PIPE SCHEDULE

The purpose of the pipe schedule standards is for all industries that use pipes to use the same standards. Pipe schedules are a means of categorizing pipe and identifying the strengths and characteristics of its capabilities.For all pipe sizes the outside diameter (O.D.) remains relatively constant. The variations in wall thickness affects only the inside diameter (I.D.). pipe schedule is an american definition to define pipe thickness and how much pressure can the pipe stand. The most commonly used schedules today are 40, 80, and 160. There is a commonly held belief that the schedule number is an indicator of the service pressure that the pipe can take.

The Iron pipe size (IPS) is an older system still used by some manufacturers and legacy drawings and equipment. The IPS number is the same as the NPS number, but the schedules were limited to Standard Wall (STD), Extra Strong (XS), and Double Extra Strong (XXS). STD is identical to SCH 40 for NPS 1/8 to NPS 10, inclusive, and indicates .375" wall thickness for NPS 12 and larger. XS is identical to SCH 80 for NPS 1/8 to NPS 8, inclusive, and indicates .500" wall thickness for NPS 8 and larger. Different definitions exist for XXS, but it is generally thicker than schedule 160

Industrial pipe thicknesses follow a set formula, expressed as the "schedule number" as established by the American Standards Association (ASA) now re-organized as ANSI - the American National Standards Institute. Eleven schedule numbers are available for use: 5, 10, 20, 30, 40, 60, 80, 100, 120, 140, & 160.

A schedule number indicates the approximate value of

Sch. = 1000 P/S

where

P = service pressure (psi)

S = allowable stress (psi)

The higher the schedule number is, the thicker the pipe is. Since the outside diameter of each pipe size is standardized, a particular nominal pipe size will have different inside pipe diameter depending on the schedule specified.

Welded and Seamless Wrought Steel Pipe

To distinguish different weights of pipe, it is common to use the Schedule terminology from ANSI/ASME B36.10 Welded and Seamless Wrought Steel Pipe:

Light Wall Schedule 10 (Sch/10, S/10) Schedule 20 (Sch/20, S/20) Schedule 30 (Sch/30, S/30) Schedule 40 (Sch/40, S/40) Standard Weight (ST, Std, STD) Schedule 60 (Sch/60, S/60) Extra Strong (Extra Heavy, EH, XH, XS) Schedule 80 (Sch/80, S/80)

Schedule 100 (Sch/100, S/100) Schedule 120 (Sch/120, S/120) Schedule 140 (Sch/140, S/140) Schedule 160 (Sch/160, S/160) Double Extra Strong (Double extra heavy, XXH, XXS)

Note that many of the schedules are identical in certain sizes.

Stainless Steel Pipe

For stainless steel pipes thru 12-inch, schedule numbers from Schedule 5S to schedule 80S are used as published inANSI/ASME 36.19M Stainless Steel Pipe.

Schedule 5S (Sch/5S, S/5S) Schedule 10S (Sch/10S, S/10S) Schedule 40S (Sch/40S, S/40S) Schedule 80S (Sch/80S, S/80S)

Orifice plate

An orifice plate is a device used for measuring the rate of fluid flow. It uses the same principle as aVenturi nozzle, namely Bernoulli's principle which states that there is a relationship between the pressure of the fluid and the velocity of the fluid. When the velocity increases, the pressure decreases and vice versa. An orifice plate is a thin plate with a hole in the middle. It is usually placed in a pipe in which fluid flows. When the fluid reaches the orifice plate, with the hole in the middle, the fluid is forced to converge to go through the small hole; the point of maximum convergence actually occurs shortly downstream of the physical orifice, at the so-called vena contracta point (see drawing to the right). As it does so, the velocity and the pressure changes. Beyond the vena contracta, the fluid expands and the velocity and pressure change once again. By measuring the difference in fluid pressure between the

normal pipe section and at the vena contracta, the volumetric and mass flow rates can be

obtained from Bernoulli's equation.

Restriction orifice plate

Restriction orifice plates can be used as a simple pressure reducing device, or to limit the flow rate in a pipeline. The outside diameter of the orifice plate is equal to the bolt circle diameter of the connecting flanges minus the diameter of the bolt. This ensures that the plate is centred accurately in the line. Plate thicknesses depend on line size and differential pressure, and should be sufficient to prevent the plate from bending under operating conditions. Recommended plate thicknesses are shown on the graph below.Orifice plates can be made in accordance with customer drawings as required.

Miter bend

A pipe bend made by mitering (angle cutting) and joining pipe ends. A mitre bend with an angle of change in direction at a single joint greater than 22,5 ° shall not be used under cyclic loadings (> 7 000 cycles).we use bends only when large radius is specified by process engineer in basic documents. It is used for utility pipeline {except ST and HO} of size 8” NB and larger to save cost.

induction bend

Induction bending is an efficient way to form a bend when only a specific area of a metal tube or pipe requires a bend. That specific area is usually heated with the use of an induction coil in order to make the material easier to bend to a preset radius. induction bending is usually used to bend a specific area of a finished piece of metal, Almost any metal or steel product can be used in the induction bending process, this includes metal bars, pipes and tubes,  The following are the top 6 advantages:

1) With induction bending you have the ability to heat a specific area of the metal pipe and this will ensure that a minimal amount of distortion occurs after the bend is completed.

