Materials - Fireproofing - for Petrochemical facilities Introduction

Fireproofing, a passive fire protection measure, refers to the act of making materials or structures more resistant to fire, or to those materials

themselves, or the act of applying such materials. Applying a certification listed fireproofing system to certain structures allows these to have

a fire-resistance rating.

The term fireproof does not necessarily mean that an item cannot ever burn: It relates to measured performance under specific conditions of

testing and evaluation. Fireproofing does not allow treated items to be entirely unaffected by any fire, as conventional materials are not

immune to the effects of fire at a sufficient intensity and/or duration.

Fireproofing is employed in refineries and petrochemical plants to minimize the escalation of a fire that would occur with the failure of

structural supports and the overheating of pressure vessels. The damage that fire could potentially do very early on, could add significant fuel

to the fire.

The purpose of fireproofing therefore, is to buy time. The traditional method of fireproofing has been poured-in-place concrete or gunite.

Other fireproofing materials, such as lightweight cements, prefabricated cementitious board, and intumescent coatings are used to a lesser

extent, primarily in areas deemed less critical and where weight reduction is a significant benefit.

Examples of Fireproofing on steel elements

Why Fireproofing is used?

Typically, fireproofing is designed to protect the structural steel which supports high risk or valuableequipment. The failure point is generally

considered to be 1000°F, as this is the point where steel has lostapproximately 50% of its structural strength. The aim then, is to prevent

structural steel from reaching 1000°F forsome period of time. Tanks, pressure vessels, and heat exchangers may experience a significant

cooling effect fromliquid contents and so, less fireproofing protection is generally required. Some thermal insulation systems mayserve a dual

role as fireproofing and this is common with some pressure vessels. Piping may be insulated but it isnot generally considered to be

fireproofed.

Fireproofing needs to be durable to survive the rigors of every day life in the plant so that if and when a fire does occur, the fire endurance

properties have been maintained and the fireproofing can be depended on to function satisfactorily. Everyday exposure may involve

mechanical abuse, exposure to oil, solvents, and chemicals, and outdoor weathering for prolonged periods of twenty, thirty, forty years or

more. As a coating for steel, fireproofing may provide a good measure of corrosion protection. When applied directly to steel, concrete may

passivate the steel surface by providing an elevated pH. Experience has shown, however, that passivation is less than certain, especially in

coastal marine environments. Corrosion under concrete fireproofing can be significant. Intumescent coatings promise better corrosion

protection than concrete by virtue of their low permeability but cases of severe corrosion under fireproofing (CUF) have been reported with

these materials.

Intumescent epoxies are complex proprietary materials. Concrete and some of the other materials that are used for fire protection are more

familiar. The materials themselves may seem simple, but the important details of system design are often overlooked.

Risk-Based Analysis

Fireproofing is a misnomer because no material is completely fireproof. All construction materials are subject to fire damage. What we really

mean is fire resistant - we seek to resist potential fire situations for a given period of time. Fireproofing is passive, built-in protection that

buys time to fight the fire, shut off the fire's fuel supply and shut down the process. The aim is to minimize the overall damage incurred.

The decision to fireproof is driven by risk-based analysis. One needs to first consider the nature of the fire threat and then make an

assessment of the required period of fire endurance for a wide variety of equipment including structural steel, pressure vessels, heat

exchangers, pipe supports, LPG spheres and bullets, valves, and cable trays. The location of specific equipment within a process unit is

important, as is a unit's location with regard to neighboring facilities.

Test Methods and required Time Rating

No fire test method is going to be typical of a real fire situation and so, there is no single correct or "best" fire test method. Standardized

testing simply provides a frame of reference for relative comparisons of fireproofing materials and designs. In the 70s, ASTM E119 "Fire Test

of Building Construction Materials" was the only internationally accepted standard for investigating the performance of fireproofing materials.

This test method, however, was designed to measure the fire performance of walls, columns, floors, and other building members in solid fuel

fire exposures. It does not simulate the high intensity of liquid hydrocarbon-fueled fires.

Where fireproofing is required, the level of fireproofing varies with the application in the plant. Typical protection requirements for a refinery

or petrochemical plant might be as follows:

For structural steel, a facility may require a fire test rating of two or three hours. Poured-in-place concrete or gunite is most common with

a specified minimum thickness of 2.0 to 3.0 inches (50-75 mm). Lightweight cementitious products may also be used.

For steel vessels, a facility may require a fire test rating of one to two hours. Gunite applied at 1.5 to 2.0 inches (40-50 mm) may be

required. Alternative fireproofing materials that provide a comparable fire resistance rating may be used, including systems that function

as both thermal insulation and fireproofing.

Plate and frame exchangers are a special concern because of the rubber gasketing material between plates. These exchangers are

provided with a protective enclosure designed to prevent the exchanger from exceeding its maximum operating temperature for an hour

or so. The maximum operating temperature is vendor specified and typically less than 300°F (150°C).

Electrical and pneumatic components (including manual initiators, valve actuators, aboveground wiring, cable, and conduit) essential to

emergency isolation, depressurization, and process shutdown are generally fireproofed to achieve a rating of at least 15-20 minutes. This

equipment needs to function properly in the first few minutes of a fire.

Fireproofing Materials Concrete

The excellent fire protection afforded by concrete has been demonstrated time and time again over 90 years of experience in the

petrochemical industry. The high mass and low thermal conductivity of concrete make it very effective at reducing heat input to the

underlying structure. Poured-in-place concrete, using forms, is common for columns and beams. Gunite is pneumatically applied to spheres

and other structures where the use of forms for poured-in-place concrete is impractical. The principal drawback with gunite application is that

it can be very messy.

