No we don't break, No we don't break
Stronger. Stronger.

("Stronger," by Sam Feldt featuring Kesha, 2021)

 

THE BONES OF THE PROCESSING PLANT ARE MADE OF STEEL 

Brilliant PTOA Readers and Students will recall that the PTOA began with exploring the Process Variable Temperature. In the PTOA PV Temperature Focus Study Area, PTOA Readers and Students learned how thermal energy is created and transferred at an industrial scale.

Next, PTOA Readers and Students persevered through the PTOA PV Pressure Focus Study Area which explained how an increase or decrease in the Pressure Energy of a flowing fluid is accompanied by a respective decrease or increase in that fluid's Velocity.

Understanding the PV Temperature and PV Flowrate took a lot of brain work!

The PV Flowrate concept is much easier to understand; anybody can observe a Flowrate when they open the valve on a garden hose or open the faucet over a bathroom sink.

PTOA Segment #245 explained how the diameter of the Piping through which the fluid flows will determine the maximum PV Flowrate.

Additional hardware found in the Piping Network includes Pipe Fittings and Valves which help direct the flow of fluids to Vessels and Towers.

Feedstocks and Intermediate Products continuously flow through all members of the Piping Network whilst being converted into Final Products.

Converting the flowing Feedstocks and Intermediate Products into Final Products requires changing their PV Temperature and PV Pressure.

Hence, the Piping Network infrastructure and its associated hardware are the infrastructure bones of the plant that make it possible for all of the main Process Variables ...Flowrate, Temperature, Pressure, and Level ... to exist.

Most of the Piping Network hardware components in a commercial-sized processing plant are fabricated from Steel, and a few other specialty metals.

The term "Metallurgy" refers to the technology used to determine the properties of metals ... like Steel ...and how these metal properties make it easier to fabricate metal hardware.

This PTOA Segment focusses on the Metallurgy jargon that is used to describe metal properties.

 

WHY PROCESS OPERATORS NEED TO KNOW ABOUT PIPING METALLURGY

Truth be known, the Process Operator has absolutely nothing to do with selecting the size and materials of manufacture for the Piping Network, Vessels, and Towers found at an industrial processing plant.

The E&C company that designs the processing facility determines the size and metallurgy for every piece of hardware in the processing facility.

The investment in processing hardware is significant; at least one third of the money needed to build a processing facility will be used for the Piping, Pipe Fittings, Valves, Piping Auxiliaries, Vessels and Towers.

Brilliant PTOA Readers and Students ... meaning those who are reading the PTOA Segments in the intended, sequential order ... learned way back in PTOA Segment #105 that each metal type expands and contracts with changes in the PV Temperature. The thermal expansion rate of pipe is just one factor the E&C company considers in the design of the Piping Network.

Every piece of hardware in the Piping Network must also withstand the flowing fluid's PV Pressure under all feasible operating conditions.

The hardware must also be compatible with the chemical composition of the flowing fluid.

Additionally, the hardware must meet manufacturing codes and specifications related to enduring the stress caused by continually changing PV Temperatures and PV Pressures.

In summary, designing a commercial processing facility requires significant engineering expertise.

Even though the Process Operator has nothing to do with the selection of pipe size, pipe pressure rating or pipe metallurgy, there are good reasons why Process Operators should be familiar with the terminology related to this hardware:

• The Process Operator should be able to intelligently question whether a section of replacement hardware meets the original design specifications so that a cheaper substitute is not installed by a different contractor.
• The Outside Process Operator will be involved with the protection procedure for the expensive Austenitic Stainless Steel that is used in some Shell and Tube Heat Exchangers.  Some types of Steel must have a protective coating prior to being exposed to the environmental atmosphere during a Turnaround.
• Because metals have different expansion rates, Process Operators should be aware of the locations of piping metallurgy interfaces which are called "pipe breaks."
• The most brilliant of Process Operators will be able to intelligently decode the P&ID Pipe Rating shorthand which is the featured topic in an upcoming PTOA Segment.

