contractors may include very specific inspection consultancy, including onsite inspection surveys. Expert advice and guidance may be required in terms of the effects of delivering better weld quality on pipes, as well as the benefits that would arise from improved engineering and the quarantining of any ‘out-of-spec’ pipes or parts. Independent inspection companies may also be asked to get involved in Pipe Reeling Trials, Weld Performance Qualification Tests (WPQTs), and Pipe Fatigue Trials, in order to help improve the engineering integrity and inspection of subsea structures. Finding an independent inspection company that can provide all of these services is not easy, but they do exist. In the offshore industry, contractors may require independent inspection of oil pipelines. Tis may involve the inspection of pipe wall thickness to ascertain what proportion of pipes supplied are outside of their manufacturing specification. Tis type of work involves comprehensive, verifiable inspection of wall thicknesses. Identifying those pipes that are out of their specification tolerance means they can be quarantined and returned to the pipe supplier. On large, land-based pipelines, the pipes supplied can sometimes cause welding issues due to a variety of reasons such as bevel imperfections or welding defects. Independent inspection companies are therefore required to conduct multi-site surveys of pipeline spreads. Measurement data of pipe weld defects can be
recorded and supporting photographic evidence gathered, including photographs of gauge measurement readings if necessary. Any defect discovered can be measured and recorded using
alternative measuring devices/systems, in order to provide comprehensive, irrefutable evidence for legal disputes. Other supporting documentation may include operator details and tools used. Weld features measured can include a variety of parameters, including diameter variations, coating contamination of pipe ends, wall thickness, bevel angle, land thickness, squareness, pitting, excessive corrosion and whether any bevel damage (dents or gorges) was present. Following completion of independent inspection
surveys, the proportion of pipes supplied that were out of specification can be reported to the pipeline contractor. In some cases, this has led to the pipeline contractor having to re-bevel all the out-of-tolerance pipes before work can continue. By providing inspection documentation, photographic evidence and expert testimony, independent inspection companies have been known to help pipeline contractors recoup multi- million pound settlement sums in disputes with their pipe supplier. For some pipeline contractors, surveys of pipe end dimensions may be required, particularly if a batch of incorrectly machined flowline pipes are discovered. Te complete batch of pipes may have to brought back onshore for inspection. What is often required is some kind of sequencing exercise, whereby the independent inspection company advises the customer of the sequence that the pipes should be fitted up and welded, in order to meet the HI/LO specification for the project. In order to do this, the inspection company may have to use or develop custom measurement tools that provide irrefutable approach to pipe end dimensional inspection. ●
Dr Richard Gooch is Director of Technology at Optical Metrology Services Ltd, Bishop’s Stortford, Hertfordshire, UK.
www.omsmeasure.com www.engineerlive.com 45
Fig. 2. Independent inspection companies can help pipeline installation contractors meet these more stringent engineering, inspection and safety requirements.
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