Post-fire inspections have shown that concrete spalls to various degrees but the general conclusion is that concrete/gunite performs

satisfactorily with the steel structures well protected. Wire reinforcement is commonly used. Reinforcement does not prevent cracking and

spalling of the concrete but it does minimize the loss of fractured material during a fire exposure.

Excellent Fire Endurance of 30 Year Old Concrete

A refinery fire initiated at a gas oil line from a crude distillation unit and burned for about 12 hours. The main pipe rack near the crude tower

at the center of the fire was damaged beyond repair. The support structure for the crude tower overhead equipment was severely damaged.

The aluminum jacketed thermal insulation on vessels and exchangers was destroyed (aluminum melts at about 660°C) but most pressure

vessels and heat exchangers, showed no visible signs of permanent damage, primarily due to the cooling effect of liquid contents. Gaskets

that had been damaged and high strength bolts that had been tempered by the fire exposure, had to be replaced.

Thermal expansion and contraction on structural support columns near ground zero caused a good deal of cracking and delamination of the

concrete fireproofing; however, no evidence of deep damage to the concrete was found. The main concern was for the support structure of

the crude distillation tower as the refinery is located in a seismic zone. The radiant heat and direct fire exposure caused spalling of the 30

year old concrete cover on the exterior of the vessel skirt. Firewater cooling added to the spalling problem. Some rebar was exposed at the

crude tower foundation, most notably on the side of the tower that faced the fire. Concrete was removed for inspection of the crude tower

skirt and anchor bolts. No heat buckling of the skirt or distortion of the bolt seatings was observed. Bolts were checked for cracks and

hardness measurements were made to confirm strength. The concrete fireproofing had prevented any permanent damage to the vessel skirt

and anchor bolts. The 30 year old concrete was now a mess but it had served its function.

Concrete exposed to hydrocarbon fires

Concrete, by itself, cannot withstand hydrocarbon fires. In the Euro tunnel that connects United Kingdom and France, an intense fire broke

out and reduced the concrete lining in the undersea tunnel down to a minimum. In ordinary building fires, concrete typically achieves

excellent fire-resistance ratings, unless it is too wet, which can cause it to crack and explode. For unprotected concrete, the sudden

endothermic reaction of the hydrates and unbound humidity inside the concrete causes such pressure as to spall off the concrete, which then

winds up in small pieces on the floor of the tunnel.

This is the reason why laboratories insert humidity probes into all concrete slabs that undergo fire testing even in accordance with the less

severe building elements curve (DIN4102, ASTM E119, BS476, or ULC-S101). The need for fireproofing was demonstrated, among other fire

protection measures, in the European "Eureka" Fire Tunnel Research Project, which resulted in building codes for the trade to avoid the

effects of such fires upon traffic tunnels. Cementitious spray fireproofing must be certification listed and applied in the field as per that listing,

using a hydrocarbon fire test curve such as the one that is also used in UL1709.

Alternative fireproofing methods

Among the conventional materials, purpose-designed spray fireproofing plasters have become abundantly available the world over. The

inorganic methods include:

Gypsum plasters

Cementitious plasters

Fibrous plasters

The industry considers gypsum-based plasters to be cementitious, even though these contain no Portland, or calcium aluminate cements.

Cementitious plasters that contain Portland cement have been traditionally lightened by the use of inorganic lightweight aggregates, such as

vermiculite and perlite.

Gypsum plasters have been lightened by using chemical additives to create bubbles that displace solids, thus reducing the bulk density. Also,

lightweight polystyrene beads have been mixed into the plasters at the factory in an effort to reduce the density, which generally results in a

more effective insulation at a lower cost.

Fibrous plasters, containing either mineral wool, or ceramic fibres tend to simply entrain more air, thus displacing the heavy fibres. On-site

cost reduction efforts, at times purposely contravening the requirements of the certification listing, can further enhance such displacement of

solids. This has resulted in architects specifying the use of on-site testing of proper densities to ensure the products installed meet the

certification listings employed for each installed configuration, because excessively light inorganic fireproofing does not provide adequate

protection and are thus in violation of the listings.

Proprietary boards and sheets, made of gypsum, calcium silicate, vermiculite, perlite, mechanically bonded composite boards made of

punched sheet-metal and cellulose reinforced concrete have all been used to clad items for increased fire-resistance.

An alternative method to keep building steel below its softening temperature is to use liquid convection cooling in hollow structural members.

This method was patented in the 19th century although the first prominent example was 89 years later.

References

API Publication 2218, Fireproofing Practices in Petroleum and Petrochemical Processing Plants

ASTM E119, Fire Tests of Building Construction and Materials

ASTM E1529, Standard Test Methods for Determining Effects of Large Hydrocarbon Pool Fires on Structural Members and

Assemblies

NACE RP0198, The Control of Corrosion Under Thermal Insulation and Fireproofing Materials - A Systems Approach

NACE Publication 6H189, A State-of-the Art Report of Protective Coatings for Carbon Steel and Austenitic Stainless Steel Surfaces

Under Thermal Insulation and Cementitious Fireproofing

Schilling, Mark S., Fireproofing for petrochemical facilities

About the American Society of Mechanical Engineers

Who is ASME?

Founded in 1880 as the American Society of Mechanical Engineers, today ASME International is a non-profit educational and technical

organization with more than 120,000 members worldwide.

The aim of ASME is to promote art, science and allied science and the practice of mechanical and multi-disciplinary engineering. ASME has

developed several codes and standards to enhance public safety and productivity of Engineers.

ASME Codes and Standards

ASME codes and standards were developed to enhance the public safety and productivity of the engineers.

The ASME standards are the sort of technical guides for the designers, manufacturers and users regarding the usage of the product. Some of

these standards are written in few paragraphs, while others may run into multiple pages.

ASME codes set the guidelines for the mechanical engineers to follow to common system of manufacturing not only in US but also in the

countries that have adopted ASME standards.

