Welded Pipe on Piping System

During the Saturday, I have to train two of the supervisor in the factory so they can use the computer properly without having trouble in the future, and I hope they can operate the computer well. and now is the time that I have to post Piping and Fabrication blog and here the rest of the post.

Welded Pipe. Welded pipe is produced by forming a cylinder from flat steel sheets coming from a hot strip mill. The strip mill takes the square bloom from the blooming mill and reduces it into plates, skelp, or coils of strip steel to be fed into the particular welding process equipment.Butt-weld pipe ismade by furnace heating and forge welding or by fusion welding using electric resistance, flash, submergedarc welding, inert-gas tungsten-arc welding, or gas-shielded consumable metal-arc welding. The welded seam is either parallel to the tube axis or in a spiral direction about the tube centerline.

Furnace-Welded (Continuous or Butt-Welded) Pipe. This is a low-cost carbon steel pipe below 4-in diameter made of steel from open-hearth or basic oxygen Bessemer steel. In this process, skelp is heated to welding temperature in a continuous furnace and passed through forming and welding rolls, welding the strip edges at the same time the tube is formed. Strips can be consecutively resistance-welded to each other to form a continuous pipe.

Fusion-Welded Pipe. Fusion-welded pipe is produced by resistance-welding, induction-welding, or arc-welding. Electric Resistance-Welded Pipe. In the electric resistance-welded (ERW) pipe process (Fig. A5.9), upon exiting the forming mill, the longitudinal edges of the cylinder formed are welded by flash-welding, low-frequency resistance-welding, high-frequency induction-welding, or high-frequency resistance-welding. All processes begin with the forming of the cylinder with the longitudinal seam butt edges ready to be welded.

In the flash-welding process, the butted cylinder surfaces are placed in contact; a voltage is applied across the contact, causing metal flashing along the seam length and raising the steel temperature locally to the metal-forming temperature. After this, the seam edges are pressed together and a pressure fusion-weld is formed at a temperature lower than the steel melting point. The upset material along both the inside and outside of the seam is removed with a scarfing tool. This process is used to produce high-strength carbon steel pipe from NPS 4 to 36 (DN 100 to 900).

In the low-frequency resistance method, electric current and pressure are simultaneously applied, and the resulting heat causes melting of the edges. The resulting seam is similar to that from the flash-welding process and requires removal of the upset material. Postweld heat treatment may be desirable for stress relief, tempering, or recrystallization. This process is applied to pipe of outside diameters up to NPS 22 (DN 550).

High-frequency welding process, using an alternating current of more than 400,000 Hz, is similar to the low-frequency resistance welding process. The lower inductance path followed by the current produces a smaller high-temperature band that minimizes the amount of upset material. This process is used for pipe up to NPS 42 (DN 1050).

For production of small-diameter pipe at high rates of production, the highfrequency induction-welding process may be used. In this process, an induction coil raises the seam temperature to welding temperature. The rapid increase in temperature caused by the high-frequency current causes little upsetting because of the resulting control of temperature and fusion. Several arc-welding processes are used in commercial welded pipe production. These include the submerged-arc-welding process, the inert-gas tungsten-arc-welding process, and the gas-shielded consumable metal-arc-welding process. In the submerged-arc-welding process, bare wire consumable electrodes are added to the weldmetal under a blanket of flux. Themelting flux creates a protective atmosphere of inert gas and a slag blanket over the solidifying weld metal. In heavywall piping, simultaneous submerged arc seam welds on inner and outer sides of the pipe are sometimes used to build up the weld thickness to the desired level. In modern pipe production facilities, automated equipment is used to control all variables in the submerged arc process, including relative movement speed between pipe and welding heads, wire feed rate, welding current, and flux feed rate. Submerged-arc seam-welded pipe is used in critical high-temperature or high-pressure applications in the electrical power generation process and chemical industries.

For carbon steel and stainless steel pipe of smaller wall thickness, the inert-gas tungsten-arc-welding process is used. The weld is protected by an inert gas such as argon or helium, which forms a blanket over the weld metal. For thicker-wall pipe, a filler wire may be fed into the protective gas blanket. For thin-wall pipe, no filler is used. A number of variations in pipe forming before welding are used, including molding, pressing, or rolling strip into cylinders.

Spiral Welded Pipe. Lightweight pipe for temporary or light operation duty such as in water systems applications may be made by the spiral-welded process. In this process, narrow strips of steel sheet are helically wound into cylinders. The edges of this strip can either be butting or overlapping and are welded by any of several electric arc-welding processes.

