The knowledge about physical properties of pipe and pipe fittings material are very important for piping engineer in performing his task, whether as piping material engineer, pipe support engineer or as piping stress engineer.

There are four (4) physical properties of pipng material in this lesson:

1. Density
2. Thermal Conductivity
3. Thermal Expansion
4. Specific Heat

 

1. DENSITY

Density is one of the physical parameter which plays an important role in all material states, whether solid, liquid, or gaseous. Density is the ratio of the mass of a material to its volume. The formula is: ρ = m/V, with unit of density as kg/cm3 or lb/in3. Below shows some of the density for some of material for reference only:

 

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2. THERMAL CONDUCTIVITY

Thermal Conductivity is the ability of a material to transmit energy in the form of the heat from a high-temperature source to a lower temperature and usually expressed as a coefficient of thermal conductivity, k. The lower the value of k, the more resistant the material is to the flow of thermal energy. Good insulators possess low coefficients of thermal conductivity.

The unit will be:

Thermal conductivity depends on the temperature of the material. For example, the coefficient of thermal conductivity of carbon steel decreases as its temperature increases, which in turn decreases its ability to transfer heat energy. Meanwhile Austenitic stainless steels, the thermal conductivity will increase when temperature increase.

 

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The following is the value of Thermal Conductivity for some of piping material commonly used in Oil and Gas Industry:

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3. THERMAL EXPANSION

Thermal Expansion is the coefficient of linear expansion of material. It is a ratio of the change in length of material per degree of temperature, compare to a length at a given standard temperature (such as room temperature, or the freezing point of water). See formula below.

The units of the coefficient are the length of growth per unit length per degree of temperature. Since it depends on the temperature, then the value of the coefficient varies with temperature. This coefficient of thermal expansion is critical in the flexibility analysis of the piping system, as shown on down below table.

Δ L = α L Δ T

Where, Δ = Change of Length, in α = Coefficient of thermal expansion of the material, 1/oF. L = Length of Material, in Δ T =Temperature Change, oF.

The units of the coefficient are the length of growth per unit length per degree of temperature. Since it depends on the temperature, then the value of the coefficient varies with temperature as we can see from below table, for reference only.

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4. SPECIFIC HEAT

Specific Heat is a measure of the quantity of heat required to raise the temperature of one gram of a material by one degree in Celsius. The unit are usually Calories or Joules per gram per Celsius degree.

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In addtion to the mechanical and physical properties, pipe material can also have to some extent the Electrical Properties. This is basically the characteristic of a pipe metal that enables the flow of electric current through or in other words to conduct electrical current. There are four (4) types of electrical properties we will present here:

1. Conductivity: Conductivity is the ability of a material to flow electrons and conduct current through a material. Represented by the symbol kappa and having the greatest value in metals, and Copper and Aluminium are the most commonly used due to having the greatest conductivity, where Aluminium has the highest conductance per unit length
 
2. Resistivity: Resistivity is the measure of the resistance to the current flow. Material who has high resistivity do not charge electricity freely and therefore consider to be insulator, such as glass, Teflon, rubber and polymer
 
3. Capacitance: Capacitance is the ability of body to store electrical charge. The amount of energy stored is proportional to the amount of stored charge. Capacitors store electrical energy in the form of electric fields between metal plates. The gap can be filled with air or some other dialectric medium such as ceramic, or polymer, which act as insulator as well as increase capacitance
 
4. Piezoelectricity: The piezoelectric property of a material is its ability to store electrical charge because of a stress that is applied to it. In fact, piezoelectricity means electricity due to pressure. Material who has piezoelectric property normally have a high elastic modulus.

 

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As part of the pipe metallic branch, non-ferrous pipe material can be found on the followings but not limited to: Copper Tubing, Brass pipe, Titanium piping, and Aluminium piping and tubing. In this lesson we will be presenting brief about each of them.

1. Copper Tubing

Copper, Bronze, and Brass elements have long been considered as an important element in pipe, mainly due to their corrosion-resistant properties, for water application. Copper Tubing considered as a very good material for delivering hot water and cold water. Therefore, it is most widely used for plumbing and hydronics applications and is most often found in piping systems in refrigerators or refrigerators.

 

Some of Specification for Copper Tubing
ANSI B16.15	Cast Copper Alloy Threaded Fittings
ANSI B16.18	Cast Copper Alloy Solder Joint Pressure Fittings
ANSI B16.22	Wrought Copper and Copper Alloy Solder Joint Pressure Fittings
ANSI B16.24	Bronze Pipe Flanges and Flanged Fittings

 

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2. Aluminium Piping

Aluminium alloys have a density of 1/3 (one third) of the density that of steel, and has properties that are malleable, ready to weld and reactive to Oxygen. This material has can resist corrosion. It is not common to see Aluminium in piping systems, but sometimes it can be found in compressed gas applications.

 

Some of Specification for Aluminium Piping
ASTM B210	Standard Specification for Aluminum and Aluminum-Alloy Drawn Seamless Tubes
ASTM B241	Standard Specification for Aluminum and Aluminum-Alloy Drawn Seamless Pipe and Seamless Extruded Tube

 

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4. Titanium Piping

Titanium is usually fallen into exotic material since is not commonly used in oil and gas facilities. However, titanium has high strength, low weigth, as well as good corrosion resistance. Titanium normally is used in the petrochemical, food processing and power generation industries.

 

Some of Specification for Titanium Pipe
ASTM B861	Standard Specification for Titanium and Titanium Alloy Seamless Pipe
ASTM B862	Standard Specification for Titanium and Titanium Alloy Welded Pipe
ASTM B363	Standard Specification for Seamless and Welded Unalloyed Titanium and Titanium Alloy Welding Fittings

 

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As explained on the lesson 1 earlier that materials are divided into two main categories, which is Metallic and Non-Metallic as shown below:

1.	Metallic Pipe: divided into Ferrous (Iron Based) and Non-Ferrous (Non-Iron based). Ferrous can be grouped further into Cast Iron and Steel, while Non-Ferrous consist of Aluminum, Nickel, etc
2.	Non-metallic Pipe: which divided into two groups, namely Plastic Pipes which consist of thermoplastic and thermosetting, and Non-Plastic pipes which normally has got concrete pipe and glass pipe.

 

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This lesson specifically discusses about Non-Metallic Pipes

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I. HDPE PIPE

A plastic is a solid material that consists of long, heavy molecules of organic compounds. There are two forms of plastic pipes, namely: Thermoplastics and Thermosetting.