2) This process results in higher energy efficient systems since only a portion of the metal requires heating the power required to create the bend is kept to a minimum.

3) The induction bending process does not require any sand filling or internal mandrels, so the overhead costs are much lower.

4) Bending times do not take as long as other processes, making this process more cost effective.

5) The overall quality of the product is better than that of cold bending, where excessive warping and wall thinning may occur.

6) And finally this process eliminates the need for mechanical or welded joints, resulting in a smoother finish.

Although there may be some crossovers in the way the finished metal products are used, induction bending is almost always used on large pipes such as petroleum pipelines, but can also be used in making smaller products such as springs, and farming tools. 

Birmingham Wire Gauge

the Birmingham Wire Gauge) is used used to specify thickness or diameter of metal wire, strip, and tube products. Wall thickness of a pipe is normally given in decimal part of an inch rather than as fraction or gage number. When gauge numbers is given for a pipe without reference to a system, Birmingham Wire Gauge - BWG - is implied. Birmingham Wire Gauge is also known as Stubs' Wire Gauge, used for drill rod and tool steel wire.The gauge starts at the lowest gauge number of 5Ø or 00000, corresponding to the largest size of 0.500" (12.7mm) to the highest gauge number of 26, corresponding to the smallest size of 0.018" (0.46mm). Size steps between gauges range from .002" between high gauge numbers to .046" between low gauge numbers and do not correspond to a particular mathematical pattern, although for the most part the steps get smaller as the gauge number goes up. Concerning wire and fine tubing, the gauge number is used to specify the outside diameter of the product, whereas for larger mechanical tubing the gauge number specifies the wall thickness independent of the overall size of the tube.

Welding symbol.

Difference between pipe and tube

A pipe is a tube or hollow cylinder used to convey materials or as a structural component. The terms pipe and tube are almost interchangeable. A pipe is generally specified by the internal diameter (ID) whereas a tube is usually defined by the outside diameter (OD) but may be specified by any combination of dimensions (OD, ID, wall thickness). A tube is often made to custom sizes and may often have more specific sizes and tolerances than pipe. Also, the term tubing can be applied to non-cylindrical shapes (i.e. square tubing). Pipe have a nominal size based on inside diameter up to about 14" while tubing has a nominal size based on outside diameter. Pipe wall thickness is based on schedule number or specific wall thickness. Tubing is always has its wall thickness set by a specific wall thickness not a schedule number. 

Both can be seamless or seamed depending on the specification to which they are manufactured. People choose pipe when they want a specific ID but increase the OD for strength or to hold pressure. Pipe is chosen for pressure situations not structural situations. 

People choose tube in structural situations. They generally want the OD to remain consistant but let the ID get smaller with a thicker wall. Tube is made by taking flat stock and rolling it to shape. You can select a controlled ID in tube if you buy DOM (Drawn over a mandrel). Generally tube has a weld seam inside because that is where the weld flash goes in the process. The outside weld seam is scarped off to provide a smooth finish. Tube will have a flat spot where the weld seam is located. 

SURFACE ROUGHNESS

Surface roughness is the measure if the finer surface irregularities in the surface texture. these are the result of the manufacturing process employed to create the surface. Surface roughness Ra is as the arithmetic average deviation of the surface valleys and peaks expressed in micro inches or micro meters. The ability of manufacturing operation to produce a specific surface roughness depends on many factors. For example in end mill cutting the final surface depends on the rotational speed of the end mill cutter ,the velocity of the traverse the rate of feed, the amount and type of lubrication at point of cutting and the mechanical properties of the piece being machined. A small change in any of the above factors can have a significant effect on the surface produced

 Pump Characteristic Curves The performance of a centrifugal pump can be shown graphically on a characteristic curve. A typical characteristic curve shows the total dynamic head, brake horsepower, efficiency, and net positive Suction head all plotted over the capacity range of the pump.

Figures 1, 2, & 3 are non-dimensional curves which indicate the general shape of the characteristic curves for the various types of pumps. They show the head, brake horsepower, and efficiency plotted as a percent of their values at the design or best efficiency point of the pump.

Fig. 1 below shows that the head curve for a radial flow pump is relatively flat and that the head decreases gradually as the flow increases. Note that the brake horsepower increases gradually over the flow range with the maximum normally at the point of maximum flow.

Fig. 1 Radial Flow Pump

Mixed flow centrifugal pumps and axial flow or propeller pumps have considerably different characteristics as shown in Figs. 2 and 3 below. The head curve for a mixed flow pump is steeper than for a radial flow pump. The shut-off head is usually 150% to 200% of the design head, The brake horsepower remains fairly constant over the flow range. For a typical axial flow pump, the head and brake horsepower both increase drastically near shutoff as shown in Fig. 3. The distinction between the above three classes is not absolute, and there are many pumps with characteristics falling somewhere between the three. For instance, the Francis vane impeller would have a characteristic between the radial and mixed flow classes. Most turbine pumps are also in this same range depending upon their specific speeds.

Fig. 2 Mixed Flow Pump

Fig. 3 Axial Flow Pump

Fig. 4 below shows a typical pump curve as furnished by a manufacturer. It is a composite curve which tells at a glance what the pump will do at a given speed with various impeller diameters from maximum to minimum. Constant horsepower, efficiency, and NPSHR lines are superimposed over the various head curves. It is made up from individual test curves at various diameters.

Fig. 4 Composite Performance Curve