribution network systems for PLNG. The supply of natural gas produced in the form of PLNG, compared to LNG, may be beneficial to the end user because PLNG is processed more economically, provided that the economic means for transportation and supply of the PLNG are available. Additionally, in comparison to CNG, the higher liquid density of the PLNG translates into greater mass of the product or energy for a given volume. The carbon arsenals commonly used in the construction of commercial pipeline distribution network systems for fluids such as natural gas do not have adequate fracture toughness at cryogenic temperatures, i.e. temperatures below about -40 ° C. C (-40 ° F). Other materials with better fracture tenaities at cryogenic temperature than carbon steel, for example the above-mentioned commercial nickel-containing steels (3 1/2 wt.% Nickel up to 9 wt.% Nickel) with tensile strength up to about 830 MPa, (120 ksi) aluminum (Al-5083 or Al-5085) or stainless steel, are traditionally used to build pipe distribution network systems that are subject to cryogenic temperature conditions. Likewise, special materials such as titanium alloys and woven glass fiber composite impregnated with special epoxy can be used. These materials tend to be expensive and can therefore often present economically unattractive projects. These disadvantages make commercially available materials currently not economically attractive to build pipeline distribution network systems for PLNG transportation. The discovery of suitable vessels for PLNG shipping, as described in the PLNG patent applications, combined with the current capabilities to process PLNG, makes the need for pipeline distribution systems for ground-based transportation essential. economically attractive of PLNG, as well as that LNG and other cryogenic fluids.

The availability of an effective source in terms of cost of natural gas transported and distributed in the form of a liquid will provide a significant advance in the ability to use natural gas as a fuel source. The following are brief descriptions of existing and emerging applications that use natural gas for energy and that would benefit significantly from the availability of a more economical system for transportation and supply based on natural gas land, such as pipe distribution network systems. LNG is sent by truck routinely to cover the fuel needs in remote sites where the infrastructure for the distribution of natural gas does not exist. Additionally, local conditions are increasingly making the transported LNG a competitive economic alternative for gas pipelines for different major energy projects. An Alaskan gas company has proposed a $ 200 million project for remote LNG base loading systems in seventeen communities in southeastern Alaska. The company also expects to ship the LNG by truck at a distance of 480 km (300 miles) from a liquefied plant in Cook Inlet to Fairbanks starting in November 1997. In eastern Arizona, a recent feasibility study has shown that remote base load LNG supply facilities can offer a lower cost energy solution that is attractive to a smaller number of isolated communities without real access to gas pipelines. This represents new trends in the transportation and use of LNG in large volume with potential for substantial growth particularly with improved economy of the transportation system. Emerging PLNG technology could be economically viable using PLNG as a fuel in these and other similar ground-based applications, if a more economical means of PLNG-based ground transportation such as pipe distribution network systems, were available. In addition, there is an increasing growth in the use of "portable pipeline" -transportable LNG / vaporizer systems- to maintain the continuous gas supply. This is to help gas companies avoid interruption of service and to continue the flow of natural gas to customers during periods of peak demand, such as cold winter days, emergencies from damaged underground pipelines, the maintenance of a gas system, etc. Depending on the particular application, an LNG vaporizer can be installed or located at a strategic point on the natural gas distribution system, and when the conditions of operation guarantee it, LNG tankers are brought to provide the LNG that is vaporized. Currently, as far as is known, there are no commercial PLNG pipe distribution network systems for transporting PLNG, instead of LNG, for such an evaporator to provide additional gas during peak demands. Finally, there are projections that several of the current and future major LNG importers in Asia offer the greatest potential for the use of LNG as a vehicle fuel (as much as 20% of imports). The transportation of the LNG pipe distribution network system to the refueling stations may be the most attractive economic option depending on local conditions. In particular, in the absence of an existing infrastructure for gas distribution, the design of the cost-effective pipe distribution system can make PLNG distribution, a more attractive and economical alternative. There is a need for economic systems for transportation of PLNG pipe distribution network to allow remote natural gas resources to compete more effectively with alternative energy supplies. Therefore, a particular object of the present invention is to provide economical pipe distribution network systems for distribution of LNG at substantially increased pressures and temperatures over conventional LNG systems. Another object of the present invention is to provide such a pipe distribution network system having pipes and other components that are constructed from materials that have adequate strength and fracture toughness to contain the liquefied and pressurized natural gas. In accordance with the two objects set forth above of the present invention, the pipe distribution network systems are provided for the transportation of pressurized liquefied natural gas (PLNG) at a pressure in the range of 1035 kPa (150 psia) to approximately 7590 kPa (1100 psia) and at a temperature on the scale of approximately -123CC (-190 ° F) to approximately -62 ° C (-80 ° F). The pipe distribution network systems of this invention have pipes and other components that are constructed from materials comprising a low alloy steel of extremely high strength containing less than 9 wt.% Nickel and having the strength and the fracture tenacity adequate to contain the pressurized liquefied gas. Steel has an extremely high resistance, for example tensile strength (as defined herein) greater than 830 MPa (120 ksi) and a DBTT (as defined herein) less than about -73 ° C (-100 ° F). BRIEF DESCRIPTION OF THE DRAWINGS The advantages of the present invention will be better understood by reference to the following detailed description and the accompanying drawings in which: Figure 1 schematically illustrates a pipe distribution network system of the present invention. FIGURE 2A illustrates a graph of the failure depth, for a fault length, as a function of fracture toughness CTOD and residual stress; and FIGURE 2B illustrates the geometry (length and depth) of a fault. Although the invention will be described in relation to its preferred embodiments, it will be understood that the invention is not limited thereto. On the contrary, it is intended that the invention cover all alternatives, modifications and equivalents that may be included within the spirit and scope of the invention, as defined by the appended claims. The present invention relates to pipe distribution systems for transporting PLNG. Pipeline distribution network systems are provided to transport liquefied and pressurized natural gas (PLNG) to approximately 1035 kPa (150 psia) to approximately 7590 kPa (1100 psia) and at a temperature of approximately -123 ° C (-190 ° F) ) up to approximately -62 ° C (-80 ° F), where the pipe distribution network systems have piping and other components that are constructed from materials comprising a low alloy steel of extremely high strength, containing less than 9% by weight of nickel and having a tensile strength greater than 830 MPa (120 ksi) and a DBTT less than about -73 ° C (-100 ° F). In addition, pipe distribution network systems are provided to transport liquefied and pressurized natural gas at a pressure of about 1725 kPa (250 psia) to about 4830 kPa (700 psia) and at a temperature of about -112 ° C (-170). ° F) up to approximately -79 ° C (-110 ° F), where the pipe distribution network systems have pipes or other components that (i) are constructed from materials comprising a low alloy strength steel extremely high that contains less than 9% by weight of nickel and (ii) have the strength and fracture toughness to contain liquefied and pressurized natural gas. PLNG Transportation Pipes The key to achieving the pipe distribution network systems of the present invention are pipes suitable for containing and transporting PLNG at a pressure of about 1035 kPa (150 psia) to about 7590 kPa (1100 psia) and a temperature from about -123 ° C (-190 ° F) to about -62 ° C (-80 ° F). Preferably, PLNG is produced and transported at a pressure in the range of about 1725 kPa (250 psia) to about 7590 kPa (1100 psia) and at a temperature in the scale of about -112 ° C (-170 ° F) to about - 62 ° C (-80 ° F). More preferably, PLNG is produced and transported at a pressure in the range of about 2415 kPa (350 psia) to about 4830 kPa (700 psia) and at a temperature on the scale of about -101 ° C (-150 ° F) to approximately -79 ° C (-110 ° F). Even more preferably, the lower ends of the pressure and temperature scales for PLNG are from about 2760 kPa (400 psia) to about -96 ° C (-140 ° F). A pipe for containing and transporting PLN is provided, wherein the pipe is constructed from a material comprising an extremely high strength low alloy steel containing less than 9 wt.