Thermoplastics pipes are pipes that can be repeatedly softened when heated and hardened when cooled, without effect on the material properties. Meanwhile, thermosetting materials are irreversibly set, or cured, or hardened into a permanent shape during manufacture. Once hardened into their final shape, thermosetting products cannot be softened and therefore may not be reshaped by heating. Thermoplastic also no need kind of reinforcement. However, thermosetting always like to be combined with reinforcement, even filler. Some of example reinforcement is glass fiber while the sand as a filler.

The chemical properties of plastic pipes and their corrosion resistance reflect the broad choice of polymers and additives that can be used in their manufacture. Thermoplastics and fiber reinforced pipes are particularly well suited for inorganic fluids such as diluted acids, ammonia gases, alkalites, acids, salts, organic fluids, natural gas, and oils.

Thermoplastics is the most type of plastic pipes used for piping application in the form of PVC (polyvinyl chloride) followed by PolyEthylene (PE).

Polyethylene is a thermoplastic pipe that used in certain underground application. They are famous of having good corrosion resistance. HDPE is widely used in gas distribution system. However, the use of plastic pipe and plastic liners is more often limited by temperature rather than corrosion resistance.

 

HDPE Properties

1. Density

PE is semicrystalline polymer composed of long, chain-like molecules of varying lengths and numbers of side branches. As the number of side branches increases, polymer crystallinity and hence, density decreases because cannot pack as closely together. Density affects many of the physical properties which associate with performance of the finished pipe, such as stress crack resistance, tensile strength, and stiffness.

HDPE pipe base resins with densities of >0.947 to 0.955 g/cc are assigned as class of 4, which as per Industry practice offers a highly beneficial combination of performance properties for the majority of piping applications

 

2. Viscoelasticity

An important mechanical characteristic of plastics is their Viscoelasticity. As we know, viscosity describes a fluid resistance to the flow, the higher the viscosity, the larger the force needed to generate a specific flow. Meanwhile elasticity is material-characteristic property that describes a solid material’s resistance to deformation.

So, viscoelasticity is the property of materials that experience both viscous and elastic characteristics when undergoing deformation. If a constant stress is applied to the plastic pipe (for example a weight is hung from one end of a plastic pipe), the pipe will deform instantaneously (short term elasticity) but if the stress remains (the weight is not removed), the deformation will continue, such as in example the pipe will keep stretching.

The material is said to creep. That is why time under load (pressure, weight or other loads), which means time of service or design life, must be considered when designing the plastic piping system. Most standards base their plastic design on a 50-year design life.

 

PE is characterized as a viscoelasticity construction material. Because of its molecular nature, PE is a complex combination of elastic-like and fluid-like elements. As a result, this material displays properties that are intermediate to crystalline metals and very high viscosity fluids. The viscoelastic nature of PE provides for two unique engineering characteristics for the design of HDPE water piping systems. These are creep and stress relaxation

 

When HDPE is subjected to a constant static load, it deforms immediately to strain predicted by the Stress-Strain modulus determined from the tensile Stress-Strain Curve. If the load is high enough, the material may yield or rupture. This time-dependent viscous flow component of deformation is called creep. The Stress Relaxation is another unique property which the load or stress generated by the deformation slowly decrease over the time. This is of considerable importance to the design of PE piping systems

 

3. Tensile Stress

Tensile stress is a short-term property that provides a basis for classification or comparison when established at specific conditions of temperature and rate of loading but is of limited from a design perspective. The tensile stress of PE is typically determined in accordance with ASTM D638..

 

4. Impact Properties

The amount of energy that a material can absorb without breaking or fracturing is referred to as the impact strength of that material. ASTM D256 describes two most common test: Izod Impact Test and Charpy Impact, which can be performed on standard test specimen. Both tests measure the ability of a PE specimen to absorb energy on failure. This test information is normally used to make a relative comparison of the material’s resistance to failure on impact under defined circumstances. In this regard, PE is a very tough material demonstrating Izod impact resistance in a complex break failure mode with values in the range of 10-12 ft-lbf/in (AWWA M55) at standard room temperature

5. Temperature Effects

PE is a thermoplastic polymer. As such, its physical properties change in response to temperature. These property changes are reversible as the temperature fluctuates. The physical properties of PE are normally determined and published at standard laboratory conditions of 73°F (23°C). The coefficient of linear expansion for unrestrained PE is generally accepted to be 1.2 × 10–4 in./in./°F. This suggests that unrestrained PE will expand or contract considerably in response to thermal fluctuation. However, while the coefficient of expansion for PE is high compared to metal piping products, the modulus of elasticity is comparatively low, approximately 1/300th of steel for example.

6. Permeability

The rate of transmission of gases and vapours through polymeric materials varies with the structure of both of both the permeating molecules and the polymer. Permeability is directly related to the
crystallinity of the PE and the size and polarity of the molecule attempting to permeate through the matrix. The higher the crystallinity (the higher the density), the more resistant is the polymer to permeation

7. Chemical Properties

Generally, PE is widely recognized for its unique chemical resistance. To assist the designer in the selection of PE for piping applications, chemical resistance charts have been published that provide some basic guidelines regarding the suitability of PE as a piping material in the presence of various chemicals which published by the Plastics Pipe Institute (PPI) as PPI TR-1913/p>

8. Corrosion

PE used in water piping applications is an electrically nonconductive polymer and not adversely affected by naturally occurring soil conditions. As such, it is not subject to galvanic action and does not rust or corrode. This aspect of PE pipe means that cathodic protection is not required to protect the long-term integrity of the pipe even in the most corrosive environments.

9. Environmental Condition

Over time, ultraviolet (UV) radiation and oxygen may induce degradation in plastics that can adversely affect their physical and mechanical properties. To prevent this, various types of stabilizers and additives are compounded into a polymer to give it protection from these phenomena. The primary UV stabilizer used in the PE pipe industry is carbon black, which is the most effective additive capable of inhibiting UV induced reactions.
Carbon black is extremely stable when exposed to the outdoor elements for long periods of time and is relatively inexpensive compared to some of the more exotic colorant systems. The result is a piping system of uniform colour that does not chalk, scale, or generate dust in response to extended periods of outdoor exposure.

10. Pressure Rating

In accordance with ASTM D2837 defined a Pressure Rating (PR) as the estimated maximum water pressure the pipe is capable of withstanding continuously with a high degree of certainty that failure of the pipe will not occur. The PR and HDS/HDB are related by the following equation:

S = HDS = HDB / FE P = [2 (HDB) x FE x FT] / (DR – 1) —- for controlled OD Where: S = Allowable Hoop Stress, psi HDS = Hydrostatic Design Stress, psi HDB = Hydrostatic Design Basis, psi FE= Environmental Design Factor based on the service fluid FT = Service Temperature Design Factor

 

11. Standard Dimension Ratio (SDR)

SDR is the Ratio of Pipe Diameter to Wall Thickness. The wall thickness is determined using the diameter divided by the wall thickness. This provides a ratio that is based on an allowable working pressure for all of the diameters in a given Dimension Ratio (DR). Common SDR values are 64, 51, 41, 32.5, 26, 25, 21, 18, 17, and 13.5.