However, the manufacturers, inspectors and installers cannot be forced to use the ASME codes and standards, as they are only the guidelines.

They will become compulsory only if they have been included in the contract.

The ASME standards are effective because they have been universally accepted. Their use makes communication between the manufacturers

and users faster and more effective.

Further, the customers will get the same product no matter where they purchase from if they are standard products.

For example, if you have purchased a Weld Neck flange in Houston, if it is standardized item, no matter where you purchase a Blind flange

from, it will fit on the flange purchased in Houston.

Note

A Standard can be defined as a set of technical definitions and guidelines that function as instructions for designers, manufacturers,

operators, or users of equipment.

A standard becomes a Code when it has been adopted by one or more governmental bodies and is enforceable by law, or when it has

been incorporated into a business contract.

About the American Society for Testing and Materials

Who is ASTM?

Organized in 1898, ASTM International is one of the world's largest international standards developing organizations.

At ASTM International, producers, users, consumers, and others from all over the world join together to develop voluntary consensus

standards. ASTM standards are developed under a process that embraces the World Trade Organization Technical Barriers to Trade

Agreement principles. The ASTM standards development process is open and transparent, allowing individuals and governments to participate

directly, and as equals, in a global consensus decision.

Standards

Thirty thousand ASTM members from 125 countries bring their technical expertise to the development of ASTM's 12,000 international

standards. These standards are used and accepted worldwide and cover areas such as metals, paints, plastics, textiles, petroleum,

construction, energy, the environment, consumer products, medical services and devices, and electronics.

Development of standards

The open process in which ASTM standards are developed is one reason why so many and such a broad range of industries have done their

diverse standards development work within ASTM International.

Professionals from all over the globe participate in the ASTM system which recognizes technical expertise, not country of origin. With a high

level of technical quality at the core of the ASTM standard, almost 50 percent of ASTM standards are distributed outside the United States.

To facilitate broad global input, ASTM International uses online technologies that encourage open participation and responsiveness to industry

needs. They include Internet-based Standards Development Forums enabling 24/7 access worldwide, on-line balloting, electronic minutes and

templates, virtual meetings, and state-of-the- art distribution methods.

Services of ASTM International

In addition to this accommodating standards development atmosphere, ASTM International provides services that expand the knowledge and

application of standards. ASTM's programs include symposia, proficiency testing programs, publications in a variety of formats, and technical

training courses. ASTM publishes a monthly magazine, Standardization News, which covers the topic of standards development around the

world.

Use of standards

The standards of ASTM International are used in research and development, quality systems, product testing and acceptance, and commercial

transactions all around the globe. They are integral components of today's competitive business strategies.

Annual book of ASTM

The Annual Book of ASTM Standards for Steel consists of 8 volumes. It contains formally approved ASTM standard classifications, guides,

practices, specifications, test methods and terminology and related material such as proposals. These terms are defined as follows in the

Regulations Governing ASTM Technical Committees.

Covers:

Steel Pipes, Tubes and Fittings

Steel Plates for General Structure

Steel Plates for Boiler and Pressure Vessels

Steels for Machine Structural Use

Steels for Special Purposes

The following data is given for each standard:

Standard number and year

Grade

Chemical composition

Mechanical properties (yield point, tensile strength, notch toughness)

When deemed useful, steel type, manufacturing method, thickness of plate, heat treatment, and other data are described.

Source: ASTM

Who is API?

The American Petroleum Institute (API) is the only national trade association that represents all aspects of America's oil and natural gas

industry. Their nearly 400 corporate members, from the largest major oil company to the smallest of independents, come from all segments

of the industry. They are producers, refiners, suppliers, pipeline operators and marine transporters, as well as service and supply companies

that support all segments of the industry.

Although their focus is primarily domestic, in recent years their work has expanded to include a growing international dimension, and today

API is recognized around the world for its broad range of programs.

Range of programs of API Advocacy

We speak for the oil and natural gas industry to the public, Congress and the Executive Branch, state governments and the media. We

negotiate with regulatory agencies, represent the industry in legal proceedings, participate in coalitions and work in partnership with other

associations to achieve our members' public policy goals.

Research and Statistics

API conducts or sponsors research ranging from economic analyses to toxicological testing. And we collect, maintain and publish statistics and

data on all aspects of U.S. industry operations, including supply and demand for various products, imports and exports, drilling activities and

costs, and well completions. This data provides timely indicators of industry trends. API's Weekly Statistical Bulletin is the most recognized

publication, widely reported by the media.

Illustration of oil rig platform by Tracey Saxby

IAN Image Library (ian.umces.edu/imagelibrary/)

Standards

For more than 75 years, API has led the development of petroleum and petrochemical equipment and operating standards. These represent

the industry's collective wisdom on everything from drill bits to environmental protection and embrace proven, sound engineering and

operating practices and safe, interchangeable equipment and materials. API maintains more than 500 standards and recommended practices.

Many have been incorporated into state and federal regulations; and increasingly, they're also being adopted by the International

Organization for Standardization, a global federation of more than 100 standards groups.

Certification

Each day, the oil and natural gas industry depends on equipment to produce, refine and distribute its products. The equipment used is some

of the most technologically advanced available in the search for oil and gas and allows the industry to operate in an environmentally safe

manner. Designed for manufacturers of production, drilling, and refinery equipment, the API Monogram Program verifies that manufacturers

are operating in compliance with industry standards. API also provides quality, environmental, and occupational health and safety

management systems certification through APIQR. This service is accredited by the ANAB (ANSI-ASQ National Accreditation Board) for ISO

9001 and ISO 14001. Let APIQR's industry expertise certify your organization to API Spec Q1, ISO/TS 29001 and OHS 18001.

