## Pressure Ratio

Reciprocating compressor efficiencies plotted against pressure ratio with a valve velocity of 3,000 fpm and a mechanical efficiency of 95 percent. Figure 1. Reciprocating compressor efficiencies. Figure 1. Reciprocating compressor efficiencies. A Product of actual lift and the valve opening periphery and is the total for inlet valves in a cylinder expressed in square in. (This is a compressor vendor furnished number.) Suction capacity Horsepower Discharge temperature Piston speed Bore 6 in....

## How to gauge a horizontal cylindrical tank

Express the depth in of the diameter then the result will be given in of total capacity of the tank. Rule 1. For depth up to 30 multiply the square root of the depth by the depth, and then by 0.155. Example. Liquid depth is 16 of tank diameter 16 x 16 x 0.155 4 x 16 x 0.155 9.9 The correct answer is 10.3 error is about .4 . Rule 2. For depth between 30 and 50 subtract 10 from the depth, multiply by 1.25. Example. Liquid depth is 44 of tank diameter The maximum error, for depths less than 5 may...

## Sdr

F3 Environmental service factor (Figure 3) Other design factors may be necessary in the design of systems where abrasion, corrosion or chemical attack may be a factor. Example A horizontal process water line, 2,000 ft. in length, 125 F water, 60psig pressure, with a desired life of five years, is proposed. Determine the standard pipe SDR for the application.

## Notes For The Table Of Physical Constants

Values in parentheses are estimated values. b. The temperature is above the critical point. c. At saturation pressure (triple point). e. The + sign and number following specify the number of cm3 of TEL added per gallon to achieve the ASTM octane number of 100, which corresponds to that of Isooctane (2,2,4-Trimethylpentane.) f. These compounds form a glass. An earlier investigator 12 reported a value of-244 F for the freezing point of 3-Methylpentane. g. Average value from octane numbers of...

## Estimate weight of pipe in metric tons per kilometer

To estimate the weight of pipe in metric tons per kilometer, multiply the nominal diameter by the number of sixteenths of an inch in wall thickness. Example. Find the weight of pipe in metric tons per kilometer for 20-inch diameter pipe, wall thickness 1 1-inch. Actual answer from pipe tables is 79 metric tons per kilometer. This rule of thumb is based on a density of 490 pounds per cubic foot for steel. For larger diameter thin wall pipe, this approximation gives an answer usually about one...

## Use nomograph to find tank capacity

This simple nomograph can be used to find the capacity of your vertical cylindrical tanks. Here's how it works Draw a straight line from the height scale through the diameter scale and to the first capacity, barrels scale. Read directly the capacity of the tank in barrels. (Note The height scale may be used to indicate the over-all height of the tank or the depth of liquid in the tank.) Draw a second straight line connecting the two capacity, barrels scales at the same reading on each scale....

## How dragreducing agents can outweigh looping or boosting

Lester & Associates Inc., Longview, Texas There often seem to be only two kinds of oil pipelines those too small or those too large. If a pipeline is too large, an operator can worry over capital funds not well utilized. But the more fearful worry inability to handle business offered remains with the operator of a pipeline which is too small to take advantage of the market. Until recently, after discharge pressures had been pushed up to the absolute maximum, the operator...

## The basics of drag reduction

Lester & Associates Inc., Longview, Texas Drag reducing agents (DRA's) can substantially reduce friction loss in most pipelines when flowing most hydrocarbon liquids. This article begins a series of four which will review DRA's, their fundamentals and applications, role in active and passive drag, and incidence as specific products and hardware. When a DRA is dissolved in a solvent, it produces a solution which in laminar flow has the same pressure drop, and therefore the...

## 200

Example 20-in. pipeline system. From this representation, we can take Hf 2,057flc, Ho 1,479, and Ha 1,102 flc. The following comparison results. Section 1 D R Ha Hf 2,102 3,448 0.610 DR 0.390 D R Ha Hf 1,102 2,057 0.536 DR 0.464 Section 2 requires a greater DR to achieve 192,000 b d than Section 1. The same pump drag must be recovered, but an additional 1,000 ft of static drag must be overcome and the active line drag on which DRA's can operate to effect drag reduction is smaller by...

## Typical formulas used for calculating pressure drop and flow rates for pipelines

P (0.241 fsQ2 )d5 f 0.0018 + 0.00662 x (1 r )0355 For viscous flow, r .0119Q dv f 0.00207 x (1 r) Viscous flow, Indeterminate region, r 0.135 to 0.4 B (0.1692)(d5P s) '5 (log(d3sP z2) + 4.35) B 0.871K(l z0104 )((Pa552d2'656 ) sa44S) P ((Bza1Msa44S )(0.871 Kd2656 )) 812 Hazen-Williams Q (0.148 d263Pa54 Vs0'54 Q barrels per day B barrels per hour P pressure loss, psi per mile d inside diameter of pipe, in. z absolute viscosity, centipoises s specific gravity K efficiency factor (Aude's formula) f...

## Vacuum drying

The vacuum drying process is shown graphically in Figure 1 and consists of three separate phases. Corrosion is generally inhibited at relative humidity (R.H.) levels below 30 but in the presence of hygroscopic dirt (present in millscale) corrosion can occur at R.H. levels of 20 . Therefore, systems should be thoroughly drained and then vacuum dried to lower than 20 R.H. for a constant temperature. Assume the lowest average temperature of the system is 0 C (during the winter months) which gives...

## Lower volumetric efficiency could result in a higher mechanical efficiency

A higher volumetric efficiency can mean higher mechanical efficiency, and with today's power costs it would appear desirable to use screws having many turns to achieve a high volumetric efficiency. This is not necessarily true. The greater the number of screw turns is, the longer the screw (screw length equals the number of turns multiplied by the screw pitch) is. Screw length has a proportional bearing on the horsepower required to drive the pump at zero outlet pressure. If a low-viscosity...