 

12. Pipe Material Designation Code

Pipe Material Number: PE4710 Where: PE = Polyethylene 4 = Density (according to ASTM D3350, from Table 1 page 2), with value of >0.940-0.947 g/cm3 7 = Slow Crack Growth (SCG) resistance (ASTM D3350 table 1 page 2) 10 = HDS of 1000 psi at 73oF in water

Below is the table of some available material for HDPE:

 

 

13. Temperature Service Factor

Factor applied to the HDS to account for the impact of temperatures greater that the temperature at which the HDS is determined

 

14. Application

In general, HDPE usually used to deliver water as well as low-pressure natural gas. Because the surface is very smooth, this type of pipe has a good fluid flow and its ability to withstand corrosion also makes HDPE increasingly chosen. Fluid temperatures can range from 40 C to 600C.

The main advantage of using this plastic pipe is that it is free from rust problems that often attack iron or metal pipes. Plastic pipe is also not affected by corrosion caused by electrolites such as acids, salts and bases. Even attacks from bacteria that generally attack metal pipes also do not work. This thermoplastic pipe is increasingly popular because it is lightweight so it is easy to store it or during installation. One more thing; the transportation cost is also cheaper.

This thermoplastic pipe also has a high thermal expansion and contraction coefficient. It’s just that this plastic pipe has limitations in terms of strength and the ability to withstand heat. Therefore, this type of material is only used in low-pressure streams and temperatures close to room temperature.

Some of Specification for HDPE
1.	API 15LE	Specification for Polyethylene Line Pipe (American Petroleum Institute)
2.	ASTM D2104	Polyethylene (PE) Plastic Pipe, Sch 40
3.	ASTM D2239	Polyethylene (PE) Plastic Pipe (SIDR-PR) Based on Controlled ID
4.	ASTM D2447	Polyethylene (PE) Plastic Pipe, Sch 40 to 80, Based on OD.
5.	ASTM D2609	Plastic Insert Fittings for Polyethylene (PE) Plastic Pipe.
6.	ASTM D3350	Polyethylene Plastics Pipe and Fittings Materials
7.	AWWA C906	Polyethylene (PE) Pressure Pipe and Fittings, 4 in (100 mm) through 63 in (1600 mm), for Water Distribution
8.	AWWA M55	PE Pipe – Design and Installation
9.	AWWA M55	PE Pipe – Design and Installation
10.	PPI TR-22	Polyethylene Plastic Piping Distribution Systems for Components of Liquid Petroleum Gas
11.	PPI TR-35	Chemical and Abrasion Resistance of Corrugated Polyethylene Pipe

 

AVAILABILITY

At the current market, the availability of HDPE pipe varies depend on the application. The Thermoplastics (HDPE) line usually is manufactured in accordance with API 15S, API Q1, and ISO 9001:2015 with design life of 20 years and standard pressure rating up to 1500 psi (103 bar).

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II. FIBERGLASS REINSFORCING PLASTIC PIPE

Fiberglass piping is used in most industries requiring corrosion-resistance pipe and have been successfully used for over fifty years. FRP available in wide-range of types, sizes, and wall thickness to meet various design requirements. Fiberglass piping can be constructed of resin which is resistant to acids, caustics or solvents. Furthermore, abrasion-resistant materials can also be added to the FRP piping, either at the inside diameter liner, or at the outside cover, in order to provide an excellent slurry water resistance

APPLICATION

FRP is widely used due to its strength and chemical resistance or in other words has a high corrosion resistance. FRP Pipe can be found to convey chemical in liquids or vapor phases. It is also used to convey water in industrial applications and can be both using underground and aboveground installation.

 

Some of Specification for FRP
1.	ANSI D5421	Standard Specification for Contact Molded “Fiberglass” (Glass-Fiber-Reinforced Thermosetting Resin) Flanges
2.	API 14LR	Specification for Low Pressure Fiberglass Line Pipe
3.	API 14HR	Specification for High Pressure Fiberglass Line Pipe
4.	API RP 15TL4	Recommended Practice for Care and Use of Fiberglass Tubulars
5.	ASTM D2996	Filament Wound Fiberglass (Glass-Fiber-Reinforced Thermosetting Resin) Pipe

 

III. NON-PLASTIC PIPE: CONCRETE PIPE

Non-plastic pipe is a branch of Non-Metallic pipe, apart from Plastic Pipe, and consist of concrete pipe whether in form of reinforced concrete pipe or rigid concrete pipe, Clay pipe, Wood pipe, and Glass pipe. Clay pipes are made from shale and clay and currently there are two varieties of clay pipes: Unglazed Clay Pipe and Clay Pipe which has been vitrified. Stormwater, sewage, and industrial waste are usually transported through Clay pipes. They are robust, long-lasting, and eco-friendly. Some of them are more than 200 years old and are still in use.

Wood drilled water pipeline normally utilize in England and certain Eastern cities in the United Kingdom. However, nowadays, they are no longer used in industries. Glass pipes normally used to withstand chemical reactions while providing cleanliness due to the extremely smooth surface and transparency. Glass pipes are widely used in the chemical and pharmaceutical industries.

Concrete pipe is a widely popular type of pipe and it normally consist of: Concrete pipe without reinforcement, reinforced concrete pipes and prestressed concrete pipe. Most of them are only suitable for a very low-pressure application. Concrete is naturally brittles but adding metal rods or mesh to reinforce it usually solve the problem and normally used in pressure and gravity applications and is often used for storm and sanitary sewers.

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Some of Specification for Concrete PIpe
1.	ASTM C14	Standard Specification for Concrete Sewer, Storm Drain, and Culvert Pipe
2.	ASTM C76	: Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe (AASHTO M170)
3.	ASTM C361	Reinforced Concrete Low-Head Pressure Pipe
4.	ASTM C443	Joints for Circular Concrete Sewer and Culvert Pipe, Using Rubber Gaskets (AASHTO M198)

In general, materials that are widely used in Oil and Gas facilities for pipes and their components are divided into two main categories:

1.	Metallic Pipe: divided into Ferrous (Iron Based) and Non-Ferrous (Non-Iron based). Ferrous can be grouped further into Cast Iron and Steel, while Non-Ferrous consist of Aluminum, Nickel, etc
2.	Non-metallic Pipe: which divided into two groups, namely Plastic Pipes which consist of thermoplastic and thermosetting, and Non-Plastic pipes which normally has got concrete pipe and glass pipe.

