Pipes:
A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-
section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries,
powders and masses of small solids
The pipe is a straight pressure tight cylindrical hollow, used in the piping system to transport
liquid, gas and sometimes solids..
In common usage the words pipe and tube are usually interchangeable, but in industry and
engineering, the terms are uniquely defined. Depending on the applicable standard to which it is
manufactured, pipe is generally specified by a nominal diameter with a constant outside
diameter (OD) and a schedule that defines the thickness. Tube is most often specified by the OD
and wall thickness, but may be specified by any two of OD, inside diameter (ID), and wall
thickness. Pipe is generally manufactured to one of several international and national industrial
standards.[1] While similar standards exist for specific industry application tubing, tube is often
made to custom sizes and a broader range of diameters and tolerances. Many industrial and
government standards exist for the production of pipe and tubing. The term "tube" is also
commonly applied to non-cylindrical sections, i.e., square or rectangular tubing. In general,
"pipe" is the more common term in most of the world, whereas "tube" is more widely used in
the United States.
Classification Can be done according to:
1- Material.
2- Dimension.
3- Manufacturing.
4- Pipe End.
Piping Materials:
Piping material selection mainly depends on process conditions such as
Fluid it transports;
at what temperature
at what pressure it transports.
1st, Process condition that will impact the selection of material is type of fluid it transport. For
corrosive fluids, you have to go for higher corrosion resistance material as compared to non-
corrosive service
Corrosive fluids such as – crude oil, Sea Water, H 2S, Ammonia, Acids etc. required high
corrosion resistance material.
On the other hand, normal carbon steel is enough for Non-Corrosive fluids such as –
Lube oil, Air, Nitrogen etc.
2nd Process condition that will impact the selection of material is the Temperature of fluids
Cryogenic
Low temperature
Medium temperature
High temperature
Increase or decrease in the service fluid temperature will greatly affect mechanical properties of
the pipe material such as impact resistance, elongation, and tensile strength; hence, you
required special material for both high temperature & Cryogenic services.
3rd Process condition that will impact the selection of material is the Pressure of service fluids.
You required high strength material or higher thickness material for high-pressure services
compare to normal pressure services.
Others non-process factor that also considered during material selection are
Cost of material
Availability – whether the material is locally available or import is required.
Weldability and Manufacturability of material also play a vital role in selection.
Preference is always given to the material which does not require any special
requirement during welding and manufacturing.
Material Properties
Similar to process fluid properties, there are certain material properties that also consider while
selecting pipe material. Some of them are
Ultimate Tensile Strength – that is the capacity of a material to withstand when
subjected to tension.
Yield Strength – that is the load at which plastic deformation or you can say permanent
deformation start.
Elasticity – is the ability of a material to resume its normal shape after the load is
removed just like rubber.
% Elongation – Percent elongation is a measure of ductility.
Hardness – is ability of a material to resist plastic deformation.
Toughness – ability of a material to absorb energy before fracture.
Creep resistance – ability to resist any kind of distortion when under a load over an
extended period.
Fatigue Resistance – is ability of material to withstand cyclic load for a given number of
cycles before it fails.
Now considering both process and material property you can choose piping material from a
verity of material available. In this chart, I have listed different types of material that used in
process piping to meet various design condition. Piping material broadly classified into three
categories. Metal, Nonmetal, and composite, which is a combination of metal to metal or metal
to non-metal.
Steels:
4 Types of Steel “CAST”
According to the American Iron & Steel Institute (AISI), Steel can be categorized
into four basic groups based on the chemical compositions:
1. Carbon Steel
2. Alloy Steel
3. Stainless Steel
4. Tool Steel
There are many different grades of steel that encompass varied properties.
These properties can be physical, chemical and environmental.
All steel is composed of iron and carbon. It is the amount of carbon, and the
additional alloys that determine the properties of each grade.
Classifications
Types of Steel can also be classified by a variety of different factors:
1. Composition: Carbon range, Alloy, Stainless.
2. The production method: Continuous cast, Electric furnace, Etc.
3. Finishing method used: Cold Rolled, Hot Rolled, Cold Drawn (Cold
Finished), Etc.
