Heat Exchanger Inspection

The Heat Exchanger Inspection article provides you with information about the inspection of heat exchanger and heat exchanger testing during the construction phase, as well as in the operational phase.

This article provides you lots of invaluable information about the following items:

  • Inspection and Testing During the Manufacturing Phase
  • Inspection and Testing During the Operation Phase
  • Heat Exchanger Codes and Regulations
  • Maintenance and Repairs

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This article, alongside other linked articles are useful for Manufacturer's Quality Control Personnel, Second and Third Party Inspectors, Purchasers, Sellers, Plant Inspectors, HSE Engineers, Integrity Engineers, Operation and Maintenance Engineers and any Other Interested Individuals.

We need to heat or to cool process fluids in industrial plants to facilitate process reactions.

So we need to use heat exchangers either to reduce the temperature or increase the temperature.

For more details, review the Heat Exchanger Theory article.

This article provides information only about the shell and tube heat exchanger inspection. For fin tube heat exchanger inspection, review following articles:

Fin Tube Heat Exchanger Inspection

Third Party Inspection for Fin Tube Heat Exchanger

Inspection and Test Plan for Fin Tube Heat Exchanger

The content covers the shop inspection requirements during the manufacturing process and the In-service Inspection requirements in the operational plants.

What are the Shell and Tube Heat Exchangers?

Shell and Tube heat exchangers are the most popular type in the industry. This type is made from 3 components as listed below:

heat exchanger inspection
  1. Two heads, one rear head and the other one stationary head
  2. Shell
  3. Tube

One fluid is in the tube side and the other one in the shell side. The heat transfer is done through tube wall.

So your heat exchanger with more tubes will have more heat transfer surfaces, and at the same time will have a higher heat exchanger diameter.

There are different kinds of shell and tube heat exchangers with different applications.

The reason for the high amount of applications is that they are easy to maintain.

In addition, the shell and tube heat exchanger is the only type that can be designed and operated at a temperature greater than 360 degrees centigrade, as well as in pressure higher than 30 bar.

What are the Shell and Tube Heat Exchanger Inspection Requirements in a Construction Shop?

The construction code for shell and tube heat exchangers is ASME Code Section VIII, and it covers the minimum requirements for design, materials, fabrication, inspection, testing, and preparation for initial delivery.

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heat exchanger inspection

You may know after the 2003 addenda of ASME Code Section VIII Div. 1, the design of the shell and tube needs to be done based on Subsection C, in UHX part. And design base TEMA, or any similar code and standards is not allowed.

So this is when you require that your shell and tube heat exchanger meets the ASME Code requirement or when you need your heat exchanger to be “U” stamped.

As you may know, heat exchangers are also pressure vessels based on ASME Code requirements, and all requirements for other types of pressure vessels also apply for heat exchangers.

For more detail about Stamped pressure vessels and requirements, review the Pressure Vessel Certification article.

With the above explanation, your inspection and test plan (ITP) for the shell and tube heat exchanger need to meet the requirements of ASME Code Section VIII.

For more detail about heat exchanger inspection in the construction process, review the following articles:

Third Party Inspection for Shell and Tube Heat Exchanger

Inspection and Test Plan for Shell and Tube Heat Exchanger

What are In-Service Inspection Requirements for the Shell and Tube Heat Exchanger Inspection?

The In-Service Inspection code for your shell and tube heat exchangers is similar to other pressure vessel in API STD 510.

The other API recommendation practices and codes also have to be used in with this Code.

heat exchanger inspection

Some of these Recommend Practices are API RP 572, API RP 577, and API RP 571, and also construction code sections might be used, such as ASME Code Section VIII and ASME Code Section IX.

For repair the requirement of API STD 510 or ASME-PCC-2 needs to be met.

The title of ASME-PCC-2, which was first published in 2006, is: “Repair of Pressure Equipment and Piping.”

Please note: if your shell and tube heat exchanger is “U” stamped and you need to do repair, you have to use a Repair Organization holding an “R” Stamp from the National Board Inspection Code.

The API 510 Pressure Vessel Inspectors are qualified persons to do shell and tube heat Exchanger inspection.

You may also review the Industrial Plant Inspection article.

What are the Important Items in the Shell and Tube Heat Exchanger Inspection in Overhaul?

