Inside Pipe Research Articles

The pipeline flow of capsules part 6 ‐ numerical analysis of some variables determining free flow

AbstractFour specific factors, concerned with the geometry and frictional effects of a cylindrical capsule flowing freely in a liquid‐filled pipe in which the liquid is in laminar flow, have been investigated numerically. The factors are: axial displacement of the capsule from the concentric position, end configuration and length of capsule, deformed circular cross‐section and frictional effect between the bottom of the capsule and the inside pipe surface. The effect which axial displacement has on any dynamic variable, e.g. capsule velocity, was found to be a uniformly increasing one for up to 90% of the total possible displacement. Beyond 90% displacement the effect was relatively much more pronounced.Friction was found to decrease capsule velocity uniformly: as the friction force was increased a critical value was reached for larger capsules which resulted in a rapid decrease to zero. The effect of end shape on velocities and flow rates was found to be negligible, although there was a considerable change in flow pattern. Deformation of the capsule, i.e. deformation through a vertical cross‐section, caused little effect for 10–20% deformations, beyond which there was almost a linear increase of percentage deformation with pressure gradient required to maintain the same capsule velocity. The rate of increase itself increased with the proximity of the capsule to the pipe wall.

Evaluation of Corrosion in Distribution Systems

Although water utility engineers have done creditable work on the problem of corrosion, there is a lack of information in two areas that are of greatest importance to effective corrosion control. There is not yet a reliable correlation of water composition with the useful life of pipe, and it is still not possible to predict accurately the effectiveness of inhibitors used in corrosion control. Although hydraulic carrying capacity values or velocity factors are not completely satisfactory criteria to determine the progress of corrosion and the physical condition of the pipe interior, it is felt that extensive records of reliably determined capacity coefficients are invaluable in establishing relations between mineral content and corrosion and in developing criteria for corrosion treatment.

CHAPTER 12 – Principles of Corrosion

This article presents Chapter 12, Principles of Corrosion, of the AWWA Committee Report on the Design and Installation of Steel Water Pipe. The chapter discusses general theory, soil corrosion investigations, corrosion of pipe interior, atmospheric corrosion, and good practice.

Noncylindrical Helix Waveguide

Small uniform deformations of the cross section of helix waveguide perturb the circular electric waves slightly. From these perturbations the added circular electric wave loss is found in a uniformly deformed helix waveguide. For a nonuniformly deformed helix waveguide Maxwell's equations are converted into generalized telegraphist's equations. By an approximate solution for small deformations, mode conversion and circular electric wave loss are found. Random imperfections with small correlation distance cause an average circular electric wave loss that is nearly independent of the wall impedance which the helix jacket presents to the waveguide interior. It is therefore nearly the same as in metallic waveguide. Near 50 kmc, the rms value of elliptical diameter differences should not be more than 0.0015 inch in order that on the average not more than 10 per cent of TE <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> loss in a perfect 2-inch inside diameter copper pipe is added to the TE <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> loss in a helix waveguide of the same inside diameter.

Combined Free and Forced-Convection Heat-Generating Laminar Flow Inside Vertical Pipes With Circular Sector Cross Sections

Combined free and forced-convection, heat-generating laminar flow inside cylindrical pipes with elements parallel to the direction of the generating body force is solved by applying the finite Fourier sine transform and finite Hankel transforms when the cross sections of the pipes are circular sectors. A numerical example is provided to show the effects of various parameters.

Internal Cathodic Protection Of Large Steel Pipes Carrying Sea Water

Abstract The internal cathodic protection of large steel pipe carrying sea water is discussed both from the practical and the theoretical viewpoint. Systems considered involved use of such devices as concentric cylindrical anodes, off-center cylindrical anodes, wall mounted anodes, and central point lead alloy anodes fed with impressed current from a dc source. The cathodic protection was applied to both bare and coated pipe. Testing was done both in the laboratory and on a full scale level. The designing of a potential measuring device and the determination of protection criteria are considered briefly. Other topics discussed include coating the pipe interior, computing the costs of cathodic protection, and determining the relationship between anode separation and anode diameter in pipes with the same coating and electrolyte. It was found that coatings will effect the largest economies on the smaller diameter pipe where the cost of the cable is lowest and where smaller anode supports can be used with small anodes. At the moment the most economical method of protection seems to involve the use of a cheap readily applied coating of reasonable resistance and cathodic protection from point anodes mounted at or close to the center line of the pipe. 5.2.3

Pressure Drop due to Friction for Parallel Flow of Mixtures of Vapour and Water in a Downcomer

In this paper, the author experimentally investigated the pressure drop due to friction for the flow of water containing bubbles in a non-heated downcomer. First, the pressure drop due to friction and dryness fraction for the parallel downward flow of the mixtures of air and water were measured in a vertical 1500 mm long and 19 mm inside diameter glass pipe. Next, the ratios of the coefficient of friction in high pressure regions were extensively computed from the results of the above experiment. Finally, in case we used nonheated downcomer, it was proposed that we might adopt 0.03 as an approximate value of the coefficient of friction.

