INTERNAL PIPELINE ALIGNMENT CLAMP

Obiettivo

Pipeline ovality and misalignment are problems which affect the success of any pipeline connection, whether onshore or subsea in a hyperbaric tie-in. To date, these problems have been resolved using manually fitted external clamps which presuppose that the pipe is readily accessible.
We believe that this problem can be overcome by an intelligent pipeline pig equipped to undertake the task internally. The alignment pig would be inserted in the pipe prior to the weld such that hydraulically powered radial rams can be extended to span the weld and correct any misalignment or distorsion in the pipe, ensuring that welds of consistent high quality are achieved. Its independent power source allows the pig to operate inside the pipe whilst controlled by external command signals. In addition, gamma rays of the weld can be undertaken using an atomic isotope, ensuring improved quality of radiography as the rays only pass through a single wall thickness of pipe.
Stage I of the Project has been totally completed. Stage II has been completed except for tests in hyperbaric chamber and the design of the gamma source but including manufacture of a prototype and functional testing in a test loop in Lingen West Germany thus providing that the IPAP could successfully negotiate 5D bends and the ability to remotely control the unit utilizing a low frequency radio signal through the pipe wall. The design of the gamma Ray Unit has been completed and approved by the UK Atomic Energy Authority. Tests in a hyperbaric chamber and Stage III were not started as this necessitates the support on a frequent user of the service. The project, following completion of Stage II, was stopped as up to this point in time no oil company could be found that was willing to operate this piece of equipment in their offshore pipelines due to a changed market situation.
All high development goals have been met. Operations of this piece of equipment will be possible following extensive hyperbaric chamber tests as soon as the market situation changes. However, operation will be limited to pipelines 16" and larger. Operating the equipment in a waterdepth of up to 650m could, if necessary, be extended to a depth of 1,200 m taking the present technical viewpoint into account.
The proposed design of the pipe alignment pig is as follows :
The unit is made up of a central frame which will house the hydraulics, electrics and microprocessor in a 60 bar box together with the gamma head for gamma raying the weld. The unit is equipped with 16 radial rams, these will be extended to span the weld and further expanded to correct the pipe distorsion and hold the pipe in position whilst the weld is made.
For transit the pig is fitted with polyurethane wheels to ensure that there is no metal to metal contact and the unit is designed such that it fails safe into this position. In addition, driving discs will be fitted to facilitate the removal of the unit on completion of the operation. The pig will be designed to negotiate 3D bends whilst withstanding acceleration and deceleration forces of up to 50 "G".
All internal units will be suitably protected to ensure that no damage is sustained when recovering the pig into the pig trap.
It is intended to install a gamma ray source of approximately 20 Curies which will enable a single panoramic scan of the weld to be taken.
This method will allow an improved gamma ray image as the rays only have to pass through a single wall thickness.
It is intended that the alignment pig should be a totally self-contained unit requiring no external power source. In addition it is proposed that the hydraulic requirements will be met using a small positive displacement pump with a pressure of approximately 700 bar.
The pig will be equipped with an "intelligence" system which will allow all stages of the operation to be monitored. It is currently proposed that a 32 function control system should be fitted.
The project has been divided into 4 sections to ensure that each stage in the development progresses with the minimum technical and financial risk.
STAGE 1
Research and development engineering leading to the construction drawings for a 16 inch diameter prototype alignment pig will be undertaken. In conjunction withthis work, a market research programme will be conducted to establish requirements, trends and possible future developments.
STAGE II
A prototype 16 inch diameter alignment pig will be constructed and tested in a service test pipeline 200 m in length with a variety of simulated pipeline bends and conditions. Pressure testing of the unit will aslo be undertaken in the hyperbaric chamber in Aberdeen. During this stage a marketing video and brochure will be produced and used for a sales drive to seek customer commitment for the use of an alignment pig for hyperbaric welds.
STAGE III
Once a client's commitment for the use of an alignment pig has been secured, the manufacturing drawings for the required diameter of the pig to suit the clients pipeline will be produced and fully tested as described above. The first production unit will then be constructed and tested prior to setting to work in the field with the client.
STAGE IV
Construction drawings for a range of pigs.

Programma(i)

ENG-HYDROCARB 2C - Programme (EEC) of support for technological development in the hydrocarbons sector, 1986-1989

Argomento(i)

1.8 - PIPELINES

Invito a presentare proposte

Data not available

Meccanismo di finanziamento

DEM - Demonstration contracts

Coordinatore

Houlder Offshore Ltd

Contributo UE

Nessun dato

Indirizzo

59 Lafone Street
SE1 2LX London
Regno Unito

Costo totale