API also certifies inspectors of industry equipment through our Individual Certification Programs, designed to recognize working professionals

who are knowledgeable of industry inspection codes and are performing their jobs in accordance with those codes. Through our Witnessing

Programs, API provides knowledgeable and experienced witnesses to observe critical material and equipment testing and verification. API's

Training Provider Certification Program provides third-party certification for a variety of oil and gas industry training courses, further ensuring

that any training provided meets industry needs.

For consumers, API provides the API's Engine Oil Licensing and Certification System (EOLCS). It is a voluntary licensing and certification

program that authorizes engine oil marketers who meet specified requirements to use the API Engine Oil Quality Marks. These emblems go

directly on each container of oil that retains the certification for and is there to help consumers identify quality engine oils for their gasoline-

and diesel-powered vehicles

Education

API organizes seminars, workshops, conferences and symposia on public policy issues. Through API University, we provide training materials

to help people in the oil and natural gas business meet regulatory requirements and industry standards. To prepare the next generation of

Americans to make informed decisions or pursue careers in our industry, we work with the National Science Teachers Association and other

educational groups to impart scientific literacy and develop critical thinking skills in the classroom. Resources developed specifically for

teachers and students include Energy & Society, a multi-disciplinary K-8 curriculum program, and www.classroom-energy.org, informative

and interactive educational resources in one easy-to-use location.

API's mission

API's mission is to influence public policy in support of a strong, viable U.S. oil and natural gas industry essential to meet the energy needs of

consumers in an efficient, environmentally responsible manner.

As the U.S. oil and natural gas industry's primary trade association, API:

Engages in federal and state legislative and regulatory advocacy that is based on scientific research; technical legal and economic analysis;

and public issues communication.

Provides an industry forum to develop consensus policies and collective action on issues impacting its members.

Works collaboratively with all industry oil and gas associations, and other organizations, to enhance industry unity and effectiveness in its

advocacy.

API also provides the opportunity for standards development, technical cooperation and other activities to improve the industry's

competitiveness through sponsorship of self-supporting programs.

Source: API

Definition and Details of Pipe Definition of Pipe

Pipe is a hollow tube with round cross section for the conveyance of products. The products include fluids, gas, pellets, powders and more.

The word pipe is used as distinguished from tube to apply to tubular products of dimensions commonly used for pipeline and piping systems.

On this website, pipes conforming to the dimensional requirements of: ASME B36.10 Welded and Seamless Wrought Steel Pipe and ASME

B36.19 Stainless Steel Pipe will be discussed.

Pipe or Tube?

In the world of piping, the terms pipe and tube will be used. Pipe is customarily identified by "Nominal Pipe Size" (NPS), with wall thickness

defined by "Schedule number" (SCH). Tube is customarily specified by its outside diameter (O.D.) and wall thickness (WT), expressed either

in Birmingham wire gage (BWG) or in thousandths of an inch.

Pipe: NPS 1/2-SCH 40 is even to outside diameter 21,3 mm with a wall thickness of 2,77 mm.

Tube: 1/2" x 1,5 is even to outside diameter 12,7 mm with a wall thickness of 1,5 mm.

The principal uses for tube are in Heat Exchangers, instrument lines and small interconnections on equipment such as compressors, boilers

etc..

Materials for Pipe

Engineering companies have materials engineers to determine materials to be used in piping systems. Most pipe is of carbon steel (depending

on service) is manufactured to different ASTM standards.

Carbon-steel pipe is strong, ductile, weldable, machinable, reasonably, durable and is nearly always cheaper than pipe made from other

materials. If carbon-steel pipe can meet the requirements of pressure, temperature, corrosion resistance and hygiene, it is the natural choice.

Iron pipe is made from cast-iron and ductile-iron. The principal uses are for water, gas and sewage lines.

Plastic pipe may be used to convey actively corrosive fluids, and is especially useful for handling corrosive or hazardous gases and dilute

mineral acids.

Other Metals and Alloys pipe made from copper, lead, nickel, brass, aluminium and various stainless steels can be readily obtained. These

materials are relatively expensive and are selected usually either because of their particular corrosion resistance to the process chemical,

their good Heat Transfer, or for their tensile strength at high temperatures. Copper and copper alloys are traditional for instrument lines, food

processing and Heat Transfer equipment. Stainless steels are increasingly being used for these.

Lined Pipe

Some materials described above, have been combined to form lined pipe systems.

For example, a carbon steel pipe can be internally lined with material able to withstand chemical attack permits its use to carry corrosive

fluids. Linings (Teflon®, for example) can be applied after fabricating the piping, so it is possible to fabricate whole pipe spools before lining.

Other internal layers can be: glass, various plastics, concrete etc., also coatings, like Epoxy, Bituminous Asphalt, Zink etc. can help to protect

the inner pipe.

Many things are important in determining the right material. The most important of these are pressure, temperature, product type,

dimensions, costs etc..

Definition and Details of Pipe - Nominal Pipe Size -

Nominal Pipe Size

Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. The name NPS

is based on the earlier "Iron Pipe Size" (IPS) system.

That IPS system was established to designate the pipe size. The size represented the approximate inside diameter of the pipe in inches. An

IPS 6" pipe is one whose inside diameter is approximately 6 inches. Users started to call the pipe as 2inch, 4inch, 6inch pipe and so on. To

begin, each pipe size was produced to have one thickness, which later was termed as standard (STD) or standard weight (STD.WT.). The

outside diameter of the pipe was standardized.

As the industrial requirements handling higher pressure fluids, pipes were manufactured with thicker walls, which has become known as an

extra strong (XS) or extra heavy (XH). The higher pressure requirements increased further, with thicker wall pipes. Accordingly, pipes were

made with double extra strong (XXS) or double extra heavy (XXH) walls, while the standardized outside diameters are unchanged. Note that

on this website only terms XS and XXS are used.