A Tubular Stone Pipe (?) from Sonora

In December of 1954, Mr. and Mrs. Ruben Emrick of Conrad, Montana, found a broken sandstone object in an arroyo cut located 30 miles north of the town of Empalme near Ortiz in Sonora, Mexico (Fig. 1). They very graciously brought the artifact to the Amerind Museum for examination where it was repaired and studied. The object resembled the tubular stone pipes found in the Southwest (Figs. 2, 3). It had the exterior and inner proportions so characteristic of these pipes, which were produced by drilling out the pipe interior until it resembled a modern venturi tube having a constricted throat.

Slip covers with inside piping

Electrochemical metallizing is an updated name for the application of metallurgical coatings by means of brush-on electrodeposition. Previous conferences have heard papers on modern advances in electrochemical metallizing, with emphasis, however, on deposits for corrosion resistance and rebuilding worn, damaged or corroded metal components.This paper deals with special applications for electrochemical metallizing, as opposed to those previously covered. A number of special applications are described. A primary example would be metallurgical coatings for the prevention of fretting and seizing, using copper, silver, tin and lead deposits. Improving brazeability of difficult to braze metals is another practical example of a very important applicatio, as is improved solderability on difficult-to-solder materials. In plastic and rubber molding, procedures for electrochemically metallizing thin layers of material for better release properties are discussed.Additional special applications for electrochemical metallizing include nickel-tungsten, nickel-cobalt and nickel-phosphorus for hard surfacing. In the printing industry, electrochemically metallized copper on inking rollers helps prevent water wetting. Black iron and black nickel deposits increase light absorption, and reference is made to electrochemical brush anodizing.Case histories of industrial applications for these special coatings are provided, including photographic illustrations. Finally, comparative advantages and disadvantages of electrochemical metallizing, as compared with welding, thermal metallizing or bath plating, are summarized.

Heat transfer to water in an annulus

AbstractA limited number of measurements were made of the heat transfer coefficient from an electrically heated rod to water flowing in an annulus. Tests were performed at Reynolds numbers ranging from 5,000 to 22,000 (based on equivalent diameter), water temperatures of 70° and 125°F., and relatively high heat fluxes of 52,000 to 208,000 B.t.u./(hr.) (sq. ft.). The annulus dimensions were 0.625 in. I.D. and 0.840 in. O.D. The coefficients varied as the 0.8 power of the velocity; they were 20% higher than predicted by use of Colburn's equation for flow inside pipes with the equivalent diameter. Over the range of conditions studied, it was found that the thermal boundary layer was fully developed in 1 1/8 in. (Lh/De=5).

Internal Coating of Pipe in Place

Abstract Procedures and results of coating internally several miles of old aluminum, steel and new steel pipe are given. The method involves scraping corrosion products from inside old pipe, descaling and drying. Coating is applied when two plugs between which coating has been poured are moved through the pipe by air pressure. Drying by air injection or aspiration follows. Economics of the lining operation are reported to be good although perfect results were not obtained with badly corroded steel pipe. Adhesion of the coating is the critical problem, even small amounts of water being conducive to separation. Coating of new steel lines is facilitated by proper design. The author suggests rigid inspection at every phase of the cleaning, drying and coating operation. At least 5 mils' thickness is recommended, this to be obtained by multiple coats, if necessary. When desiccants are used in the drying operation some means of determining when the desiccant is saturated should be employed. Better cleaning is ne...

On the Design of Sound Absorbing Ducts

General design charts for square and circular sound absorbing ducts have been developed by an application of Morse's theory for the transmission of sound inside pipes. These charts have been developed specifically for ducts with all four walls lined with an absorbing material with or without an air space behind it. Interesting results of this study are that attenuations of 15 to 20 db per wavelength can be obtained over a frequency range of about one-half octave and that by scaling the size of the duct and the impedance of the acoustical material on the side walls this peak in attenuation may be placed at any desired frequency. Measurements on ducts ranging in size from 8×8 in. to 4×4 ft. show that the measured attenuation curves result in somewhat higher values of attenuation above and below the peak value and a slightly lower value at the peak than are calculated from the charts. For those ducts in which an air space is used behind the absorbing inner wall, the partitioning of the air space plays an important part. In order to realize the calculated values of attenuation, the partitions should be spaced at intervals of about one-quarter wavelength.