## Estimating the contents of horizontal cylindrical tanks

Horizontal cylindrical tanks are frequently used for water and fuel storage and in many cases it is important to be able to gage these vessels to determine the volume of liquid contained in them. However, it is normally much more difficult to establish a volume per inch scale for a horizontal tank than for one which is in a vertical position. The accompanying nomograph simplifies this problem. To use the nomograph, it is necessary to gage the tank and determine the ratio of the depth of liquid...

## Nominal interest rate vs effective annual interest rate

Almost all interest rates in the financial world now involve compound rates of interest, rather than simple interest. Compound interest rates can be quoted either as a nominal rate of interest, or as an effective annual rate of interest. The nominal rate is the stated annual interest rate compounded periodically (at the stated compounding time interval). The effective annual rate is the rate that produces the same final value as the nominal rate, when compounded only once per year. When the...

## 04170

If heat capacities are required for process calculations, they can be extracted from the thermodynamic tables mentioned above by the following procedure Example. Find the heat capacity for superheated methane at 15 psia and 100 F. From the Matthews and Hurd superheat table 13,1'

## Speeding computational procedures

Estimating computations are often lengthy and redundant. Estimating can be performed quickly either by simplifying the computations (often with an associated loss in accuracy) or by computerization in which case accuracy need not be sacrificed. Current and future construction estimating procedures involve the use of spreadsheet-based cost models. There are three basic types of spreadsheets. Spreadsheets are typically large ledger-like sheets of paper upon which are spread the cost factors and...

## How to control corrosion at compressor stations Eight factors design engineers should consider

Hodge, Superintendent of Corrosion Control, Natural Gas Pipeline Co. of America Corrosion failures at compressor stations result from carelessness on the part of the user, or poor choice of material configuration by the designer. Design engineers should consider the following Coat everything underground, except ground rods, with a coating properly selected for the conditions Use proper coating application and inspection Use ground rods anodic to steel and insulated (coated) ground wires...

## Pipeline Pigging

Often the debris-removal operation, after completion of construction, is combined with gauging to detect dents and buckles. This operation will prove that the pipeline has a circular hole from end to end. Typically an aluminum disc with a diameter of 95 of the nominal inside diameter of the pipe is attached to the front of a pig and is inspected for marks at the end of the run. The pig could also be equipped with a transmitter to facilitate tracking the location of the pig. If the pig hangs,...

## Defects originating from pipe manufacture

(a) Defects not necessarily in the seam weld (primarily in the body *Lap Fold of metal which has been rolled or otherwise worked against the surface of rolled metal, but has not fused into sound metal. *Pit A depression resulting from the removal of foreign material rolled into the surface during manufacture. *Rolled-in slugs A foreign metallic body rolled into the metal surface, usually not fused. *Seam Crevice in rolled metal which has been more or less closed by rolling or other work but has...

## Cathodic protection

Protecting a pipeline from corrosion is an important and expensive part of building and running a pipeline system safely. Every year, operators spend millions of lb on pipe coatings, gas detectors, and sacrificial anodes to lengthen the effective life of pipelines by reducing the effects of corrosion. Whenever a steel structure of any type comes into contact with the soil and or water there is almost certainly going to be corrosion. The structure, in our case the pipeline, divides itself into...

## M

Pi Initial Pressure Pf Final Pressure Pv Vapour Pressure Se Effective Pump Speed V System Volume Sp Pump Speed C Conductance M Mass of Water Dv Vapour Density Preq Required Dewpoint Pressure Figure 2. Vacuum Drying Calculations. The dryness of a pipeline is measured in terms of dewpoint, which is the temperature at which mist or dew will begin to form. A convenient method of measuring dewpoint is to use an instrument called a mirror hygrometer where the water vapour is passed across a polished...

## Precise engineering

There is more to lowering an existing line than just digging a hole and letting gravity take over. Engineering and design of a new profile must be precise so that the line is not dropped too suddenly, causing a buckle or rupture (the larger the pipeline, the more critical the profile). Figure 3. Formulas for changes in slope. Figure 3. Formulas for changes in slope. Excavation begins. Ten-foot soil plugs remained at 50-ft centers to act as temporary pipe supports for the 36-in. line. For...

## Chart changing

Charts must be changed on time and clocks must be kept wound and adjusted (Figure 4). Each measuring station has its own flow pattern, which is recognizable by experienced chart changers. Any change in this flow pattern indicates a possible error, which should be corrected if possible. If the correction cannot be made by the chart changer, he should notify the field measurement personnel who are qualified to perform required adjustment and or repairs. Each chart must be properly dated and...

## Estimate volume of onshore oil spill

An irregular shape can be converted into a series of rectangles that approximate the area of the irregular shape. There will be about the same amount of spill area outside the rectangle as there is dry area inside the rectangle. This can be done by stretching a steel tape along the ground outside the spill area. The area can then be quickly estimated by multiplying the length of the sides. In Figure 1, the following area is determined Area A 70' x 20' 1400 square feet Area B 60' x 10' 600...

## Determine the most economical size for electric power conductors

To calculate quickly the most economical size copper wire for carrying a specified current load, use the formula where A Conductor cross-sectional area (circular mils) I Current load (amperes) Ce Cost of electrical power (cents per KWH) Cc Cost of copper (cents per lb) t Hours of service per year F Factor for fixed charges (amortization, insurance, taxes, etc.) Selection of the proper size electric conductor will depend on the load to be carried and the mechanical strength required, as well as...

## Four ways to calculate orifice flow in field Rogers G Thompson

Several methods are available for orifice flow field calculations. The particular method used is determined by such factors as company policy, advance warning, time available, individual preference, accuracy required and the information and equipment available at the time of need. A good rule to follow is to calculate as precise a volume as possible at all times. The use of methanol-containing mended as the inhibitor often tubes. Any volume calculated manually will be considered a field...