4. Form or shape: Bar, Rod, Tube, Pipe, Plate, Sheet, Structural, Etc.
5. De-oxidation process (oxygen removed from steelmaking process): Killed
& Semi-Killed Steel, Etc.
6. Microstructure: Ferritic, Pearlitic, Martensitic, Etc.
7. Physical Strength (Per ASTM Standards).
8. Heat Treatment: Annealed, Quenched & Tempered, Etc.
9. Quality Nomenclature: Commercial Quality, Drawing Quality, Pressure
Vessel Quality, Etc.
Steel Numbering Systems
There are two major numbering systems used by the steel industry, the first
developed by the American Iron & Steel Institute (AISI), and the second by
the Society of Automotive Engineers (SAE). Both of these systems are based on
four digit code numbers when identifying the base carbon and alloy steels. There
are selections of alloys that have five digit codes instead.
If the first digit is a one (1) in this designation it indicates a carbon steel. All
carbon steels are in this group (1xxx) in both the SAE & AISI system. They are
also subdivided into four categories due to particular underlying properties
among them. See below:
Plain Carbon Steel is encompassed within the 10xx series (containing
1.00% Mn maximum)
Re-Sulfurized Carbon steel is encompassed within the 11xx series
Re -Sulfurized and Re-Phosphorized Carbon Steel is encompassed within
the 12xx series
Non-Re-Sulfurized High-Manganese (up-to 1.65%) carbon steel is
encompassed within the 15xx series.
The first digit on all other alloy steels (under the SAE-AISI system), are then
classified as follows:
2 = Nickel steels.
3 = Nickel-chromium steels.
4 = Molybdenum steels.
5 = Chromium steels.
6 = Chromium-vanadium steels.
7 = Tungsten-chromium steels.
8 = Nickel-chromium-molybdenum steels
9 = Silicon-manganese steels and various other SAE grades
The second digit of the series (sometimes but not always) indicates the
concentration of the major element in percentiles (1 equals 1%).
The last two digits of the series indicate the carbon concentration to 0.01%.
For example: SAE 5130 is a chromium alloy steel containing about 1% of
chromium and approximately 0.30% of carbon.
Carbon Steel
Carbon Steel can be segregated into three main categories: Low carbon steel
(sometimes known as mild steel); Medium carbon steel; and High carbon steel.
Low Carbon Steel (Mild Steel): Typically contain 0.04% to 0.30% carbon content.
This is one of the largest groups of Carbon Steel. It covers a great diversity of
shapes; from Flat Sheet to Structural Beam. Depending on the desired properties
needed, other elements are added or increased. For example: Drawing Quality
(DQ) – The carbon level is kept low and Aluminum is added, and for Structural
Steel the carbon level is higher and the manganese content is increased.
Medium Carbon Steel: Typically has a carbon range of 0.31% to 0.60%, and a
manganese content ranging from .060% to 1.65%. This product is stronger than
low carbon steel, and it is more difficult to form, weld and cut. Medium carbon
steels are quite often hardened and tempered using heat treatment.
High Carbon Steel: Commonly known as “carbon tool steel” it typically has a
carbon range between 0.61% and 1.50%. High carbon steel is very difficult to
cut, bend and weld. Once heat treated it becomes extremely hard and brittle.
Most Commonly Used ASTM Grades:
Carbon Steels:
A53/A53M-02. Standard specification for pipe—steel, black and hotdipped, zinc-coated,
welded, and seamless.
A105/A105M-02. Standard specification for carbon steel forgings for piping applications.
A106-02a. Standard specification for seamless carbon steel pipe for high-temperature
service.
A134-96(2001). Standard specification for pipe—steel, electric-fusion (arc)- welded
(sizes NPS 16 and over).
A135-01. Standard specification for electric-resistance-welded steel pipe.
A139-00. Standard specification for electric-fusion (arc)-welded steel pipe (NPS 4 and
over).
A179/A179M-90a(2001). Standard specification for seamless cold-drawn low-carbon
steel heat-exchanger and condenser tubes.
A181/A181M-01. Standard specification for carbon steel forgings, for general-purpose
piping.
A194/A194M-03b. Standard specification for carbon and alloy steel nuts for bolts for
high-pressure or high-temperature service or both.
