Heat Treatment - What is It
Content
07/08/2015
Heat Treatment What Is It?
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Technical Articles
A Boiler: The Explosive Potential of a
Bomb
Acoustic Emission Examination of
Metal Pressure Vessels
Anatomy of a Catastrophic Boiler
Accident
Austenitic Stainless Steel
AutoRefrigeration
Heat Treatment What Is It?
J.G. Gillissie
October 1981
Category: Design/Fabrication
Summary: The following article is a part of National Board Classic Series and it was published in the National
Board BULLETIN. (4 printed pages)
Basic Weld Inspection Part 1
Basic Weld Inspection Part 2
Black Liquor Recovery Boilers An
Introduction
Boiler Efficiency and Steam Quality:
The Challenge of Creating Quality
Steam Using Existing Boiler
Efficiencies
Boiler Logs Can Reduce Accidents
Boiler/Burner Combustion Air Supply
Requirements and Maintenance
Carbon Monoxide Poisoning
Preventable With Complete
Inspection
Combustion Air Requirements:The
Forgotten Element In Boiler Rooms
Creep and Creep Failures
Description of Construction and
Inspection Procedure for Steam
Locomotive and Fire Tube Boilers
Ensuring Safe Operation Of Vessels
With QuickOpening Closures
Environmental Heat Exchangers
Factors Affecting Inservice Cracking
of Weld Zone in Corrosive Service
Failure Avoidance in Welded
Fabrication
Finite Element Analysis of Pressure
Vessels
Fuel Ash Corrosion
Fuel Firing Apparatus Natural Gas
Grain Boundaries
Heat Treatment What Is It?
How to Destroy a Boiler Part 1
How to Destroy a Boiler Part 2
How to Destroy a Boiler Part 3
Identifying Pressure Vessel Nozzle
Problems
Inspection, Repair, and Alteration of
Yankee Dryers
Inspection, What Better Place to
Begin
Laminations Led to Incident
Layup of Heating Boilers
Liquid Penetrant Examination
Low Voltage Short CircuitingGMAW
Low Water CutOff Technology
LowWater Cutoff: A Maintenance
Must
A short time ago during a joint review of an ASME Certificate Holder, I found myself asking the question, "Do
you use heat treatment?"
The immediate answer was, "Oh yes."
I have asked the same question many hundreds of times in a like number of fabricators' shops, knowing full
well that my question was allinclusive and covered a number of processes. Ninetyfive times out of any
hundred the answer I got was a straight "yes" or "no." Once in a blue moon the company representative would
explain that he uses only stress relieving of weldments for those material Pnumbers and material thicknesses
as required by the Code sections to which he is fabricating.
When I get an answer like that I think to myself, "This gent knows what he's talking about." At the same time, I
have a deep suspicion that HE is thinking to HIMSELF, "This clown probably doesn't know the difference
between stress relieving and stealing third base."
Generalized questions usually get generalized answers. As an example, if somebody asks me the question,
"Do you travel?", my answer would probably be, "Yes." If I were asked, "How do you travel?", my answer
would possibly be, "By airplane, train and automobile but not by bicycle, pogostick or horseback."
Get the point? There is a difference. There is nothing wrong with the term, "heat treatment," but it is a
generalized term covering various processes. Heat treatment in any of its forms is used to achieve a desirable
improvement in the characteristics of material or to regain those characteristics which may have been
adversely affected by production processes such as welding/bending/forming etc.
Let's take a short look at some of the most frequently used processes of heat treatment, those which the
Authorized Inspector may encounter in boiler and pressure vessel fabrication shops.