## Plunger or piston rod load

Plunger or piston rod load is an important power and design consideration for reciprocating pumps. Rod load is the force caused by the liquid pressure acting on the face of the piston or plunger. This load is transmitted directly to the power frame assembly and is normally the limiting factor in determining maximum discharge pressure ratings. This load is directly proportional to the pump gauge discharge pressure and proportional to the square of the plunger or piston diameter. Occasionally,...

## Piston rod load doubleacting pump

The computed axial hydraulic load, acting upon one piston rod during the forward stroke (toward head end) is the piston rod load. It is the product of piston area and discharge pressure, less the product of net piston area (rod area deducted) and suction pressure. It is expressed in pounds force. Liquid pressure p- ) or (psi) (3.1416) X (Radius(inches))2 (3.1416) X (diameters(inches))2 Cylinder force (pounds) pressure (psi) X area(square inches) Cylinder speed or average liquid velocity through...

## Pipe Laying

How to determine the degrees of bend in a pipe that must fit a ditch calling for a bend in both horizontal and vertical planes Rule. To find the number of degrees in the combination bend, square the side bend and the sag or overbend add them together and extract the square root. The answer will be the number of degrees necessary to make the pipe fit the ditch. Example. Determine the bend to make in a pipe whose ditch has a 3 overbend and a 4 sidebend. Let X the unknown angle Example. Determine...

## Variable orifice rotary control valves

The flow coefficient, which describes the flow capacity of a valve, is an empirically determined constant equal to the valve's flow capacity in U.S. gallons per minute of water at 60 F when a pressure drop of 1 psi exists across the valve in its most wide-open position. Table 1 lists Cv's for all sizes of DANTR0L-270 valves, with and without trim. The flow capacity of a valve in a partially open position may be calculated by selecting the appropriate Cv from Table 1 and...

## How much gas is contained in a given line section

Multiply the square of the inside diameter, in in., by the gauge pressure, in lb in.2 multiply this by 0.372 the answer is the approximate number of cubic ft of gas (standard conditions) in 1,000 ft of line. Example. How much gas in 1,000 ft of 16-in. schedule 30 pipe at 350 lb pressure 15.25 x 15.25 x 350 x 0.372 30,280 cubicft of gas Example. Approximately how much gas in eight miles of .250 wall 24-in. pipe if the pressure is 400 psi Cubic ft (23.5)(23.5)(400)(8)(5.28)(0.372) 3,470,000...

## Standard Welding Reducer Cv

CV for standard welding reducers. Figure 1. CV for standard welding reducers. Cv vs. K or Valve Flow Coefficient vs. Resistance Coefficient 1 2 3 4 5 6 7 8 9 10 20 30 40 5 6 7 8 9 100 200 300 4 5 6 7 8 9 1,000 2,000 3 4 5 6 7 8 9 10,000 20,000 3 4 5 6 7 8 9 100,000 Cv Valve Flow Coefficient Figure 2. Cv versus K values for valves.

## J

Examples of modern computer-based-pipeline systems (courtesy Oil and Gas Journal, 1986). fluid and the actual dimensions of the line. Both will give rise to sources of errors in pipeline inventory if compensation is not included in the calculations. Figure 11 shows typical input data requirements for simple on-line inventory calculations. At the other extreme, computer-based systems can control entire networks with almost no need for the operators to intervene unless serious problems...

## Dewatering and drying

After the hydrotest has been completed, the water is generally displaced by the product or by nitrogen. The same arguments apply to dewatering as to flooding. A pig is used to provide an interface between the hydrotest water and the displacing medium so that the water is swept out of all low points. A bidirectional batching pig may be used during hydrotest and left in the line during hydrotest and then reversed to dewater the line. In some cases, it may be necessary to dry the pipeline. This is...

## Programs written for the HP 41 CV computer equipped with printer work with English or metric units Frank E Hangs P E

Pipeline engineers, accountants, and system operators are deeply involved with data concerning line pipe such as How much does it weigh (lb ft, tons mi) What are the corresponding metric units How much will it contain (bbl mi, gal 100 ft, cu m km) What are velocities at various feed rates (ft sec, mi hr, m hr) The following program, written for the Hewlett Packard HP 41 CV hand-held computer, develops a lot of useful data for steel pipe for any outside diameter and wall thickness. Either...

## Types of defects

Classes of defects listed in Table 1 are Manufacturing defects cracks, undercut, lack of fusion, and lack of penetration in seam welds laps, pits, cracks, and rolled-in slugs in the pipe body hard spots. Environmentally caused defects selective corrosion and hydrogen stress cracking in electric resistance welded or flash welded seams general pipe corrosion pitting corrosion stress corrosion cracks hydrogen stress cracking in hard spots. Defects caused by outside forces which include dents and...

## Determine buoyancy of bare steel pipe

Multiply the square of the outside diameter of the pipe, in inches, by 0.341, and subtract the pipe weight in lb ft the answer is the buoyancy per foot in fresh water. Example. 12 (12.75 OD) 33.4lb pipe (7 wall). 162.56 x 0.341 33.4 55.4 33.4 22 lb ft Since all of the coating materials in common use are heavier than water (but not as much so as steel), coated pipe will have less buoyancy than indicated by the rule. For sea water, use 0.350 for the constant.

## Estimating comparative capacities of gas pipelines

To estimate capacity of one diameter line in terms of another read downward in the appropriate column to desired diameter line. Example. A 24-in. (23.375-in. ID) pipeline has a capacity 160 that of a 20-in. (19.500-in. ID) line. This chart is based on diameter factors using the Panhandle equation. Equivalent inlet and outlet pressures, lengths of line section, and uniform flow are assumed for both lines. (Figures give capacity of one diameter pipe as percent of another.) Internal Nominal 36 34...