A210/A210M-02. Standard specification for seamless medium-carbon steel boiler and
superheater tubes.
A234/A234M-03. Standard specification for piping fittings of wrought carbon steel and
alloy steel for moderate- and high-temperature service.
A333/A333M-99. Standard specification for seamless and welded steel pipe for low-
temperature service.
A334/A334M-99. Standard specification for seamless and welded carbon and alloy-steel
tubes for low-temperature service.
A350/A350M-02b. Standard specification for carbon and low-alloy steel forgings,
requiring notch toughness testing for piping components.
A369/A369M-02. Standard specification for carbon and ferritic alloy steel forged and
bored pipe for high-temperature service.
A381-96(2001). Standard specification for metal-arc-welded steel pipe for use with high-
pressure transmission systems.
A420/A420M-02. Standard specification for piping fittings of wrought carbon steel and
alloy steel for low-temperature service.
A524-96(2001). Standard specification for seamless carbon steel pipe for atmospheric
and lower temperatures.
A530/A530M-03. Standard specification for general requirements for specialized carbon
and alloy steel pipe.
A587-96(2001). Standard specification for electric-resistance-welded lowcarbon steel
pipe for the chemical industry.
A671-96(2001). Standard specification for electric-fusion-welded steel pipe for
atmospheric and lower temperatures.
A672-96(2001). Standard specification for electric-fusion-welded steel pipe for high-
pressure service at moderate temperatures.
A691-98(2002). Standard specification for carbon and alloy steel pipe, electric-fusion-
welded for high-pressure service at high temperatures.
Alloy Steels:
A182/A182M-02. Standard specification for forged or rolled alloy-steel pipe flanges,
forged fittings, and valves and parts for high-temperature service.
A193/A193M-03. Standard specification for alloy-steel and stainless steel bolting
materials for high-temperature service.
A194/A194M-03b. Standard specification for carbon and alloy steel nuts for bolts for
high-pressure or high-temperature service or both.
A234/A234M-03. Standard specification for piping fittings of wrought carbon steel and
alloy steel for moderate- and high-temperature service.
A320/A320M-03. Standard specification for alloy-steel bolting materials for low-
temperature service.
A334/A334M-99. Standard specification for seamless and welded carbon and alloy-steel
tubes for low-temperature service.
A350/A350M-02b. Standard specification for carbon and low-alloy steel forgings,
requiring notch toughness testing for piping components.
A369/A369M-02. Standard specification for carbon and ferritic alloy steel forged and
bored pipe for high-temperature service.
A335/A335M-03. Standard specification for seamless ferritic alloy-steel pipe for high-
temperature service.
A437/A437M-01a. Standard specification for alloy-steel turbine-type bolting material
specially heat treated for high-temperature service.
A530/A530M-03. Standard specification for general requirements for specialized carbon
and alloy steel pipe.
A691-98(2002). Standard specification for carbon and alloy steel pipe, electric-fusion-
welded for high-pressure service at high temperatures.
Stainless Steels:
A268/A268M-03. Standard specification for seamless and welded ferritic and
martensitic stainless steel tubing for general service.
A269-02a. Standard specification for seamless and welded austenitic stainless steel
tubing for general service.
A312/A312M-03. Standard specification for seamless and welded austenitic stainless
steel pipes.
A358/A358M-01. Standard specification for electric-fusion-welded austenitic chromium-
nickel alloy steel pipe for high-temperature service.
A376/A376M-02a. Standard specification for seamless austenitic steel pipe for high-
temperature central-station service.
A403/A403M-03a. Standard specification for wrought austenitic stainless steel piping
fittings.
A409/A409M-01. Standard specification for welded large-diameter austenitic steel pipe
for corrosive or high-temperature service.
A453/A453M-02. Standard specification for high-temperature bolting materials, with
expansion coefficients comparable to austenitic stainless steels.
A789/A789M-02a. Standard specification for seamless and welded ferritic/austenitic
stainless steel tubing for general service.
A790/A790M-03. Standard specification for seamless and welded ferritic/austenitic
stainless steel pipe.
A815/A815M-01a. Standard specification for wrought ferritic, ferritic/austenitic, and
martensitic stainless steel piping fittings.