 

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This lesson specifically discusses about Metallic Pipes – Ferrous

I. FERROUS – CAST IRON PIPE

Ferrous pipe is the first branch of metallic pipe and is basically iron based material. Cast Iron is an alloy between iron and carbon with a carbon weight content of more than 2 weight percent of Carbon. Some says between 2 and 6.67 percent carbon.

This material is often combined with other elements in an effort to increase corrosion resistance, such as by adding elements of Silicon, Nickel or Chromium. Other elements that are also sometimes given are manganese, phosphorus and sulphur.

Cast Iron is strong in compression, but low in ductility and malleability, and very brittle, Thus this type is not suitable for pressure piping applications. The properties of Cast Iron depend on how much carbon content and the shape of the carbon itself is graphite or carbide.

Where we can use Cast Iron Pipe?

Cast Iron type pipes are widely used for drain, waste, and vent (DWV) applications, which is also known as “soil pipe.”

 

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Some of Specification for Cast Iron Pipe
1.	ANSI/AWWA C105/A21.5	American National Standard for Polyethylene Encasement for Ductile-Iron Pipe system
2.	ANSI/ASME B16.45	Cast Iron Fittings for SoventR Drainage System
3.	ASME A-74	Some of Standard Specification for Cast Iron Soil Pipe and Fittings
4.	ASME A-674	Standard Practice for Polyethylene Encasement for Ductile Iron Pipe for Waster or Other Liquids.
5.	ASME A-888	Standard Specification for Hubless Cast Iron Soil Pipe and Fittings for Sanitary and Storm Drain, Waste, and Vent Piping Applications.
6.	ASME C-564	Standard Specification for Ruber Gaskets for Joining Cast Iron Soil Pipe and Fittings

 

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II. FERROUS – DUCTILE IRON PIPE

Ductile Iron Pipe is part of Ferrous pipe or iron based material. Ductile Iron is type of material that is stronger and tougher that Cast Iron. It is a high-carbon magnesium-treated product containing graphite in the form of spheroids.

Similar to Cast Iron, Ductile Iron pipe also used for drain, waste, and vent (DWV) applications or sewage system.

Some of Specification for Ductile Iron Pipe
1.	ANSI/AWWA C105/A21.5	American National Standard for Polyethylene Encasement for Ductile-Iron Pipe system
2.	ANSI/ASME B16.42	Ductile Iron Pipe Flanges and Flanged Fittings, Classes 150 and 300.
3.	ASME A716	Ductile Iron Culvert Pipe
4.	ASME A-746	Ductile Iron Gravity Sewer Pipe
5.	ASME A-888	Polyethylene Encasement for Ductile- Iron Pipe Systems .
6.	AWWA C110/A21.10	Standard Specification for Ruber Gaskets for Joining Cast Iron Soil Pipe and Fittings

 

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III. FERROUS – CARBON STEEL PIPE

This is the most popular type of material and widely used in the Oil and Gas industry due to wide availability, high strength, and huge amount of connection systems as well as fittings. Steel is usually a combination of Iron elements (iron) and with not more than 2 weight percent of Carbon.

Some oxygen, which remain in the molten steel, has to be removed by process called a deoxidizing practice, which achieved by adding silicon, aluminum, or other agents to the molten steel, which depend on the amount of oxygen being removed, the Steel can be categorized into:

1. Killed Steel: deoxidized completely
2. Semi Skilled Steel: only partially deoxidized
3. Rimmed Steel: No addition of deoxidizing agent, have a CC range of 0.12% to 0.15%.

There are literally hundreds of wrought grades of steel that range in composition and can be divided into three general groups according to carbon content, namely:

1. Low Carbon Steel: 0.05 to 0.25% carbon
2. Medium Carbon Steel: 0.25% to 0.50%
3. High-Carbon-Steel: 0.50% and greater carbon content

Where Carbon Steel Pipe normally used?

Carbon Steel pipe is most used often in industrial application due to its wide range availability, high strength, hige connection system as well as fiitngs and have been used for oil and gas services for both above and underground

Carbon Steel is used for liquid and gas services, both aboveground and underground. Carbon Steel is also used for steam distribution services. It is not suitable for corrosive services unless protective measures are taken

 

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Meanwhile, based on the way its manufactured, Carbon Steel pipe can be grouped into several as below:

1. SEAMLESS PIPE

This type of pipe is the strongest type because it is a homogeneous substance with no weld stresses. In short, there is no welding involvement during the process making of this pipe.

Seamless pipe has value of 1.0 for Longitudinal Well joint Quality factor of Ej. The value of Ej will have to be included in any calculation where the product of SE appears, such as during calculation of Internal Design Pressure Thickness

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2. ELECTRIC RESISTANCE WELD (ERW) PIPE

Coils are cupped longitudinally by forming rolls and a fin pas section rolls that brings the coil together to form a cylinder. Welding is carried out using a “high frequency welder” that heats the steel to 2600oF.

The weld is then heat treated to remove welding stress, and the pipe is cooled, sized to proper Outside Diameter and cut to the desired length. The value of Ej will have to be included in any calculation where the product of SE appears, such as during calculation of Internal Design Pressure Thickness.

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3. DOUBLE SUBMERGED ARC WELD (DSAW) PIPE

This pipe also goes through a welding process on two sides of its plate, which is from the inside and from the outside.

The pipe seam would then be welded on the interior and exterior surfaces. The welding arc is submerged under flux. From this process we can see that welds would penetrate 100% of the pipe wall and produce a very strong bond of the pipe

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4. SPIRAL WELDED PIPE

This pipe is produced from the coils of steel that formed by angle rolles into a cylinder of the desired diameter, and then exterior and interior submerged arc welds seal the spiral seam. .

Used to be relegated for low pressure and structural application. But due to development of submerged arc-welding process, it is now possible to produce Spiral Weld pipe for high pressure service. The Longitudinal Well Joint Quality factor of Seam Welded Pipe can be improved from 0.8 to 1.0 for example, by supplementary Non-Destructive Examination (NDE) as per B31.3 para 302.3.4. The E factor is applicable only for calculating the wall thickness of pipe and other pressure containing components.

 

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Below is the table to show value of Longitudinal Weld Joint Quality Factor taken from ASME B31.3.

