Pipe Inspection – Heat Treatment, NDT, Hydrotesting and Marking
Learn about Pipe Inspection - Heat Treatment, NDT, Hydrotesting, and Marking.
In this video, you will learn about various testing and inspection performed during and after the manufacturing of the pipe to ensure the quality of the pipe before it dispatched to the site for use. You will learn about Heat Treatment, Non Destructive Testing, Distractive Testing, Metallurgical Testing, Hydrostatic Test, Visual & Dimension Inspection and Marking. I highly recommended you to watch my other video about pipe manufacturing process to have complete understanding. links are given in the description.
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Heat treatment of pipe depends on the way it is manufactured.
In the case of hot finished Pipe, no heat treatment is required. As during the manufacturing, Pipe Temp. remain in the range of heat treatment temperature till the final size and thickness are achieved
Whereas in the case of Cold Finished Pipe, Heat treatment is required as per applicable ASTM standard. As the pipe is either cold drawn or temperature is not in maintained in the hot finish range.
Selection of heat treatment methods will depend on types of material and on what material properties you want to restore or further enhancement on existing properties.
These heat treatment methods are Normalizing, Quenching, Tempering, Solution Annealing, Stress relieving, or it is a Combination of these.
Non-Destructive testing is carried out on the piping components to ensure the soundness of the body & weld. NDT will check whether any physical subsurface defects such as crack, porosity or lack of fusion are present, this defects may affect the performance of components during the service. Most common methods of NDT that used are Flux leakage examination or Magnetic flaw detection , Eddy current, Ultrasonic testing, Radiography (Only for Weld), Magnetic particle test of pipe ends & weld seam, And Positive Material Identification.
Ultrasonic testing can be done on full body or only for weld seam, whereas radiography is performed on weld seam only. Magnetic particle test is performed on pipe ends & weld seam. Hardness check is also performed on metal to confirm the standard requirements.
In the future video, I will try to cover a brief overview of these NDT methods so that you have working level understanding of these NDT methods. If you are an inspection engineer, you need to know all these testing in much detail.
Distractive tests confirm the mechanical requirements of the manufactured pipe.
In Distractive Testing- a sample from the actual material is cut to performed various tests.
The tensile test is done to check yield and ultimate tensile of the material. If required by the purchaser or by standard, high or low-temperature tensile test are also performed.
Bend test or Guided bend test are used to check integrity of weld joint
Flattening test examines ability of plastic deformation in pipe
Impact test / Charpy V-Notch Test, check the ability of material to withstand under low-temperature conditions
Creep test is performed to check the long-term effect of continued temperature under constant load on steel.
Metallurgical Tests confirm the chemical requirements of material grades as per the applicable material standard.
Metallurgical Tests are normally known as Micro and Macro testing
Micro Analysis or Chemical Analysis of Raw material, Product, and Weld ensures that all the alloying elements are within the range as specified in the material standard.
Macro Analysis for Weld will check proper fusion of weld material with pipe material.
There are some Special tests that also carried out on the material when it is going to be used in aggressive environments. These tests will ensure that pipe material is able to withstand in such aggressive environments also. Some of the tests are Grain size (AS & SS), IGC- Intergranular Corrosion Test(SS), Ferrite (SS), HIC- Hydrogen-induced Cracking, SSC- Sulfide Stress Corrosion Cracking, these tests are performed when it is asked by the purchaser in his specification.
Hydrostatic Test of a pipe is carried out to ensure that pipe is 100% leak proof. It also ensures the ability of pipe to withstand pressure.
Hydro test pressure is calculated based on equation given in ASTM A530, this equation is based on three parameters Pipe OD, Pipe Thickness and Pipe Wall Stress
Holding time for the hydro test is minimum 5 secs as per ASTM A530. Pressure is monitored by the computerized system.
For welded pipe, the test pressure should be held for a time, sufficient to permit the inspector to examine the entire length of the weld seam
Hydrostatic test can be waived under certain conditions as set in the standard
Visual Inspection is one of the most effective inspection method used to check overall product quality. During the visual inspection, you will check for overall product finish. You will check for surface imperfections such as mechanical marks, lamination, tears or any other visual imperfections and also check weld defects such as porosity, undercuts, uneven weld bead, and excess or under fill of weld material. Acceptance of these imperfections are as per applicable standard
Dimension inspection of the pipe is carried out based on the Dimension Standard, final dimension of the pipe must confirm the standard or it should be as specified in purchaser’s specification.
For Welded and Seamless Wrought Steel Pipe dimensional requirements are cover in ASME B36.10
For Stainless Steel Pipe dimensional requirements are cover in ASME B36.19
During dimensional inspection Diameter, Length, Thickness, Straightness, Ovality & Weight are checked. Permissible Variations depends on manufacturing standard. You can visit my website hardhatengineer.com to know about acceptable tolerances in pipe dimension.
Once the pipe is cleared all test and inspection, it is marked as per the standard requirements. Pipe shall be marked with Manufacturer logo, ASTM material code, Material Grade, Size, Thickness- schedule no., Length, Heat No and Special marking WR for weld repair or NH for non-hydro tested pipe.
These Marking can be done by paint or by Hard punching. For stainless steel pipe, stenciling is also used
Please note that for carbon steel no hard punching below 6 mm thickness and for stainless steel no hard punching below 12 mm thickness
This is all about testing, inspection, and marking of the pipe.
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