Forged Seamless Pipe

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Forged Seamless Pipe. Forged pipe is used for large-diameter, NPS 10–30 (DN 250–750), and thickness, 1.5–4 in (40–100 mm), pipe, where equipment availability and cost for other seamless grades are limiting. There are two processes available for the production of forged seamless pipe, namely, forged and bored pipe and hollow forged pipe.

Forged and Bored Seamless Pipe. In the forged and bored process a billet or ingot heated to forging temperature is elongated by forging in heavy presses or forging hammers to a diameter slightly larger than that of the finished pipe. After turning in a lathe to the desired outside diameter, the inside diameter is bored to the specified internal diameter dimensions. The resulting pipe can be made to very close tolerances. Sections 50 ft (15 m) long have been produced by this process.

FIGURE A5.7 Hollow-forged seamless pipe-Erhardt-type process

Hollow Forged Seamless Pipe Erhardt Type Process. The Erhardt process (Fig. A5.7), developed by Heinrich Erhardt in Germany in 1891, consists of heating a square ingot to forging temperature, placing it into a circularly hollow die, and incompletely piercing it with a vertical piercing mandrel such that a cup shape is obtained. As a result of the piercing at forging temperature, the square ingot becomes the (circular) shape of the die. After reheating, the cup-shaped shell is mounted on a mandrel and pushed through a series of dies to the desired diameter and wall thickness, after which the cupped end is removed and the inside and outside pipe diameters are machined. This process is used for large-diameter and heavy-wall seamless pipe for boiler headers and main steam line piping. It can be applied to produce low and medium carbon steel pipe (ASTM A53, A106, A161, A179, A192, A210), stainless steel pipe (TP329, TP304, TP304L, TP321, TP347, TP316), and high nickel alloys (A333, A334).

Cold and Hot Finishing of Seamless Pipe and Tube. Pipe that has been produced by the Mannesmann plug-mill, mandrel mill, Ugine Sejournet, or Erhardt forging process can be used as hot finished seamless steel pipe or tube if the application does not require further finishing. If further finishing is required, the pipe or tube may be further reduced by a cold reduction process (Fig. A5.8). If the cold reduction processes are used, the reduced tube must be heat-treated in a furnace such as a bright annealing furnace or in a continuous barrel furnace. Subsequent to the heat treatment of the cold finished pipe, the pipe must pass through a straightening process which corrects any non straight sections caused in the pipe by the heat treatment of cold reduced pipe. The straighteners are either a series of rolls through which the pipes pass cold or a device which bends the pipe at discreet locations along the pipe. The resulting product is called cold finished seamless pipe or tube.

FIGURE A5.8 Cold and hot finishing of seamless pipe and tube.

In applications of tube to fossil fuel boilers, cold finishing is sometimes specified. Cold finishing improves the surface finish and dimensional accuracy. Some boiler manufacturers, however, consider the hot finished tube surface satisfactory and specify it as such because of its reduced cost.

Continuing from the last post from Piping & Fabrication, and we now will talk about Mannesman Plug-Mill Process and Ugine Sejournet Type Extrusion Processes.

Mannesmann Plug-Mill Process.
In the Mannesmann plug-mill process (Fig. A5.5) the billet may be pierced in two hot rotary piercers because of the greater reduction needed for medium size pipe and tube. Following the piercing process, the pierced billet is placed in a plug-mill, which reduces the diameter by rotating the tube over a mandrel.

FIGURE A5.5 Mannesmann plug-mill process

Having some ovality, the tube is next inserted between the rolls of reelers which provide for dimensional correction and burnish the inside and outside diameters of the tube. Finally, after reheating, the tube reenters a reeler and sizing rollers to provide for greater dimensional uniformity.

The Mannesmann plug-mill process is a standard process for making large quantities of thin-wall stainless steel tube or pipe of uniform size and roundness throughout its entire length.

Ugine Sejournet Type Extrusion Processes. The Ugine Sejournet extrusion process (Fig. A5.6) is used for high-alloy steel tubes and pipe such as those of stainless steel and specially shaped pipe. A descaled billet, heated to approximately 2300_F (1260_C), is placed in the vertical press compartment with an extrusion die at its bottom. After applying a hydraulic ram to the billet, a piercing mandrel within the ram punches the billet, producing a cylinder from which the punch piece is ejected through the extrusion die opening. Following this, the ram is activated to apply pressure to the billet, and the billet is extruded through the annulus formed between the piercing mandrel and die cavity. In horizontal presses, piercing is done as a separate operation, or a hollow is used with amandrel and die. Themandrels and dies are made of high-alloy steels containing tungsten, molybdenum, and chromium having Rockwell C hardness values of approximately 46. Powdered glass is the lubricant used in this process. Heavy-wall pipe in sizes NPS 8–48 (DN 200–1200), having a wall thickness ranging from 1 in (25 mm) to 6 in (150 mm), is extruded vertically to 45 ft (14 m) lengths using procedural steps in the Ugine Sejournet process and a graphite lubricant. These large extrusions of carbon-, alloy-, and nickel-based materials include ASTM specifications A 106, Grades B & C; A 312; A 333; A 335; A 376; B 167; and B407. Heavy-wall pipe per ASTM A335, Grades P11, P22, and P91 is increasingly being used in power generation. In addition, heavywall pipe is utilized in offshore oil drilling and production.