Shell and Tube Heat Exchanger Inspections are categorized in the following way:

Shell and Structure in Heat Exchanger Inspection:

  • Neutralization of Austenitic Stainless Steel shell, clads, liner or weld overlay, which contains H2S service. The process needs to be done based on approved procedures by a corrosion engineer.
heat exchanger inspection
  • Neutralization is also required for shell material with admiralty brass to reduce the risk of SCC.
  • Neutralization of thermocouples, if necessary, and doing dye penetration test
  • Sampling from shell fouling and corrosion products and making lab analysis and making interpretation by corrosion engineer (if necessary)
  • Cutting small area of insulation sheet and removing the insulation and doing visual inspection for any sign of corrosion under insulation
  • Thickness measurement of different parts of shell and shell nozzles and making corrosion rate and remaining life calculation
  • Inspection of shell cleaning and approval i.e. water jetting etc.
  • Checking inside surface for any cladding, liner failure or separation
  • Inspection of Shell flange gasket seating area for any erosion, damage and cracking
  • Inspection of longitudinal and circumferential weld joints, inlet and outlet nozzles, reinforcement pads and small bore connections for any crack, corrosion and mechanical damage and deformation
  • Dye penetration test on weld joints that are susceptible to cracking, austenitic flange face, weld overlay and cladding surface and exchangers exposed to amine and caustic
  • Hydrogen blistering inspection in hydrogen services (hand lamp procedure)
  • Heat exchanger support, steel structure, foundation, bolt and nut inspection

Bonnet in Heat Exchanger Inspection:

  • Thickness measurement and making corrosion rate and remaining life calculation
heat exchanger inspection
  • Girth flange inspection for corrosion and erosion
  • Internal surface inspection for corrosion and fouling
  • Painting inspection of external surface
  • Dye penetration or magnetic particle examination of weld joints susceptible to cracking

Tube Bundle 

heat exchanger inspection
  • Taking care in the pulling out of tube bundle to avoid any mechanical damage
  • Sampling from tube side fouling and corrosion products and making lab analysis and making interpretation by corrosion engineer (if necessary)
  • Controlling of water jetting or lancing cleaning process
  • Controlling wire brushing process of inner tube edge and rolling area (preparation for ID measurement)
  • Inside diameter measurement in tubes and tubes rolling areas
  • Rate off and accordingly plugging the tubes when their OD reaches to the ID plus one thickness
  • Retubing of tube bundle if more than 10% of tubes reach the above rejection limit
  • Inspection from tube bundle components such as tubesheet, tube, tie rods and spacers, transfer baffles or support plate, impingement baffle, floating head flange and floating head backing device
  • Inspection from internal surface of tubes for corrosion and fouling
heat exchanger inspection
  • Pulling out a sample tube for sectioning and corrosion anlaysis if necessary
  • Retubing when sectioning result proves the thickness is half of the nominal value
  • Visual inspection and dye penetration test from tube to tubesheet seal or strength weld
  • Eddy current testing if it is necessary

Channel in Heat Exchanger Inspection:

  • Thickness measurement and making corrosion rate and remaining life calculation
  • Inspection of gasket seating area, pass partition and nubbing for corrosion and deformation
  • Inspection of internal surface for fouling, corrosion and soundness of linings (if any)
  • Balance hole inspection for corrosion and erosion
heat exchanger inspection
  • Welding joints inspection for any possible cracks
  • Reinforcement pad inspection and doing soap test if necessary
  • Cathodic protection anodes inspection and replacement if necessary
  • Diaphragm and division box visual inspection and dye penetration test of diaphragm for any possible cracks (for high pressure exchangers)

Channel Cover in Heat Exchanger Inspection:

  • Thickness measurement and making corrosion rate and remaining life calculation
  • Inspection of gasket seating area for corrosion and deformation
  • Inspection for internal surface for fouling, liner, cladding and coating soundness
  • Soap test in channel cover with liner
  • Lifting lug weld joint inspection for any possible crack

Floating Head Inspection:

  • Thickness measurement and making corrosion rate and remaining life calculation
  • Inspection of gasket seating area, pass partition and nubbing for any possible corrosion and deformation
  • Girth flange weld joint inspection for any possible crack and corrosion
  • Internal surface inspection for corrosion and fouling and soundness of liner, coating and cladding (if any)

Expansion Joint Inspection:

The heat exchangers with expansion joints need to be inspected for:

heat exchanger inspection
  • Flange inspections for corrosion and erosion
  • Inspection from internal surface for corrosion and erosion
  • Air test

The tube and shell hydrostatic test need to be done after the above stated inspection activities.

Related Articles
Boiler Inspection, Above Ground Storage Tank Inspection, Piping Inspection, Valve Inspection, Heater Inspections, Pressure Vessel Certification, Pressure Vessel RT Test, Pressure Vessel Dimension Inspection, ASME Impact Test Requirement, ASME Pressure Vessel Joint Efficiencies, Pressure Vessel Plate Material


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