% Nickel and having a higher tensile strength. of 830 MPa (120 ksi) and a DBTT of less than -73 ° C (-100 ° F). Additionally, other components of the system such as accessories are provided, wherein the fittings are constructed from a material comprising a low alloy steel of extremely high strength which contains less than 9 wt% nickel and which has a voltage resistance greater than 830 MPa (120 ksi) and a DBTT less than approximately -73 ° C (-100 ° F). Storage containers suitable for use in the pipe distribution network systems of this invention are described in greater detail in the PLNG Patent Applications. Steel for Construction of Pipes and Other Components Any low alloy steel of extremely high strength with less than 9% by weight of nickel and having adequate strength to contain fluids at cryogenic temperature, such as PLNG, under operating conditions, in accordance with the known principles of fracture mechanics as described herein, may be used to construct the pipes and other components of this invention. Illustrative steel for use in the present invention, but not limited to the invention, is an extremely high strength, weldable low alloy steel that contains less than 9 wt.% Nickel and has a resistance to tension greater than 830 MPa (120 ksi) and adequate tenacity to prevent the initiation of a fracture, that is, a failure event, in the operating conditions of cryogenic temperature. Another illustrative steel for use in the present invention, without thereby limiting the invention, is a low alloy steel of extremely high weldable strength which contains less than about 3% by weight of nickel and which has a resistance to voltage of at least about 1000 MPa (145 ksi) and adequate tenacity to prevent the initiation of a fracture, i.e. a failure event, in the operating conditions of cryogenic temperature. Preferably, those illustrative steels have DBTTs of less than about -37 ° C (-100 ° F). Recent advances in steelmaking technology have made it possible to manufacture new extremely high strength low alloy steels with excellent cryogenic temperature toughness. For example, three North American patents issued for Koo et al., 5, 531, 842, 5,545, 269 and 5,545, 270 describe new steels and methods for processing them to produce steel plates with tensile strengths of approximately 830 MPa (120 ksi), 965 MPa (140 ksi) and above. The steels and processing methods described in these have been improved and modified to provide combined steel chemistries and processing to manufacture extremely high strength low alloy steels with excellent cryogenic temperature toughness in the base steel and in the zone. affected with heat (HAZ) when welding. These extremely high strength low alloy steels have also improved the toughness on the commercially available, extremely high strength low alloy steels. Improved steels are described in a co-pending North American provisional patent application entitled "ULTRA-HIGH STRENGTH STEELS WITH EXCELLENT CRYOGENIC TEMPERATURE TOUGHNESS", which has a priority date of December 19, 1997 and is identified by. United States Patent and Trademark Office ("USPTO") as Application Number 60/068194; in a co-pending provisional US patent application entitled "ULTRA-HIGH STRENGTH AUSAGED STEELS WITH EXCELLENT CRYOGENIC TEMPERATURE TOUGHNESS" which has a priority date of December 19, 1997 and is identified by the USPTO as Application Number 60/068252; and in a co-pending provisional North American patent application entitled "ULTRA-HIGH STRENGTH DUAL PHASE STEELS ITH EXCELLENT CRYOGENIC TEMPERATURE TOUGHNESS", which has a priority date of December 19, 1997 and is identified by the USPTO as Application Number 60 / 068816 (collectively, the "Steel Patent Applications"). The new steels described in the Steel Patent Applications and described further in the following examples, are especially suitable for constructing the pipes for storing and transporting PLNG of this invention since steels have the following characteristics, preferably for plate thicknesses. Steel of about 2.5 cm (1 inch) and above: (i) DBTT less than about -73 ° C (-100 ° F), preferably less than about -107 ° C (-160 ° F), in the base steel and in the welding BEAM; (ii) tensile strength greater than 830 MPa (120 ksi), preferably greater than about 860 MPa (125 ksi), and still more preferably more than 900 MPa (130 ksi); (iii) superior weld capacity; (iv) microstructure and substantially uniform thickness properties; and (v) improved tenacity over commercially available low alloy steels, of extremely high strength commercially available standards. Even more preferably, these steels have a tensile strength of more than about 930 MPa (135 ksi), or more than about 965 MPa (140 ksi), or more than about 1000 MPa (145 ksi). First Example of Steel As described above, a co-pending provisional American patent application that has a priority date of December 19, 1997, entitled "Ultra-High Strength Steels With Excellent Cryogenic Temperature Toughness," and identified by the USPTO as Application No. 60/068194, provides a description of steels suitable for use in the present invention. A method is provided for preparing an extremely high strength steel plate having a microstructure comprising predominantly fine-tempered rod martensite, fine-grained lower-fine bainite, or mixtures thereof, wherein the method comprises the steps of (a) heating a steel plate to a sufficiently high reheat temperature to (i) substantially homogenize the steel plate, (ii) dissolve substantially all the niobium and vanadium carbides and nitrite in the steel plate, and (iii) establish the initial austenite grains fine in the steel earthenware; (b) reducing the steel plate to form the steel plate in one or more hot rolling steps to a first temperature scale at which the austenite is recrystallized; (c) further reducing the steel plate in one or more hot rolling steps in a second temperature scale below about the temperature Tnr and above about the transformation temperature Ar3; (d) tempering the steel plate to a cooling scale of about 10 ° C per second to about 40 ° C per second to a tempering finish temperature below about the transformation temperature Ms plus 200 ° C (360 ° F) ); (e) stop tempering; and (f) reworking the steel plate at an annealing temperature of about 400 ° C (752 ° F) to about the Aci transformation temperature, preferably up to, but not including, the Aci transformation temperature, for a sufficient period to give rise to the precipitation of hardening particles, ie one or more of (-copper, Mo2C, or the niobium and vanadium carbides and carbonitrides.) The period sufficient to cause the precipitation of hardening particles depends mainly on the thickness of the Steel plate, the chemistry of the steel plate, and the tempering temperature and can be determined by someone skilled in the art. (See Glossary for particular definitions of hardening, temperature Tnr, transformation temperatures Ar3, Ms, and Aci, and Mo2C). To ensure the tenacity at room temperature and cryogenic, the steels according to this first steel example preferably have a microstructure comprised predominantly of lower fine-grained fine bainite, martensite-grade fine-tipped rod or mixtures thereof. It is preferable to substantially reduce to a minimum the formation of brittle components such as upper bainite, irregular martensite and MA. As used in the first steel example, and in the claims, "predominantly" means at least about 50 volume percent. More preferably, the microstructure comprises at least about 60 percent to about 80 volume percent of fine-grained, fine-grained, fine-grained rod martensite or mixtures thereof. Even more preferably, the microstructure comprises at least about 90 volume percent of fine-grained lower fine-grained, fine-grained tempered-grade martensite, or mixtures thereof. More preferably, the microstructure comprises substantially 100% tempered fine-grained rod martensite. A steel earthenware processed according to the first steel example is manufactured in a common manner and, in one embodiment, comprises iron and the following alloying elements, preferably in the weight scales indicated in Table 1 below: I Elements of Scale (% by weight) Carbon Alloy (C) 0.04-0.12, more preferably 0.04-0.07 Manganese (Mn¡ 0.5-2.5, more preferably 1.0-1.8 Nickel (Ni) 1.0-3.0, more preferably 1.5-2.5 Copper (Cu) 0.1-1.5, more preferably 0.5-1.0 Molybdenum (Mo) 0.1-0.8, more preferably 0.2-0.5 Niobium (Nb) 0.02-0.1, more preferably 0.03-0.05 Titanium (Ti) 0.0O8-0.03, more preferably 0.01 -0.02 Aluminum (Al) 0.001-0.05, more preferably 0.005-0.03 Nitrogen (N) 0.002-0.005, more preferably 0.002-0.003 Vanadium (V) is sometimes added to steel, preferably up to about 0.10% by weight, and more preferably about 0.02% by weight to about 0.05% by weight. Chromium (Cr) is sometimes added to the steel, preferably up to about 1.0% by weight, and more preferably about 0.2% by weight to about 0.6% by weight. The silicone (Si) is sometimes added to the steel, preferably up to about 0.5% by weight, and more preferably about 0.01% by weight to about 0.05% by weight, and even more preferably about 0.5% by weight to about 0.1% by weight. Boron (Br) is sometimes added to the steel, preferably up to about 0.0020% by weight, and more preferably about 0.0006% by weight to about 0.0010-% by weight. The steel preferably contains at least about 1% by weight of nickel. The nickel content of the steel can be increased by about 3% by weight if it is desired to improve the performance after welding. Each addition of 1% by weight of nickel is expected to reduce the DBTT of the steel by approximately 10 ° C (18 ° F). The nickel content is preferably less than 9% by weight, more preferably less than 6% by weight. The nickel content is preferably reduced to a minimum in order to minimize the cost of steel. If the nickel content is increased to about 3% by weight, the manganese content can be decreased below about 0.5% by weight to below 0.0% by weight. Therefore, in a broad sense, up to about 2.5% by weight of manganese is preferred. Additionally, the residues are preferably substantially reduced in the steel. The phosphorus content (P) is preferably less than about 0.01% by weight. The sulfur content (S) is preferably less than about 0.004% by weight. The oxygen content (O) is preferably