FIGURE A5.6 Ugine Sejournet extrusion process

Pipe-and Tube-Forming Processes

Actually I should feel sorry for myself because I can't do the fasting for the whole days. I know the reason because I have problem with my stomach so I can't do it. But today I have to force myself to do it and to forget all the pain, it's better I post the Piping & Fabrication first before start another activity.

Pipe-and Tube-Forming Processes
There are basically two types of pipe- and tube-forming processes, namely, seamless and welded. Each process imparts unique properties to the pipe or tube. Seamless pipe or tube does not have the presence of a welded seam along the length of the pipe. This seam has traditionally been believed to be a potential weakness. The development of automated welding processes and quality control, however, has made this a virtually nonexistent concern. The control of thickness uniformity and concentricity is relatively easy with welded pipe and tube. In general, the seamless pipe is more expensive to produce. The classification of cylindrical tubular products in terms of either pipe or tube is a function of end use. This is discussed further under Tubular Product Classification.

FIGURE A5.2 Continuous casting process

Seamless Pipe. Seamless tube and pipe (Fig. A5.3) are manufactured by first producing a hollow tube which is larger in diameter and thickness than the final tube or pipe. The billet is first pierced by either a rotary (Mannesmann) piercer or by a press piercing method. For tubes of small diameter, the mandrel mill process is used. For medium outside diameter tubes of carbon or low-alloy steel, the Mannesmann plug mill process is used. Large-diameter, heavy-wall carbon steel, alloy, and stainless pipe is manufactured by the Erhardt push bench process and vertical extrusion similar to the Ugine Sejournet type extrusion process. High-alloy and specially shaped pipe are manufactured by the Ugine Sejournet extrusion-type process. These processes are performed with the material at hot-metal-forming temperatures. Further cold processing may or may not be performed to obtain further dimensional accuracy, surface finish, and surface metallurgical structure.

FIGURE A5.3 Seamless tube and pipe manufacturing processes

Mandrel (Pilger) Mill Process. In the mandrel (pilger) mill process (Fig. A5.4), a steel billet is heated to forging temperature and placed between the rolls of a hot rotary piercing mill. A piercing point is placed at the center of the billet, and the rotating rolls are designed to advance the billet over the piercing point, thereby forming a hole through the center of the billet along its entire length as it advances into the tilted rolls. A mandrel of outside diameter approximately that of the inside finished pipe diameter is pressed into the pierced hole of the billet. This combination of mandrel and billet is placed between rolls of a pilger-mill having a cam-shaped contour revolving counter to the direction in which the billet is being forced by means of a hydraulic and pneumatic ram mechanism.

FIGURE A5.4 Mandrel (pilger) mill process

In the pilger-mill, the rolls first grab the hot billet and after some rotation form a shaft. The pressure of the rolls forces the billet backward, and the resulting tube section is squeezed and smoothed out in the adjacent part of the roll groove. This process is equivalent to forging the billet against the mandrel and driving the billet and mandrel against the ram. After reaching the open portion of the cam shape, the ram mechanism again forces the billet into the rolls. Following the pilger mill process, the tube is reheated and passed through a reducer or sizer to provide a more uniform diameter. The resulting tube or pipe is called hot finished seamless.

The pilger-mill process is slower than conventional drawing. However, since large reductions in diameter are possible in a single pass, the process is applied to the production of tubes of small diameter such as heat exchangers, fossil fuel boilers, and nuclear steam generators

FERROUS PIPE-MAKING PROCESSES

FERROUS PIPE-MAKING PROCESSES
Iron-Making
The making of steel for ferritic piping begins with the smelting of iron ore found in deposits in the crust of the earth throughout the world in forms such as hematite and magnetite. In preparation for the smelting process, the iron ore may be treated by any of several methods to convert it into a suitable form for introduction into the blast furnaces. One method is sintering, which converts ores into a porous mass called clinkers. Another is smelting, which is performed in a blast furnace. The process involves the chemical reaction of iron ore with limestone, coke, and air under heat, reducing the iron ore to iron. The ‘‘pig’’ iron obtained from the blast furnace is used as the basic component in the steel-making process.

