Carbon steel pipe, as the name implies, is fabricated of an admixture of carbon and steel. It is artificial or casting in a way that there are no seams to abate the pipe. You have to use accessories such as a array of flanges or base bond accessories area necessary. These accessories have to aswell be fabricated of carbon steel.

Carbon Animate Pipe

Carbon animate aqueduct comes in sizes from 1/8-inch alien bore to 72-inch alien diameter. It comes in capricious thicknesses depending on the purpose it is getting acclimated for. You can use carbon animate aqueduct to carriage gas in your house, to move liquids about in an automated ambience or for pipelines affective huge amounts of of oil. It has even been acclimated in geothermal applications.

Small Aqueduct Fittings

Carbon animate aqueduct that has an autogenous bore of beneath than 2 1/2 inches is usually threaded and abutting with a carbon animate abutment of the aforementioned admeasurement with the aforementioned cilia configuration. You will aswell acquisition added carbon animate accessories such as threaded elbows, both at 45 degrees and 90 degrees. Caps are accessible if you charge to shut off a line. Flanges and bifold absolution unions can advice in awkward places in gas lines. There are aswell threaded reductions, such as 2 inch to 1 1/2 inch, or 1 inch to 3/4 inch, fabricated of carbon steel.

Accessories for Large Pipe

Large automated carbon animate usually has anchored unions. One of the exceptions is if the aqueduct has some blazon of liner to advice anticipate corrosion. These liners are usually fabricated of artificial or fiberglass articles and can be damaged by the calefaction of welding. Large carbon animate flanges are accessible for applications with lined pipe. They aswell use carbon animate basics and bolts which can be up to 1 inch in diameter. While these are added big-ticket to install than a simple weld, they radically abate bane at joins.

Specialty Fittings

You can buy T joins, both with threads, as able-bodied as flanges in carbon steel. These, as able-bodied as a lot of added fittings, appear in a array of carbon animate alloys. Lap joins and blooper on joins are aswell accessible for carbon animate aqueduct up to 4 inches in diameter. These accessories are acclimated on carbon animate aqueduct acclimated for aggregate from domiciliary gas curve to the busline of baneful liquids in an automated setting.

Carbon steel pipe abide of an adamant and carbon admixture that is able to be angled into shapes during accomplish afterwards abbreviation its top compactness strength. It is important to assure the animate apparent from bane due to the adamant ferrite agreement that will blight through agitation from baptize contact. The pipework that food blaze sprinkler systems is generally carbon steel, and requisite backbone apparatus such as cam and crank shafts in aircraft and cars use carbon animate pipes and tubing. Painting carbon animate pipes to finer abstain bane requires the use of the actual album and paint.

1

Use wire absolute and abolish all apparent blight from the carbon animate pipe. Sweep up any blight particles application a duke besom to accumulate the plan breadth bright of dust.

2

Use a solvent-based cleaner and a bolt to abrade off all grease and oil stains from the apparent of the pipe. Wipe the bolt over the absolute apparent of the aqueduct to aggregate any dust or blight particles that remain. Allow the carbon animate to dry.

3

Open the zinc phosphate acrylic album and use a activity stick to mix the album to a compatible consistency. Use zinc phosphate acrylic album because the zinc forms a barrier that acts as an anode in the electrochemical bane action and deflects pitting on the carbon steel.

4

Load the album assimilate a paintbrush and administer a blubbery covering to the carbon animate pipe. Allow the album to dry according to the manufacturer's instructions.

5

Use a activity stick and mix the polyurethane acrylic acrylic to a constant color. Use a paintbrush and administer a covering of acrylic to the aqueduct surface. Wipe up any acrylic that enters the ends of an uninstalled carbon animate aqueduct in adjustment to anticipate aqueduct contamination.

6

Allow the aboriginal covering of acrylic to dry according to the manufacturer's instructions. Generally, a lot of acrylic acrylic is accessible for a afterward covering afterwards two hours. Acrylic a final covering of polyurethane acrylic over the apparent of the carbon animate aqueduct to complete the task.

The aim of the present invention is to provide a carbon steel pipe adapted to convey flue gases which is entirely protected against the danger of corrosion caused by condensation and further ensures high efficiency in the transmission of heat from the flue gases to the fluid, and in particular to the water, to be heated.

 

The proposed aim is achieved by a protected carbon steel pipe for fire tube heat exchange devices, particularly boilers, according to the invention, characterized in that it comprises the features disclosed in the appended claims.

 

The described invention is susceptible of numerous other modifications and variations, all of which are within the scope of the appended claims: thus, for example, it is important to stress the fact that the various means for protecting the carbon steel pipe made of corrosion-resistant material may cover different lengths within the described pipes.

 

A method of inhibiting corrosion of metallic piping of condensate and feed water systems in a power generating plant having a heat generator, during shutdown of said plant,characterized by continuing the water in said piping to flow, at a flow velocity of at least 0.2 cm/sec, after said plant has been shut down until it is restarted up, the water being kept flowing in the piping without flowing through the heat generatorof the power generating plant, and by keeping the specific electric conductivity of the flowing water at 0.5 μS/cm or less, and wherein the dissolved oxygen concentration of said water is 40 to 30,000 ppb, whereby the dissolving of at least 40 ppboxygen in the water, together with continuation of the water flow and keeping the specific electrical conductivity at 0.5 μS/cm or less, passivates the metal of the piping and prevents corrosion thereof.