less than about 0.002% by weight. A bit in more detail, a steel according to the first steel example is prepared by forming a slab of the desired composition as described herein B. ; heating by heating the ware to a temperature from about 955 ° C to about 1065 ° C (1750 ° F - 1950 ° F); hot rolling of the earthenware to form the steel plate in one or more steps that provide about 30 percent to about 70 percent reduction in a first temperature scale at which the austenite is recrystallized, ie over about temperature Tnr, and further hot rolling the steel plate in one or more passages which provide about 40 percent to about 80 percent reduction at a second temperature scale below about the temperature Tnr and about about Ar3 transformation temperature. The hot-rolled steel plate is then tempered at a cooling rate of about 10 ° C per second to about 40 ° C per second (18 ° F / sec. -72 ° F / sec.) To a QST (as shown in FIG. defined in the Glossary) after approximately the transformation temperature Ms plus 200 ° C (360 ° F) at which time the tempering is finished. In one embodiment of the first steel example, the steel plate is cooled with air at room temperature. This process is used to produce a microstructure comprising preferably fine-grained rod martensite, fine-grained lower bead, or mixtures thereof, or more preferably substantially comprising 100% fine-grained rod martensite. The direct tempered martensite in the steels according to the first steel example has a high strength although its tenacity can be improved by tempering at a suitable temperature from about 400 ° C (752 ° F) to about the Aci transformation temperature. The tempering of the steel within this temperature scale also leads to the reduction of the tempering tensions, which in turn lead to improved toughness. While tempering can improve the toughness of steel, it usually leads to loss of strength. In the present invention, the usual resistance loss from quenching is out of phase by the induction of precipitate hardening. The hardening by dispersion from precipitates of fine copper and mixed carbides and / or carbonitrides is used to optimize the strength and tenacity during tempering of the martensite structure. The unique chemistry of the steels of the first steel example allows tempering within the broad scale from about 400 ° C to about 650 ° C (750 ° F-1200 ° F) without any significant loss of strength when tempered. The steel plate is tempered at an annealing temperature from about 400 ° C (752 ° F) to less than the Acx transformation temperature for a sufficient period to cause precipitation of the hardening particles (as defined herein) . This processing facilitates the transformation of the microstructure of the steel plate for the predominantly remelted fine-grained rod martensite, the fine-grained lower-grain vainite or mixtures thereof. Again, the period sufficient to cause the precipitation of hardening particles depends mainly on the thickness of the steel plate, the chemistry of the steel plate and the tempering temperature and can be determined by someone skilled in the art. Second Example of Steel As described above, a co-pending provisional American patent application that has a priority date of December 19, 1997, entitled "Ultra-High Strength Ausaged Steels With Excellent Cryogenic Temperature Toughness," and identified by the USPTO as Application No. 60/068252, provides a description of steels suitable for use in the present invention. A method for preparing an extremely high strength steel plate having a micro-laminate microstructure comprising about 2% by volume to about 10% by volume of austenite film layers and about 90% by volume up to about 98% by volume is provided. volume of predominantly fine-grained martensite rods and fine-grained lower bainite, the method comprises the steps of: (a) heating a steel earthenware to a sufficiently high reheat temperature to (i) substantially homogenize the steel earthenware, ( ii) dissolving substantially all the niobium and vanadium carbides and nitride in the steel earthenware; and (iii) establishing the initial fine austenite grains in the steel earthenware; (b) reducing the steel plate to form the steel plate in one or more hot rolling steps in a first temperature scale in which the austenite is recrystallized, (c) further reducing the steel plate in one or more hot rolling steps in a second temperature scale below approximately the temperature Tnr and above approximately the transformation temperature Ar3; (d) quench the steel plate at a cooling rate of about 10 ° C per second to about 40 ° C per second (18 ° F / sec - 72 ° F / sec) to a Temper Finish Temperature ( QST) below about the transformation temperature Ms plus 100 ° C (180 ° F) and about about the transformation temperature Ms; and (e) stop tempering. In one embodiment, the method of this second example of steel further comprises the step of allowing the steel plate to cool to air to room temperature from QST. In another embodiment, the method of this second steel example further comprises the step of holding the substantially isothermal steel plate in the QST until about 5 minutes before allowing the steel plate to cool in air to room temperature. In yet another embodiment, the method of this second example of steel further comprises the step of slow cooling of the steel plate from the QST at a rate of less than about 1.0 ° C per second (1.8 ° F / sec.) To about 5 minutes before allowing the steel plate to cool in air to room temperature. In yet another embodiment the method of this invention further comprises the step of slow cooling of the steel plate from QST at a rate of less than about 1.0 ° C per second (1.8 ° F / sec.) For up to about 5 minutes before to allow the steel plate to cool in air to room temperature. This processing facilitates the transformation of the microstructure of the steel plate to approximately 2% by volume to approximately 10% by volume of austenite film layers and approximately 90% by volume to approximately 98% by volume of predominantly grain martensite rods. fine and fine grain lower bainita. (See Glossary for temperature definitions Tnr, and transformation temperatures Ar3 and Ms). To ensure tenacity at room temperature and cryogenic, the rods in the micro-laminate microstructure preferably comprise lower bainite or predominantly martensite. It is preferable to substantially reduce the formation of brittle components such as upper bainite, irregular martensite and MA. As used in this second example of steel, and in the claims, "predominantly" means at least about 50 volume percent. The rest of the microstructure may comprise additional fine-grained lower bainite, additional fine-grained martensite or ferrite. More preferably, the microstructure comprises at least about 60 volume percent up to about 80 volume percent lower bainite or rod martensite. Even more preferably, the microstructure comprises at least about 90% by volume of lower bainite or rod martensite. A steel earthenware processed in accordance with this second example of steel is manufactured in a customary manner and, in one embodiment, comprises iron and the following alloying elements, preferably in the scales by weight indicated in the following Table II: Table II Elements Alloy Scale (% by weight) Carbon (C) 0.04-0.12, more preferably 0.04-0.07 Manganese (Mn) 0.5-2.5, more preferably 1.0-1.8 Nickel (Ni) 1.0-3.0, more preferably 1.5-2.5 Copper (Cu) ) 0.1-1.0, more preferably 0.2-0.5 Molybdenum (Mo) 0.1-0.8, more preferably 0.2-0.4 Niobium (Nb) 0.02-0.1, more preferably 0.02-0.05 Titanium (Ti) 0.008-0.03, more preferably 0.01-0.02 Aluminum (Al) 0.001-0.05, more preferably 0.005-0.03 Nitrogen (N) 0.002-0.005, more preferably 0.002-0.003 Chromium (Cr) is sometimes added to steel, preferably up to about 1.0% by weight, and most preferably up to 0.2% by weight to about 0.6% by weight. Silicon (Si) is sometimes added to the steel, preferably up to about 0.5% by weight, more preferably about 0.01% by weight to about 0.5% by weight, and even more preferably about 0.05% by weight to about 0.1. % in weigh. Boron (B) is sometimes added to steel, preferably up to about 0.0020% by weight, and more preferably about 0.0006% by weight to about 0.0010% by weight. The steel preferably contains at least about 1% by weight of nickel. The nickel content of the steel can be increased approximately above 3% by weight if it is desired to improve the performance after welding. Each addition of 1% by weight of nickel is expected to reduce the DBTT of the steel by approximately 10 ° C (18 ° F). The nickel content is preferably less than 9% by weight, more preferably less than about 6% by weight. The nickel content is preferably reduced to a minimum in order to also minimize the cost of the steel. If the nickel content is increased to about 3% by weight, the manganese content can be decreased below about 0.5% by weight to below 0.0% by weight. Therefore, in a broad sense, up to about 2.5% by weight of manganese is preferred. Additionally, the waste is substantially reduced to a minimum preferably in steel. The phosphorus content (P) is preferably less than about 0.01% by weight. The sulfur content (S) is preferably less than about 0.004% by weight. The oxygen content (O) is preferably less than about 0.002% by weight. In a greater detail, a steel according to this second example is prepared by forming a slab of the desired composition as described herein; heating a tile to a temperature of about 955 ° C to about 1065 ° C (1750 ° F -1950 ° F); hot roll of the earthenware to form the steel plate in one or more steps providing approximately 30 percent to 70 percent reduction at a first temperature scale at which the austenite is recrystallized, i.e., approximately above the temperature Tnr, and the additional hot rolling of the steel plate in one or more passes providing about 40 percent to about 80 percent reduction in a second temperature scale below about the temperature Tnr and about the transformation temperature Ar3. The hot rolled steel plate is then tempered at a