Heat Exchangers

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Heat Exchangers are pieces of process equipment built and designed for maximum efficiency of heat transfer between two different machines or mediums. In most industrial processes, the loss of heat is very wasteful and inefficient. Because of this, heat exchangers were created to capture and reuse heat that would otherwise be lost to the environment.

In general, a heat exchanger functions by allowing a hot fluid to flow through the exchanger past a cold fluid without intermixing the two. Heat flows from the hot fluid to the cold fluid, heating the cold fluid and cooling the hot fluid. This allows the heat to be transported and reused rather than simply discarded. The two fluids will flow past each other, with one usually being in a narrow pipe while the other flows outside the pipe in a surrounding shell.

There many different types of heat exchangers; some more appropriate for certain environments than others. Some have built-in dividers to separate the heat storage, while others allow the mixing of heat. Of these different types, each one fits into one of three larger classifications depending on its type of flow.

  1. Parallel-flow Exchangers involve two different fluids entering the exchanger from the same end and flowing in the same direction.
  2. Counter-flow Exchangers push the cold fluid from one direction of the exchanger while the hot will enter from the other direction and they will flow past each other. Counter-flow exchangers are often considered the most efficient at transferring heat.
  3. Cross-flow Exchangers push the hot and cold fluids in a perpendicular flow and exchanging heat at the intersection where they meet.

In the oil and gas and chemical processing industries, inspection and maintenance responsibilities for heat exchangers are often grouped in with other fixed equipment.

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Articles about Heat Exchangers
January/February 2024 Inspectioneering Journal

A detailed analysis revealed the weaknesses of an existing gasket seating design and bolt tensioning effectiveness to be the root cause of a chronic leak issue.

September/October 2022 Inspectioneering Journal

Inadequate consideration of corrosion and material degradation of many older facilities has complicated the implementation of modern-day RBI programs. This article presents a case study of a heat exchanger with such a design.

January/February 2022 Inspectioneering Journal

The application of a detailed design-by-analysis method using ASME Sec-VIII Div-2 confirms field-observed ratcheting and fatigue type failures in the tubesheet due to the complex cyclical thermal-mechanical loading encountered during operation.

January/February 2021 Inspectioneering Journal

The purpose of baseline inspections is to provide cost savings upfront versus the cost incurred during operations. So, what are the possible heat exchange tubing defects or anomalies and how are they validated?

Authors: Timothy L. Rush
January/February 2020 Inspectioneering Journal

Decision trees can be used to help with decisions related to nearly any closed loop mechanical integrity or inspection workflow process. This article focuses on how decision trees can be applied to heat exchanger tubular inspection.

Authors: Zach Burnett
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Our proprietary furnace tube inspection system, FTIS is an ultrasonic inspection technology capable of rapid, automated fired heater coil inspection in refinery fired heaters. The data captured by our furnace tube inspection system is...

May/June 2018 Inspectioneering Journal

This article presents a case study from a Middle Eastern refinery that explores a heat exchanger that failed unexpectedly after five years in service. There are multiple initiators that can cause under deposit corrosion (UDC) in heat exchangers in...

May/June 2018 Inspectioneering Journal

HTHA of hydrogen-containing equipment can be prevented with appropriate material selection and fabrication, appropriate welding procedures, regular inspection of equipment using proven, effective technologies and equipment operated by qualified...

Authors: Samer E. Ibrahim
January/February 2018 Inspectioneering Journal

Cleaning of heat exchangers and other process equipment is typically done with the use of pressurized water (e.g., hydro-blasting). However, in some situations thermal decomposition, a technique that utilizes heat rather than water to break down...

Authors: Kyle Dunn
September/October 2017 Inspectioneering Journal

Fired heaters are among the most critical equipment in refineries and chemical plants. This article provides an overview of what a fired heater tube mechanical integrity program should include.

September/October 2017 Inspectioneering Journal

Amine systems that scrub H2S from hydrogen-rich gas experience rapid fouling of the heat transfer equipment, especially in a hot summer. Learn how temporary cooling solutions can improve process conditions during critical periods of the year with no...

Authors: Massimo Capra
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Traditional pressure vessel inspections often require taking assets out of service. However, MISTRAS’ Non-Intrusive Inspection (NII) programs provide data as good or better than internal inspections, while assets remain in service. NII is...

Online Article

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Authors: Massimo Capra
September/October 2016 Inspectioneering Journal

Detecting, quantifying, and sizing indications characterized as a “crack" in critical equipment have long been the global benchmark of asset integrity programs. Therefore, the increased precision that inspection programs obtain using advanced...

Authors: Kimberley Hayes
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Inspectioneering recently had the opportunity to chat with Barney Smith, Turnaround Manager at Aggreko, a global leader in power, heating, cooling, and oil-free compressor rental solutions. Our discussion focused on catalyst cooling during...

Authors: Jeremiah Wooten
January/February 2016 Inspectioneering Journal

Heat exchangers operating in refineries or petrochemical plants must be thoroughly cleaned and inspected throughout their operational lifetime to ensure safe and efficient operations.