Pipe Schedule

So, at the IPS time only three walltickness were in use. In March 1927, the American Standards Association surveyed industry and created a

system that designated wall thicknesses based on smaller steps between sizes. The designation known as nominal pipe size replaced iron pipe

size, and the term schedule (SCH) was invented to specify the nominal wall thickness of pipe. By adding schedule numbers to the IPS

standards, today we know a range of wall thicknesses, namely:

SCH 5, 5S, 10, 10S, 20, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160, STD, XS and XXS.

Nominal pipe size (NPS) is a dimensionless designator of pipe size. It indicates standard pipe size when followed by the specific size

designation number without an inch symbol. For example, NPS 6 indicates a pipe whose outside diameter is 168.3 mm.

The NPS is very loosely related to the inside diameter in inches, and NPS 12 and smaller pipe has outside diameter greater than the size

designator. For NPS 14 and larger, the NPS is equal to 14inch.

For a given NPS, the outside diameter stays constant and the wall thickness increases with larger schedule number. The inside diameter will

depend upon the pipe wall thickness specified by the schedule number.

Summary:

Pipe size is specified with two non-dimensional numbers,

nominal pipe size (NPS)

schedule number (SCH)

and the relationship between these numbers determine the inside diameter of a pipe.

Stainless Steel Pipe dimensions determined by ASME B36.19 covering the outside diameter and the Schedule wall thickness. Note that

stainless wall thicknesses to ASME B36.19 all have an "S" suffix. Sizes without an "S" suffix are to ASME B36.10 which is intended for carbon

steel pipes.

The International Standards Organization (ISO) also employs a system with a dimensionless designator.

Diameter nominal (DN) is used in the metric unit system. It indicates standard pipe size when followed by the specific size designation

number without a millimeter symbol. For example, DN 80 is the equivalent designation of NPS 3. Below a table with equivalents for NPS and

DN pipe sizes.

NPS ½ ¾ 1 1¼ 1½ 2 2½ 3 3½ 4

DN 15 20 25 32 40 50 65 80 90 100

Note: For NPS ≥ 4, the related DN = 25 multiplied by the NPS number.

Do you now what is "ein zweihunderter Rohr" ?. Germans means with that a pipe NPS 8 or DN 200. In this case, the Dutch talking about a "8

duimer". I'm really curious how people in other countries indicates a pipe.

Examples of actual Inside and Outside Diameters

Actual outside diameters

NPS 1 actual O.D. = 1.5/16" (33.4 mm)

NPS 2 actual O.D. = 2.3/8" (60.3 mm)

NPS 3 actual O.D. = 3½" (99.9 mm)

NPS 4 actual O.D. = 4.1/2" (114.3 mm)

NPS 12 actual O.D. = 12.3/4" (323.9 mm)

NPS 14 actual O.D. = 14" (355.6 mm)

Below you will find an example of the true inside diameters of a 1 inch pipe.

NPS 1-SCH 40 = O.D.33,4 mm - WT 3,38 mm - I.D. 26,64 mm

NPS 1-SCH 80 = O.D.33,4 mm - WT. 4,55 mm - I.D. 24,30 mm

NPS 1-SCH 160 = O.D.33,4 mm - WT 6,35 mm - I.D. 20,70 mm

Such as above defined, no inside diameter corresponds to the truth 1" (25,4 mm).

The inside diameter is determined by the wall thickness (WT).

Facts that you need to know!

Schedule 40 and 80 approaching the STD and XS and are in many cases the same.

From NPS 12 and above the wall thickness between schedule 40 and STD are different, from NPS 10 and above the wall thickness between

schedule 80 and XS are different.

Schedule 10, 40 and 80 are in many cases the same as schedule 10S, 40S and 80S.

But watch out, from NPS 12 - NPS 22 the wall thicknesses in some cases are different. Pipes with suffix "S" have in that range thinner wall

ticknesses.

ASME B36.19 does not cover all pipe sizes. Therefore, the dimensional requirements of ASME B36.10 apply to stainless steel pipe of the sizes

and schedules not covered by ASME B36.19.

Remark(s) of the Author...

The Story Behind Nominal Pipe Size March 9, 2006

A question was put to the PM Engineer (PME) staff (one of SUPPLY HOUSE TIMES sister magazines) asking how nominal pipe size

came to be. Here is the answer provided by PME Editorial Director Julius Ballanco.

The person directly responsible for the nominal pipe size was a gentleman by the name of Robert Briggs. Briggs was the superintendent of

the Pascal Iron Works in Philadelphia. In 1862, he wrote a set of pipe specifications for iron pipe, and passed them around to all of the

mills in the area.

Realize that in 1862, the United States was engaged in the Civil War. Each pipe mill made its own pipe and fittings to its own

specifications. Briggs tried to standardize the sizing, which would also help the war effort. The pipe and fittings would be interchangeable

between mills. This was rather novel in 1862.

The pipe standards went on to become known as the "Briggs Standards". They eventually became the American Standards, and finally the

standards used for modern day pipe.

The current ASTM A53 Steel Pipe Standard uses basically the Briggs Standard for pipe sizes 1/2 inch through 4 inch. You will notice that

after 4 inches, pipe starts to get closer to the actual dimension used to identify the pipe.

So, you are probably asking, where did the sizes come from ?. Well, they were the sizes of the dies used in Pascal Iron Works. Briggs

made everyone adjust to him. Hence, the name "nominal" pipe size came about, meaning "close to" or "somewhere in the proximity of"

the actual dimension.