## Estimate leakage amount through small holes in a pipeline

The amount of fluid lost through a small hole in a pipeline can be estimated using the following equation Q flow in cu. ft. second A cross sectional area, sq. ft. g gravitational constant, ft sec sec h head, feet Example. Assume the following conditions Hole diameter 0.125 inches Pressure 30 psig Sp. gr. of fluid 0.85 A 0.0000852 sq. ft. h 81.5 feet g 32.2 Q 0.61x0.0000852 2x32.2x81.5 Q 0.002765 cu. ft sec

## Normal engagement

The normal amount of engagement to make a tight joint for various types of screwed material is given in the table. These dimensions have been established from tests made under practical working conditions. The normal engagement specified for American Standard Pipe Thread and API Line Pipe Thread joints is based on parts being threaded to the American Standard for Pipe Threads or the API Standard for Line Pipe Threads. In order to obtain the thread engagements listed in the table it is necessary...

## Nomograph for calculating velocity of liquids in pipes

The mean velocity of any liquid flowing in a pipe of circular cross section can be calculated from the following formula v 183.3 7* 0.408-v 0.0509- where v average fluid velocity, ft sec d inside diameter of pipe, in. q rate of flow, cubic ft sec Q rate of flow, gal min W rate of flow, lb hr p fluid density, lb cubic ft The Nomograph for Calculating Velocity of Liquids in Pipes (see Figure 1, p. 302) can be used to calculate the liquid velocity when the rate of flow is in cubic ft, gallons or...

## Payback method

The payback method is a simple technique that determines the number of years before the cash flow from an investment or project pays back the initial investment. Obviously, the shorter the length of time it takes a project to pay off the initial investment, the more lucrative the project. Example. A company wants to add a new product line and is evaluating two types of manufacturing equipment to produce this new line. The first equipment type costs 700,000 and can produce enough product to...

## References For The Table Of Physical Constants

Ambrose, D., National Physical Laboratory, Teddington, Middlesex, England Feb. 1980, NPL Report Chem 107. 2. Ambrose, D. Hall, D. J. Lee, D. A. Lewis, G. B. Mash, C. J., J. Chem. Thermo., 11, 1089 (1979). 3. Angus, S. Armstrong, B. de Reuck, K. M., Eds. Carbon Dioxide. International Thermodynamic Tables of the Fluid State-3 Pergamon Press Oxford, 1976. 4. Angus, S. Armstrong, B. de Reuck, K. M., Eds. Methane. International Thermodynamic Tables of the Fluid State-5 Pergamon Press Oxford, 1978....

## How to estimate the monthly power bill for a cathodic protection rectifier

Multiply the rectifier output voltage and current together, and multiply this by 11 2 the result is the power consumption for one month, in kilowatt-hours. If the unit is on a meter of its own, figure the bill by the utilities rate schedule if it represents an additional load, use the rate per kilowatt-hour for the highest bracket reached. Example. The terminal voltage of a rectifier is 10.2 volts, and the current output is 21 amperes. The power consumption will be about 320 kwh per month at 3...

## By W Kent Muhlbauer WKM Consultancy Austin Texas and E W McAllister Houston Texas

The safety of pipelines relative to other modes of transportation is generally not in question. Statistics show that moving products by pipeline is safer than by any alternate means. Yet even as pipelines claim a superior safety record, catastrophic failures are a real possibility. With an aging infrastructure, ever-encroaching population areas, and increasing economic pressures, the perceived, if not actual, risk of pipeline failure is increasing. Pipeline safety can and probably should be...

## Beginning risk management

As the first, and arguably the most critical step in risk management, risk assessment must be performed. It is important to recognize what a risk assessment can and cannot do. The ability to predict pipeline failures would obviously be a great advantage in reducing risk. Unfortunately, this really cannot be done at present. So, modern risk assessment methodologies provide a surrogate for such predictions. Our risk efforts are normally NOT attempts to predict how many failures will occur or...

## Control valve selection

A control valve may be thought of as a section of pipe with a variable resistance. Control valves are typically used to match pumps to the pipeline system characteristics. They are not normally used with reciprocating compressors but may be used with centrifugal compressors for preventing surge. Liquid pipeline applications usually involve controlling the flow rate, suction and discharge pressure, and other variables for centrifugal pumps. Control valves may also be used with reciprocating...

## 20 Economics

Rule of thumb speeds payroll Rule of thumb estimates optimum time to keep construction How to estimate construction Cost estimating strategies for pipelines, stations, Simple interest vs. compound Nominal interest rate vs. effective annual interest Present value of a single cash flow to be received in the Future value of a single The importance of cash flow Analyzing and valuing investments projects with multiple or irregular cash Future value of a periodic series of Annuities, loans, and...

## Fundamental relations

A too-small pipeline is one which has no more physical room to produce an increased unit friction loss in the exist ing pipe. That is, the discharge pressures of the existing pump stations cannot be increased nor the suction pressures decreased. If an operator needs to double the capacity of his pipeline, his obvious solution is to loop it completely. If he needs an increase of 10-30 , he has the choice of partial loops, booster pump stations, or injecting a DRA. We will look at problems in...

## Comments

Units - all dimensional values are reported in terms of the following three units, which are defined in terms of the corresponding SI units mass - pound (avdp), lbm 0.45359337 kg Physical constants length - foot, ft 0.3048 m gas constant, R 1.98598 Btu(I.T.) ( Rlb mol) temperature - degree fahrenheit, (t F) 32 + l.8(t C) Temperature of the Celsius scale is defined by the International Practical Temperature of 1968 (IPTS-68). volume - cubic foot, ft3 0.02831685 m3 gallon 231 in3 0.003785412 m3...

