Welded joint in which the weld metal and parent material have significant differences in mechanical properties and/or chemical composition. Example: A repair weld of a cast iron item performed with a nickel-based electrode. Heterogeneous welding is one way of performing fusion welding with the application of external filler whose metallurgical composition is substantially different from that of the base metals. So if filler material is applied during joining and the metallurgical composition of filler is different from that of the base metal then it is termed as heterogeneous welding. It is to be noted that heterogeneous welding is not a … Continue reading What is heterogeneous welding

Autogenous welding is one way of performing fusion welding without the application of external filler material. It is to be noted that autogenous welding is not a particular type of welding process like MMAW, TIG, GMAW, etc.; instead, it is one of the three different ways or modes of doing fusion welding. Note that solid state welding processes are usually autogenous as they don’t use any filler during welding. Tungsten Inter Gas (TIG) and oxy-fuel welding processes can be performed in autogenous mode/way. Various advanced welding processes, such as Plasma Arc Welding (PAW), Laser Beam Welding (LBW), Electron Beam Welding … Continue reading What is Autogenous Welding

When welding using a fusion process, the edges of a component are melted together to form weld metal. Table: Heat source, mode of shielding, thickness range and metal deposition rates for various fusion processes Process Heat source Shield Parent metal thickness mm Deposition rate kg/hr Arc MMA Arc Gas/flux 1-100 1-4 MIG Arc Gas 0.5-100 1-8 TIG Arc Gas 0.1-100 1-4 SAW Arc Flux 5-250 5-20 ES/EG Resistance/arc Flux/gas 5-250 5-20 Stud Arc – 4-20 – Gas Oxyfuel Flame Gas 0.6-10 1-2 Power beam Laser Radiation Gas 0.2-25 – EB Electrons Vacuum 0.2-250 – Resistance Spot/Seam Resistance – 0.2-10 – Thermit Thermit Chemical … Continue reading Typical welding deposition rate

Factors which must be taken into account when choosing a suitable welding or joining process are: material type product form: plate or tubular quality and strength requirements degree of mechanization capital cost Although consideration of these factors will identify the most suitable welding process, the choice within a company may be restricted by the cost of implementing a new process, availability of plant or current workforce skill. Welding and joining processes available to the welding engineer can be separated into the following generic types: Fusion arc gas power beam resistance Thermomechanical friction flash explosive Mechanical fasteners Solid state adhesive soldering … Continue reading How to choose a suitable welding process

The European standard, BS EN ISO 4063:2010 Welding and allied processes – Nomenclature of processes and reference numbers, assigns a unique number to the main welding processes. These are grouped as follows: Arc welding Resistance welding Gas welding Forge welding Other welding processes Brazing, soldering and braze welding Each process is identified within the group by a numerical index or reference number. For example, the MIG welding process has a reference number of 131 which is derived as follows: 1 – Arc welding 3 – Gas-shielded metal arc welding 1 – Metal arc inert gas welding The main arc welding … Continue reading Welding process terminology BS EN ISO 4063

Currently, several reports for incidents that sea water leakage was detected from distance piece attached to hull on SOx scrubber discharge water line. Until now, the leakages were detected at an early stage and did not cause heavy water ingress into E/R. Upon the above incidents, we would like to recommend the owners and the managers as follows: To inform the above incidents of the masters of your vessels on which SOx scrubber is installedand instruct them to inspect the discharge water lines especially around the distance piecesexternally from E/R with more attentions and frequencies. To inspect the distance pieces … Continue reading Corrosion of ship distance piece (Scrubber system)

What is friction in a pump system (cont.) Another cause of friction is all the fittings (elbows, tees, y’s, etc) required to get the fluid from point A to B. Each one has a particular effect on the fluid streamlines. … Continue reading Pump Friction Head Loss

Continue from Pump Total Differential Head The static head difference across the pump is the difference in head between the discharge static head and the suction static head. Static head difference = discharge static head – suction static head Discharge Static Head The discharge static head is sum of the gas pressure at the surface of the liquid in the discharge vessel (expressed as head rather than pressure) and the difference in elevation between the outlet of the discharge pipe, and the center line of the pump. Discharge static head = Discharge vessel gas pressure head + elevation of discharge … Continue reading Pump Static Head Difference

Pump System Diagram Flow Rate Usually, the flow rate of liquid a pump needs to deliver is determined by the process in which the pump is installed. This ultimately is defined by the mass and energy balance of the process. For instance the required flow rate of a pump feeding oil into a refinery distillation column will be determined by how much product the column is required to produce. Another example is the flow rate of a cooling water pump circulating water through a heat exchanger is defined by the amount of heat transfer required. Total Differential Head The total … Continue reading Pump Total Differential Head