Nondestructive Testing service providers

  Material testing Mechanical testing  have been designed to test several weld properties.Few other material testing techniques are Charpy V-Notch Toughness: Notch toughness is the capacity that a material possesses to  absorb energy  in the  presence of a flaw , such as a notch or crack. The material will likely exhibit a lower level of toughness. When a flaw is present in a material, loading induces a triaxial tension stres s state adjacent to the flaw. The material  develops plastic strains  as the yield stress is exceeded, near the crack tip. Notch-toughness is  measured with a variety of specimens  such as the  Charpy V-notch impact  specimen or the dynamic tear test specimen. As with regular impact testing the tests are often repeated numerous times with specimens tested at a different temperature. With these specimens and by varying the loading speed and the temperature, it is possible to  generate curves such as those s...

  Welding Safety with Gas Cylinders On an oxyacetylene system there will be three types of valves,  the cylinder valve, the regulator valve, and the torch valve . There will always be a set of three valves for each system, since  the gas in the cylinders is at high pressure. A broken off valve will release extremely high pressures, which could cause the cylinder to become an extremely deadly flying missile. For this reason, never move an oxygen tank around without its valve cap screwed in place. An oxygen tank is especially dangerous for the reason that the oxygen is at a pressure of  21 MPa (3000 lb./in² = 200 atm) . Oxygen cylinders are generally filled to approximately  2200 psi . The regulator  converts the high pressure  gas  to a low pressure  stream suitable for welding. It is not recommended to directly use high-pressure gas. Pressurized cylinders must at all times be handled with great care.  Shielding gases  such as carbon...

  Failure investigation often   uncovers facts  that lead to changes in design, manufacturing, or operating practice, which will eliminate similar failures in the future. Failures of insignificant parts can also lead to advances in knowledge and should be done objectively, as with a large structure. The following four areas of interest should be investigated to determine the cause of weld failure or weld defects and the interplay of factors involved: Initial observation . The detailed study by visual inspection should be made at the failure site as quickly as Photographs should be taken, preferably in color, of all parts, structures, failure surfaces, fracture texture appearance, final location of component debris, and all other factors.   Background data . All information concerning specifications, drawings, component design, fabrication methods, welding procedures, weld schedules, repairs in and during manufacturing and in service, maintenance, and service use. Att...

  Fillet Weld Sizes as per AWS D1.1 & AWS D1.2 This blog here answers your questions about: What is the tolerance for Fillet weld sizes as per AWS D1.1 ? What is the weld size tolerance? What is the required fillet weld size for structures ? Selection of Fillet Size Acceptance criteria clauses for Weld Profile in AWS 7.23.1 Fillet Welds. The faces of fillet welds may be slightly   convex, flat, or slightly concave as shown in Figure 7.4 and as allowed by Tables 7.8, 7.9, 8.1 , and 10.15. Recommended weld profile in AWS Recommended weld profile Allowable reduction in throat Convexity Conclusion for AWS D1.1 Minimum size (leg length) of fillet weld to be achieved as per Table 7.7 , the same shall be in the drawing too. Under size of leg length is not acceptable, Throat thickness convexity acceptance criteria is from Table 7.9 Over size is not described in the standard, but can be mutually agreed between client and manufacturer through contract document, if not additiona...

  The procedure requirements for welding electrodes and preheating temperatures are as follows: Welding must be done with the same process (SMAW or FCAW) used for qualification If the operator has qualified on any of the steel permitted (ASTM A36 and A588), that same operator is qualified to weld on the other and on SAE 1010 or ASTM. A welder qualified for manual shielded metal-arc welding with an  E7018  electrodes may also weld with  E7016 electrodes .Identifying electrode numbers are as follows:  a. The  70 designation  shall be understood to mean the  70 series  unless an alloy steel of higher strength is to be welded. b. The third digit indicates the position permitted. If the  digit is “1,”  the electrode may be used for welding in any position. If “2,” only the down hand position may be used. c. The  fourth digit  indicates the chemical make-up of the electrode coating. The  digit 6  indicates  low hy...

  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...

  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 ...

  Positions for Welding Pipe For welding pipe in shops, power plants, oil refineries, and chemical plants for crude oil, gasoline, and natural gas, the same basic welding positions described previously are used. Flat Butt Weld Pipe Position – 1G A pipe to be welded in the flat position  is usually placed on roller dollies or wooden skids . As the pipe is welded, it’s rotated on the dollies or skids. This procedure  is the same as the flat position plate welding . The speed of rotation should be the same as the welder’s forward welding speed. Horizontal Butt Weld Pipe Position – 2G In this position, the weld around the vertical pipe  is the same of a horizontal position plate welding.  There is little difference whether the pipe is rotated or fixed because the welding is the same. Either the welder will circle around the joint, or the pipe itself can be turned in a circle if it’s free to rotate. Multiple Butt Weld Pipe Position – 5G In this position, the axis of ...