STRESS RELIEVING (postweld heat treatment)
This is by far the most frequently used form of heat treatment which will confront the authorized inspector. As
a result of welding processes used to join metals together, the base materials near the weldment, the
deposited weld metal and, in particular, the heat affected zones transform through various metallurgical
phases. Depending upon the chemistry of the metals in these areas, hardening occurs in various degrees,
dependent mainly upon carbon content. Again, this is particularly true in the heat affected zone (HAZ) adjacent
to the weld metal deposit where the highest stresses due to melting and solidification result. Stress relieving,
as the name implies, is designed to relieve a proportion of these imposed stresses by reducing the hardness
and increasing ductility, thus reducing danger of cracking in the vessel weldments.
The Code sections contain requirements for stress relieving, specifying rate of heating and cooling above
800oF and requiring a holding temperature, usually one hour per inch of thickness of the material. The holding
temperatures vary with the Pnumbers of the material which in turn are based on alloy content. As an example,
P1 through P4 require 1100F holding temperature, P1 being carbon steels, P3 being carbon steels alloyed
in relatively small percent with molybdemum, manganese and vanadium. P4 steels are the nickel steels,
chromemolys and nickel chromemolys. P5, P6 and P7 high alloy steels generally require a higher holding
temperature ranging up to 1350oF. Some of the special steels now listed in the Code sections call for even
higher temperatures.
Following the holding (soaking) time, controlled cooling down to 800oF or lower is vitally important. Many high
carbon steels are subject to surface cracking if cooled too rapidly.
QUENCHING AND TEMPERING
Oriented toward carbide steels such as carbonmoly, this process is designed to enhance toughness as well
as controlling yield strength and ultimate tensile strength of steel. The steel is heated to above its upper critical
temperature and quickly immersed in fresh water or brine to achieve rapid setting of the desired metallurgical
structure. Oil quenching is sometimes used. The usual practice is to quench until cooling reaches around
800oF, quickly followed by a tempering period in a fired furnace in order to soften the martensitic structure and
achieve the desired mechanical properties in the material including a desired measure of ductility. The
tempering process is, in effort, a stress relieving process.
NORMALIZING AND TEMPERING
This process is used for virtually the same purposes as quenching and tempering. It differs in that normalizing
is accomplished by cooling in air in place of fast quenching in a liquid. Air normalizing, much slower than liquid
quenching, may be used by itself or the material may be subjected to a controlled furnace tempering process
in order to better control desired mechanical properties.
Steel manufacturers will furnish material in either of the above conditions when so specified on the purchase
order or as required by the material specification.
As a cautionary note; alloyed steel mechanical properties are ultimately determined by the tempering process
and if the materials are subsequently welded during fabrication, subsequent stress relieving temperature, if
http://www.nationalboard.org/index.aspx?pageID=164&ID=177
1/3
07/08/2015
Magnetic Particle Examination
Maintaining Proper Boiler Inspections
Through Proper Relationships
Microstructural Degradation
Miracle Fluid?
Organizing A Vessel, Tank, and
Piping Inspection Program
Paper Machine Failure Investigation:
Inspection Requirements Should Be
Changed For Dryer Can
Pipe Support Performance as It
Applies to Power Plant Safety and
Reliability
Polymer Use for Boilers and
Pressure Vessels
Pressure Vessel Fatigue
Heat Treatment What Is It?
and if the materials are subsequently welded during fabrication, subsequent stress relieving temperature, if
used, should not exceed that of the tempering process, otherwise mechanical properties of the material may
be adversely affected.
SOLUTION HEAT TREATMENT (solution annealing)
While the Code sections state that heat treatment of austenitic stainless steel (P8) is neither required nor
prohibited, this refers to postweld stress relieving. There are certain processes to which this material may be
subjected. These are performed almost exclusively by the material manufacturers due to the fact that
temperature ranges and holding time are critical and require careful controls, otherwise damage to the material
can result from either too high or too low a furnace temperature. Material manufacturers have the metallurgical
staffs to determine requirements.
In solution heat treatment the material is subjected to a high heat, around 2000oF, and rapidly cooled in liquid
in order to achieve an evenly distributed solution of carbon and austenite in the metallurgical structure of the
material.