 

 

CLASSIFICATION OF PIPING MATERIALS

PTOA Readers and Students also recently learned in PTOA Segment #245 that Piping is used to transport fluids in commercial-sized processing plants whereas Tubing is used when a smaller amount of fluid needs to be transported.

Piping can be made from metals or non-metals. Examples of non-metallic pipe include cement and PVC (polyvinyl chloride).

The decision on whether to use metal or non-metal piping depends upon the service of the pipe and the desired maximum flowrate through the pipe.

There are physical manufacturing limits regarding how large the diameter of a metal pipe can be.

Very large diameter cement pipe can successfully be used for the fast movement of a large capacity of water. The water is not chemically reactive nor potentially corrosive, and the flowing PV Pressure range is manageable.

However, cement would not be a good choice for moving fluids in a processing facility.

A processing facility is intentionally built to upgrade chemically active fluids which flow at elevated PV Temperatures and elevated PV Pressures.

Carbon Steel Alloys and Stainless Steel are typically used in industrial processing services. Specialty metal pipe will also be used where it is needed.

The left-hand side of the nearby "Classification of Piping Material" chart illustrates that Metal Piping Material has two subcategories, Ferrous Metal and Non-Ferrous Metal.

The vast majority of the Piping Network in an industrial-sized processing plant will be fabricated from Ferrous Metal, which is further defined below.

 

METAL PIPING CHARACTERISTICS 

Ferrous Metals and Non-Ferrous Metals.

Why is the symbol for elemental Iron abbreviated Fe? Fe is derived from "ferrum" the Latin word for "firmness."

A "Ferrous Metal" has Iron in it.

Since Carbon Steel is an alloy of Iron and Carbon, Carbon Steel is a Ferrous Metal.

Iron is magnetic. Since Ferrous Metals contain Iron, they are likewise magnetic.

Important Caveat:  Austenitic Stainless Steel has iron in it but is not magnetic. Austenitic Stainless Steels are featured in the next PTOA Segment.

Which Brilliant PTOA Readers and Students remember that the only chemical reaction that takes place at Atmospheric Pressure and ambient Temperatures is the rusting of Iron, which can be seen in the rusting of a common Iron nail? Ferrous Metals are susceptible to rusting and corrosion.

A Non-Ferrous Metal does not contain Iron. Since Brass is an alloy of Copper and Zinc, Brass is a Non-Ferrous Metal.

Without Iron content, Non-Ferrous Metals resist rusting and are not magnetic. 

The nearby classification chart indicates that Copper (Cu), Nickel (Ni), and Aluminum (Al) are also Non-Ferrous Metals.  Like duh! Copper, Nickel, and Aluminum are basic elemental metals so of course they do not contain any iron!

 

Ductility and Malleability

Ductility is a metal's ability to be shaped into a new form without breaking. Copper is so ductile that it can be pulled into wire.

A Malleable metal can be shaped easily, typically after being heated and then hammered.

Gold is the most malleable metal. Other malleable metals are Aluminum, Titanium, Nickel, Copper, Silver, Tin, and Platinum.

 

Alloyed Metals.

Humankind has been breeding canines to achieve desirable puppy characteristics for many thousands of years. However, Humankind has only recently in the past few decades learned how to optimize favorable characteristics of metals by incorporating Alloys into the structure of base metals.

Alloyed Metals are made from combining two or more pure metals together.

For example, Brass is an alloy of just two metals, Copper (Cu) and Zinc (Zn).

Metals can also be alloyed with non-metals. For example, Steel (aka "Carbon Steel") is made by incorporating non-metallic Carbon (C) atoms in between the base metal Iron (Fe) atoms.

The Specification for making AISI 9310 Alloyed Steel is shown in the nearby graphic. Manganese (Mn), Silicon (Si), Chromium (Cr), Nickel (Ni) and Molybdenum (Mo) are intentionally alloyed with Carbon Steel in amounts that lie within the minimum and maximum limits.

The amount of Alloy will impact how the metal can be fabricated.