cooling rate of about 10 ° C per second to about 40 ° C per second (18 ° F / sec. - 72 ° F / sec.) To a QST suitable to approximately the transformation temperature Ms plus 100 ° C (180 ° F) and about the transformation temperature Ms at which time the tempering is finished. In one embodiment of this second example of steel, after the tempering is finished the steel plate is allowed to cool to ambient air from QST. In another embodiment of this second steel example, after the tempering is finished the steel plate is maintained substantially exothermic to the QST for a period of time, preferably up to about 5 minutes, and then air cooled to room temperature. In yet another embodiment, the steel plate is slowly cooled at a rate lower than that of air cooling, that is, at a rate less than about 1 ° C per second (1.8 ° F / sec.), Preferably for about 5 minutes. In another embodiment, the steel plate is cooled slowly from Ms at a lower speed than that of air cooling, i.e. at a rate less than about 1 ° C per second (1.8 ° F / sec.), preferably for about 5 minutes. In at least one embodiment of this second example of steel, the transformation temperature of Ms is approximately 350 ° C (662 ° F) and, therefore, the transformation temperature Ms plus 100 ° C (180 ° F) is approximately 450 ° C (842 ° F). The steel plate can be substantially isothermally supported to the QST by any suitable means, as is known to those skilled in the art, such as by placing a thermal pattern on the steel plate. The steel plate can be cooled slowly after the tempering is completed by any suitable means, as known to those skilled in the art, such as the placement of an insulating pattern on the steel plate. Third Example of Steel As described above, a co-pending provisional American patent application that has a priority date of December 19, 1997, entitled "Ultra-High Strength Dual Phase Steels With Excellent Cryogenic Temperature Toughness," and identified by the USPTO as Application No. 60/068816, provides a description of steels suitable for use in the present invention. A method is provided for preparing a double-phase, extremely high strength steel plate having a microstructure comprising about 10% by volume to about 40% by volume of a first phase of substantially 100% by volume (i.e. substantial or "essentially" pure) of ferrite and about 60% by volume to about 90% by volume of a second phase of predominantly fine grain rod martensite, fine-grained lower bainite, or mixtures thereof, wherein the method comprises steps of (a) heating a steel earthenware to a sufficiently high reheat temperature to (i) substantially homogenize the steel earthenware, (ii) substantially dissolve all the niobium and vanadium carbides and nitrite in the earthenware, and (iii) establish the fine initial austenite grains in the steel earthenware; (b) reducing the steel plate to form the steel plate in one or more hot rolling steps in a first temperature scale in which the austenite is recrystallized; (c) further reducing the steel plate in one or more hot rolling steps to a second temperature scale below about the temperature Tnr and above about the transformation temperature Ar3; (d) further reducing the steel plate in one or more hot rolling steps to a third temperature scale below about the transformation temperature Ar3 and above about the Ari transformation temperature (i.e., the scale of intercritical temperature); (e) tempering the steel plate at a cooling rate scale of about 10 ° C per second to about 40 ° C per second (18 ° F / sec. - 72 ° F / sec.) to a Termination Temperature of Tempering (QST) preferably below approximately the transformation temperature Ms plus 200 ° C (360 ° F); and (f) stop tempering. In another embodiment of this third example of steel, the QST is preferably below approximately the transformation temperature Ms plus 100 ° C, and more preferably below about 350 ° C per second. (662 ° F). In one embodiment of this third example of steel, the steel plate is allowed to cool to air to room temperature after step (f). This processing facilitates the transformation of the microstructure of the steel plate to about 10% by volume to about 40% by volume of a first phase of the ferrite and about 60% by volume to about 90% by volume of a second phase of martensite. of predominantly fine grain rod, fine grain lower bainite, or mixtures thereof. (See Glossary for temperature definitions Tnr, and transformation temperatures Ar3 and An).

To ensure tenacity at room temperature and cryogenic, the microstructure of the second phase in the steels of this third example comprises lower bainite of predominantly fine grain, fine-grained rod martensite or mixtures thereof. It is preferable to substantially reduce to a minimum the formation of brittle components such as upper bainite, irregular martensite and MA in the second phase. As used in this third example of steel, and in the claims, "predominantly" means at least about 50 volume percent. The rest of the microstructure of the second phase may comprise additional fine-grained lower bainite, additional fine-grained rod martensite or ferrite. More preferably, the microstructure of the second phase comprises at least about 60 volume percent up to about 80 volume percent fine-grained lower bainite, fine-grained rod martensite, or mixtures thereof. Even more preferably, the microstructure of the second phase comprises at least about 90% by volume of fine-grained lower bainite, fine-grained rod martensite or mixtures thereof. A steel earthenware processed in accordance with this third example of steel is manufactured in a customary manner and, in one embodiment, comprises iron and the following alloying elements, preferably at the weight scales indicated in the following Table III: Table III Alloy Elements Scale (% by weight) Carbon (C) 0.04-0.12, more preferably 0.04-0.07 Manganese (Mn 0.5-2.5, more preferably 1.0-1.8 Nickel (Ni) 1.0-3.0, more preferably 1.5-2.5 Niobium (Nb) 0.02-0.1, more preferably 0.02-0.05 Titanium (Ti) 0.008-0.03, more preferably 0.01-0.02 Aluminum (Al) 0.001-0.05, more preferably 0.005-0.03 Nitrogen (N) 0.002-0.005, more preferably 0.002- 0.003 Chromium (Cr) is sometimes added to steel, preferably up to about 1.0% by weight, and more preferably around 0.2% by weight to about 0.6% by weight Molybdenum (Mo) is sometimes added to steel, preferably up to about 0.8% by weight and more preferably up to about 0.1% to about 0.3% by weight Silicon (Yes) is sometimes added to the steel, preferably up to about 0.5% by weight, more preferably about 0.01% in weight until aproximadame 0.5% by weight, and more preferably still, about 0.05% by weight to about 0.1% by weight. Copper (Cu), preferably in the range of about 0.1% by weight to about 1.0% by weight, more preferably in the range of about 0.2% by weight to about 0.4% by weight is sometimes added to the steel. Boron (B) is sometimes added to steel, preferably up to about 0.0020% by weight, and more preferably about 0.0006% by weight to about 0.0010% by weight. The steel preferably contains at least about 1% by weight of nickel. The nickel content of the steel can be increased approximately above 3% by weight if it is desired to improve the performance after welding. Each addition of 1% by weight of nickel is expected to reduce the DBTT of the steel by approximately 10 ° C (18 ° F). The nickel content is preferably less than 9% by weight, more preferably less than about 6% by weight. The nickel content is preferably reduced to a minimum in order to also minimize the cost of the steel. If the nickel content is increased above about 3% by weight, the manganese content can be decreased below about 0.5% by weight down to 0.0% by weight. Therefore, in a broad sense, it is preferred that the manganese be up to about 2.5% by weight. Additionally, the waste is preferably reduced substantially to the minimum in the steel. The phosphorus content (P) is preferably less than about 0.01% by weight. The sulfur content (S) is preferably less than about 0.004% by weight. The oxygen content (O) is preferably less than about 0.002% by weight. In a greater detail, the steel according to this third example is prepared by forming a slab of the desired composition as described herein; the earthenware is heated to a temperature of about 955 ° C to about 1065 ° C (1750 ° F - 1950 ° F); The hot rolling of the earthenware is done to form the steel plate in one or more steps that provide about 30 percent to about 70 percent reduction in a first temperature scale at which the austenite is recrystallized, is say, about the temperature Tnr, the additional rolling of the steel plate in one or more steps that provides about 40 percent to about 80 percent reduction on a second temperature scale below the temperature Tnr and about above the transformation temperature Ar3 and the completion of the rolling of the steel plate in one or more steps to provide approximately 15 percent to approximately 50 percent reduction in the inter-critical temperature scale below the transformation temperature Ar3 and above the Ari transformation temperature. The hot-rolled steel plate is then tempered at a cooling rate of about 10 ° C per second to about 40 ° C per second (18 ° F / sec. - 72 ° F / sec.) Up to a Stopping Temperature of Tempering (QST) preferably below the transformation temperature Ms plus 200 ° C (360 ° F), at which time the tempering is completed. In another embodiment of this invention, the QST is preferably below the transformation temperature Ms plus 100 ° C (180 ° F), and more preferably it is below about 350 ° C (662 ° F). In one embodiment of this third example of steel, the steel plate is allowed to cool in air to room temperature after the tempering is finished. The steels of the third example above, since Ni is an expensive alloying element, the Ni content of the steel is preferably less than about 3.0% by weight, more preferably less than 2.5% by weight, more preferably less than 2.0% by weight, and even more preferably less than about 1.8% by weight, to substantially reduce the cost of steel.