STABILIZING HEAT TREATMENT
Everything said in the first paragraph under solution heat treatment also applies to stabilizing heat treatment. In
the latter process the material is cooled slowly in order to bring as much carbon as possible out of solution and
into evenly distributed concentrations apart from the austenite.
Pressure Vessels: Analyzing Change
Both solution heat treatment and stabilizing heat treatment are used to reduce susceptibility to intergranular
stress corrosion and embrittlement also to increase high temperature creep strength.
Preventing Corrosion Under
Insulation
PREHEATING
Preventing Steam/Condensate
System Accidents
Proper Boiler Care Makes Good
Business Sense:Safety Precautions
for Drycleaning Businesses
Putting a Stop to Steam Kettle Failure
Quick Actuating Closures
QuickActuating Door Failures
RealTime Radioscopic Examination
Recommendations For A Safe Boiler
Room
Recovering Boiler Systems After A
Flood
Rendering Plants Require Safety
Repair or Alteration of Pressure
Vessels
Residential Water Heater Safety
School Boiler Maintenance Programs:
How Safe Are The Children?
Secondary LowWater Fuel Cutoff
Probe: Is It as Safe as You Think?
ShortTerm High Temperature
Failures
Specification of Rupture Disk Burst
Pressure
Steam Traps Affect Boiler Plant
Efficiency
Steps to Safety: Guide for Restarting
Boilers after Summer LayUp
Stress Corrosion Cracking of Steel in
Liquefied Ammonia Service A
Recapitulation
While most of us do not look upon preheating as a form of heat treatment, its use can contribute substantially
in reducing hardness in all three constituents of a weldment; the parent metal, the weld metal deposit and the
heat affected zone. As a weldment cools, it goes through various transformations in which molecules rearrange
themselves. If cooling is rapid, this rearrangement is arrested resulting in entrapment of stresses and
hardening of the material with coincident loss of ductility which is the highly desirable ability of the material to
bend elastically, under stress.
Preheating of the weldment area achieves better weld penetration and slows the cooling process, thus allowing
added relief of stresses and reduced hardening of the materials.
The ASME Code sections take cognizance of the foregoing, in some cases allowing exemption from postweld
stress relieving PROVIDED preheating of a specified temperature is used.
Here again, a word of caution is in order. Preheat, like any other heat treatment, must be carefully planned and
used. Specific written procedures should be provided for each individual use. Misuse, such as light surface
heating, can do more harm than good. A soaking heat and maintenance of interpass temperature throughout
the weldment and beyond, are recommended.
In all cases, high chromemoly steels should be preheated prior to welding and postweld stress relieved at
around 1400oF.
In summary, the authorized inspector (or ANI) is not assigned the duty of being an authority on metallurgy of
all the various ferrous and nonferrous materials used in boiler, pressure vessel or piping system fabrication.
The various Code sections do, however, require that results of heat treatment be made available to him for his
review in order that he may assure himself that temperature readings and holding (soaking) time conform with
Code requirements. Only a diligent study of Code requirements will enable him so make this decision.
As previously mentioned, heat treatments which will confront the AIANI are for the most part preheating and
postweld heat treatment, that is, stress relieving.
Some points to remember:
Post weld heat treatment is designed to return a metal as near as possible to its prefabrication state of yield,
ultimate tensile and ductility.
The rate of temperature rise, holding time at temperature and rate of cooling are vitally important. For this
reason, furnace thermocouples must measure metal temperature, not furnace atmospheric temperature.
Heat treatment of any type must be a planned, systematic action. Poorly performed heat treatment can result
in far more harm to material than any good which may result.
Test coupons must be subjected to the identical conditions as the vessel or part in order to obtain meaningful
tensile and toughness (Charpy) test results.
The foregoing is a short generalization. Specific requirements are found in ASME Section II "Material
Specifications" and in the "Material Tables", of the various Code sections.