For example ...

A small amount of Carbon (C) and slag added to Iron (Fe) makes it possible to hammer and forge the Iron into decorative shapes producing what is known as "Wrought Iron."

Adding a small amount of Silicon (Si) to Carbon Steel makes it possible to heat the metal and pour it into a cast (aka Cast Iron). Cast Iron is hard, but brittle, which means the metal will fracture (aka crack up) upon stress without giving any indication that failure is about to happen.

Adding 3% to 5% Nickel (Ni) makes it possible for Steel to resist embrittlement to -150 °F, which otherwise would become a concern at PV Temperatures below -50 °F.

Stainless Steel has up to 9% Chromium (Cr) Alloy. Chromium reduces the metal's tendency to oxidize at high PV Temperatures and helps to resist sulfur-induced corrosion.

Adding a small amount of Molybdenum (Mo) to Low Carbon Steel greatly increases the metal's sustained strength above 900 °F.

Annealed Metal

An annealed metal has been cooled gradually which makes the metal less brittle because the annealing process relieves internal stress and strain present in the metal's atomic structure.

The below graphic attempts to illustrate how the soft annealing process of sheet metal (on the left) makes the metal more deformable and easily machinable (on the right).

 

TAKE HOME MESSAGES: The Piping Network of a commercial-sized processing facility includes the Piping, Pipe Fittings, Valves, Towers and Vessels through which raw materials and intermediate products flow while being converted into Final Products. None of the Process Variables could exist without the Piping Network.

The materials of manufacture for the vast majority of a processing facility's Piping Network will be made from metal, not non-metal materials like cement or PVC.

Most of the metal piping will be ferrous, meaning the pipe will contain iron as the base metal. Ferrous metals are magnetic (exception: Austenitic Stainless Steel). Non-ferrous metals (for example Copper and Nickel Alloys) do not contain iron and are not magnetic.

The Piping Network is designed by an Engineering and Construction company. The Process Operator is not involved with the Piping Network design. The Process Operator inherits the design and must make certain that replacement components to the Piping Network adhere to the original design. The Process Operator should be core competent interpreting the metallurgy codes on the P&ID and be knowledgeable where pipe breaks exist. The Process Operator should be aware of the use of Austenitic Stainless Steel and protect this metal from Stress Corrosion Cracking.

The term "Metallurgy" encompasses technologies used for metal extraction, metal properties, and metal fabrication techniques. 

Properties of metal include:

• Ferrous (has Iron in it) or Non-Ferrous (has no Iron in it, for example Copper tubing).
• Magnetic or non-Magnetic - most ferrous metals are magnetic and non-ferrous metals are not magnetic.
• Ductility - how easy it is to shape the metal into a new form without breaking. 
• Malleability - how easy it is to shape the metal after the metal is heated and hammered.
• Embrittlement Tendency - the tendency for a metal to crack up without any prior indication of pending failure.
• Anneal metal - a metal that has undergone a special cooling step during the manufacturing process so that the metal is easier to form and has decreased embrittlement tendency. 

 

The vast majority of The Piping Network in an industrial processing facility will be made from Steel, which is Iron alloyed with other metals and non-metals (like Carbon).

Alloyed Metals are fabricated from incorporating two or more metals together or incorporating a metal and a non-metal together (e.g., Carbon and Iron to make Carbon Steel). The purpose of alloying metals is to metal easier to fabricate and/or achieve desirable metal properties/characteristics.

In general:

• Alloyed Carbon and Silicon with Iron change the fabrication possibilities of Iron.
• Alloyed Nickel reduces embrittlement within specific PV Temperature ranges.
• Alloyed Chromium resists oxidation (e.g. "Stainless Steel") and resists sulfur-induced corrosion.
• Alloyed Molybdenum increases the strength of metal at high temperatures.

 

©2023 PTOA Segment 0246

PTOA PV FLOWRATE FOCUS STUDY AREA
PIPING NETWORK HARDWARE

You need to login or register to bookmark/favorite this content.