Other steels suitable for use in connection with the present are described in other publications disclosing extremely high strength low alloy steels containing about 1% nickel, which have tensile strengths in excess of 830 MPa (120 ksi), and They have excellent tenacity at low temperature. For example, such steels are described in the European Patent Application published on February 5, 1997 and having the International application number PCT / JP96 / 00157 and the International Publication Number WO 96/23909 (08.08 1996 Gazette 1996/36 ) (such steels preferably have a copper content of 0.1% by weight up to 1.2% by weight), and in a pending North American provisional patent application with a priority date of July 28, 1997, entitled "Ultra-High Strength, Weldable Steels with Excellent Ultra-Low Temperature Toughness ", and identified by the USPTO as Application No. 60/053915. For any of the steels referred to above, as understood by those skilled in the art, and as used herein "percent reduction in thickness" refers to the percentage reduction in the thickness of the steel plate or plate before the referred reduction. For the purposes of explanation only, without thereby limiting the invention, a steel plate of approximately 25.4 cm (10 inches) in thickness can be reduced by approximately 50% (a reduction of 50 percent), on a first temperature scale, to a thickness of approximately 12.7 cm (5 inches) and then reduced by approximately 80% (a reduction of 80 percent), on a second temperature scale, to a thickness of approximately 2.5 cm (1 inch). Again, for purposes of explanation only, without thereby limiting the invention, a steelware of approximately 25.4 cm (10 inches) can be reduced by approximately 30% (a reduction of 30 percent), on a first temperature scale , to a thickness of approximately 17.8cm (7 inches) then reduced by approximately 80% (an 80 percent reduction) in a second temperature scale, to a thickness of approximately 3.6cm (1.4 inches), and then reduces approximately the 30th% (a reduction of 30 percent), to a third temperature scale, up to a thickness of approximately 2.5 cm (1 inch) . As used herein, "earthenware" means a piece of steel having any dimensions. For any of the aforementioned steels, as understood by those skilled in the art, the steelware is preferably reheated through suitable means for raising the temperature substantially of all the ware, preferably the complete china, up to the temperature of desired reheating, for example, by placing the ware in an oven for a period. The specific reheat temperature to be used for any of the aforementioned steel compositions can be readily determined by a person skilled in the art, either by experiment or by calculation using suitable models. Additionally, the oven temperature and the reheat time necessary to raise the temperature substantially of the entire plate, preferably the entire plate, to the desired reheat temperature can be readily determined by a person skilled in the art by reference to standard industrial publications. For any of the aforementioned steels, as understood by those skilled in the art, the temperature that defines the boundary between the recrystallization scale and the scale without recrystallization, the temperature Tnr depends on the chemistry of the steel, and more particularly , of the reheat temperature before rolling, the carbon concentration, the niobium concentration and the amount of reduction given in the rolling steps - Those skilled in the art can determine this temperature for each steel composition either by experiment or by model calculation. Similarly, the Aci, Ari, Ar3, and Ms transformation temperatures referred to herein may be determined by persons skilled in the art for each steel composition either by experiment or by model calculation. Any of the steels referred to above, as will be understood by those skilled in the art, except for the reheat temperature, which applies substantially to all crockery, the subsequent temperatures referred to in the description of the processing methods of this invention are measured temperatures. on the surface of steel. The temperature of the steel surface can be measured by the use of an optical pyrometer, for example, or by any other suitable device for measuring the surface temperature of the steel. The cooling rates referred to herein are those in the center, or substantially in the center of the thickness of the plate; and the Tempering Termination Temperature (QST) is the highest, or substantially the highest temperature reached on the surface of the plate, after the tempering is finished, because the heat transmitted from the average thickness of the plate. For example, during the processing of the heats experienced from a steel composition according to the examples provided herein, a thermocouple is placed in the center, or substantially in the center of the thickness of the steel plate for temperature measurement central, while the surface temperature is measured by the use of an optical pyrometer. A correlation between the core temperature and the surface temperature is developed to be used during the subsequent processing of the same, or substantially the same, steel composition, so that the core temperature can be determined by means of the direct measurement of the temperature Of surface. Also, the required temperature and flow rate of the tempering fluid to achieve the desired accelerated cooling rate can be determined by someone skilled in the art for reference to standard industrial publications. A person skilled in the art has the requisite knowledge and ability to use the information provided herein to produce extremely high strength low alloy steel plates that have the strength and toughness suitable for use in the construction of pipelines and pipes. other components of the present invention. Other suitable steels may exist or be developed from the present. All such steels are within the scope of the present invention. A person skilled in the art has the requisite knowledge and ability to use the information provided herein to produce extremely high strength low alloy steel plates having modified thicknesses, as compared to the thicknesses of the steel plates produced. according to the examples provided herein, while still producing steel plates having adequate strength and cryogenic temperature toughness suitable for use in the system of the present invention. For example, one skilled in the art can use the information provided herein to produce a steel plate with a thickness of approximately 2.54 cm (1 inch) and a high strength and cryogenic temperature toughness suitable for use in the construction of pipes and other components of the present invention. Other suitable steels may exist or be developed from the present. All such steels are within the scope of the present invention. When a double phase steel is used in the construction of pipes according to this invention, the double phase steel is preferably processed in such a way that the period during which the steel is kept on the intercritical temperature scale for the purpose of Creation of a double-phase structure occurs before accelerated cooling or tempering stage. Preferably, the processing is such that the double-phase structure is formed during the cooling of the steel between the transformation temperature Ar3 to approximately the transformation temperature Ari. A further preference for the steels used in the construction of pipes in accordance with this invention is that the steel has a tensile strength greater than 830 MPa (120 ksi), and a lower DBTT of about -73 ° C (-100 °). F) at the end of the accelerated cooling or the tempering step, that is, without any additional processing that requires the reheating of the steel such as tempering. More preferably, the tensile strength of the steel at the end of the quenching or the cooling step is greater than about 860 MPa (125 ksi) and more preferably greater than about 900 MPa (130 ksi). In some applications, a steel having a tensile strength of more than about 930 MPa (135 ksi), or greater than about 965 MPa (140 ksi) or greater than about 1000"MPa (145 ksi), upon completion of tempering or Cooling step is preferable Joining Methods for Construction of Pipes and Other Components In order to build the containers and other components of the present invention, a suitable method of joining steel plates is required. joints with strength and toughness suitable for the present invention, as described above, is considered to be suitable, Preferably, a suitable welding method to provide adequate strength and fracture toughness to contain the fluid that is retained or transported is used to build the pipes and other components of the present invention Such a welding method preferably includes a suitable consumable wire, a suitable consumable gas, a suitable welding process and a suitable welding procedure. For example, gas metal arc welding (GMAW) and inert gas welding of tungsten (TIG), which are known