## Dewatering

Dewatering is considered to commence with the running of the first pig after hydrostatic testing is completed and begins with the insertion of a displacer, commonly referred to as a pig, in the pipeline. The dewatering pig may be pushed through the pipeline with crude oil or other petroleum product if no drying is required. If the pipeline is to be cleaned and or dried, the pig will be pushed by either compressed air or gas. In either case, proper precautions must be taken to be sure the test...

## Minimizing shock hazards on pipelines near HVAC lines

As right-of-way for pipelines becomes more difficult to obtain, especially in congested areas, rights-of-ways are being shared by pipelines and high voltage transmission lines. Sharing a common right-of-way can pose problems during operation and especially during pipeline construction unless special precautions are taken. Considerable voltage can be induced in pipelines above ground on skids unless the section of pipeline is grounded. Without grounding, a lethal shock hazard to construction...

## Inductance

If the reactance of the 100-ft (30.5-m) measurement span is 0.3 mW at 60 Hz, this adds in quadrature to the 0.5 mW resistance (R) so the impedance (Z) becomes 0.58 mW a 16 increase. At 60 Hz, skin effect may add even more Z. At 120 Hz, the major ripple frequency for most full-wave rectifiers, the reactance is likely doubled to 0.6 mW, so Z increases to 0.78 mW, a 56 increase. Skin effect is also greater. Figure 5. Impedance (Z) of cast-iron lab sample pipe vs frequency of current in pipe....

## Info

System head curve design normal runout throttle. Figure 5. System head curve design normal runout throttle. Figure 6. Example 8 variable speed operation. Figure 6. Example 8 variable speed operation. rate of .085 kW-hr for service 24hrs x 360 days. Higher heads or flows would magnify the costs. There is nothing wrong with safety factors, and it is always better safe than sorry, but after installation, check the hydraulics and if gross over-sizing was the case, trimming the impeller...

## How many pounds of electrodes are required per weld on line pipe

Divide the nominal pipe size by two and multiply the result 10 by one-fourth pound. Pounds of electrode x .25 1.25 pounds per weld. Pounds of electrode x .25 Example. How many pounds of electrode will be used per Example. How many pounds of electrode wiU be used per Solution. Pounds of electrode 12 x .25 or 3 pounds weld on 10-inch line pipe per weld

## Accounting rate of return ROR method

The accounting rate of return for an existing company or project can be easily calculated directly from the company's or project's quarterly or annual financial accounting statements. If a potential (rather than existing) project is to be evaluated, financial results will have to be projected. Since ROR is an accounting measure, it is calculated for the same time period as the company or project's income statement. The rate of return on an investment is simply the net income generated during...

## Estimate hp required to compress natural gas

To estimate the horsepower to compress a million cubic ft of gas per day, use the following formula BHP MMcfd f 5-16 + 124LogR 1 R + RJ I 0.97 - 0.03R ) where R compression ratio. Absolute discharge pressure divided by absolute suction pressure J supercompressibility factor assumed 0.022 per 100psia suction pressure Example. How much horsepower should be installed to raise the pressure of 10 million cubic ft of gas per day from 185.3psi to 985.3psi This gives absolute pressures of 200 and...

## Galvanic Anodes

Zinc and magnesium are the most commonly used materials for galvanic anodes. Magnesium is available either in stan dard alloy or high purity alloy. Galvanic anodes are usually pre-packaged with backfill to facilitate their installation. They may also be ordered bare if desired. Galvanic anodes offer the advantage of more uniformly distributing the cathodic protection current along the pipeline and it may be possible to protect the pipeline with a smaller amount of current than would be required...

## The abilities of pulsation dampeners

Hydro-pneumatic bladder pulsation dampeners are able to prevent the generation of the most destructive low-frequency pulses such as those generated by the pump's rotary motion and the combination of flow from each of the pump's cylinders. (This is basically rpm multiplied by the number of cylinders.) Accordingly, based on a maximum of 500 rpm for most small pumps, the maximum frequency involved should not be more than about 50 Hz. Performance comparisons. Figure 10 compares the performance of...

## Troubleshooting cathodic protection systems Magnesium anode system

The basic technique is the same as that outlined above more measurements are required, because of the multiplicity of drain points. First, the current output of stations nearest the point of low potential should be checked if these are satisfactory, a similar check should be extended in both directions until it is clear that the trouble must be on the line. When a given anode group shows a marked drop in current output, the cause may be drying out, shrinkage of backfill, or severed or broken...

## Estimating suction and discharge volume bottle sizes for pulsation control for reciprocating compressors

Pressure surges are created as a result of the cessation of flow at the end of the compressor's discharge and suction stroke. As long as the compressor speed is constant, the pressure pulses will also be constant. A low pressure compressor will likely require little if any treatment for pulsation control however, the same machine with increased gas density, pressure, or other operational changes may develop a problem with pressure pulses. Dealing with pulsation becomes more complex when...

## 8 Corrosion Coatings

Hand-held computer determines concrete coating thickness 186 How much coal-tar enamel for a mile of pipe 192 How much wrapping for a mile of 192 Estimating coating and wrapping materials required per mile Coefficient of friction for pipe coating materials 193 Trouble shooting cathodic protection systems Magnesium anode 195 Estimate the pounds of sacrificial anode material required for Comparison of other reference electrode potentials with that of copper-copper sulfate reference electrode at 25...

## Side bend angles

Side bends are determined by eyeballing a P.I. in the ditch and setting the instrument up over it. A back sight is taken on the ditch or preceding P.I., whichever is more easily read. The scope is flipped and a foresight is taken on the ditch ahead. Referring to Figure 2 at station 1 + 00, the deflection angle is 6 left station 4 + 00 shows a deflection of 8 right.

