Subsea pipelines | testing
test methods for deep sea fi eld joints
Embracing
Coated steel pipelines face a hazardous journey from the factory to the seabed, with numerous points along this route where damage can occur. Testing methodolo- gies such as the developing draft ISO/CD 12736 specifi cation (ISO/CD 12736 Petroleum and natural gas industries – wet thermal insulation coatings for pipelines, fl ow lines, equipment and subsea structures) need to refl ect the challenges faced during this installation process. This will require the industry to accept new test methods that are better prepared for the increasingly harsh environments encountered. Common factory applied pipe coatings include
polypropylene insulation systems which consist of fi ve distinct layers: fusion bonded epoxy, adhesive, solid polypropylene, foam polypropylene and an outer shield. During application there are no external problems that can occur as application is carried out in a controlled manner with internal quality control departments. Three main types of fi eld joints are used in deep sea
applications: injection moulded polypropylene, injection moulded polyurethane, and elastomeric fi eld joints. These compatible fi eld joint coating systems provide anti-corro- sion and, where necessary, thermal insulation properties similar to the mainline factory coating while allowing routine application within the rapid production cycle times demanded by today’s pipeline laying processes.
Installation techniques can challenge pipeline coating and joint integrity.
Exova’s coating specialist John Carter argues the developing ISO/CD 12736 test specifi cation should adopt new test methods that recognise this
Field joints need to be pre-qualifi ed using the equipment that will be used on-site, to prove the principle of the application. On-site there should be both pre-production and on-going quality control testing. However, applicators have to be capable of performing consistently under extreme conditions, which can frequently change on an hourly basis. During the laying process the pipe, and therefore the
coating, goes through tremendous temperature variations and conditions: Heating during welding Re-heating for fi eld joint application Quenching in seawater Cooling during lowing to seabed
Field joints face some of their toughest
challenges during laying. This image
shows Heerema Marine
Contractors’ DCV Balder
vessel confi g- ured for J-Lay.
November 2012 | PIPELINE COATING 35
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