in the steelmaking industry, can be used to join steel plates, providing that they are used a suitable gas-wire combination suitable. In a first example of the welding method, gas metal arc welding (GMAW) is used to produce a welded metal chemistry comprising iron and about 0.07 wt% carbon, about 2.05 wt% manganese, about 0.32. % by weight of silicon, approximately 2.20% by weight of nickel, approximately 0.45% by weight of chromium, approximately 0.56% by weight of molybdenum, less than approximately 110 ppm of phosphorus and less than approximately 50 ppm of sulfur. The welding is done on a steel, such as any of the steels described above, using a shielding gas based on argon with less than about 1% by weight of oxygen. The weld heat input is in the range of approximately 0.3 kJ / mm to approximately 1.5 kJ / mm (7.6 kJ / inch to 38 kJ / inch). Welding by this method provides a weld (see Glossary) which has a tensile strength greater than about 900 MPa (130 ksi), preferably, greater than about 930 MPa (135 ksi), more preferably greater than about 965 MPa ( 140 ksi), and even more preferably at least about 1000 MPa (145 ksi). In addition, welding by this method provides a welded metal with a DBTT below about -73 ° C (-100 ° F), preferably below about -96 ° C (-140 ° F), more preferably below about -106 ° C (-160 ° F) and even more preferably below about -115 ° C (-175 ° F). In another example of the welding method, the GMAW process is used to produce a welded metal chemistry comprising iron and about 0.10% by weight of carbon, (preferably less than about 0.10% by weight of carbon, more preferably from about 0.07 to about 0.08% by weight of carbon), about 1.60% by weight of manganese, about 0.25% by weight of silicon, about 1.87% by weight of nickel, about 0.87% by weight of chromium, about 0.51% by weight of molybdenum , less than about 75 ppm of phosphorus and less than about 110 ppm of sulfur. The weld heat input ranges from approximately 0.3 kJ / mm to approximately 1.5 kJ / mm (7.6 kJ / inch to 38 kJ / inch) and a preheat of approximately 100 ° C is used (212 ° F). The welding is done on a steel, such as any of the steels described above using a shielding gas based on argon, with less than about 1% by weight of oxygen. Welding through this method provides a weld having a tensile strength greater than about 900 MPa (130 ksi), preferably greater than about 930 MPa (135 ksi), more preferably greater than about 965 MPa (140 ksi) ), and even more preferably of at least about 1000 MPa (145 ksi). In addition, welding by this method provides a method to the soldier with a DBTT below about -73 ° C (-100 ° F), preferably below about -96 ° C (-140 ° F), more preferably below about -106 ° C (-160 ° F) and even more preferably below about -115 ° C (-175 ° F). In another example of the welding method, the inert gas welding process of tungsten (TIG) is used to produce a welded metal chemistry containing iron and about 0.07% by weight of carbon, (preferably less than about 0.07% in weight). weight of carbon), approximately 1.80% by weight of manganese, approximately 0.20% by weight of silicon, approximately 4.00% by weight of nickel, approximately 0.5% by weight of chromium, approximately 0.40% by weight of molybdenum, approximately 0.02% by weight of copper, approximately 0.02% aluminum, approximately 0.010% by weight titanium, approximately 0.015% by weight zirconium (Zr), less than approximately 50 ppm phosphorus and less than approximately 30 ppm sulfur. The weld heat input is in the range of approximately 0.3 kJ / mm to approximately 1.5 kJ / mm (7.6 kJ / inch to 38 kJ / inch) and a heating of approximately 100 ° C (212 ° F) is used . The welding is done on a steel, such as any of the steels described above using a shielding gas based on argon, with less than about 1% by weight of oxygen. Welding by this method provides a weld having a tensile strength greater than about 900 MPa (130 ksi), preferably greater than about 930 MPa (135 ksi), more preferably greater than about 965 MPa (140 ksi), and even more preferably at least about 1000 MPa (145 ksi). In addition, welding by this method provides a welded metal with a DBTT below about -73 ° C (-100 ° F), preferably less than about -96 ° C (-140 ° F), more preferably below - 106 ° C (-160 ° F) approximately, and still more preferably below about -115 ° C (-175 ° F). Welded metal chemistries similar to those mentioned in the examples can be made using any of the GMAW or TIG welding processes. Nevertheless, TIG welds are anticipated to have lower impurity content and a more highly refined microstructure than GMAW welds, and therefore improving toughness at low temperature. A person skilled in the art has knowledge and experience of requirement to use the information provided herein to weld extremely high strength low alloy steel plates to produce joints having adequate high strength and fracture toughness for use. in the construction of the pipes and other components of the present invention. Other suitable joining or welding methods may exist or be developed from the present. All joining or welding methods are within the scope of the present invention. Construction of Pipes and Other Components Without thereby limiting the invention: pipes and other components (i) constructed from materials comprising extremely high strength low alloy steels containing less than 9% by weight of nickel and (ii) ) that have adequate strength and fracture toughness at cryogenic temperature to contain cryogenic temperature fluids, particularly PLNG, are provided; in addition, pipes and other components constructed from materials comprising extremely high strength low alloy steels containing less than 9% nickel and having a tensile strength greater than 830 MPa (120 ksi) and a lower DBTT approximately -73 ° C (-100 ° F) is provided; in addition, containers and other components (i) constructed from materials comprising extremely high strength low alloy steels containing less than about 3% by weight of nickel and (ii) having strength and fracture toughness at cryogenic temperature suitable for containing cryogenic temperature fluids, particularly PLNG, are provided; in addition, pipes and other components, (i) constructed from materials comprising extremely high strength low alloy steels containing less than about 3% by weight of nickel and (ii) having tensile strength exceeding approximately 1000 MPa (145 ksi) and a DBTT less than approximately -73 ° C (-100 ° F) are provided. Such pipes and other components are preferably constructed from extremely high strength low alloy steels with excellent cryogenic temperature tenaities described herein. The pipes and other components of this invention are preferably constructed from discrete plates of low alloy steel of extremely high strength with excellent tenacity at cryogenic temperature. When applicable, pipe joints and other components preferably have the same strength and toughness as low alloy steel plates of extremely high strength. In some cases, a weld with lower tensile strength in the range of about 5% to about 10% can be justified for lower voltage locations. The bonds with the preferred properties can be made by any of the suitable joining techniques. The illustrative joining techniques described herein, under the subheading "Union Methods for Construction of Pipes and Other Components". As will be familiar to those skilled in the art, the Charpy V-notch (CVN) test can be used for the purpose of determining fracture toughness and fracture control in the design of pipes to transport fluids at cryogenic temperature. pressurized, such as PLNG, particularly through the use of the transition temperature from ductile to brittle (DBTT). The DBTT defines two fracture regimes in structural steel. At temperatures below the DBTT, the fault in the Charpy V notch test tends to occur due to the fracture (fragile) of the low energy crack, whereas at temperature above the DBTT, the fault tends to occur through ductile fractures of the DBTT. high energy. Pipes that are constructed from welded steels for the transportation of PLNG and for other services, at cryogenic load bearing temperatures, must have DBTTs, as defined by the Charpy V notch test, below the service temperature of the structure in order to avoid failure due to fragility. Depending on the design, service conditions and / or requirements of the applicable classification society, the required DBTT temperature shift may be from 5 ° C to 30 ° C (9 ° F to 54 ° F) below the temperature of service. As will be known to those skilled in the art, the operating conditions taken into consideration in the design of pipes constructed from welded steel for storing and transporting pressurized cryogenic fluids, such as PLNG, include, among other things, pressure and temperature. of operation, as well as additional stresses that are probably imposed on steel and welding (see Glossary). Measurements of standard fracture mechanisms such as (i) a critical stress intensity (KIC), which is a measure of the fracture toughness of flat deformation, and (ii) displacement of crack end opening (CTOD), which can be used to measure the toughness of the plastic-elastic fracture both of which are known to those skilled in the art, they can be used to determine the fracture toughness of steel and welds. The generally acceptable industrial codes for steel structure design, for example, as presented in the BSl publication "Guidance on methods for assessing the acceptability of flaws in welded structures", frequently referred to as "PD 6493: 1991", can used to determine the maximum allowable failure sizes for the pipe based on the fracture toughness of the steel and the weld (including HAZ) and the stresses imposed on the pipe. A person skilled in the art can develop a fracture control program to mitigate the initiation of the fracture through (i) an appropriate design of the pipe to minimize the stresses imposed, (ii) quality control of manufacturing appropriate to minimize defects, (iii) appropriate control of life cycle loads and pressures applied to the pipe, and (iv) an adequate inspection program to reliably detect faults and defects in the pipeline. A preferred design philosophy for the system of the present invention is "failure before spill," as is known to those skilled in the art. These considerations are generally referred to herein as "known principles of fracture mechanics". The following is a non-limiting example of application of those principles of known fracture mechanisms in a procedure for calculating the critical failure depth for a given failure length for use in a fracture control plan to prevent initiation of fracture in a fracture. pipe according to the invention. FIGURE 2B illustrates a failure length fault 315 and failure depth 310. PD6493 is used to calculate the values for the critical failure size chart 300 shown in FIGURE 2A based on the following design conditions for a container or Pressure vessel: Pipe diameter: 914mm (36 in) Pipe wall thickness: 20 mm (0.787 in) Operations Axial Resistance 0.80 mm (multiplied by) SMYS = 662 MPa (96ksi; For the purpose of this example, a surface failure length of 1QQ mm (4 inches), for example, a circumferential failure located in a girth weld is assumed. Referring now to FIGURE 2A, graph 300 shows the depth value of the critical fault as a function of fracture toughness CTOD and residual stress, for residual voltage levels of 15, 25, 50, 75 and 100 percent elastic limit. The residual stresses can be generated due to manufacturing and welding; and PD6493 recommends the uao of a residual stress value of 100 percent of the yield strength in welding (including HAZ welding) unless the welds are relieved of stress using techniques such as post weld heat treatment (PWHT) or the release of mechanical stress. Based on the CTOD fracture toughness of the steel at the minimum service temperature, the pipe fabrication can be adjusted to reduce residual stresses and an inspection program can be implemented (both for initial inspection and in-service inspection) to detect and measure the faults for comparison against the critical failure size. In this example, if the steel has a CTOD tenacity of 0.30 mm at the minimum service temperature (as measured using laboratory samples) and the residual stresses are reduced up to 15 percent steel yield strength, then the value for the Critical failure depth is approximately 1 mm (see point 320 in FIGURE 2A). Following similar calculation procedures, most well known to those skilled in the art, the depths of critical failure for various failure lengths as well as various fault geometries can be determined. Using this information, a quality control program and inspection program (techniques, detectable failure dimensions, frequency) can be developed to ensure that failures are detected and resolved before they reach the critical failure depth or before the application of Design charges. Based on published empirical corrections between CVN, K? C and CTOD fracture toughness, the CTOD tenacity of 0.30 mm is generally related to a CVN value of about 44 J. That example is not intended to limit this invention in any way. any. For pipes and other components that require bending of the steel, for example, in a cylindrical shape for a pipe or in a tubular shape for a pipe, the steel is preferably bent into the desired shape at room temperature in order to prevent it from affecting in any way. harmful to the -excellent tenacity at cryogenic temperature of steel. The steel must be heated to achieve the desired shape after bending, the steel is preferably heated to a temperature no higher than about 600 ° C (1112 ° F) in order to preserve the beneficial effects on the steel microstructure as described before The unique advantages associated with such pipes and other components are described in detail below. Pipe Network Distribution Systems Referring to FIGURE 1, a pipe distribution network system 10 according to the present invention for the distribution of PLNG preferably includes at least one storage container 12, at least one pipe 14 of primary distribution, and at least one destination site 16. The destination site 16 may be, for example purposes only, without thereby limiting this invention, a refueling station, a manufacturing plant, or a LNG vaporization site in a natural gas pipeline. The pipe distribution network system illustrated in Figure 1 also has at least one pipe 18 of secondary distribution, and at least one tertiary distribution pipe 15. The pipe distribution network system 10 is preferably designed to control the leakage of heat in the system, to control the vaporization of PLNG. The heat leakage can be controlled by means known to those skilled in the art, such as by appropriate insulation and thickness of insulation around the pipes, such as the primary distribution pipe 14, and around the storage container 12. Additionally, the steam management facility (not shown in Figure 1) includes a relicuefactor that can be included in the pipe distribution network system 10, or the excess steam can be used for the supplied gas fuel equipment. The PLNG is preferably pumped by a cryogenic pump (not shown in Figure 1). Additionally, the cryogenic pumps are preferably used in several locations completely of the pipe distribution network system 10 to maintain the pressure, and thus the temperature, of the PLNG being pumped through the system within the desired ranges. The appropriate cryogenic pumps can be selected by those skilled in the art. Preferably, a check valve (not shown in Figure 1) between the target site 16 and the pump in the system, eg, the secondary distribution pipe 18, prevents the flow from returning from the destination site 16- behind of the pipe. An advantage of the pipe distribution network system of this invention is that the PLNG (a liquid) can be pumped to the destination sites, thereby avoiding the increased cost of compression associated with the typical gas distribution system.

A typical reception terminal for PLNG is located on the slope to receive PLNG from a PLNG tank ship. The terminal preferably has at least one storage container 12 PLNG and facilities (not shown in Figure 1) to vaporize the PLNG. A pipe distribution network system 10 for a metropolitan network with 100 PLNG distributors / users each requiring approximately 3,000 gallons of PLNG a day, for example, including 10"of primary distribution pipe 14, approximately ten 3" of pipes 18 of secondary distribution, and approximately one hundred 1.5"of tertiary distribution pipes 15. The pipes and other components of the pipe distribution network systems described above for the distribution of PLNG are preferably constructed from any low alloy steel. suitable extremely high strength as described herein, such as any of the steels described above under the heading "Steel for Construction of Components and Vessels." Pipes and other components are sized according to the needs of the PLNG project in which The pipe distribution network system will be used. In addition to the information provided in this specification, a person skilled in the art can use standard and reference engineering practices available in the industry to determine the necessary dimensions, wall thickness, etc., for pipes and other components and to build and operating the pipe distribution network system of this invention. The systems of the invention are advantageously used to contain and distribute / transport PLNG. Additionally, the systems of this invention are advantageously used (i) to contain and transport other pressurized cryogenic fluids, (ii) to contain and transport pressurized non-cryogenic fluids, or (iii) to contain and transport cryogenic fluids at atmospheric pressure. While the above invention has been described in terms of one or more preferred embodiments, it can be understood that other modifications can be made without departing from the scope of the invention, which is set forth in the appended claims.