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SPECIFICATION

1. ASTME A53

This pipe specification covers Seamless and welded black and Hot-Dipped galvanized steel pipe with size from NPS 1/8 to NPS 26 (DN 6 to DN 650), inclusive. The types and grades cover by this specification is as below:

1. Type F: Furnace-butt-welded, continuous welded Grade A, B.
2. Type E: Electric-Resistance-Welded, Grades A and B
3. Type S: Seamless, Grade A and B

2. ASTME A106

This is for Seamless Carbon Steel Pipe for High Temperature Service in NPS ½ to NPS 48 [DN 6 to DN 120] inclusive. This type has three grades, namely Grade A, B, and C. This grade refers to the amount of Tensile Strenght of the material as shown below:

1. Grade A : SMTS of 48 ksi and SMYS of 30 ksi
2. Grade B : SMTS of 60 ksi and SMYS of 35 ksi
3. Grade C : SMTS of 70 ksi and SMYS of 40 ksi

3. ASTME A333

This is for Seamless Carbon Steel Pipe for High Temperature Service in NPS ½ to NPS 48 [DN 6 to DN 120] inclusive. This type has three grades, namely Grade A, B, and C. This grade refers to the amount of Tensile Strength of the material as shown below:

4. API 5L SPECIFICATION PIPE

API 5L Specification provides standards for pipe to be used in conveying gas, water and oil. API 5L Specification covers seamless and welded steel line pipe. There are two Product Specification Level (PSL), PSL 1 and PSL 2, which define different levels of standard technical requirement.

This specification specifies requirements for the manufacture of two products specification levels (PSL 1 and PSL 2) of seamless and welded steel pipe for pipeline transportation systems in the petroleum and natural gas industries. The grades are available in ranging from A25, A, B, X42, X46, X52, X56, X60, X65, X70. For more detail, please refer to API Specification 5L Line pipe at page 17. The API 5L Specification also provide the additional requirements or information concerning the manufacturing of line pipe

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As similar to other material, API 5L Pipe also produced with having pipe ends as below:

Plain End (PE) Threaded End (TE), limited to Seamless and Longitudinal Seam Welded pipe with D ≤ 508 mm. Belled End (BE): limited to pipe with D ≤ 219.1 mm and t ≤ 3.6 mm. Plain End for Special Coupling

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IV. ALLOYING ELEMENTS

Alloying of carbon steel with other elements normally done in attempt to improve the material properties. The followings are some of the common alloying elements along with the effects:

CARBON: The adding carbon content into Carbon Steel will make the carbon steel has a higher ultimate strength and hardness but may lower the ductility and toughness and decrease the thermal and electrical conductivities.

Manganese: This type of alloy normally present at all of commercial steels. In combination with sulphur will improve the impact toughness.

Chromium: Chromium is a hardening element and is frequently used with a toughening element such as a nickel to produce superior mechanical properties as well as increasing the temperature oxidation resistance of steels. It will also increase resistance to abrasion and wear while also improves resistance to high temperature hydrogen attack and graphitization.

Nickel Nickel is a ferrite strengthener and toughener and easily hardened. Nickel also increases the strength and toughness and fatigue resistance.

Molybdenum: Molybdenum will increase the creep resistance and high temperature strength as well as improving resistance to pitting corrosion.

Copper: The uses of copper increases resistance to atmospheric corrosion and increases yield strength. Copper also used to scavenge sulphur and improve atmospheric corrosion resistance.

Aluminum: Aluminum widely used as a deoxidizer in molten steel and for controlling grain size.

Boron: Boron is normally added to improve hardenability, which is to increase the depth of hardening during quenching.

Silicon: Deoxidizer that captures dissolved oxygen and avoid porosities and improve casting ability.

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V. FERROUS – STAINLESS STEEL PIPE

Stainless Steel pipe normally used whenever corrosion resistance is needed. Adding Chromium will provide good corrosion resistance to the material. However, it is very rare to see stainless steel pipe to be used for underground application due to economic reason. There are three types of stainless-steel pipe, as shown below:

1. AUSTENITIC STAINLESS STEEL

This type of pipe can be identified by 300 series and having maximum content of 0.15 percent carbon and minimum of 16 percent chromium, as well as other elements such as Nickel and or Manganese. Austenitic Stainless Steel poses an excellent combination of strength, ductility and corrosion resistance.

 

2. FERRITIC STAINLESS STEEL

usually identify with 400 series, and having chromium content between 14 to 27 percent, while Martensitic Stainless Steel contain 11.5% up to 18% Chromium and they both are magnetic. However, the most stainless-steel piping comes from the Austenitic variety, with the common grade is 304 and 316. There are also Austenitic Stainless Steel with lower carbon content and designated by the suffix “L”.

 

APPLICATION

Stainless steel piping is used for foods, beverages, and also at pharmaceutical, where iron dissolution cannot be allowed. This pipe never be installed underground and also no painting needed.

 

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Some of Specification for Stainless Steel Pipe
ASTM A312	Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes
ASTM A358	Electric-Fusion-Welded Austenitic Chromium-Nickel Alloy Steel Pipe for High-Temperature Service
ASTM A409	Welded Large Diameter Austenitic Steel Pipe for Corrosive or High-Temperature Service
ASTM A790	Seamless and Welded Ferritic /Austenitic Stainless-Steel Pipe
ASTM A999	General Requirements for Alloy and Stainless Steel Pipe
ASTM C220	Stainless-Steel Pipe, 1/2 in (13 mm) and Larger

 

Carbide Precipitation

It is a phenomenon that occurs when austenitic (300 series) stainless steels are heated, as for example during welding, that the carbides attract chromium atoms. The surrounding region of the stainless contains less chromium since it is bound with the carbides, which make that regions, where the corrosion resistant properties are deficient, and prone to corrosion attack.

There are two ways to prevent carbide precipitation during welding. One is to use a LOW-CARBON GRADE of Stainless-Steel, identified by the suffix “L” (for “low-carbon”). The other option is to stabilize the stainless steel with the addition of columbium or titanium. However, in practice, it is more common to use the low-carbon grades of stainless

 

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Mechanical properties of pipe and pipe fittings are very important since it defines the response and the behavior of pipe material to the applied force. The followings are the brief explanation of the properties:

 

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1. MODULUS ELASTICITY

Modulus Elasticity is the ratio of normal stress to the corresponding strain for tensile and compressive stress in elastic region. This ratio is linear through a range of stress, known as Hooke’s law.

The material behavior in this range is elastic (meaning that if the applied load is released the material will return to its original shape). The value of the slope in the elastic range is defined as Young’s Modulus, which measured using tension test.

