The phrases “Industrial plant inspection activities” refers to the inspection or integrity department in oil, gas, chemical or other industrial plants, which is responsible for carrying out the inspection in an operating unit.

What is inspection?

According to API 510 2006, Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, And Alteration, Inspection is the external, internal, or on-stream evaluation (or any combination of the three) of a pressure vessel’s condition.

External inspection is a visual inspection performed from the outside of a pressure vessel to find conditions that could impact the vessel’s ability to maintain pressure integrity or conditions that compromise the integrity of the supporting structures, e.g. ladders, platforms. This inspection may be done either while the vessel is operating or while the vessel is out-of-service.

Internal inspection is an inspection performed from the inside of a pressure vessel using visual and/or NDE techniques. Moreover, on-stream inspection is an inspection performed from the outside of a pressure vessel while it is on-stream using NDE procedures to establish the suitability of the pressure boundary for continued operation.


The inspections are done according to the following timelines:

  • Periodic external inspections
  • Overhaul or shutdown internal inspections
  • Emergency shutdown inspections

The inspection department in the industrial plants generally takes care of the static equipment. Rotating, electrical and instrumental equipment are not in the scope of the inspection department, and normally, maintenance department takes care of those.

Local authorities mandate that pressurized equipment be inspected in specific intervals by third party inspection agencies. This is normally called third party inspection of a plant.

The static equipment can be categorized as follows when referring to industrial plant inspections:

  • Pressure vessels
  • Piping Systems
  • Storage Tank
  • Steam Boiler
  • Process Heater
  • Industrial Valves
  • Risk Based Inspection

The inspection activity covers the inspection from material inspection to final inspection and dispatch to site.

Inspection Technique

There are two categories of inspection technique; non-destructive and destructive testing.  Non-destructive testing (NDT) is the process of inspecting, testing, or evaluating materials, components or assemblies for discontinuities, or differences in characteristics without destroying the serviceability of the part or system. In other words, when the inspection or test is completed the part can still be used.


Example of Non-Destructive Testing Method

In contrast to NDT, other tests are destructive in nature and are therefore done on a limited number of samples rather than on the materials, components or assemblies actually being put into service. These destructive tests (DT) are often used to determine the physical properties of materials such as impact resistance, ductility, yield and ultimate tensile strength, fracture toughness and fatigue strength, but discontinuities and differences in material characteristics are more effectively found by NDT.


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Example of Destructive Testing Method

During construction, NDT is used to ensure the quality of materials and joining processes during the fabrication and erection phases, and in-service NDT inspections are used to ensure that the products in use continue to have the integrity necessary to ensure their usefulness and the safety of the public.