On the Calculation of Heat Transmission Inside Pipe

On the Calculation of Heat Transmission Inside Pipe

Rectangular artificial roughness in open channels

Numerous experiments on artificial roughness in closed channels have been made in Europe and the United States since about 1920: In Europe, SHILLER [see 12 of “References” at end of paper] experimented with pipes roughened with spiral threads cut into the inner surface; HOPF [6]. and FROMM [5] investigated roughness in a rectangular closed conduit; NIKURADSE [8] investigated relative roughness over a wide range by gluing sand to the inside of pipes; and SCHLICHTING [10] experimented with a closed conduit roughened with various arrangements of spheres, spherical segments, cones, short and long angles, and sand. A brief discussion of the results of the work of SHILLER, HOPF, FROMM, and NIKURADSE may be found in the paper by STREETER [15]. The more recent investigation of SCHLICHTING has been translated into English by the National Advisory Committee for Aeronautics and published as a Technical Memorandum [11].

The Transmission of Sound Inside Pipes

Methods developed in a previous paper are used to obtain an exact solution for the transmission of sound inside a rectangular pipe with absorbing material on its inner walls. Plots are given whereby it is possible to determine the phase velocity and attenuation of the simpler type waves in terms of the specific acoustic impedance of the walls and the frequency of the wave. Several examples are given of the effect of the absorbing surfaces on the distribution of the sound pressure amplitude over a plane perpendicular to the axis of the pipe. The effect of the reactive part of the material's acoustic impedance on the attenuation of the sound is also discussed. Formulas are developed for the transmission of sound in tubes of circular cross section. The plots for rectangular pipes can also be used in calculations of the acoustical properties of rectangular rooms.

Reducing Unaccounted‐for Water

One of the essential factors in maintaining adequate service pressure is to preserve as nearly as possible the original tightness of a water distribution system. To accomplish this purpose the town of Cicero has organized a crew consisting of 2 engineers and 6 assistants who are specially trained in the technique of measuring and locating underground pipe leakage. District surveys are made regularly and the principal methods for locating leaks involve the use of the rod meter, 1-inch and 2-inch meters, aquaphone leak detectors, and a geophone. In addition to the underground leakage survey, a careful examination of all inside piping, plumbing and meters is being made by a master plumber employed by the department. Underground leakage surveys, resulting in an average water saving of 3,000,000 gallons daily, have not only afforded an appreciable and immediate financial return, but also play an important part in helping to meet the financial program because of the recent waterworks extension project completed with P.W.A. assistance. This program included 20 miles of new mains ranging in size from 8-inch to 30-inch, a 1,000,000 gallon elevated storage tank, the placing of 580 new hydrants, and the installation of an automatic pumping station of the latest design. The cost of the improvement ran upwards of $1,300,000, so that any saving in unaccounted for water tends to lessen the burden of the department. In addition, regular maintenance costs are reduced because every leakage survey includes an inspection of all valves, hydrants and service pipes on the mains tested and thus defects may be located and the necessary repairs made.

Flushing of Water Mains

This is a subject on which little has been written. Probably the title itself signifies its simplicity, and, hence, heretofore, few have deemed it of sufficient importance to have a place in our discussions. Yet I venture the opinion that many waterworks men here assembled can relate some interesting incidents which have happened along the lines of this subject, while they have been engaged in the pursuit of their official duties. If this paper in some small way may be the means of bringing to light some of these experiences, I shall deem it to have been worth the effort. The various deposits which lessen the carrying capacity of water mains may be classified under the following heads: 1. Incrustations which form on the inside of water pipes and are commonly known as tuberculation. These form more readily on unprotected or imperfectly protected surfaces. 2. Deposits or growths on the inner surface of iron pipes, whether this surface is protected or unprotected, the nature of these deposits depending upon the chemical or biological composition of the water. 3. Accumulation of debris and mud in the inverts, hollows and dead ends of the mains.

Use and Benefits of Pressure Recording Gages

Recording gages for keeping a permanent record of steam and water pressures and vacuum have been used by water works for many years. In 1891 Mr. Charles A. Hague, in his introduction of his valuable paper entitled Value of Pressure Records in Connection with Water said that we should know what is going on inside of steam and water pipes, just the same as we have found out what is going on inside the steam cylinder by the use of the indicator. In his paper Mr. Hague quotes Mr. Edwin Darling in his 1889 report of the Pawtucket, Rhode Island, Water Works, as follows: No well conducted water works can afford to be without recording gauges, and, when properly located, they will, in my opinion, pay for themselves within one year (Proceedings Am. W. W. A. Philadelphia, 1891, p. 77). These extracts go to show that the value and usefulness of recording gages were fully recognized, more than twenty years ago. We certainly do need to know what is going on inside of the steam and water pipes under our charge, and at all times. A look at the nonrecording gage shows us the pressure at that time, but is no proof or indication of what it was a minute before. The recording gage does give this information; it tells what the pressure was at any time, day or night, and on any date. It is a constant watchman, just as a water meter is a constant inspector. It keeps a complete and indisputable record of pressure at all times.