I found the story behind Nominal Pipe Size on Supplyhouse Times

Definition and Details of Pipe - Lengths & Ends - Types, Lengths and Ends of Pipes

Pipe manufacturing refers to how the individual pieces of pipe are made in a pipe mill; it does not refer to how the pieces are connected in the

field to form a continuous pipeline. Each piece of pipe produced by a pipe mill is called a joint or a length (regardless of its measured length).

In some cases, pipe is shipped to the pipeline construction site as "double joints", where two pieces of pipe are pre-welded together to save

time. Most of the pipe used for oil and gas pipelines is seamless or longitudinally welded, although spirally welded pipe is common for larger

diameters.

Steel Pipes are manufactured in 4 versions:

• Longitudinally Welded SAW • Spiral Welded • Electric Resistance Welded (ERW) • Seamless

Welded Pipe

Welded pipe (pipe manufactured with a weld) is a tubular product made out of flat plates, known as skelp, that are formed, bent and

prepared for welding. The most popular process for large diameter pipe uses a longitudinal seam weld.

Spiral welded pipe is an alternative process, spiral weld construction allows large diameter pipe to be produced from narrower plates or skelp.

The defects that occur in spiral welded pipe are mainly those associated with the SAW weld, and are similar in nature to those for

longitudinally welded SAW pipe.

Electric Resistance Welded (ERW) and High Frequency Induction (HFI) Welded Pipe, originally this type of pipe, which contains a solid phase

butt weld, was produced using resistance heating to make the longitudinal weld (ERW). But most pipe mills now use high frequency induction

heating (HFI) for better control and consistency. However, the product is still often referred to as ERW pipe, even though the weld may have

been produced by the HFI process.

Seamless Pipe Plug Mill Process

This process is used to make larger sizes of seamless pipe, typically 6 to 16 inches (150 to 400 mm) diameter. An ingot of steel weighing up

to two tons is heated to 2,370°F (1,300°C) and pierced. The hole in the hollow shell is enlarged on a rotary elongator, resulting in a short

thick-walled tube known as a bloom.

An internal plug approximately the same diameter as the finished diameter of the pipe is then forced through the bloom. The bloom

containing the plug is then passed between the rolls of the plug mill. Rotation of the rolls reduces the wall thickness. The tube is rotated

through 90° for each pass through the plug mill to ensure roundness. The tube is then passed through a reeling mill and reducing mill to even

out the wall thickness and produce the finished dimensions. The tube is then cut to length before heat treatment, final straightening,

inspection, and hydrostatic testing.

Seamless Pipe Mandrell Mill Process

This process is used to make smaller sizes of seamless pipe, typically 1 to 6 inches (25 to 150 mm) diameter. The ingot of steel is heated to

2,370°F (1,300°C) and pierced. A mandrel is inserted into the tube and the assembly is passed through a rolling (mandrel) mill. Unlike the

plug mill, the mandrel mill reduces wall thickness continuously with a series of pairs of curved rollers set at 90° angles to each other. After

reheating, the pipe is passed through a multi-stand stretch-reducing mill to reduce the diameter to the finished diameter. The pipe is then cut

to length before heat treatment, final straightening, inspection, and hydrostatic testing.

Seamless Pipe Extrusion Process

This process is used for small diameter tubes only. The bar stock is cut to length and heated to 2,280°F (1,250°C) before being sized and

descaled. The billet is then extruded through a steel die. After extrusion, the final tube dimensions and surface quality are obtained with a

multi-stand reducing mill.

Electric Resistance Welded (ERW) and High Frequency Induction (HFI) Welded Pipe

Originally this type of pipe, which contains a solid phase butt weld, was produced using resistance heating to make the longitudinal weld

(ERW), but most pipe mills now use high frequency induction heating (HFI) for better control and consistency. However, the product is still

often referred to as ERW pipe, even though the weld may have been produced by the HFI process.

The defects that can occur in ERW/HFI pipe are those associated with strip production, such as laminations and defects at the narrow weld

line. Lack of fusion due to insufficient heat and pressure is the principal defect, although hook cracks can also form due to realignment of non

metallic inclusions at the weld interface. Because the weld line is not visible after trimming, and the nature of the solid phase welding process,

considerable lengths of weld with poor fusion can be produced if the welding parameters fall outside the set limits. In addition, early ERW pipe

was subject to pressure reversals, a problem that results in failure in service at a lower stress than that seen in the pre-service pressure test.

This problem is caused by crack growth during the pressure test hold period, which in the case of early ERW pipe was due to a combination of

low weld line toughness and lack of fusion defects.

A note about the lack of fusion in ERW weld

As a result of these early problems, ERW pipe was generally regarded as a second-grade pipe suitable only for low pressure applications.

However, prompted by a shortage of seamless pipe and the lower cost of ERW pipe, suppliers and end users directed a major effort toward

improving the pipe mill quality in the 1980s. In particular, accurate tracking of the weld line by the automatic ultrasonic inspection equipment

was found to be crucial, since the weld line can rotate slightly as the pipe leaves the welding station. In addition, the standard of heat

treatment of the weld line, which is necessary to ensure good toughness, was found to be important and some specifications call for local

weld line heat treatment using induction coils followed by full body normalizing of the whole pipe in a furnace. As a result of these

improvements, modern ERW/HFI pipe has much better performance than the traditional product and has been accepted by a number of

operators for high pressure gas transmission.

Text about types of welded and seamless pipe for this page are coming from: General Electric Company

Length of Pipes

Piping lengths from the factory not exactly cut to length but are normally delivered as:

Single random length has a length of around 5-7 meter

Double random length has a length of around 11-13 meter

Shorter and longer lengths are available, but for a calculation, it is wise, to use this standard lengths; other sizes are probably more

expensive.

Ends of Pipes

For the ends of pipes are 3 standard versions available.