The expansion ratio of the carbon steel pipe varies depending on the size and shape of the carbon steel pipe to be expanded, the mechanical characteristics of the carbon steel pipe, the state of the inner surface of the carbon steel pipe and the size, shape, the state of the surface, a lubricating method and the expanding speed of the mandrel. The expansion ratio is 25% to 30% or lower.

Heating the carbon steel pipes by a high frequency induction heating method, a high frequency direct energizing heating method or a resistance heating method performs the joining process. In particular, each of the high frequency induction heating method and the high frequency direct energizing heating method is able to easily heat relatively large carbon steel pipes. Thus, high heating efficiency can be realized and the temperature can be raised to the required joining temperature in a considerably short time. Therefore, the foregoing methods are preferred methods to heat the carbon steel pipes.

It is preferable that the frequency of high frequency electric currents for use in the high frequency induction heating method or the high frequency direct energizing heating method is 100 kHz or lower. If the frequency is higher than 100 kHz, only the surface is undesirably heated owing to the skin effect. Thus, uniform heating of the overall joined surfaces cannot be performed.

The process for expanding the joint of carbon steel pipes will now be described. The expanding process is a process for expanding the joint 32 of carbon steel pipes 30 manufactured in the foregoing joining process so as to uniform the inner diameter of the joint 32 of carbon steel pipes 30.

Specifically, a mandrel 33 is inserted into an end of the joint 32 of carbon steel pipes 30 each having the structure that the inner diameter of the non-joined portions is d0, as shown in FIG. 2A. Then, hydraulic pressure is applied from a rear position. Thus, as shown in FIG. 2B, the mandrel 33 is moved to another end of the joint 32 of carbon steel pipes 30 so as to enlarge the inner diameter of the joint 32 of carbon steel pipes 30 to d1. In the present invention, the amount of the inner diameter realized after the expanding process and enlarged from the minimum inner diameter of the non-joined portion before the expansion is called an "expansion ratio" which is defined by the following equation.

Patent Documents 1 and 2 describe methods of manufacturing seamless pipe one feature of which is to employ a plug tip draft of not lower than 95% or not lower than 97%. However, while these documents define the plug tip draft as "gap betweenthe rolls at the plug tip position/billet diameter", the above-cited "not lower than 95%" and "not lower than 97%" should properly be described as "not lower than 0.95" and "not lower than 0.97", respectively. And, these plug tip draft ranges correspondto "not higher than 0.05" and "not higher than 0.03", respectively, according to the original definition given above.

[Patent Document 1] Japan Patent Unexamined Publication No. 2001-162307 (Application No. H11-346513)

[Patent Document 2] Japan Patent Unexamined Publication No. 2001-162306 (Application No. H11-346514)

Another difficulty arising from such reduction in plug tip draft consists in a decrease in piercing efficiency. The piercing efficiency is the percentage of the longitudinal advancement velocity of the raw pipe to the longitudinal directioncomponent of the roll gorge peripheral velocity and is defined as follows: η=(VH/VR sin θ)×100(%) where η is the piercing efficiency (%), VH is the longitudinal velocity of the raw pipe (m/s) and VR is the rollgorge peripheral velocity (m/s).

FIG. 4 shows the results of tests carried out for piercing efficiency investigations using plugs of the same shape under the conditions shown in Table 1. As shown, the piercing efficiency decreases with the increase in plug tip draft and, inparticular, the decrease in piercing efficiency is remarkable when the plug tip draft is 0.04 or lower.

[Table 1]

TABLE-US-00001 TABLE 1 Billet material and size S45C, SUS304, diameter: 70 mm Hollow raw pipe size diameter: 75 mm, wall thickness: 8 to 9 mm Roll gorge diameter 410 mm Toe angle γ 15° Feed angle β 10° Plug tip draftTDFT 0 to 0.05 Maximum plug diameter 58 mm Distance from plug tip to 115 mm maximum diameter site

A reduction in piercing efficiency means a decrease in the longitudinal velocity of the raw pipe (above-mentioned VH) or, in other words, a decrease in the longitudinal velocity of the billet and means that the time during which the rotaryforging effect is exercised on the billet is prolonged (the number of times of roll forging at the predetermined position of the billet is increased). Thus, with steel species having defects at the central portion, for example continuously castingmaterials, an excessive rotary forging effect even if the plug tip draft is set at a low level causes inner surface defects.

Furthermore, as a result of a decrease in piercing efficiency, the metal flow of the rolling target material is restrained in the axial direction and is facilitated in the circumferential direction. Then, the additional shear deformation in thecircumferential direction increases, and the defects produced in front of the plug are further intensified by that shear deformation and, as a result, they remain on the raw pipe as large-size inner surface defects. In addition, the time required forpiercing is prolonged by the decrease in piercing efficiency, so that a further problem arises, namely the thermal load on the plug increases and the life of the plug is shortened.