3rd Part Exam Resum

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3rd Part Exam Resum
  127. Describe the composition of the solid polyurethane field joint infill material. Polyol (provides the material properties) Isocyanate (hardener) Catalyst (decrease the hardening time) 128. List the manufacturers of the solid polyurethane field joint infill material that you   know. Dow Chemicals Field Pipe Systems 133. Describe the composition of the solid polyurethane with gravel field joint infill   material. Polyol (provides the material properties) Isocyanate (hardener) Catalyst (decrease the hardening time) Gravel (Reduce the total cost) 138. Describe the composition of the polyurethane foam field joint infill material. Polyol with foaming agent (provides the material properties) Isocyanate (hardener) 143. Where it has to be avoided the measurement of the coating dry film thickness? Coating thickness measurement shall be avoided directly over the welds and near the edges of the coated object. 144. Where it has to be used the high voltage holiday detector and where it has to be used the wet sponge holiday detector? High voltage holiday detector should be used for inspections of coating materials having the thickness over 500 μ m. Wet sponge holiday detector should be used for measurement of non-conductive coatings up to the 500 μ m by setting the inspection voltage to 9 V, 67 V or 90 V. 145. What is the dismoulding time when referring to the application of polyurethane based field joint coating materials? The dismoulding time is the time starting from completion of pouring of mixed polyurethane resin until the start of removal of the mould where the applied material shall not have any single damage caused by the removal of the mould. Dismoulding time is measured using a chronometer and as a target the dismoulding time is maximum 1 minute for solid polyurethane with gravel and 2 minutes for solid polyurethane and polyurethane foam. 146. For which two tests is used the differential scanning calorimeter instrument? ã cure test for FBE ã oxidation induction time  147. What is the purpose of the cure test for FBE by DSC method and what it means when the Δ T g = T g2  –   T g1 is negative or positive? Purpose of the cure test for FBE by DSC method is verification of the proper curing of FBE field joint coating material. For verification of the proper curing of the applied standard FBE material it is used the acceptance criterion Δ T g = T g2  –  T g1 where the commonly used acceptance criteria is Δ T g = -3 C to + 3 C The result Δ T g = lower than - 3 C means “overcuring”, too much heat is given to FBE; this is generally considered positive but the FBE loses its already small flexibility. The result Δ T g = higher than +3 C means “undercuring” that cannot be acceptable because it will cause the disbondment of applied coating after some time. 148. Describe the performance of the hot water immersion test Hot water immersion test is carried out as follows: ã a test piece coated with coating material having dimensions of 150 mm x 100mm x pipe wall thickness is cut from coated simulated field joint ã test sample is immersed in the container with tap water (artificial seawater may also be used) ã container wi th water and test sample is heated and maintained at the requested test temperature for specified time (for example at 80°C for 28 days) ã afterwards, various adhesion tests are carried out on test sample 149. Describe the performance of the compression strength test on solid polyurethane The test is carried out in a manner that the cylindrical sample (50 mm diameter x 100 mm length) casted directly from the polyurethane application equipment is put under the press that travels at the speed of 50 mm/min and it is measured the pressure when the sample starts to crack. The expected values for solid polyurethanes are within a range from 30 MPa to 70 MPa but the actual acceptance criteria are defined in project specifications. 150. Describe the performance of the compression strength test on polyurethane foam The test is carried out in a manner that cube samples (30 mm x 30 mm x 30 mm) are cut from the applied field joint and put under the press that travels at the speed of 50 mm\min and it is measured the pressure at 10% deflection or at 90% deflection (reduction of initial height). 151. Describe the performance of water absorption test and its purpose The water absorption test is carried out in order to determine the quantity of tap water or seawater absorbed by the coating material at specific temperature for specific period of time. The test is carried out as follows: ã sample is weighed on the laboratory scale before immersion ã sample is immersed in tap water or artificial seawater at specifie d temperature that is maintained for specific time (for example: 20 0 C for 7 days or 95 0 C for 30 days) ã sample is weighed after removal of the water from the surface as soon as possible but without forced drying of test sample ã difference in weight expr essed in the percentage of gained weight represents the absorption  152. Describe the performance of the impact resistance test from the fishing trawl gears The test is usually carried out in accordance with the DNV RP F-111 specification but in many occasions the Clients specify their own requirements for this test. The test is based on the following principle: ã The impact test equipment is made to simulat e the shape of the part of the fishing equipment that will impact the coating (usually this shape is rectangular and has dimensions of 300 mm x 50 mm) ã In reality the fishing equipment has a mass that travels at certain speed at the sea bottom, for example: 2.7 tons fishing trawl gear travels at the speed of 7.2 km/h resulting with an impact of 5.4 KJ ã The impact test equipment has a fixed weight and during the test it will be positioned at the height that will produce the same energy of impact as the traveling fishing trawl gear considering the formula: E = mass of impact tester x g x h (difference in height from the impact tester and point of impact) 153. Describe the purpose of the scraping test The purpose of the scraping test is to verify if the fishing trawl gear will damage the coating by cutting it (not by impacting it) in case it passes over the coating. 154. Describe the purpose of the roller load test and describe how this test is carried out The purpose of the roller load test is to verify if the applied field joint coating will be damaged when passing over the rollers onboard the pipelay vessel. This is especially important to verify when the field joint coating is still hot and to see the deformations on the field joint coating when the hot field joint coating material is in contact with the roller. The test is based on the following: ã the rollers having the same geometry as the rollers onboard the vessel are positioned on the roller load test machine ã the roller load test machine  can apply various pressures of the roller on the applied field joint ã the roller load test machine can move the pipe with field joint at various speeds and it is also possible to move the roller ã the roller is lowered on the pipe with field joint and the pressure is applied on the roller while the filed joint moves under the roller for the entire length of field joint ã after the roller load test it is performed a visual inspection and holiday inspection to verify damages on applied field joint coating ã the roller load machine can also measure how deep the roller penetrated in field joint coating material during the test and this result is taken as a reduction of thickness of applied field joint coating after the passage over the rollers
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