Nondestructive Testing service providers

  Hardness is the resistance of a material to localized deformation. The term can apply to   deformation from indentation, scratching, cutting or bending . In metals, ceramics and most polymers, the deformation considered is plastic deformation of the surface. For  elastomers  and some polymers,  hardness is defined at the resistance to elastic deformation  of the surface. The lack of a fundamental definition indicates that  hardness is not a basic property  of a material, but rather a composite one with contributions from the yield strength, work hardening, true tensile strength, modulus, and others factors. Hardness measurements are widely used for the  quality control of materials  because they are quick and considered to be nondestructive tests when the marks or indentations produced by the test are in low stress areas. There are a large variety of  methods used for determining  the hardness of a substance, as can be seen b...

  Welding of Stainless Steels: General Concepts: Stainless steels, resumed here in a general way, are defined as steel alloys, where the  chromium content  ranges from  10.5% to 30%.  There are five distinct types of stainless steel: Ferritic stainless steel: Contains from  10.5 to 30% chromium , is low in carbon, with some alloys containing major amounts of molybdenum, columbium and titanium. Austenitic stainless steel: Contains from  16% to 26% chromium  and up to 35% nickel and have very low carbon content. Some of these steels are also alloyed with a minor amount of molybdenum, columbium and titanium. Martensitic alloy steel: Contains from  12% to 17% chromium  and up to 4% nickel and 0.1% to 1.0% carbon. Some alloys will also have minor additions of molybdenum, vanadium, columbium, aluminum and copper. Duplex stainless alloys: Contain  18% to 28% chromium , 2.5% to 7.5% nickel and low carbon contents. Some of the alloys will al...

Here are some rarely used  NDT – Few Other Methods 1.   Eddy Current Testing – ET: Eddy-current inspection uses  electromagnetic induction  to detect flaws in  conductive  materials. A circular coil carrying current is placed in proximity to the test specimen (electrically conductive). The alternating current in the coil generates changing magnetic field which interacts with test specimen and generates eddy current. The  term eddy current  (also called Foucault currents) comes from analogous currents seen in   water  where localized areas of turbulence  known as eddies  give rise to persistent vortices. When alternating current is applied to the conductor, such as copper wire, a magnetic field develops in and around the conductor. Variations in the electrical conductivity or magnetic permeability of the test object, or the presence of any flaws, will cause a change in eddy current. A corresponding change in the phase ...

  Non destructive Testing (NDT)- Common Methods are: Visual Inspection – VT Liquid Penetrant Testing – LT Magnetic Particle Testing – MT Radiographic Testing – RT Ultrasonic Testing – UT 1.   Visual Inspection – VT: Visual inspection after welding is very useful in evaluating quality, even if other testing methods are to be employed. As welding progresses, surface flaws such as cracks, porosity, and unfilled craters can be detected only by Visual Inspections, leading to repairs or rejection of the work. Welds must be cleaned from slag to make inspection for surface flaws possible. A  10x magnifying glass  is helpful in detecting fine cracks and other faults. As indicated before, a  borescope and dental mirrors , are useful for inspection inside vessels, pipe, or confined areas. Visual inspection  is the most popular and the most widely used of the non-destructive inspection techniques. Completed welds should be checked according to the plans and the sp...

  We would see about Recommendations for Welding of Structural Steel as per AWS D1.1 , 2020 revision Groove Weld: (Clause 4.4.1) Weld Length : shall be the width of the parts joined , perpendicular to the direction of compressive or tensile stress, Weld Size:  Thickness of thinner part of two joining sections, (with no excess re-enforcement achieved with a improper weld bead) Partial Penetration Weld : Weld Thickness: (Clause: 4.4.1.3) The size of Partial Penetration Groove welds shall be selected from the below  table 5.5  based on the thickness ‘ T’ of the joining base metal , Consider the thickness of the thicker part if two different thickness is joined. Fillet Weld Size. Minimum size of Fillet: (Clause :4.4.2.8) The minimum Throat thickness of fillet weld shall be selected from table below Size of Fillet Weld in Lap Joints: For Base Metal Thickness < 6mm , the fillet Leg size = thickness of base metal For Base Metal Thickness  >  6mm, the Fillet ...

  The sole purpose of welding procedures is to describe the details that are to be followed in the welding of specific materials or type of joint. The following is a   list of standard specifications for welding procedures  that are normally covered in welding procedures specification for all welding processes. Nondestructive Examination – ASME Section V A. Article 1, General Requirements: The Welding Inspector should be familiar with, and understand The Scope of Section V Rules for use of Section V Responsibilities of the Owner / User and Subcontractors Calibration, Inspection and Examination Record Keeping Requirements B. Article 2, Radiographic Examination: The Scope of Article 2 and General Requirements, The Rules for Radiography applied on butt welded seams: Required Marking; Type, Selection, Number, and Placement of IQI’s; Allowable Density and Density Ranges; Control of Backscatter Radiation; 3. Recording of inspection; C. Article 6, Liquid Penetrant Examination (I...