## Qh kT 366 V k 1M

Where F Reactive force at valve outlet centerline (lb) Qh Flow capacity (lb h) k Ratio of specific heats (Cp Cv) T Inlet temperature, absolute ( F + 460) M Molecular weight of flowing media. If bracing is not feasible, a dual outlet valve (available in some pilot operated safety relief valves) can be used. The Figure 5. Reactive forces during valve relief. Figure 5. Reactive forces during valve relief. reactive forces are equal but opposite, resulting in zero force on the valve outlet, but if...

## 10000 20000 30000 40000 50000 60000 70000 60000 90000 100000

Series and parallel operation centrifugal pumps. slightly more than one single pump. The maximum flow rate with two pumps in series will be 2,594 gpm or 89,439 b d. The maximum flow rate for one pump will be 1,917gpm or 66,092 b d. For system rates between 66,092b d and 89,439b d, pressure throttling will be necessary to match the pump performance to the system curves, unless the pumps are equipped with variable speed drives. If throttling is necessary, it may be minimized by...

## Engineering economics

G., Engineering Economic Analysis. San Jose, CA Engineering Press, 1976. 2. Canada, J. R. and White, J. A., Capital Investment Decision Analysis for Management and Engineering. Engle-wood Cliffs, NJ Prentice-Hall, 1980. 3. Park, W. R., Cost Engineering Analysis A Guide to Economic Evaluation of Engineering Projects, 2nd ed. New York Wiley, 1984. 4. Taylor, G. A., Managerial and Engineering Economy Economic Decision-Making, 3rd ed. New York Van Nostrand, 1980. 5. Riggs, J. L.,...

## Proving run

2.1 Initiate the SVP proving sequence by commanding the prover computer controller to obtain a VMFt. (Acceptable repeatability for the turbine meter is five consecutive runs in which the volumetric meter factor, VMFt, does not exceed a tolerance of 0.05 .) The computer will print a proving report when this criterion has been met. 2.2 Calculate the turbine meter's mass meter factor, MMFt. 2.3 Clear the turbine meter flow computer's internal mass prover counter. 2.4 Reset and program the master...

## Glt7

Pavg 2 3 P1 + P2 - (P1 x P2 ) P1 + P2 Pavg is used to calculate gas compressibility factor 7 Nomenclature for Panhandle equations G gas specific gravity (air 1.0) h2 elevation at terminus of line, ft h1 elevation at origin of line, ft E 1 for new pipe with no bends, fittings, or pipe diameter changes E 0.95 for very good operating conditions, typically through first 12-18 months E 0.92 for average operating conditions E 0.85 for unfavorable operating conditions Q flow rate, SCFD Tb base...

## Internal Undercut

Radiographs of internal undercut. This defect may be intermittent or continuous (Figure 2) and either on one side or both sides of the weld centerline. WHEN RADIOGRAPHS ARE INDICATIVE OF POOR WORKMANSHIP, BEST RESULTS CAN BE OBTAINED BY SHOWING THE RADIOGRAPHS TO THE WELDER SO THAT HE CAN UNDERSTAND WHAT HE IS DOING WRONG AND CORRECT IT. Figure 2. Radiographs of internal undercut and the lack of penetration which tends to occur at a stop and start. Figure 2. Radiographs of internal...

## 335

Setting seat pressure to set flow pressure. Figure 2. Setting seat pressure to set flow pressure. Can achieve short blowdown without chatter Pop or modulating action available Easy verification of set pressure without removing relief valve from service Flexible options for remote operation, backpressure protection, valve position indication. Maximum temperature limitations Should not be used in extremely dirty or polymerizing type service. Safety relief valve installation requires...

## Calculate maximum bend on cold pipe

How much of a bend can cold straight pipe take without over stressing In other words, in laying straight pipe crosscountry, what is the smallest radius of curvature possible within the allowable stress The following is an analytical solution to these questions. The deflection equation for a length of straight pipe used as a cantilever beam with a concentrated end load is The maximum bending moment is M - Pl If the allowable stress is SA, rewriting Equation 2 gives Taking the first and second...

## Ditching

How many cubic yards of excavation in a mile of ditch Multiply the width in inches by the depth in inches by 1.36 12 x 30 x 1.36 490 cubic yards per mile. the answer is cubic yards per mile. The rule is correct within about 1 5 of 1 percent actually the errors in depth and width are much greater than this. To Example. How many cubic yards of excavation in a mile get the cubic yards per 1,000 feet, as in computing rock ditch-of 12-inch ditch 30-inch deep ing, use 0.257 instead of 1.36. Shrinkage...

## How to estimate the number of magnesium anodes required and their spacing for a bare line or for a corrosion hot spot

Soil and pipeline conditions will vary widely but where these given assumptions hold, an estimate can be made for test installations using this method. First find the area of pipe to be protected, multiply by the milliamperes per sq ft necessary to protect the line and divide by design output of an anode in this type soil. This will give the number of anodes required to find spacing, divide number of anodes into the length of line. Example. Find the number of 17lb magnesium anodes needed and...

## 1 General Information

Basic Mathematics surfaces and volumes 4 Cables and Estimating strength of Find the working strength of Manila rope 5 How large should drums and sheaves be for various types of wire rope Find advantages of block and tackle, taking into account pull out friction Safe loads for wire Stress in guy Strength and weight of popular wire rope 9 Measuring the diameter of wire rope 9 Wire rope field troubles and their causes 9 Capacity of drums Belts and Shafts Determine length of a Calculate stress in...

## VSAT decisions

Because a distributed mainframe application was planned, the Ku-band scenario was cost-effective at a majority of sites. A secondary decision was made not to add more C-band VSAT sites. Also, because of the economics mentioned earlier, radio became the first choice for the short-haul option. The com-binedradio VSATorradio microwave became the radio hub. Operating costs, for a Ku-band VSAT at each SCADA site, was 375 to 450 per month. The exact cost varied depending on vendor, data traffic...