Suggested Daily Boiler Log Program
Suggested Maintenance Log
Program
Editor's note: Some ASME Boiler and Pressure Vessel Code requirements may have changed because of
advances in material technology and/or actual experience. The reader is cautioned to refer to the latest edition
and addenda of the ASME Boiler and Pressure Vessel Code for current requirements.
System Design, Specifications,
Operation, and Inspection of
Deaerators
Tack Welding
Temperature And Pressure Relief
Valves Often Overlooked
Temperature Considerations for
Pressure Relief Valve Application
The Authorized Inspector's
Responsibility for Dimensional
Inspection
The Effects of ErosionCorrosion on
Power Plant Piping
The Forgotten Boiler That Suddenly
Isn't
http://www.nationalboard.org/index.aspx?pageID=164&ID=177
2/3
07/08/2015
Heat Treatment What Is It?
Isn't
The Trend of Boiler/Pressure Vessel
Incidents: On the Decline?
The Use of Pressure Vessels for
Human Occupancy in Clinical
Hyberbaric Medicine
Thermally Induced Stress Cycling
(Thermal Shock) in Firetube Boilers
Top Ten Boiler and Combustion
Safety Issues to Avoid
Typical Improper Repairs of Safety
Valves
Wasted Superheat Converted to Hot,
Sanitary Water
Water Maintenance Essential to
Prevent Boiler Scaling
Water Still Flashes to Steam at 212
Welding Consideration for Pressure
Relief Valves
Welding Symbols: A Useful System
or Undecipherable Hieroglyphics?
What Should You Do Before Starting
Boilers After Summer LayUp?
Why? A Question for All Inspectors
About Us | Get Directions | Contact Us | Disclaimer | Logo & Marks Policy | Privacy Statement | Terms of Use | Site Map
Copyright 2015 The National Board of Boiler and Pressure Vessel Inspectors | 1055 Crupper Avenue Columbus, OH 43229 Ph.614.888.8320
http://www.nationalboard.org/index.aspx?pageID=164&ID=177
3/3
Heat Treatment What Is It?
Home
General Meeting
NB Members
Authorized Inspection Agencies
OwnerUser Inspection Organizations
Create Account
Review Team Leaders
Login
Test Lab
Technical Articles
A Boiler: The Explosive Potential of a
Bomb
Acoustic Emission Examination of
Metal Pressure Vessels
Anatomy of a Catastrophic Boiler
Accident
Austenitic Stainless Steel
AutoRefrigeration
Heat Treatment What Is It?
J.G. Gillissie
October 1981
Category: Design/Fabrication
Summary: The following article is a part of National Board Classic Series and it was published in the National
Board BULLETIN. (4 printed pages)
Basic Weld Inspection Part 1
Basic Weld Inspection Part 2
Black Liquor Recovery Boilers An
Introduction
Boiler Efficiency and Steam Quality:
The Challenge of Creating Quality
Steam Using Existing Boiler
Efficiencies
Boiler Logs Can Reduce Accidents
Boiler/Burner Combustion Air Supply
Requirements and Maintenance
Carbon Monoxide Poisoning
Preventable With Complete
Inspection
Combustion Air Requirements:The
Forgotten Element In Boiler Rooms
Creep and Creep Failures
Description of Construction and
Inspection Procedure for Steam
Locomotive and Fire Tube Boilers
Ensuring Safe Operation Of Vessels
With QuickOpening Closures
Environmental Heat Exchangers
Factors Affecting Inservice Cracking
of Weld Zone in Corrosive Service
Failure Avoidance in Welded
Fabrication
Finite Element Analysis of Pressure
Vessels
Fuel Ash Corrosion
Fuel Firing Apparatus Natural Gas
Grain Boundaries
Heat Treatment What Is It?
