Internal inspection of welds on subsea pipes

Paul Boughton
In the last few months, Optical Metrology Services (OMS) has completed several pipe measurement surveys for Technip. The first of these was carried out at Technip’s Evanton Spool base in Scotland in August 2011. OMS engineers internally inspected Serimax welds on subsea pipes that were destined for use on BP’s Devenick high pressure, high temperature gas project.

OMS engineers spent five days on site inspecting the welds immediately after the second pass, using its own combination of video and laser-based measurement tools.

As Jim Buston, Client Solutions Executive at OMS states: “This powerful combination of tools enabled our fully qualified weld inspectors to verify, unquestionably, whether the welds met the HiLo requirements of the project and if any weld features were within allowable tolerances. Used in conjunction with OMS’ pipe fit-up optimisation software (SmartFit), this creates a very powerful toolbox for customers such as Technip, resulting in better, faster welds and fewer cut-outs.”

Following this successful survey, OMS was invited by Technip’s OED research and development division to carry out a pipe measurement survey (also at Evanton) of pipe end geometry and the implications of this on pipe fit-up. The survey involved OMS inspecting a small sample of 8-inch and 10-inch pipes and then analysing the resulting measurement data. The pipes were fatigue string joints with a 3mm thick nickel alloy overlay. The pipes were internally counterbored.[Page Break]

The objective of OMS’ survey was to provide Technip with the best fit-up in terms of pipe end-to-end matching, reducing the centre eccentricity, out-of-roundness match and local Hi-Lo. OMS inspected the pipe ends using its Laser End Dimensioning Tool and SmartFit fit-up optimisation and sequencing software. Technip’s aim was to achieve a maximum external Hi-Lo of 1.2mm on the project. The measurement results showed that this figure could be reduced to 0.4mm using SmartFit.

“Laser measuring of pipe ends is nothing new. Many pipe mills supply laser-gathered data with the pipes they produce. However, our SmartFit software takes this further by utilising 2,000 data points linked circumferentially to create a measurement profile. This is then used to simulate two pipe ends meeting for a joint – producing the details of HiLo misalignment as well as the best fit rotation,” explains Jim Buston.[Page Break]

OMS has recently been invited to carry out a further similar pipe measurement survey at Technip’s Evanton spool base on a small sample of fatigue-sensitive pipes. On this survey, OMS will inspect six, 10-inch pipes (12 pipe ends) that have a 50mm long, machined clad overlay. OMS will provide best fit-up in terms of pipe end-to-end matching using its Laser End Dimensioning tool and SmartFit software. The project will take place in October 2011.

Technip also requested OMS to inspect mechanically lined pipes for reeling. To demonstrate this, two 10-inch pipes were manufactured and bending trials carried out at the Heriot Watt University in Edinburgh on 21st September 2011. On the day, in order to demonstrate the robustness of the pipe design, OMS provided internal video inspection pre- and post-bending in order to verify and monitor the results.

“The high resolution video inspection system with super bright variable, multi-axis lighting enabled our engineers to look for any unwanted wrinkles in the liner of the pipe, particularly before and after the bend. We were also able to record and provide still images and video footage to Technip as and when required. The reeling tests were successful and were witnessed by some of the world’s leading oil producers,” adds Jim Buston.

For more information, visit www.omsmeasure.com

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