Plain Ends (PE)

Threaded Ends (TE)

Beveled Ends (BE)

The PE pipes will generally be used for the smaller diameters pipe systems and in combination with Slip On flanges and Socket Weld fittings

and flanges.

The TE implementation speaks for itself, this performance will generally used for small diameters pipe systems, and the connections will be

made with threaded flanges and threaded fittings.

The BE implementation is applied to all diameters of buttweld flanges or buttweld fittings, and will be directly welded (with a small gap 3-4

mm) to each other or to the pipe. Ends are mostly be beveled to angle 30° (+ 5° / -0°) with a root face of 1.6 mm (± 0.8 mm).

Steel Pipe and Manufacturing Processes Introduction

The advent of rolling mill technology and its development during the first half of the nineteenth century also heralded in the industrial

manufacture of tube and pipe. Initially, rolled strips of sheet were formed into a circular cross section by funnel arrangements or rolls, and

then butt or lap welded in the same heat (forge welding process).

Toward the end of the century, various processes became available for the manufacture of seamless tube and pipe, with production volumes

rapidly increasing over a relatively short period. In spite of the application of other welding processes, the ongoing development and further

improvement of the seamless techniques led to welded tube being almost completely pushed out of the market, with the result that seamless

tube and pipe dominated until the Second World War.

During the subsequent period, the results of research into welding technology led to an upturn in the fortunes of the welded tube, with

burgeoning development work ensuing and wide propagation of numerous tube welding processes. Currently, around two thirds of steel tube

production in the world are accounted for by welding processes. Of this figure, however, about one quarter takes the form of so-called large-

diameter line pipe in size ranges outside those which are economically viable in seamless tube and pipe manufacturing.

Seamless Tube and Pipe

The main seamless tube manufacturing processes came into being toward the end of the nineteenth century. As patent and proprietary rights

expired, the various parallel developments initially pursued became less distinct and their individual forming stages were merged into new

processes. Today, the state of the art has developed to the point where preference is given to the following modern high-performance

processes:

The continuous mandrel rolling process and the push bench process in the size range from approx. 21 to 178 mm outside diameter.

The multi-stand plug mill (MPM) with controlled (constrained) floating mandrel bar and the plug mill process in the size range from approx.

140 to 406 mm outside diameter.

The cross roll piercing and pilger rolling process in the size range from approx. 250 to 660 mm outside diameter.

Mandrel Mill Process In the Mandrel Mill Process, a solid round (billet) is used. It is heated in a rotary hearth heating furnace and then pierced by a piercer.

The pierced billet or hollow shell is rolled by a mandrel mill to reduce the outside diameter and wall thickness which forms a multiple length

mother tube. The mother tube is reheated and further reduced to specified dimensions by the stretch reducer. The tube is then cooled, cut,

straightened and subjected to finishing and inspection processes befor shipment.

* Note: Processes marked by an asterisk are conducted specification and/or customer requirements

Video

Tube production at Sandvik (mandrel mill process)

3D Animation of integrated tube production at Sandvik. The film visualze the uniqeness of Sandviks processes and the complete manufacturing

process of stainless steel tubes. Sandvik controls the entire steel making process -- from the melt to finished product. 250 engineers are continuously

developing new alloys and making modifications to existing products in order to satisfy new market needs and customer requests.

Some employers block "You Tube"...Sorry

Mannesmann plug mill process In the Plug Mill Process, a solid round (billet) is used. It is uniformly heated in the rotary hearth heating furnace and then pierced by a

Mannesmann piercer. The pierced billet or hollow shell is rollreduced in outside diameter and wall thickness. The rolled tube simultaneously

burnished inside and outside by a reeling machine. The reeled tube is then sized by a sizing mill to the specified dimensions. From this step

the tube goes through the straightener. This process completes the hot working of the tube. The tube (referred to as a mother tube) after

finishing and inspection, becomes a finished product.

Welded Tube and Pipe

Ever since it became possible to manufacture strip and plate, people have constantly tried to bend the material and connect its edges in order

to manufacture tube and pipe. This led to the development of the oldest welding process, that of forge-welding, which goes back over 150

years.

In 1825, the British ironware merchant James Whitehouse was granted a patent for the manufacture of welded pipe. The process consisted of

forging individual metal plates over a mandrel to produce an open-seam pipe, and then heating the mating edges of the open seam and

welding them by pressing them together mechanically in a draw bench.

The technology evolved to the point where strip could be formed and welded in one pass in a welding furnace. The development of this butt-

welding concept culminated in 1931 in the Fretz-Moon process devised by J. Moon, an American, and his German colleague Fretz.

Welding lines employing this process are still operating successfully today in the manufacture of tube up to outside diameters of approx. 114

mm. Aside from this hot pressure welding technique, in which the strip is heated in a furnace to welding temperature, several other processes

were devised by the American E. Thomson between the years 1886 and 1890 enabling metals to be electrically welded. The basis for this was

the property discovered by James P. Joule whereby passing an electric current through a conductor causes it to heat up due to its electrical

resistance.

In 1898, the Standard Tool Company, USA, was granted a patent covering the application of electric resistance welding for tube and pipe

manufacture. The production of electric resistance welded tube and pipe received a considerable boost in the United States, and much later in

Germany, following the establishment of continuous hot strip rolling mills for the production of the bulk starting material necessary for large-

scale manufacture. During the Second World War, an argon arc welding process was invented - again in the United States - which enabled the

efficient welding of magnesium in aircraft construction.

As a consequence of this development, various gas-shielded welding processes were developed, predominantly for the production of stainless

steel tube.Following the far-reaching developments which have occurred in the energy sector in the last 30 years, and the resultant

construction of large-capacity long-distance pipelines, the submerged-arc welding process has gained a position of pre-eminence for the

welding of line pipe of diameters upward of approx. 500 mm.