How to Destroy a Boiler Part 1
How to Destroy a Boiler Part 2
How to Destroy a Boiler Part 3
Identifying Pressure Vessel Nozzle
Problems
Inspection, Repair, and Alteration of
Yankee Dryers
Inspection, What Better Place to
Begin
Laminations Led to Incident
Layup of Heating Boilers
Liquid Penetrant Examination
Low Voltage Short CircuitingGMAW
Low Water CutOff Technology
LowWater Cutoff: A Maintenance
Must
A short time ago during a joint review of an ASME Certificate Holder, I found myself asking the question, "Do
you use heat treatment?"
The immediate answer was, "Oh yes."
I have asked the same question many hundreds of times in a like number of fabricators' shops, knowing full
well that my question was allinclusive and covered a number of processes. Ninetyfive times out of any
hundred the answer I got was a straight "yes" or "no." Once in a blue moon the company representative would
explain that he uses only stress relieving of weldments for those material Pnumbers and material thicknesses
as required by the Code sections to which he is fabricating.
When I get an answer like that I think to myself, "This gent knows what he's talking about." At the same time, I
have a deep suspicion that HE is thinking to HIMSELF, "This clown probably doesn't know the difference
between stress relieving and stealing third base."
Generalized questions usually get generalized answers. As an example, if somebody asks me the question,
"Do you travel?", my answer would probably be, "Yes." If I were asked, "How do you travel?", my answer
would possibly be, "By airplane, train and automobile but not by bicycle, pogostick or horseback."
Get the point? There is a difference. There is nothing wrong with the term, "heat treatment," but it is a
generalized term covering various processes. Heat treatment in any of its forms is used to achieve a desirable
improvement in the characteristics of material or to regain those characteristics which may have been
adversely affected by production processes such as welding/bending/forming etc.
Let's take a short look at some of the most frequently used processes of heat treatment, those which the
Authorized Inspector may encounter in boiler and pressure vessel fabrication shops.
STRESS RELIEVING (postweld heat treatment)
This is by far the most frequently used form of heat treatment which will confront the authorized inspector. As
a result of welding processes used to join metals together, the base materials near the weldment, the
deposited weld metal and, in particular, the heat affected zones transform through various metallurgical
phases. Depending upon the chemistry of the metals in these areas, hardening occurs in various degrees,
dependent mainly upon carbon content. Again, this is particularly true in the heat affected zone (HAZ) adjacent
to the weld metal deposit where the highest stresses due to melting and solidification result. Stress relieving,
as the name implies, is designed to relieve a proportion of these imposed stresses by reducing the hardness
and increasing ductility, thus reducing danger of cracking in the vessel weldments.
The Code sections contain requirements for stress relieving, specifying rate of heating and cooling above
800oF and requiring a holding temperature, usually one hour per inch of thickness of the material. The holding
temperatures vary with the Pnumbers of the material which in turn are based on alloy content. As an example,
P1 through P4 require 1100F holding temperature, P1 being carbon steels, P3 being carbon steels alloyed
in relatively small percent with molybdemum, manganese and vanadium. P4 steels are the nickel steels,
chromemolys and nickel chromemolys. P5, P6 and P7 high alloy steels generally require a higher holding
temperature ranging up to 1350oF. Some of the special steels now listed in the Code sections call for even
higher temperatures.
Following the holding (soaking) time, controlled cooling down to 800oF or lower is vitally important. Many high
carbon steels are subject to surface cracking if cooled too rapidly.
QUENCHING AND TEMPERING
Oriented toward carbide steels such as carbonmoly, this process is designed to enhance toughness as well
as controlling yield strength and ultimate tensile strength of steel. The steel is heated to above its upper critical
temperature and quickly immersed in fresh water or brine to achieve rapid setting of the desired metallurgical
structure. Oil quenching is sometimes used. The usual practice is to quench until cooling reaches around
800oF, quickly followed by a tempering period in a fired furnace in order to soften the martensitic structure and
achieve the desired mechanical properties in the material including a desired measure of ductility. The
tempering process is, in effort, a stress relieving process.