Steel-Making
Steel for piping can be produced in several ways (Fig. A5.1), depending on the facilities available and the desired characteristic of the steel.Generally, steel requires the removal of carbon from the pig iron to a degree required by the carbon steel properties desired. Alloy steel also requires the addition of alloying elements such as chromium, nickel, manganese, and molybdenum to provide the special properties
associated with the alloying element.

Bessemer Converter. The Bessemer method of making steel (due to Sir Henry Bessemer in 1856) consisted of blowing a current of cold air through the molten pig iron, thereby using the oxygen in the air to burn carbon and other impurities from the melt. After burning out the carbon in the pig iron, the exact amount of carbon required for the steel is reintroduced into the heat.

Basic Oxygen Process. The basic oxygen process (BOP) is essentially the same as the Bessemer process except that it uses pure oxygen (instead of air) together with burned lime converted from limestone. This process burns out the impurities more quickly and completely and provides for more precise control of the steel chemistry.

Open-Hearth Furnace. The open-hearth furnace is used to produce much of the steel in the United States; however, it is being superseded by the basic oxygen process. Its significant advantage is the ability to use scrap steel as well as pig iron as ferrous stock in producing steel. The open-hearth furnace is a large rectangular brick floor, or hearth, completely covered with a brick structure through which the
charge of ferrous stock and limestone is introduced. It is fueled with coke gas, oil, or tar introduced through a burner playing a flame across the hearth while the products of combustion escape through the furnace wall away from the burner. An advantage of the open-hearth process is that testing for carbon content during the heating is possible, allowing adjustments to be made to the feed-stock at that time to control the chemistry of the product.

Electric Arc Furnace. The electric arc furnace is a large kettle-shaped chamber lined with fire brick, into which a charge of steel scrap with coke is melted by means of heat produced by an electric arc. Since no burning of fuel is required, the oxygen of the steel can be controlled and kept to a minimum. Alloying elements can be added without the fear of oxidation. Because of the control of heat time, temperature,
and chemistry, the electric arc furnace is used in the production of high-quality alloy steels.

Argon Oxygen Process. The argon oxygen process (AOP) is used in the production of specialty steels with low carbon and sulfur and high chromium content. A charge of steel of almost the desired properties is introduced into a basic oxygen furnacelike vessel, and controlled amounts of oxygen and argon are introduced into the melt. This reducing process conserves valuable chromium.

Vacuum Degassing Process. When exceptionally high quality steel is required, steel can be ‘‘degassed’’ in a vacuum environment. This vacuum degassing process provides strong reduction in hydrogen, oxygen, nitrogen, inclusions, and contaminants such as lead, copper, tin, and arsenic.

Ingots, Blooms, and Billets. Ingots, blooms, and billets are the shapes into which the molten metal is solidified before using it in a particular pipe-making (or other) process. An ingot is poured from the molten steel and after solidification goes to the blooming mill to be rolled into square blooms, which are further formed onto bar rounds. Alternately, in the case of large pipe, the ingot may be formed into pierced billets to be used in the seamless tube-making process.

Continuous Casting Process. Although the development of the continuous casting process (Fig. A5.2) began in the nineteenth century, it was after World War II that its use became of great commercial interest. In the continuous casting process, molten steel is poured from the melting furnace to a ladle feeding a reservoir called a tundish. The tundish feeds a lubricated mold that has a cooled copper surface, and the solidifying steel is continuously drawn from the mold. In the case of piping steel, the mold is the shape of the billet or slab used in the tube-making process. There are many types of continuous casting processes, ranging from vertical to horizontal, with variations of bent sections in between. This process is now used in more than half the world’s steel production. In Japan, 85 percent of the total steel produced is by the continuous casting process.

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MANUFACTURING OF METALLIC PIPE

After take a break for few days, Piping & Fabrication ready to go again and this is the other topics from this blog, and I believe this will be more interesting.

MANUFACTURING OF METALLIC PIPE

DEVELOPMENT OF COMMERCIAL PIPE-MAKING
There have been increasing societal demands for modern structures and facilities and concomitant increased emphasis on safety and reliability of equipment under all operating conditions. Piping manufacturing processes have been developed to provide the quality and reliability commensurate with these demands, together with economically feasible production methods. To meet the more stringent reliability goals, the quality control of the piping manufacturing process from the production of the raw material to the finished product is of significant importance. Driving the need for process quality improvement are the social and economic consequences of equipment failure in critical applications such as power generation, chemical and petroleum production, and transportation.