Electric Weld Pipe Mill

Steel strip in coil, which has been slit into the required width from wide strip, is shaped by a series of forming rolls into a multiple length shell.

The longitudinal edges are continously joined by high frequency resistance/induction welding.

The weld of multiple length shell is then head treated electrically, sized and cut to specified lengths by a flying cut-off machine. The cut pipe

is straightened and squared at both ends.

These operations are followed by ultrasonic inspection or hydrostatic testing.

Definition and Details of Pipe - Materials - ASTM Grades

Dimensions from carbon steel pipes are defined in the ASME B36.10 standard, dimensions for stainless steel pipe are defined in the ASME

B36.19 standard. The material qualities for these pipes are defined in the ASTM standards.

These ASTM standards, define the specific manufacturing process of the material and determine the exact chemical composition of pipes,

fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by "Grade".

For example, a carbon steel pipe can be identified with Grade A or B, a stainless-steel pipe with Grade TP304 or Grade TP321 etc..

Below you will find as an example a table with chemical requirements for fittings ASTM A403 Grade WP304, WP304L, WP316L and a table

with frequent Grades, arranged on pipe and pipe-components, which belong together as a group.

As you may be have noted, in the table below, ASTM A105 has no Grade. Sometimes ASTM A105N is described; "N" stands not for Grade, but

for normalized. Normalizing is a type of heat treatment, applicable to ferrous metals only. The purpose of normalizing is to remove the

internal stresses induced by heat treating, casting, forming etc..

Chemical requirements composition, %

Grade F304 (A) Grade F304L (A) Grade F316L (A-B)

Carbon, max 0.08 0.035 0.035

Manganese, max 2.00 2.00 2.00

Phosphorus, max 0.045 0.045 0.045

Sulfur, max 0.030 0.030 0.030

Silicon, max 1.00 1.00 1.00

Nickel 8 - 11 8 - 13 10 - 15

Chrome 18 - 20 18 - 20 16 - 18

Molybdenum - - 2.00-3.00

(A) Carbon 0.040% max. is necessary where many drawing passes are required, as with outside diameter <0.5 inch (12.7 mm), or nominal wall

thickness <0.049 inch (1.2 mm).

(B) On pierced tube, Nickel may be 11 - 16.00%.

ASTM Grades

Material Pipes Fittings Flanges Valves Bolts & Nuts

Carbon Steel A106 Gr A A234 Gr WPA A105 A216 Gr WCB A193 Gr B7

A194 Gr 2H A106 Gr B A234 Gr WPB A105 A216 Gr WCB

A106 Gr C A234 Gr WPC A105 A216 Gr WCB

Carbon Steel

Alloy

High-Temp

A335 Gr P1 A234 Gr WP1 A182 Gr F1 A217 Gr WC1 A193 Gr B7

A194 Gr 2H A335 Gr P11 A234 Gr WP11 A182 Gr F11 A217 Gr WC6

A335 Gr P12 A234 Gr WP12 A182 Gr F12 A217 Gr WC6

A335 Gr P22 A234 Gr WP22 A182 Gr F22 A217 Gr WC9

A335 Gr P5 A234 Gr WP5 A182 Gr F5 A217 Gr C5

A335 Gr P9 A234 Gr WP9 A182 Gr F9 A217 Gr C12

Carbon Steel

Alloy

Low-Temp

A333 GR 6 A420 Gr WPL6 A350 Gr LF2 A352 Gr LCB A320 Gr L7

A194 Gr 7 A333 Gr 3 A420 Gr WPL3 A350 Gr LF3 A352 Gr LC3

Austenitic

Stainless

Steel

A312 Gr TP304 A403 Gr WP304 A182 Gr F304 A182 Gr F304 A193 Gr B8

A194 Gr 8 A312 Gr TP316 A403 Gr WP316 A182 Gr F316 A182 Gr F316

A312 Gr TP321 A403 Gr WP321 A182 Gr F321 A182 Gr F321

A312 Gr TP347 A403 Gr WP347 A182 Gr F347 A182 Gr F347

ASTM Materials Pipes

A106 = This specification covers carbon steel pipe for high-temperature service.

A335 = This specification covers seamless ferritic alloy-steel pipe for high-temperature service.

A333 = This specification covers wall seamless and welded carbon and alloy steel pipe intended for use at low temperatures.

A312 = Standard specification for seamless, straight-seam welded, and cold worked welded austenitic stainless steel pipe intended for

high-temperature and general corrosive service.

Fittings

A234 = This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction.

A420 = Standard specification for piping fittings of wrought carbon steel and alloy steel for low-temperature service.

A403 = Standard specification for wrought austenitic stainless steel piping fittings.

Flanges

A105 = This specification covers standards for forged carbon steel piping components, that is, flanges, fittings, Valves, and similar parts,

for use in pressure systems at ambient and higher-temperature service conditions.

A182 = This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and Valves and parts for high-

temperature service.

A350 = This specification covers several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and Valves for

low-temperature service.

Valves

A216 = This specification covers carbon steel castings for Valves, flanges, fittings, or other pressure-containing parts for high-

temperature service and of quality suitable for assembly with other castings or wrought-steel parts by fusion welding.

A217 = This specification covers steel castings, martensitic stainless steel and alloys steel castings for Valves, flanges, fittings, and other

pressure-containing parts intended primarily for high-temperature and corrosive service.

A352 = This specification covers steel castings for Valves, flanges, fittings, and other pressure-containing parts intended primarily for

low-temperature service.

A182 = This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and Valves and parts for high-

temperature service.

Bolds & Nuts

A193 = This specification covers alloy and stainless steel bolting material for pressure vessels, Valves, flanges, and fittings for high

temperature or high pressure service, or other special purpose applications.

A320 = Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service.

A194 = Standard specification for nuts in many different material types.