Glossary of terms: Aci transformation temperature: the temperature at which austenite begins to form during heating; Ac3 transformation temperature: the temperature at which the transformation of ferrite to austenite is completed during heating; Ari transformation temperature: the temperature at which the transformation of austenite to ferrite or for ferrite plus cementite is completed during cooling; Ar3 transformation temperature: the temperature at which the austenite begins to transform to ferrite during cooling; Cryogenic temperatures: temperatures below about -40 ° C (-40 ° F) CTOD: crack end opening displacement; CVN: Charpy notch in V DBTT (Ductile to Temperature delineates the two regimes of Fragility Transition): fracture in structural steel; At temperatures below the DBTT, the fault tends to occur by low energy crack fracture (brittleness), while at temperatures above the DBTT, the fault tends to occur by high energy ductile fracture; Essentially; substantially 100% by volume; g: local acceleration due to gravity; Gm3: one billion cubic meters; GMAW: gas metal arc welding Hardening particles: one or more of e-copper, Mo2C, or the niobium and vanadium carbides and carbonitrides; MAKE: area affected by heat; Intercritical temperature range: from approximately the Aci transformation temperature to approximately the Ac3 transformation temperature on heating, and from approximately the Ar3 transformation temperature to approximately the Ari transformation temperature on cooling; K-ic- critical stress intensity factor; kJ: kilojoule; kPa: thousands of Paséales; ksi: thousands of pounds per square inch; Low alloy steel: a steel containing iron and less than about 10% by weight of total alloy additives; MA: martensite-austenite; Maximum permissible failure size: length and depth of critical failure; Mo2C: a form of molybdenum carbide; MPa: millions of Paséales; Ms transformation temperature: the temperature at which the transformation of austenite or martensite begins during cooling; PLNG: liquefied and pressurized gas; Predominantly: at least 50 percent in volume approximately; ppm: parts per million; psiar: pounds per absolute square inch; Tempered: accelerated cooling by any means by which a fluid is selected by its tendency to increase the rate of cooling of the steel used, as opposed to cooling with air; Tempering speed the cooling rate at (cooling): center, or substantially at the center, of the plate thickness; Termination Temperature of the highest temperature, or Tempering: substantially the highest reached on the surface of the plate, after the tempering ends, due to the heat transmitted from the average thickness of the plate; QST: Tempering Termination Temperature; Earthenware: a piece of steel that has any dimensions; Tanker: Any means for distribution based on vehicular ground of PLNG-LNG, or other cryogenic fluids, including without limitation, tanker trucks, railroads and barges; TCF: one trillion cubic feet; Resistance to tension: in tension test, the maximum load ratio to the original cross-sectional area; TIG welding-: welding of inert gas of tungsten; Temperature T ^: the temperature below which the austenite does not recrystallize; USPTO: United States Patent and Trademark Office; and Welding: a welded joint, which includes: (i) the welded metal, (ii) the heat affected zone (HAZ), and (iii) the base metal in the "close proximity" of the HAZ. The portion of the base metal that is considered within the "close proximity" of the HAZ and therefore, a part of the weld, varies depending on the factors known to those skilled in the art, for example, without limitation, the width of the weld, the size of the article that was welded, the number of welding required to manufacture the article, and the distances between the welds.

Claims (14)

1. CLAIMS 1. A pipe suitable for use in a pipe distribution network system for transporting liquefied and pressurized natural gas at a pressure of approximately 1035 kPa (150 psia) to approximately 7590 kPa (1100 psia) and at a temperature of -123 ° C (-190 ° F) to approximately -62 ° C (-80 ° F), wherein the pipe is constructed by bending and joining joints of at least one discrete plate of a material comprising a low alloy strength steel extremely high that contains less than 9% by weight in nickel and has a tensile strength of more than 830 MPa (120 ksi) and a DBTT of less than about -73 ° C (-100 ° F), and where any The seam formed by the joint has adequate strength and tenacity under pressure and temperature conditions to contain the liquefied and pressurized natural gas.
2. 2. The pipeline according to claim 1, characterized in that the seam has a strength of at least about 90% of the tensile strength of the low alloy steel of extremely high strength.
3. 3. The pipeline according to claim 1, characterized in that the seam has a DBTT of less than about -73 ° C (-100 ° F).
4. 4. The pipe according to claim 1, characterized in that the seam is formed by gas metal arc welding.
5. The pipe according to claim 1, characterized in that the seam is formed by welding inert gas of tungsten.
6. 6. A pipe distribution network system for distributing a pressurized liquefied natural gas, wherein the pipe distribution network system has at least one pipe that is constructed by bending and joining together at least one discrete plate of a material comprising a low alloy steel of extremely high strength which contains less than 9% by weight in nickel and which has a tensile strength greater than 830 MPa and a DBTT less than about -73 ° C (-100 ° F) ), and wherein any seam formed by the joint has the strength and adequate tenacity under pressure and temperature conditions to contain the liquefied and pressurized natural gas at a pressure of about 1035 kPa (150 psia) to about 7590 kPa (1100) psia) and at a temperature of about -123 ° C (-190 ° F) to about -62 ° C (-80 ° F).
7. 7. A method of transporting a liquefied and pressurized natural gas from a storage site to a destination site, the method comprising the steps of: (a) administering the pressurized liquefied natural gas having a pressure of approximately 1035 kPa ( 150 psia) to approximately 7590 kPa (1100 psia) and a temperature of approximately -123 ° C (-190 ° F) to approximately -62 ° C (-80 ° F), for an inlet of a distribution network system pipe at the storage site, wherein the pipe distribution network system has at least one pipe which is constructed by bending and joining joints of at least one discrete plate of a material comprising a low alloy steel of strength extremely high that contains less than 9% by weight of nickel and that has a tensile strength greater than 830 MPa (120 ksi) and a DBTT less than approximately -73 ° C (-100 ° F), and wherein any seam formed by the joint has a strength and tenacity suitable to pressure and temperature conditions to contain the pressurized liquefied natural gas; and (b) pumping liquefied and pressurized natural gas to an outlet of the pipe distribution network system at the destination site.
8. The method according to claim 7, characterized in that the vaporization equipment for converting the pressurized liquefied natural gas to a gas and the supply of the gas to the users or distributors is connected to the outlet of the distribution network system. pipe.
9. 9. The method according to claim 8, which further comprises the step of: (c) supplying the gas to a gas pipe.
10. The method according to claim 7, characterized in that the pipe distribution network system has at least one storage container, wherein the storage container is constructed by joining a plurality of discrete plates of a material comprising a low alloy steel of extremely high strength which contains less than 9% by weight of nickel and has a tensile strength greater than 830 MPa (120 ksi) and a DBTT less than approximately less than -73 ° C (-100 ° F), and where the joints between the discrete plates have the strength and tenacity appropriate to the pressure and temperature conditions to contain the natural gas liquefied pressurized.
11. 11. A system for distributing pressurized liquefied natural gas at a pressure of about 1035 kPa (150 psi) to about 7590 kPa (1100 psia) and at a temperature of about -123 ° C (-190 ° F) to about -62 ° C (-80 ° F), the system comprising a pipe distribution network system with an inlet to receive liquefied and pressurized natural gas, where the pipe distribution network system has at least one pipe that is constructed by flexing and joining at least one discrete plate of a material comprising a low alloy steel of extremely high strength which contains less than 9% by weight of nickel and which has a tensile strength greater than 830 MPa (120 ksi) and a DBTT less than approximately minus -73 ° C (-100 ° F), and where any seam formed by the joint has the strength and tenacity appropriate to the pressure and temperature conditions to contain the natural gas liquefied.
12. Pressurized The system according to claim 11, characterized in that the pipe distribution network system at least one storage container, wherein the storage container is constructed by joining a plurality of discrete plates of a material that it comprises an extremely high strength low alloy steel containing less than 9 wt.% nickel and having a tensile strength of more than 830 MPa (120 ksi) and a DBTT of less than about -73 ° C ( -100 ° F), and where the joints between the discrete plates have the strength and tenacity appropriate to the pressure and temperature conditions to contain the pressurized liquefied natural gas.
13. 13. A vessel for storing pressurized liquefied natural gas at a pressure of about 1725 kPa (250 psia) to about 7590 kPa (1100 psia) and at a temperature of about -112 ° C (-170 ° F) to about -62 ° C (- 80 ° F), the container that is constructed by joining a plurality of discrete plates of materials comprising a low-alloy high-strength steel containing less than about 2% by weight of nickel and having the strength and toughness to the adequate fracture to contain the pressurized liquefied natural gas, where the unions between the discrete plates have the resistance and tenacity adapted to the pressure and temperature conditions to contain the pressurized liquefied natural gas.
14. 14. A container suitable for use in a pipe distribution network system for transporting pressurized liquefied natural gas at a pressure of about 1725 kPa (250 psia) to about 7590 kPa (1100 psia) and at a temperature of about -112 ° C (-170 ° F) to about -62 ° C (-80 ° F), the container being constructed by joining a plurality of discrete plates of materials comprising a high-strength low-alloy steel containing less than about 2% by weight of nickel and having the strength and fracture toughness to contain the liquefied and pressurized natural gas, where the bonds between the discrete plates have adequate strength and toughness under pressure and temperature conditions to contain the liquefied natural gas pressurized.