Exploration • Drilling • Field Services
Power is applied to the skid’s drive axle for movement on the structure under maximum control. Tis means a survey can be conducted faster, more economically and in far more hostile environments than would be the case if diving teams were employed. One immediate benefit is that cameras, imaging sonars, etc. are kept at a consistent distance from the structure with absolutely no relative motion. Terefore, excellent quality images and data are achieved. Additionally, the ability to set the ROV operator control unit down and focus solely on the incoming data allows the pilot to analyse the information, free from distraction in a 2D rather than 3D environment. With its introduction to the military and security
markets for inspection, damage survey and limpet mine clearance, a natural progression was then inspection, repair and maintenance (IRM) tasks, including more advanced non-destructive testing (NDT). Other missions for the crawler include harbour or hydro dam walls and offshore salvage operations – as in 2009, when a grounded container ship stuck on a reef in the Singapore Strait was surveyed in currents of 5+ Kts down to the seabed by an LBC, to determine if the hull had been breached. Additionally, these systems have been employed internally, in bilge tanks, sea chests and fresh water supplies. FPSOs and ballast tanks of semi-submersible platforms are other ideal work environments for this system, plus there are numerous applications within the nuclear industry.
An integrated approach Te latest example of innovative partnership and development of capability is a project with Sonasearch, headquartered in the US state of Washington. Tis involves the integration of the storage tank surveyor (STS) acoustic camera on a vLBC for internal wall and weld NDT inspection in water, fuel and other liquid storage containers. Te clear advantage is that this is achieved without needing to drain the tanks – thereby potentially saving a client millions of dollars annually and removing the obvious inherent danger of diver intervention in potentially volatile liquids. By fitting a standard vLBC with a ‘dozer’ blade (to loosen settled sludge, sand, wax paraffin and other detritus), the STS is mounted on the vehicle for precise inspection of the tank. Using phased-array 3D imaging, the STS incorporates an electronically beam-steered, multi-element scanning head, measuring the tank thickness and weld integrity at an ultra-high resolution of up to 113 microns and
mapping returns passing bi-directionally through the tank wall.
Fig. 2. Direct measure of steel thickness. Photo courtesy of Sonasearch.
With the provision of power and communication channels to the acoustic camera via its tether, real- time data is extracted at the surface as the vLBC traverses a pre-planned survey path, thus ensuring complete and accurate coverage; the result being inspection point, ≤ 6.35mm (¼-in) accuracy to reliably detect corrosion areas measuring 25.4mm (1-in) in diameter in order to provide an accurate prediction of when corrosion has reached the point of intervention or replacement. Te advantage of this method over others is
threefold:
l Te physical overlap between two consecutive beams that are electronically adjustable depending on the size of the defects being detected;
l Te large helicoidal pitch covered by only one phased-array probe rather than several mechanical-interlacing inspection heads;
l Te optimised beam profile with less than 2dB drop between apertures, obtaining a very high density of energy in the tank floor and improving repeatability performance (missing rate = 0%).
Te first customer trials of this latest SeaBotix package with an oil major are due to begin in Q3 2014. Tis will soon be followed by deployment in fuel storage tanks, oil tanker and FPSO hulls (inner and outer). l
For more information ✔ at
www.engineerlive.com/iog
Alasdair Murrie is vice president of sales, SeaBotix, San Diego, California, USA.
www.seabotix.com
www.engineerlive.com 41
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100