Pre / Post ​Weld Heat Treatment


Post  Weld Heat Treatment
Heat treatment can be defined as an operation or combination of operations, involving heating and cooling of metal or alloy, in solid state, to obtain desired properties. The reson for heat treatment are to obtain higher strength & hardness, toughness, to homogenise the meterial, remove segregation, refine the grainsize, remove cold work effects, soften the meterial, improve machinability, relieve internal stresses, improve wear & corrosion resistance.

Purpose:

  • To avoid haz / weld metal cold cracking (by preventing the formation susceptible micro
  • structure and allowing the diffusion of hydrogen away from the joint)
  • To minimize residual stress
  • To provide sufficient ductility in the weld metal and haz

    • POST WELD HEAT TREATMENT:

    Heat treatment of the welded joint, normally to sub-critical       temperatures, after completion of welding operations


    Pre Weld Heat Treatment

    PRE HEAT TREATMENT:

    Heating of the base metal, at the area to be welded is performed prior to commencement of welding 
    To relieve internal / residual stress
    To remove hydrogen
    To improve the metallurgical properties of weld joint by tempering of haz
    To obtain dimensional stability

    CATHODIC PROTECTION

    Cathodic protection (CP) is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. It is a method used to protect metal structures from corrosion.

    Application

    Cathodic protection systems are most commonly used to protect steel, water/fuel pipelines and storage tanks; steel pier piles, ships, offshore oil platforms and onshore oil well casings. Cathodic protection systems are widely used, particularly with engineering structures such as building reinforcement and buried metallic pipeline and cables. Cathodic protection devices protect structures and metalwork from corrosion, making the metal surface to be protected by a cathode element in a path of electric current, encouraging corrosion to form elsewhere in the circuit in a less critical or cheaper (anode) material.

    EDDY CURRENT INSPECTION (ECT)

    Eddy currents are created through a process called electromagnetic induction. When alternating current is applied to the conductor, such as copper wire, a magnetic field develops in and around the conductor. This magnetic field expands as the alternating current rises to maximum and collapses as the current is reduced to zero. If another electrical conductor is brought into close proximity with this changing magnetic field, current will be induced in this second conductor. Eddy currents are induced electrical currents that flow in a circular path. They get their name from Eddies, which are formed when a liquid or gas flows in a circular path around obstacles when conditions are right.ID probes, which are also referred to as Bobbin probes or feed-through probes, are inserted into hollow products, such as pipes, to inspect from the inside out. ID probes have housing that keeps the probe centered in the product and the orientation of the coil(s) somewhat constant relative to the test surface. The coils are most commonly wound around the circumference of the probe so that the probe inspects an area around the entire circumference of the test object in one go.


    ASSET INTEGRITY MANAGEMENT

    • Failure Analysis
    • Fitness for Services
    • Root Cause Analysis
    • Remaining Life Assessment
    • Risk Base Inspection (RBI)

    Metallurgy & Laboratory Services

    Services

    • In-situ Metallography (Replica Test)
    • SEM-EDS Analysis (BSE & SE detector)
    • Characterization of Materials
    • Gold Coating
    • Fractography Analysis
    • Failure / Root Cause Analysis (FA/RCA)
    • Remaining Life Assessment (RLA)
    • Risk Based Inspection (RBI)
    • Fitness For Services (FFS)
    • Micro structure Analysis Including Metallography Sample Preparation (Destructive)
    • Micro Hardness Testing (100 – 2000gmf)
    • Macro Etching
    • Carburization Testing
    • Passivation Test
    • Corrosion Testing (IGC, HIC, Pitting, Ferrite Content, Passivation, Corrosion Test)
    • Picking of Steel Billet Sample for defects findings
    • Chemical Analysis (Wet Chemical, Water, Oil & Mud Analysis, OES Metal Analysis, Ferrite Content test)
    • Mechanical Testing (TS, Hardness, Bend, Fracture, Peel test & YS)
    • High Temperature Creep Testing
    • General
    • Chemistry & Microbiology Services
    • Welding Procedure Qualification (WQT)

    FACILITIES

    Micro structural Characterization

    • Field Microscope
    • Optical Microscope
    • Stereo Binocular Microscope
    • Scanning Electron Microscope

    Field Microscope

    • Portable lightweight microscopes for hand-held field inspection of prepared surface and replicas. It provides up to 400x magnification.Eye piece: 10xObjective: 4x, 10x, 20x, 40xFilter: Blue, GreenAnalysis: Micro structural analysis onsite
    • Application
    • Field-proven and commonly used in boilers, heat exchangers and fin-fan tubes.

    Optical Microscope

    • Eye piece: 10xObjective: 5x, 10x, 20x, 50x, 100xFilter: Blue, Green, YellowAnalysis:Microstructural analysis, grain number, grain size, layer thickness measurement, inclusion etc.

    Stereo Binocular Microscope

    • A stereo microscope provides a three-dimensional view of the specimen. It does this with separate objective lenses and eyepieces for each eye. They have lower magnification when compared to compound microscopes, but they also have a longer working distance and It uses for failure analysis & investigation of a component at low magnification on fracture surface to see the crack/failure initiation zone or other features.

    Scanning Electron Microscope

    • Scanning electron microscope (SEM) is a versatile equipment which works on the principle of interactions of the electron beam with the atoms at various depths within the sample to produce the images. It produces various types of signals containing the information about the surface topography as well as the compositions of the sample.Specificaion:Accelerating Voltage: 0.5 to 30kVResolution: 3.0nm at 30kV,SEI8.0nm at 3kV SEISignal: Secondary Electron Image (SEI)            Backscattered Electron Image (BSEI)Magnification: 5x to 300000x based on the display size of 128mm x 96mm

    Particle Characterization

    • Particle Size Analysis
    • Grain Size Measurement
    • Inclusion Rating
    • Carbide precipitation
    • Sigma phase counting