 

Young’s Modulus, named after a British doctor, physicist, and Egyptologist, is a measure of the elasticity of the material. Young Modulus has a symbol of E. As you can see from the below table, the value of Young Modulus varies with temperature. The higher the temperature, the softer the material, and the lower its Young’s Modulus.

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In conducting Piping Stress Analysis for a piping system, there are usually requirements that are commonly carried out in EPC companies, as follows:

1. For piping system with High temperature, the Modulus of Elasticity at the cold temperature will be used.
2. Conversely, for lines with low or cold temperature, the Modulus of Elasticity at a minimum temperature will be used.
 

In the piping stress analysis software, usually there will be a request to input the values of Modulus Elasticity for the subject material for each of temperature input in the analysis, starting with Cold Temperature, followed by Hot Temperature or Operating/Design Temperature, in accordance to the project requirement. If no value inputted for ambient temperature, then the value for Cold Elastic Modulus will be used

 

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2. STRENGTH

Strength means toughness, which is basically the ability of the material to withstand the force or weight placed on it without affecting the performance. Strength’s words are more often shown to boxers, for example, who are ready and resistant to being beaten by their opponents. The stronger a person’s body receives a blow, it shows the strength of the puncher. There are two types of strength known in the material properties, namely : Yield Strength and Tensile Strength

YIELD STRENGTH

Yield Strength is the maximum stress that material can accept while maintaining elastic behaviour before beginning to deform in a plastic manner. The transform from purely elastic to purely plastic behaviour will not occur abruptly, but rather a gradual transition occurs as represented by a curve on the stress – strain diagram above. The most common is termed the 0.2 percent offset method, by drawing a parallel line to the elastic portion of the curve anchored to the point displaced 0.2% percent along the strain axis (dashed line on stress-strain figure below).

ULTIMATE TENSILE STRENGTH

The ultimate tensile strength or often shortened to Tensile Strength is the maximum applied load divided by the original specimen cross-sectional area (Stress) that can be sustained before breaking. As we can see from the figure stress-strain below, that when the load further increases under constant strain rate, the specimen will continue to stretch until the loss of load carrying cross section. The highest point on the graph is the Ultimate Tensile Strength and has units of Stress.

STRESS – STRAIN

Stress is defined as the ratio of applied force per unit area, or F/A, while Strain is deformation of material due to stress. Below graph will show the relation between σ and ε. The Strain increases when Stress changes until it reaches the Yield Strength and eventually to the Ultimate Strength before fracture.

σ = E ε

Where, σ = Stress, Psi. E = Young’s Modulus, Psi. ε = Strain

 



   

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Below is the the table that showing the value of Yield Strength and Tensile Strength for some common material use in piping system, which was taken from ASME B31.3, for reference only. For more material, please visit ASME B31.3.

 



 

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3. ELONGATION AND REDUCTION OF AREA

Percent Elongation is a measurement of how much the material will deform plastically and elastically before it rupture. It basically measures the ductility, where it relates to the amount of straining that a material undergoes when subjected to a stress.

Because, whenever the material experiencing strains, then it will also decrease the area of cross section, which called as Reduction of Area (RA). Below is the formula to calculate two of those changes, where Ao is the original cross section area, Af is final cross section area, L is the final length and Lo is the original length.

 



 

4. HARDNESS AND TOUGHNESS

Hardness is the measure of the material ability to resist deformation. The hardness number from the hardness test constitute a non-dimensioned, with increasing number will represent the harder of the surface. The two most common hardness test methods are Brinell Hardness and Rockwell Hardness.

Toughness is the ability of the material to resist the fracture. This normally happen when load is rapidly applied. There are two most common methods used to measure the toughness of the material, namely Charpy Impact Test, defined in ASTM Specification E 23, and the Drop Weight Test, defined in ASTM E 208. Charpy Impact test which employs a small, machined specimen stuck by a pendulum weight, produce the result which measured in kilojoules or ft – lb force, which basically the energy loss to the pendulum as it passes through and breaks specimen. This is a measure of the toughness of the specimen.

Gaskets and Bolting are a very important part of piping system to ensure the good connection between two flanges, since they will provide the perfect seal to prevent the inside fluid to leaking out. The leak performance of the gasket is dependent on the stress on the gasket during operation. The higher the gasket stress, the higher the leak-tightness capability.

As we know that it is impossible to get a pair of flanges that can perform their task without any leakage during the operation, due to the following things as an example:

• It is impossible to produce perfect flanges with a very smooth surface.
• The possibility of presence of rust on the surface of flanges during operation

Therefore, the main purpose of the gasket is to provide protection against leaks in the flanges connection or can also be referred to as “sealing elements”. Tightness factor of new flange and gasket designs need to be taking into account during the calculations to reduce leak rates.

ASME Section VIII code utilizes m and y gasket factors in the design calculation of flanges, which use the flange design required to ensure the establish the integrity of the system, although not quite useful to predict flange leak rates.

 

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Things need to consider when choosing and selecting the Gaskets:

Compatibility with the fluid Operating Temperature and Pressure of Fluid Compressibility of the Material The selected material must be suitable for the flanges material on which the gasket will be installed

 

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GASKET PROPERTY

Ideally, a gasket is comprised of a body with good load bearing and recovery characteristics, with a soft conformable surface layer and have a combination of elastic and plastic characteristics, with following properties

Compressibility: to suit the style and surface finish of the flange to fil any imperfection of the flange. Resilience: Gasket with high resilience will enable the gasket to move with the dynamic loadings of the flange to maintain its seating stress. No Change in the thickness of Gasket: under varying load cycles of temperature and pressure or under a constant load at elevated temperatures (creep)

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TYPE OF GASKET: 1. NON-METALLIC GASKET

Also called a soft gasket, this is a composite sheet of materials and normally used for flat-face flanges and low-pressure class application and manufactured with non-asbestos material or compressed asbestos fibre, examples: glass fibre, elastomer, Poly Tetra Fluoro Ethylene (PTFE), and flexible graphite gaskets. The dimensions of this soft gasket are based on ASM B16.21. This type of gasket normally used for Low Pressure Class of 150 300 and can be used for maximum temperature ranging from 390 up to 1000/sup>F.

 

TYPE OF GASKET: 2. SEMI-METALLIC GASKET

This is composite of metal and non-metal materials. Example of this type are spiral wound, metal jacketed, and a variety of metal-reinforced graphite gaskets. Unlike non-metal, this type of gasket can be used for wide range of operating conditions of pressure and temperature. Spiral Wound Gaskets are the most common gaskets for Raised Face Flanges from Class 150 to 2500. Suitable for use both at low and high temperatures which can reach up to 750oF depends on the material. This type refers to ASME B16.20/16.5.

