FAQsWhy should I use TranScan™ instead of MagneScan™ ™?TranScan™ will inspect the both the long seam and the pipe body. Axial MFL tools are not good at detecting axial defects in the long seam. TranScan™ is suitable for thin wall pipe, for pipe in which girth weld inspection is not a necessity, and for pipe where a slightly reduced sizing accuracy and depth detection specification can be accepted. TranScan™ would also be the first choice over MagneScan™ for external or internal NAEC problems. What kind of defects will it detect?Seam Weld Defects - TranScan™ will detect manufacturing defects in the long seam weld as long as they exceed 0.004 in (0.1 mm) width.
Metal Loss Defects - TranScan™ has many similarities with axial field MagneScan™ , so it is also good at detecting metal loss. The performance specification for metal loss has been generated along with the sizing databases. Metal loss depth detection is inferior to MagneScan™ (20 percent for general metal loss, 40 percent for pits) and the sizing accuracy is less (±15 percent, not ±10 percent). The length determination of corrosion is excellent; features up to 9.8 ft (3 m) in length have been detected.
Mechanical Damage - such as gouges from third-party interference and dents What type of seam welds will it inspect?ERW Welds - All ERW pipe manufactured prior to 1970 is prone to manufacturing defects within the weld area due to the DC or low frequency welding techniques used at that time. Better high frequency AC techniques were employed after 1970. SAW Welds - Submerged arc welded pipe tends to be concentrated in the larger pipe diameters. Some pipe can exhibit manufacturing problems such as lack of fusion of the root weld. Flash Butt Welds - Flash butt welded pipe was produced by forcing together two square plate edges and the resultant flow of metal runs radially both outwards and inwards. Any faults in this method start on the plate edges and end in the center of the weld running outwards or inwards. This manufacturing process is now discontinued. Will it detect third-party damage?Dents are very visible on the TranScan™ data, much more so than MagneScan™ data. In addition, the axial extent of the dent is better characterized on TranScan™ data. Dents on the seam weld are also visible. Axial gouges are visible, within the detection specification of the tool. Dents with axial gouges (or metal loss) are very visible on the TranScan™ data. These are one of the most significant features affecting pipeline integrity. The sizing of the associated metal loss or gouge is not possible, but once detected, they require immediate repair regardless of the radial indentation or metal loss magnitude. The radial depression of the dent cannot be estimated on the current TFI tool build. Will it detect SCC?Yes, to a degree. Some large SCC colonies have been detected in unpressurized pipe in the pull through tests with 32/36 in Interim TranScan™ . The narrowness of SCC and fatigue cracks is the major influence on whether they can be discriminated. The performance specification has a width limit of 0.004 in (0.1 mm) to cover this. Detection is probable, but due to the low level of the signal, it may be difficult to discriminate the crack from other signals produced by non-crack-like features. Will it detect fatigue cracks?Yes, large ones. On pull-through tests at atmospheric pressure we have seen a fatigue crack 8.9 in (225 mm) long and 75 percent deep, but had difficulty seeing a 3.9 in (100 mm) long by 50 percent deep fatigue crack. Fatigue cracks are very tight, and in the unpressurized condition, there is no real metal loss to cause a sizeable magnetic signal. Is axial MFL blind to these defects?MagneScan™ will not see seam weld defects. It usually sees the seam weld by virtue of its unevenness. It will see pitting in the seam weld but has trouble seeing axially extended seam weld defects. MagneScan™ struggles with characterizing the length of long axial corrosion. As with seam welds, it tends to see the start and the end of long corrosion. MagneScan™ is not blind to denting, just less sensitive than the TranScan™ tool. Axial gouging is much more difficult to see with MagneScan™ . MagneScan™ will not see large SCC or axial fatigue cracks. MagneScan™ and TranScan™ both have little sensitivity to HIC and lamination defects; UltraScan™ WM™ is the choice in this case. Do I need to do two inspections?If there is reason to believe that inspections for both metal loss and seam weld integrity are required, then the answer is yes. Using TranScan™ for full body analysis and seam weld inspection checks for both types of defect, but metal loss detection and sizing performance are inferior to MagneScan™ . Are you trying to get me to double my inspection budget?No. This is a new inspection service. Inspection for seamweld defects has not been possible previously with MagneScan™ . TranScan™ should be regarded as an alternative to hydrotest spend. Does TranScan™ replace hydrotest?Yes. TranScan™ identifies seamweld features in the pipeline without making them worse. Hydrotest can grow a feature during the test, which can subsequently fail within months of the test. One pipeline operator did more than 2,000 excavations following TranScan™ runs. Many of these defects were cut-out from the line. Some were burst tested. These burst tests identified one joint that burst at 105 percent of the hydrotest pressure and many more that burst at higher pressures. This shows that TranScan™ can identify features for cutout or repair far in advance of hydrotest. In-service failure of features is therefore less likely, and the pipeline does not have to be taken out of service (with revenue losses) to find those features. The first two sections of the pipeline system above were hydrotested after TranScan™ inspection, report and repair. They passed at 1.25 MAOP. Thereafter, the DOT regulator accepted TranScan™ inspection and repair as an alternative to hydrotest for the hook crack problem on their pipeline system. Can you combine TranScan™ and MFL?Yes, but at present we must run two tools on two passes and merge the inspection data. We have considered combining the two technologies on one train, but the excessive vehicle length would often be a problem for pig launcher and receiver lengths. How small a defect will it see?
How accurate is it on length and depth measurement?The TranScan™ performance specification for reported sizes of crack-like features (wider than 0.1 mm) for 80 percent of features is:
Does it handle thick wall as well as MFL?TranScan™ tools have a limited amount of bristle contact with the pipewall due to the geometry of the magnetic circuit. As a result, less magnetic flux can be circulated through the pipewall than for a MagneScan™ tool, and the maximum wall thickness that can be inspected is less. It’s longer, so what about launch traps?Tools in the size range from 12 to 30 inches (305 to 762 mm) are option kits on the standard MagneScan™ tools. They have an extra MV that increases the train length as shown below.
A = Rear of vehicle to rear cup As with MagneScan™ , a series of short trap kits can reduce the length of the standard inspection train behind the rear cup rubber. These kits consist of shorter tow bars for pipelines with 5D to 9D bends, and removal of tow bars for pipelines with bends of 10D or greater. What are its operational limitations?TranScan™ is designed as an option kit (for 12/30 in [305/762 mm]) on the MagneScan™ systems. There is a high degree of commonality between TranScan™ and MagneScan™ as a result.
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