The Heat Exchanger Inspection article provides you with information about the inspection of the heat exchanger and heat exchanger testing during the manufacturing phase, as well as in-service inspection in operating units.
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.
After the 2003 addenda of ASME Code Section VIII Div. 1, the design of the shell and tube heat exchanger needs to be done based on Subsection C, in UHX part. The design based on TEMA, or any similar code might be accepted which meeting the requirements of UHX part.
The heat exchanger still is a pressure vessel and all requirements for ASME pressure vessel does apply for heat exchanger as well. We are going to avoid to repeat those requirements for the heat exchanger. You may review pressure vessel inspection article for those requirements.
There are several inspection requirements that only apply to the heat exchanger and not regular pressure vessel:
Tube Inspection - The tube outside diameter, inside diameter, thickness, and ovality shall be checked before the building of the tube bundle. You need to refer to ASME Section II to get the acceptance tolerances.
For example, if your tube material is SA 179, you have to refer to the SA 179 and that will refer you to the SA 450 ( Specification for General Requirements for Carbon, Ferritic Alloy, and Austenitic Alloy Steel Tubes) for acceptance tolerance. You have to use your caliper, machinist ruler, etc. to make these measurements and make sure the values fall within acceptance range.
Tube Bundle Inspection - The bundle dimension shall be checked based on the approved drawing. The baffle diameter and distance between them shall be controlled and meet the acceptance tolerances in the drawing.
The tightness of stay bolts and spacers must be controlled. The shell cleanliness needs to be verified and make sure the inside welds are complete and are ground as per drawing requirements.
Tubesheet Inspection - The Tubesheet shall be inspected before welding to the shell. The hole diameter, grooves dimensions, drilling pattern, the thickness of the tubesheet and surface finish shall be measured and checked aginst acceptance tolerances in the approved drawing.
Tube Rolling Inspection - The tube rolling shall be checked based on customer specification. The wall reduction (after rolling) and depth of roll shall be measured and shall meet the customer specification. The wall reduction should not be less than 5% and should not be more than 8% of the tube wall thickness.
Leak Testing of Seal Weld (Tube to Tubesheet) - if seal welding considered, then the leak test will be a mandatory requirement. The shell side will be subjected to the air pressure, and water and soap solution will be sprayed to the tubesheet to make sure all seal welds are defect free. The bubble will be developed if there was any welding defect such as crack, pinhole, etc.
Shell side Hydrostatic Testing - After manufacturing completion, the heat exchange shell side will be subjected to the hydrostatic testing. The test pressure amount shall be consistent with the value indicated in the approved drawing. The holding time shall be based on the supplier approved test procedure.
The pressure gages calibration and range shall be controlled. The pressure gage range shall be within 1.5 thru 4 times of test pressure. The shell body and welding seams shall be inspected. The tubesheet also shall be checked. No leakage is allowed.
The test pump hose shall be disconnected, and no pressure drop is allowed. The test result will be satisfactory if no leakage being observed and no pressure being dropped while the shell side was under pressure.
Tubeside Hydrostatic Testing - After successful completion of shell side hydrostatic testing, the bonnets are assembled, and tube side is subjected to hydrostatic testing. Similarly, the amount of test pressure shall be as the one indicated in the approved drawing. Other requirement is similar to the shell test. No leakage and pressure drop shall be observed while the tube side is under pressure.
Third Party Inspection for Shell and Tube Heat Exchanger article provides you a procedural content for heat exchanger inspection. Review following standard Inspection and Test Plan for Shell and Tube Heat Exchanger.
You might be interested in reviewing following related articles:
Shell and Tube heat exchangers are the most popular type in the industry. This type is made from 3 components as listed below:
One fluid is in the tube side and the other one in the shell side. The heat transfer is done through the 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.
Besides, 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.
The In-Service Inspection code for shell and tube heat exchangers is API STD 510. The other API recommended practices and codes also have to be used in with this Code.
Some of these Recommended 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 the 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 perform shell and tube heat Exchanger inspection. You may also review the Industrial Plant Inspection article.
Shell and Tube Heat Exchanger Inspections are categorized in the following way:
Shell and Structure in Heat Exchanger Inspection:
Bonnet in Heat Exchanger Inspection
Tube Bundle in Heat Exchanger Inspection
Channel in Heat Exchanger Inspection
Channel Cover in Heat Exchanger Inspection
Floating Head Inspection:
Expansion Joint Inspection
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