 

TYPE OF GASKET: 3. METALLIC GASKET

Fabricated from one or combination of metal. Example of this type are Ring-Joint Gasket and lens ring and suitable for high-temperature and pressure applications and require high-bolt loads seal. Ring Joint Gaskets are manufactured to API 6A and ASME B16.20, while Lens Rings Gaskets are manufactured to DIN 2696. Produced using metal materials.

The dimensions of this gasket are based on API 6A, API 17D and ASME B16.20/16.5 standards. The metallic gasket normally used for medium and high-pressure class (600 – 2500) with maximum temperature can reach to 650oF depends on the material.

 

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It is important to not here that for high temperature applications, such as above 650oF or 343oC, gasket selection becomes even more critical. This is due to the fact that many gaskets may perform well at low temperatures but fail to meet leak-tightness requirement for high temperatures.

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INSULATING GASKET

There is a potential of galvanic corrosion to occur when utilizing a dissimilar metal, for example Carbon Steel Flange bolted to Stainless Steel Flanges. Insulating gasket is also to be used where aboveground piping connects to underground piping.

However, due to a believe that this kind of gasket is generally unreliable, then their use should be minimized to areas where only absolute necessary and only then when agreed with the engineering team as well as with client

 

If selected to be used, then the Insulating Gasket kit will consist of the followings:

1. Insulating Gasket
2. Insulating Sleeves to be placed around the stud bolts
3. Insulating washers and Steel washers

 

CODES AND STANDARDS
ANSI B16.20	Metallic Gaskets for pipe flanges, Ring-Joint, Spiral Wound and Jacketed.
ANSI B16.21	Non-metallic Flat Gaskets for Pipe Flanges.
BS 4865 PART 1	Flat Ring Gaskets to suit BS4504 and DIN Flange
BS 3381	Spiral Wound Gaskets to suit BS1560 Flanges
API 6A	Specification for Wellhead and Christmas Tree Equipment

Pipe Flange is a type of pipe connection that is commonly used to connect one pipe with another in addition to the welding connection. Flange connections are preferred for piping connection to nozzle equipment or to other component where regular maintenance required. Piping Flange is also used for line breaks or spec. breaks.

If Elbow, Tee, Reducer, Cap are components made of the same material as the pipe material to which it will be connected, then flanges have a difference because generally flanges are made of metal material through the forging process, which is the process of forming metal by applying pressure. In addition, flange also undergoes a process called “machined surface”.

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FLANGES STANDARD

The dimensions and drilling for all line or end flanges shall conform to one of the following standards:

Some of Specification for FLANGES
ANSI B16.1	Gray Iron Pipe Flanges and Flanged Fittings: Classes 25, 125, and 250.
ANSI B16.5	Pipe Flanges and Flanged Fittings: NPS 1/2 through 24 metric/Inch standard.
ANSI B16.24	Cast Copper Alloy Pipe Flanges and Flanged Fittings, Classes 150, 300, 600, 900, 1500, and 2500.
ANSI B16.42	Ductile Iron Pipe Flanges and Flanged Fittings: Classes 150 and 300.
ANSI B16.47	Large Diameter Steel Flanges: NPS 26 through NPS 60 Metric/Inch Standard.
ANSI B31.8 Table I-1	Light Weight Flanges
MSS SP-44	Steel Pipe Line Flanges.

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FLANGE FACES

The Face of flanges is the most important aspect flanges since it will provide a seal to the fluid inside the piping system or piping connected to the nozzle of equipment. There are lots of configuration available with utilizing gasket between the flange surface:

1. FLAT FACE: Usually often use a cast iron material with classes 125 and 250. One of the reasons is to distribute compressive stress to a wider area and avoid the occurrence of flexible moments that can crack the cast iron.

2. RAISED FACE: This is a common and commonly used type of flange. The flange surface will rise by 0.06 inches for class 150 and 300, while for class400 it will rise by 0.25 inches. Because there is a rising surface, the gasket is smaller than the bolt circle

3. LAP JOINT AND RING FACE: For the Lap Joint, it has a face like a raised face but is made using pipes, while the Ring Face, the metal ring will be tucked in advance of the flange with the aim of avoiding leakage.

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TYPE OF FLANGE

The Face of flanges is the most important aspect flanges since it will provide a seal to the fluid inside the piping system or piping connected to the nozzle of equipment. There are lots of configuration available with utilizing gasket between the flange surface:

1. WELDING NECK FLANGES

The Weld Neck Flanges are attached to the adjoining pipe with a circumferential butt weld. It is important to ensure that the ID of the adjoining pipe matches with the bore of the flange. This type of flanges is most common used at piping system and suitable for severe services where temperature extremes or high pressures services. The tapered hub of the Weld Neck Flanges can add significantly to their strength and rigidity as well as to their weight

 

2. SLIP ON FLANGES

This type of flange is the ring that is placed over the pipe end, with the flange face extends from the end of the pipe.

 

3. SOCKET WELD FLANGES

This type of flange contains a shoulder on the inside of the flange as a guide to set the depth where the pipe to be welded to the flange

 

4. THREADED WELD FLANGES

This flange on figure below is normally used for low-pressure systems where no thermal cycles could cause the threads to be loosen. As normally done for threaded fittings, they are sometimes back welded (seal welded) to prevent leaking, not to provide or added strength due to the welded.

 

5. BLIND FLANGES

Blind flanges are used whenever there is a need for the line to be capped off at a flange. Blind Flanges are also useful to provide the provision for future connections, as well as for manways at the pressure vessel or tankages

 

6. ORIFICE FLANGES

This is special type of flange, which normally use to the measure the pressure drops across a fixed orifice, which inserted between the flange faces. Jack screws are also provided to assist in spreading the flanges so that the orifice plate can be easily removed

 

7. API FLANGES

TAPI flanges are normally used in the oil fields where pressure can be high. It is advised not to mix and matched with ANSI flanges

 

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FLANGE RATING

Initially, Flange has its own rating designation, which is under the name of “Class”, followed by a dimensionless number, as follows:

Class:150, 300, 400, 600, 900, 1500, 2500

 

The flanges are grouped into “Classes” using “Rating” according to Design Pressure and depend on the temperature. The Flange Rating is mentioned in “psi”, but more often it is simply called “pound”, although a flange of 300 pounds does not mean that the Design Pressure is 300 Psi

ANSI B16.5 provides the Pressure-Temperature ratings on Table 2-1.1 through 2-3.19 for the applicable material and class designation and Table 2-1.1C through 2-3.19C list pressure-temperature ratings using psi units for pressure at the temperature in degrees Fahrenheit. Pressure-Temperature ratings are basically a maximum allowable working gage pressure in bar (psi) units at the temperatures in degrees Celsius or Fahrenheit.