This chapter considers the methods by which different types of metallic pipe are produced. It also considers the various steel-making processes which are important to the ultimate quality of the manufactured pipe.

Historical Background
The history of pipe manufacturing goes back to the use of hollow wooden logs to provide water for medieval cities. The use of cast-iron pipes in England and France became prevalent in the early nineteenth century. The first major cast-iron water pipeline for Philadelphia was obtained in 1817 and for New York in 1832. Distribution of gas for gaslights was initiated in England, using sheet iron drawn through a die to a cylindrical shape and with the edges welded together. In 1887 the first pipe was made of Bethlehem steel in the United States.

Seamless pipe manufacture was attempted in the mid–nineteenth century by various means; the Mannesmann process was developed in Germany in 1885 and operated commercially in England in 1887. The first seamless pipe mill in the United States was built in 1895.

In the early twentieth century, seamless tubes gained wide acceptance as the Industrial Revolution proceeded with automobiles, oil refineries, oil pipelines, oil wells, and fossil power generation boilers. At that time, the welded tube had not achieved the reliability of present-day electric resistance welded tubes. The development of pipe and tube production methods, together with the development of steel alloys capable of withstanding the demanding environmental conditions of temperature, chemistry, pressure, and cyclic thermal and pressure load application have enabled pipe and tube to be used reliably in the most critical applications, ranging from Alaskan pipelines to nuclear power generation plants.

World Tubular Product Production Capability
World production and consumption of iron and steel tubular products makes up almost 14 percent of the worldwide crude steel conversion. World production of steel tubular products is continuously increasing to meet the demands of worldwide industrialization and growing population. The production of iron and steel tubular products vary depending on a wide range of worldwide economic factors such as oil exploration, power generation plant construction, and automotive production.

For example, in economic climates where oil prices are low, there is less incentive to drill new oil wells. Consequently, the production of steel pipe for oil drilling casings would be reduced. Similar examples of steel pipe production as a function of economic climate can be seen in the power generation and automotive industries. Total world production of pipe is an integration of the effects of the local national economic climates throughout the world.

FOREIGN CODES AND STANDARDS

Probably this is the last post about Pipe Code's and tomorrow Piping & Fabrication will continue with other Piping System topics and hope that will make us know better about Piping.

FOREIGN CODES AND STANDARDS
The basic principles of piping design and construction may not differ much from one country to another, but the requirements of country-specific codes and standards may vary substantially. Therefore, the personnel involved in the engineering design, construction, operation, and maintenance of piping systems must ensure that the requirements of applicable codes and standards are complied with to ensure the safety of the general public and workers associated with the facility.

The user is advised to verify the latest applicable version/edition of the code and/or standard before invoking their requirements for any application. Appendix E10 provides a listing of British, DIN, Japanese, and ISO codes, standards, and specifications related to piping.

BRITISH STANDARDS AND SPECIFICATIONS
Pipe, Tube, and Fittings
Appendix E10, Table E10.B1 lists British standards and specifications for pipe, tube, and fittings.

Flanges, Bolts, Nuts, and Gaskets
Appendix E10, Table E10.B2 lists British standards and specifications for flanges, bolts, nuts, and gaskets.

Valves
Appendix E10, Table E10.B3 lists British standards and specifications for valves.


DIN STANDARDS AND SPECIFICATIONS
Pipe, Tube, and Fittings
Appendix E10, Table E10.D1 lists DIN standards and specifications for pipe, tube, and fittings.

Flanges, Bolts, Nuts, and Gaskets
Appendix E10, Table E10.D2 lists DIN standards and specifications for flanges, bolts, nuts, and gaskets.

Valves
Appendix E10, Table E10.D3 lists DIN standards and specifications for valves.

JAPANESE STANDARDS AND SPECIFICATIONS
Pipe, Tube, and Fittings
Appendix E10, Table E10.J1 lists Japanese standards and specifications for pipe, tube, and fittings.

Flanges, Bolts, Nuts, and Gaskets
Appendix E10, Table E10.J2 lists Japanese standards and specifications for flanges, bolts, nuts, and gaskets.

Valves
Appendix E10, Table E10.J3 lists Japanese standards and specifications for valves.

ISO STANDARDS AND SPECIFICATIONS
Pipe, Tube, and Fittings
Appendix E10, Table E10.I1 lists ISO standards and specifications for pipe, tube and fittings.

Flanges, Bolts, Nuts, and Gaskets
Appendix E10, Table E10.I2 lists ISO standards and specifications for flanges, bolts, nuts, and gaskets.

Valves
Appendix E10, Table E10.I3 lists ISO standards and specifications for valves. Other chapters include reference to other international or foreign