## Meeting Todays Quality Requirements For Manual Vertical Down Techniques

Pipelines are inspected more critically than ever before and today's radiographic equipment and techniques produce clearer radiographs with greater sensitivity than in the past. Although codes have not changed drastically, interpretation standards have been upgraded. The combination of more rigorous inspection, better testing methods, and high acceptability standards often approaches an attitude requiring zero defects. This poses some serious problems because the job of welding cross-country...

## Porosity

Within limits, this can be fairly effective. For example Land too small. Land too large. High-low condition. Bevel too small. Decrease root spacing. Increase root spacing. Decrease root spacing. Increase root spacing. A skillful line-up crew can be helpful in juggling the root spacing to bring about the most favorable results, but this has limitations. And it is at best a poor substitute for a uniform and consistent joint preparation.

## Pipeline coating

Coatings are applied to provide a corrosion barrier and an abrasion barrier. Directional crossings generally encounter varying materials and often can be exposed to extra abrasion during the pullback. An outer abrasion-resistant overcoat is often warranted. To facilitate the pullback of the pipeline the coating should bond well to the pipe to resist soil stresses and have a smooth, hard surface to reduce friction and maintain the corrosion barrier. As in any pipeline construction, the...

## Nomograph for determining breakeven point

The nomograph gives the break-even point for a plant as percent of design capacity when the unit fixed cost, Cf, the sales price, S, and the unit variable cost, Cv are known. It is based on the following equation The nomograph can also be used to determine the sensitivity of the break-even point to any combination of fixed variable costs or sales price or to determine the maximum fixed cost that can be absorbed for a given break-even point. Example. Determine the break-even point when Design...

## 6

Maximum polytropic head per stage English system. Refer to Figure 2, p. 216 to find Z2, discharge compressibility. Determine average k-value. For simplicity, the inlet value of k will be used for this calculation. The polytropic head equation is insensitive to k-value (and therefore n-value) within the limits that k normally varies during compression. This is because any errors in the n (n 1) multiplier in the polytropic head equation tend to balance corresponding errors in the (n 1)...

## The compressibility factor Z

The compressibility factor (Z) can be found from Figure 4 after the reduced pressure (PR) and reduced temperature (TR) have been calculated from these equations Inlet Pressure (Absolute) Critical Pressure (Absolute) Inlet Temperature (Absolute) Critical Temperature (Absolute) Sonic velocity at the valve's outlet will cause shock waves which produce vibration and noise problems. Therefore, you should make sure the outlet velocity does not reach sonic velocity for gas and steam service. The...

## Pressure Loss Through Valves And Fittings

Equivalent Lengths L and L D and Resistance Coefficient K Reprinted by permission and courtesy of Crane Co. from Technical Report 410 Reprinted by permission and courtesy of Crane Co. from Technical Report 410 Equivalents of Resistance Coefficient K And Flow Coefficient Cv Equivalents of Resistance Coefficient K And Flow Coefficient Cv Reprinted by permission and courtesy of Crane Co. from Technical Report 410 Reprinted by permission and courtesy of Crane Co. from Technical Report 410

## Runs per header

The number of runs, or meter tubes, for a given header is limited by the velocity criterion selected, the operating pressure, the size of fittings obtainable, and the relationship of the peak load to the normal load or capacity for which the meter setting is designed. The operating pressure has an important bearing on the number of orifice tubes used with a given Figure 1. The flow-resistant paths are identical for this layout and each of the two runs will furnish its full capacity with near...

## Sample data

The maximum flow of 200 gpm originates from the storage tank. Length of the 8 cast iron suction pipe is 106 ft. Difference of elevation between the storage tank and centerline of pump suction inlet is 23 ft. Fittings (1) 8-90 elbows, (1) 8-45 elbows, (4) 8 Tees Flow rate 200 gpm (800 gpm for all 4 pumps) Min NPSH 23 ft. of column of water Anaerobically digested municipal sludge conditioned with 10 lime, and 5 ferric chloride. Analysis. In order to determinate the Net Positive Suction Head...

## Estimating coating and wrapping materials required per mile of pipe

Gallons of primer and tons of coal-tar enamel are based on covering new pipe in good condition. For rough pipe, increase primer quantities by 25 and the coal-tar quantities by 20 . No allowance is included for spillage or waste. Squares are based on machine wrapping, allowing 3 4-in. laps on pipe sizes through 10-in., and 1-in. laps on pipe sizes greater than 10 in. No allowance is included for wrapping drips, patching holidays or short ends which are usually discarded.

## 05394

Qb 737 x (5a 14.7)10a0 x (4.026)253 x 1 x ,a , _ ,a 0.0375 x 0.6 x 100 x(1,76a)a Q 0.433 x (520 14.7) x (a, 000)a - (1,500)2 (0.6 x 20 x 560 x 0.835))2 x (4.026)2 Q 11,101 MCFD Pipecalc 2.0, Gulf Publishing Company, Houston, Texas. Note Pipecalc 2.0 will calculate the compressibility factor, minimum pipe ID, upstream pressure, downstream pressure, and flow rate for Panhandle A, Panhandle B, Weymouth, AGA, and Colebrook-White equations. The flow rates calculated in the above sample calculations...

## 1

I 1,943 in.4 Z 162in.3 SA 25,500psi (from Code for Pressure Piping) 3 X 29 X106 X 1,943 The section modulus Z 2I D, and may be simplified to Z I r and substituted for Z in Equation 12. I Moment of inertia r Distance from center pipe D Outside diameter of pipe Equation 12 then becomes R 3Er 2Sa R (21.75 X 106 Sa)x D Sa, the allowable stress, is determined by the design factor permitted by the design code used. Equation 14 may be further simplified by using the following...