Authors: Harold Marburger
Online Article

Inspectioneering recently had the opportunity to sit down and chat with Brian Fahnestock about heat exchanger issues in the refining and petrochemical sectors and how temporary solutions can help mitigate the damage should a problem arise.

Authors: Jeremiah Wooten
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Contact us at to learn how DIMATE PACS digitizes NDT methods (RT, UT, VT, ...) and how it leads to paperless inspections.

September/October 2015 Inspectioneering Journal

This article is Part II of a three-part series that explores the various methods, benefits, challenges and solutions to efficiently and effectively clean heat exchangers, both onsite and offsite.

Authors: Harold Marburger
March/April 2015 Inspectioneering Journal

The tubes of heat exchangers (HX), whether for a shell and tube bundle or an airfin, are typically subject to some form of nondestructive examination (NDE) to try and quantify the remaining wall thicknesses and corrosion rates to help a plant to...

Authors: A.C. Gysbers

We talk about heat exchangers quite a bit here on Inspectioneering, most recently in the January/February issue of the Journal. This is because heat exchangers are vital pieces of equipment in nearly every type of plant or facility.

January/February 2015 Inspectioneering Journal

Whether onsite or offsite, the methods for cleaning shell and tube heat exchangers can vary. Refining and petrochemical operators will agree that high standards must be employed with each method. Choosing the right method can make the difference...

Authors: Harold Marburger
November/December 2014 Inspectioneering Journal

Dual mode pulse reflectometry shows promising results in detecting a wide range of defect types and sizes in heat exchanger mock-ups.

Authors: Dr. Noam Amir
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With the IMS Suite, you can calculate optimal intervention periods and lay out efficient maintenance strategies. Click here to learn more.

September/October 2014 Inspectioneering Journal

A small leak from top tubesheet-to-tube welds prompted further inspection of the 1¼Cr- ½Mo Ammonia Converter Boiler Feed Water (BFW) Exchanger during a planned shutdown. Further cracks were identified in the top channel to tubesheet butt weld that...

July/August 2012 Inspectioneering Journal

At most operating facilities, a significant amount of time, effort, and money is expended on problem flanged joints that repeatedly leak. Joints that are repeatedly tightened online, that require installation of leak clamps, or that have resulted in...

Authors: Robert C. Davis
March/April 2012 Inspectioneering Journal

Air-cooled heat exchangers (AC-HEs) are used extensively throughout the oil and gas industry, from upstream production to refineries and petrochemical plants, under high pressure and high temperature conditions, as well as corrosive fluids and...

Authors: Fernando Vicente
July/August 2011 Inspectioneering Journal

Once again there is a crack found in the inlet tubesheet in your high-pressure high temperature heat exchanger. As head of the maintenance engineering effort, you know that plant management will ask you if it can run safely and reliability until...

January/February 2011 Inspectioneering Journal

Washington DC, January 27, 2011 - A U.S. Chemical Safety Board (CSB) case study released today on the 2008 heat exchanger rupture and ammonia release at the Goodyear Tire and Rubber Company in Houston, Texas, identifies gaps in facility emergency...

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FER's extensive TA experience, combined with our custom software (RAMI Scope) that tracks all aspects of TA activities, we have the ability to keep your turnaround flowing flawlessly with the methodology to maximize your value of premium time.

September/October 2010 Inspectioneering Journal

In the first article in this series entitled How to Put It All Together - Guide to Organizing a Successful PEI Program, (1) I provided an overview of the necessary Management Systems (MS) for a successful program to achieve excellence in pressure...

Authors: John Reynolds
July/August 2008 Inspectioneering Journal

This paper covers most of the common (and some not so common) types of NDE methods for heat exchanger (HX) tubular in-service inspections. In addition to noting some of the various advantages and limitations with these methods, the paper covers heat...

May/June 2007 Inspectioneering Journal

Tube Inspection is a vital tool for the refining and petrochemical industries. Heat exchangers and condensers are designed to sustain 100% separation between the products in the tube (tube side) and the products in the vessel (shell side). A...

Authors: Brian Beresford
January/February 2001 Inspectioneering Journal

Part 5 of this article continues to outline the 101 essential elements that need to be in place, and functioning well, to effectively and efficiently, preserve and protect the reliability and integrity of pressure equipment (vessels, exchangers,...

Authors: John Reynolds
September/October 1999 Inspectioneering Journal

This paper describes the use of a UT fixture for detection of stress corrosion cracking in ferrous heat exchanger tube-to-tubesheet welds and external tube corrosion or pitting near the tubesheets including crevice OD corrosion.

Authors: Reggie Cross
May/June 1999 Inspectioneering Journal

Southwest Research Institute (SwRI) has developed an innovative method for rapid screening of heat exchanger tubing using Guided Wave technology. This screening method can lead to an improvement in heat exchanger reliability and a reduction in the...

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