NORMALIZING AND TEMPERING
This process is used for virtually the same purposes as quenching and tempering. It differs in that normalizing
is accomplished by cooling in air in place of fast quenching in a liquid. Air normalizing, much slower than liquid
quenching, may be used by itself or the material may be subjected to a controlled furnace tempering process
in order to better control desired mechanical properties.
Steel manufacturers will furnish material in either of the above conditions when so specified on the purchase
order or as required by the material specification.
As a cautionary note; alloyed steel mechanical properties are ultimately determined by the tempering process
and if the materials are subsequently welded during fabrication, subsequent stress relieving temperature, if
http://www.nationalboard.org/index.aspx?pageID=164&ID=177
1/3
07/08/2015
Magnetic Particle Examination
Maintaining Proper Boiler Inspections
Through Proper Relationships
Microstructural Degradation
Miracle Fluid?
Organizing A Vessel, Tank, and
Piping Inspection Program
Paper Machine Failure Investigation:
Inspection Requirements Should Be
Changed For Dryer Can
Pipe Support Performance as It
Applies to Power Plant Safety and
Reliability
Polymer Use for Boilers and
Pressure Vessels
Pressure Vessel Fatigue
Heat Treatment What Is It?
and if the materials are subsequently welded during fabrication, subsequent stress relieving temperature, if
used, should not exceed that of the tempering process, otherwise mechanical properties of the material may
be adversely affected.
SOLUTION HEAT TREATMENT (solution annealing)
While the Code sections state that heat treatment of austenitic stainless steel (P8) is neither required nor
prohibited, this refers to postweld stress relieving. There are certain processes to which this material may be
subjected. These are performed almost exclusively by the material manufacturers due to the fact that
temperature ranges and holding time are critical and require careful controls, otherwise damage to the material
can result from either too high or too low a furnace temperature. Material manufacturers have the metallurgical
staffs to determine requirements.
In solution heat treatment the material is subjected to a high heat, around 2000oF, and rapidly cooled in liquid
in order to achieve an evenly distributed solution of carbon and austenite in the metallurgical structure of the
material.
STABILIZING HEAT TREATMENT
Everything said in the first paragraph under solution heat treatment also applies to stabilizing heat treatment. In
the latter process the material is cooled slowly in order to bring as much carbon as possible out of solution and
into evenly distributed concentrations apart from the austenite.
Pressure Vessels: Analyzing Change
Both solution heat treatment and stabilizing heat treatment are used to reduce susceptibility to intergranular
stress corrosion and embrittlement also to increase high temperature creep strength.
Preventing Corrosion Under
Insulation
PREHEATING
Preventing Steam/Condensate
System Accidents
Proper Boiler Care Makes Good
Business Sense:Safety Precautions
for Drycleaning Businesses
Putting a Stop to Steam Kettle Failure
Quick Actuating Closures
QuickActuating Door Failures
RealTime Radioscopic Examination
Recommendations For A Safe Boiler
Room
Recovering Boiler Systems After A
Flood
Rendering Plants Require Safety
Repair or Alteration of Pressure
Vessels
Residential Water Heater Safety
School Boiler Maintenance Programs:
How Safe Are The Children?
Secondary LowWater Fuel Cutoff
Probe: Is It as Safe as You Think?
ShortTerm High Temperature
Failures
Specification of Rupture Disk Burst
Pressure
Steam Traps Affect Boiler Plant
Efficiency
Steps to Safety: Guide for Restarting
Boilers after Summer LayUp
Stress Corrosion Cracking of Steel in
Liquefied Ammonia Service A
Recapitulation
While most of us do not look upon preheating as a form of heat treatment, its use can contribute substantially
in reducing hardness in all three constituents of a weldment; the parent metal, the weld metal deposit and the
heat affected zone. As a weldment cools, it goes through various transformations in which molecules rearrange
themselves. If cooling is rapid, this rearrangement is arrested resulting in entrapment of stresses and
hardening of the material with coincident loss of ductility which is the highly desirable ability of the material to
bend elastically, under stress.