## Considerations For Selecting Energy Measurement Equipment

Keeping Track of Gas Heating Value is Important Phase of Today's Market Paul E. Kizer, Applied Automation, Inc., Houston, Texas With natural gas energy determination becoming an integral part of the transmission and distribution business in today's market, companies are placing increased emphasis on choosing the correct measuring device. Most current contracts have a Btu specification and many others use MMBtu instead of gas volume. Here is what happens at the burner tip. The following is the...

## Orifice flow equation

The API Manual of Petroleum Measurement Standards, Chapter 14, Section 3 (also API 2530, AGA Report No. 3, ANSI API 2530-1985, and GPA 8185-85) provides the widely accepted formulation for mass flow. Mass flow is considered by this source to be the fundamental orifice meter flow equation. Equation (38) of this publication, Equation for Mass Flow Rate when Density of Fluid Flowing is Known is shown in Figure 3. K and Y, the flow coefficient and the expansion factor, are the empirical elements of...

## Generalized compressibility factor

The nomogram (Figure 1) is based on a generalized compressibility chart.1 It is based on data for 26 gases, excluding helium, hydrogen, water, and ammonia. The accuracy is about one percent for gases other than those mentioned. To use the nomogram, the values of the reduced temperature (T Tc) and reduced pressure (P Pc) must be calculated first. where T temperature in consistent units Tc critical temperature in consistent units P pressure in consistent units Pc critical pressure in consistent...

## References

H., Chemical Engineers Handbook, Fifth Edition, McGraw-Hill, Inc., New York, section 25, p. 3. 2. Constantinescu, S., Payback Formula Accounts for Inflation, Chemical Engineering, Dec. 13, 1982, p. 109. 3. Horwitz, B. A., How Does Construction Time Affect Return Chemical Engineering, Sept. 21, 1981, p. 158. 4. Kasner, E., Breakeven Analysis Evaluates Investment Alternatives, Chemical Engineering, Feb. 26, 1979, pp. 117-118. 5. Cason, R. L., Go Broke While Showing A...

## Hydraulic gradients

Some of the pressure drop formulas used to calculate pressure drop and flow rates for pipelines are shown earlier in this section. In order to use these formulas, it is first necessary to determine the characteristics of the fluid to be transported primarily the specific gravity, viscosity, and either the flow rate or allowable pressure drop. Before the system design is completed, it is necessary to know the elevation of the terrain to be traversed by the pipeline. Once the elevation of the...

## Pipeline drying

Pipelines used to transport petrochemicals such as pro-pylene and ethylene must be dried in order for the delivered product to meet moisture specifications. Natural gas pipelines are usually dried to a lesser extent to prevent the formation of hydrates. It is not unusual for a petrochemical line to be dried to a dew point of 80 F. A typical dew point for a pro-pylene pipeline will be -70 F. A carbon dioxide pipeline might be typically dried to a 40 F dew point. The natural gas industry...

## Causes and economic aspects of leaks

There are four main categories of pipeline failures. These are Pipeline corrosion and wear Operation outside design limits Unintentional third party damage Many pipelines are operated for a number of years with no regard to any possible mechanical changes occurring in the line. Some of the products may be corrosive, the pipeline may be left partially full for periods of time, or atmospheric effects may cause external damage. These three reasons are responsible for pipeline corrosion and this...

## Decision Tree Analysis Of Investments And Financial Projects

Financial managers often use decision trees to help with the analysis of large projects involving sequential decisions and variable outcomes over time. Decision trees are useful to managers because they graphically portray a large, complicated problem in terms of a series of smaller problems and decision branches. Decision trees reduce abstract thinking about a project by producing a logical diagram which shows the decision options available and the corresponding results of choosing each...

## Stress in guy wires

Guys are wire ropes or strands used to hold a vertical structure in position against an overturning force. The most common types of guyed structures are stacks, derricks, masts for draglines, reversible tramways and radio transmission towers. As a general rule, stresses in guys from temperature changes are neglected, but in structures such as radio masts this is an important feature and must be subject to special analysis. The number of guys used for any particular installation is contingent on...

## Chart gives API gravity of blends quickly

API gravity of a crude oil blend may be readily estimated from the gravity of the components and their percentage composition. It is a simple procedure to use these curves to find the resulting API gravity of the blend. Example. If you blend a 14 API pitch (60 ) with a 36 API cutting stock (40 ), the resulting fuel oil has an API gravity of 22 as read from the nomograph. Calculated result from gravity tables would be 22.1 API. Results found using this nomograph checked out within 1 API over the...

## Net present value NPV method

Net present value (NPV), as its name suggests, calculates the net amount that the discounted cash flows of an investment exceed the initial investment. Using the discounted cash flow (DCF) formula, the future cash flows are discounted by the rate of return offered by comparable investment alternatives (i.e., the opportunity cost of capital), and then summed and added to the initial investment amount (which is usually negative). where Co initial cash flow (negative for a cash outflow Ci cash...

## Simple leak detection systems

The most basic method of leak detection involves either walking, driving, or flying the pipeline right-of-way to look for evidence of discoloration of vegetation near the line or actually hear or see the leak. Often unofficial pipeline monitoring is performed by people living nearby who can inform the operator of a problem with the line. The most cost effective way to detect leaks in nonflammable products is to simply add an odorant to the fluid. This requires some care in selection, as...

## Equipment

The data required for a centrifugal pump includes rated flow, rated head differential, shutoff head differential (PSOH), maximum allowed discharge pressure, minimum allowed suction pressure, discharge pressure trip setting, initial speed, final speed, time it takes to go from initial to final speed (ramp-down time), time when the pump starts to ramp down, and if the pump is protected by a check valve in the pump discharge line. The data required for valves includes valve closure time, time or...