Please note that the temperature shown for a corresponding pressure rating is the temperature of the component, which is basically is the same as that of the contained fluid.

So, for example, as per Table 2-1.1C, ANSI B16.5 -2020, for Carbon Steel Flange, Class 150, at Temperature 100oF, the Allowable Pressure is 285 psig, and Class 150 at 500oF will have 170 psig as Allowable Pressure. Flanged joints and flagged fittings maybe subjected to piping system hydrostatic test at a pressure of 1.5 times the 38oC (100oF) rating, rounding off to the next higher 1 bar increment.

WORKING PRESSURE EQUATION

ANSI B16.5, Appendix A-2 Pressure – Temperature Rating method, describes the equation to calculate the working pressure for materials listed on the table at the ANSI B16.5, as below:
Rating Equation Class 300 and Higher:

The working pressure (P T) of a flange is a function of Rating Pressure (Pt) and Allowable Stress (ST).

C1 = 10, when S1 is expressed in MPa, and the resultant pt will be in bar

C1 = 1, when S1 is expressed in psi, and the resultant pt will be in psi units.

pc = ceiling pressure, bar (psi), at temperature, T as specified in section A-3, ANSI B16.5 (Table A-1 page 196 (for bar units) and 197 (for psi units).

S1 = Selected Stress, Mpa (psi), for specific material at Temperature T, as described in ANSI B16.5.

1. PIPE DESIGNATION

There are two commonly used methods to pipe designation, namely:

1. NPS: Nominal Pipe Size: a dimensionless designator of pipe. It indicates standard pipe size when followed by the specific size designation number without an inch symbol (for example, NPS 1¹⁄₂, NPS 12).

 

2. DN: Nominal Diameter: a dimensionless designator of pipe in metric system. It indicates standard pipe size when followed by the specific size designation number without the millimeter symbol (for example, DN 40, DN 300).

Furthermore, pipes are often grouped as below:

Large Bore Pipe: i.e. pipes larger than 2 inches. Small Bore Pipe: for pipes that size of 2 inches and below. Tubing: has a size of up to 4 inches but with a wall thickness smaller than the Large Bore and Small Bore

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Pipe sizes that are normally used in the Oil and Gas Industries are starting from NPS sizes of 1/2, ¾, 1, 2, 3, 4, 6, 8, 10, 12 and etc. have an Outer Diameter (OD) that has been standardized and is not the same as the NPS. While pipes 14 inches and above have the same Outer Diameter as the NPS.

When selecting the pipe size for the project, the availability of fittings and valves must also be taken into account, since any pipe must necessarily mate with fittings. For this reason, 3 ½ in and 5 in diameter is hardly ever specified. As might be expected, 5 in would fill the gap between 4 in and 6 in nicely in terms of flow velocities. But it is never specified for industrial projects.
In term of wall thickness, that pipes are produced in various thicknesses that have been standardized. Each specific thickness on the pipe is named in the form of a Schedule Number instead of in the form of the actual pipe thickness.

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Initially, there were only three types of pipe wall thickness:

Standard (STD) Extra Strong (XS) Double Extra Strong(XXS)

However, with the development of the stronger and corrosion-resistant piping materials which can produce thinner pipe, then there is a need to specify pipe size and wall thickness. The schedule number subsequently added as a convenient designation for use in ordering pipe. Currently, the wall thickness of pipe has been given the number which start from 5 and 5S, followed by 10 and 10S, so on in multiples of 10 to Schedule 40 (20, 30, 40), and then has multiples of 20, namely 60, 80, 100, 120, 140, 160. The suffix “S” on some of the schedules indicates that these are available in corrosion resistant (stainless) steel

In general, the thickness of pipes that have a schedule of 40 with an STD schedule is having the same values for pipes of size 1/8 to pipes of size 10 inches inclusive. Likewise, schedule 80 is having the same value as schedule XS for pipes size up to 8 inches inclusive. All larger sizes of XS have ½ in. (12.70 mm) wall thickness.

Pipes are usually produced with different lengths depending on the material, size and schedule. However, in general, pipes are produced by having an average length of 20 ft or 6 meters for Carbon Steel pipes which are also known as single random length and 40 ft or approximately 12 meters or also with the term Double Random Lenght (DRL).

2. PIPE FORMULA

Several data about pipes, such as pipe weight, pipe area, and other pipe properties will be needed by piping engineer as well as piping stress engineer when performing his job to do stress analysis or to design pipe support as well as to calculate load on pipe support. Below are some useful formula:

Example Calculation

Example#1
Pipe Size: 10 inches
Wall Thickness: Sch 40
Find A_m and A_i

For 10 inches, Pipe Outside Diameter (OD) will be 10.75 inches.
Meanwhile, Sch 40 is equal to 0.365 inches. (Refer to ASME B36.10 – 2022)
To find Inside Diameter, ID, subtract OD with 2 times of wall thickness, which is
ID = OD – 2t = 10.75 – 2 (0.365) = 10.02 inches.

Therefore, Area of Inside of the pipe, A_i = 0.7854 x ID² = 0.7854 x 10.02 = 78.85 in²
Area of Metal, A_m = 0.7854 (OD² – ID²) = 0.7854 (10.75² – 10.02² = 11.908 in²

 

Example#2
Pipe Size: 10 inches
Wall Thickness: Sch 40
Calculate the Pipe End Weight, W_pe

For 10 inches, Pipe Outside Diameter (OD) will be 10.75 inches.
Meanwhile, Sch 40 is equal to 0.365 inches. (Refer to ASME B36.10 – 2022)

Therefore, Pipe End Weight, W_pe = 10.69 x (10.75 – 0.365) x 0.365 = 40.52 lb/ft
If we check the result of 40.52 lb/ft at ASME B36.10 page 7, for pipe size 10, Sch. 40, we will get the result of W_pe = 4.52. This to confirm that our calculation was correct.

Below is the result of the calculation using the above formula to determine the Plain End Weight for several common pipe size.

On the above table we can observe that there is a different between the NPS with the OD starting from pie size of ¼ inches up to 12 inches inclusive. Only starting from NPS 14, the OD pipe will have identical with the NPS. It is explained that the difference is because at the beginning of pipe manufacturing in the 1930s, pipes were made based on the inner diameter with 1/16″ wall thickness, so the size of the outer diameter became larger by 1/8″. Along with the development of metallic technology, they are also able to make pipes with a thinner thickness, while maintaining the size of the outer diameter of the pipe.