Preheating of the weldment area achieves better weld penetration and slows the cooling process, thus allowing
added relief of stresses and reduced hardening of the materials.
The ASME Code sections take cognizance of the foregoing, in some cases allowing exemption from postweld
stress relieving PROVIDED preheating of a specified temperature is used.
Here again, a word of caution is in order. Preheat, like any other heat treatment, must be carefully planned and
used. Specific written procedures should be provided for each individual use. Misuse, such as light surface
heating, can do more harm than good. A soaking heat and maintenance of interpass temperature throughout
the weldment and beyond, are recommended.
In all cases, high chromemoly steels should be preheated prior to welding and postweld stress relieved at
around 1400oF.
In summary, the authorized inspector (or ANI) is not assigned the duty of being an authority on metallurgy of
all the various ferrous and nonferrous materials used in boiler, pressure vessel or piping system fabrication.
The various Code sections do, however, require that results of heat treatment be made available to him for his
review in order that he may assure himself that temperature readings and holding (soaking) time conform with
Code requirements. Only a diligent study of Code requirements will enable him so make this decision.
As previously mentioned, heat treatments which will confront the AIANI are for the most part preheating and
postweld heat treatment, that is, stress relieving.
Some points to remember:
Post weld heat treatment is designed to return a metal as near as possible to its prefabrication state of yield,
ultimate tensile and ductility.
The rate of temperature rise, holding time at temperature and rate of cooling are vitally important. For this
reason, furnace thermocouples must measure metal temperature, not furnace atmospheric temperature.
Heat treatment of any type must be a planned, systematic action. Poorly performed heat treatment can result
in far more harm to material than any good which may result.
Test coupons must be subjected to the identical conditions as the vessel or part in order to obtain meaningful
tensile and toughness (Charpy) test results.
The foregoing is a short generalization. Specific requirements are found in ASME Section II "Material
Specifications" and in the "Material Tables", of the various Code sections.
Suggested Daily Boiler Log Program
Suggested Maintenance Log
Program
Editor's note: Some ASME Boiler and Pressure Vessel Code requirements may have changed because of
advances in material technology and/or actual experience. The reader is cautioned to refer to the latest edition
and addenda of the ASME Boiler and Pressure Vessel Code for current requirements.
System Design, Specifications,
Operation, and Inspection of
Deaerators
Tack Welding
Temperature And Pressure Relief
Valves Often Overlooked
Temperature Considerations for
Pressure Relief Valve Application
The Authorized Inspector's
Responsibility for Dimensional
Inspection
The Effects of ErosionCorrosion on
Power Plant Piping
The Forgotten Boiler That Suddenly
Isn't
http://www.nationalboard.org/index.aspx?pageID=164&ID=177
2/3
07/08/2015
Heat Treatment What Is It?
Isn't
The Trend of Boiler/Pressure Vessel
Incidents: On the Decline?
The Use of Pressure Vessels for
Human Occupancy in Clinical
Hyberbaric Medicine
Thermally Induced Stress Cycling
(Thermal Shock) in Firetube Boilers
Top Ten Boiler and Combustion
Safety Issues to Avoid
Typical Improper Repairs of Safety
Valves
Wasted Superheat Converted to Hot,
Sanitary Water
Water Maintenance Essential to
Prevent Boiler Scaling
Water Still Flashes to Steam at 212
Welding Consideration for Pressure
Relief Valves
Welding Symbols: A Useful System
or Undecipherable Hieroglyphics?
What Should You Do Before Starting
Boilers After Summer LayUp?
Why? A Question for All Inspectors
About Us | Get Directions | Contact Us | Disclaimer | Logo & Marks Policy | Privacy Statement | Terms of Use | Site Map
Copyright 2015 The National Board of Boiler and Pressure Vessel Inspectors | 1055 Crupper Avenue Columbus, OH 43229 Ph.614.888.8320
http://www.nationalboard.org/index.aspx?pageID=164&ID=177
3/3
