Durham Pipeline Technology - Pipeline Crawlers / Tractors

DPT's pipeline crawlers, also known as pipeline tractors, are based on patented bristle tractor technology. Unlike other crawlers that use wheels or tracks, DPT's self-propelled machines use oversized brushes to generate significant traction forces.

PRINCIPLE OF OPERATION

DPT crawlers exploit the asymmetric behaviour of oversized circular brushes located inside tubular conduits, whereas it is easier to push a brush forward than to pull it back. Where two sets of such brushes are interconnected by a mechanism that generates a reciprocating motion towards and away from each other, the whole assembly moves in successive steps.

TETHERED CRAWLERS

DPT crawlers are available with pneumatic, hydraulic or electrical actuation. The tools are powered and controlled using dedicated umbilicals with lengths from one hundred metres to several kilometres.

FREE-SWIMMING CRAWLERS (SHUTTLEPIG)

Contra-flow free-swimming DPT ShuttlePig crawlers extract power from the pipeline flow and are able to travel against the flow in oil, gas and multi-phase pipelines. In its most advanced configuration, the ShuttlePig free-flow tractors use electrical motors powered by battery packs which are rechargeable using an onboard mini-power plant that includes a turbine, a generator and control module.

DPT CRAWLERS - POWERFUL, VERSATILE, CONTROLLABLE

Unlike conventional pigs, the movement of DPT crawlers is controllable, does not depend on differential pressure, allows the free flow of fluid in either direction and offers a negligible pressure drop across the machine.

By customising the bristle material, dimensions and arrangement, DPT tractors can accommodate significant variations in diameter, travel through damaged or partially collapsed pipes and overcome significant debris and obstacles.

DPT Crawlers are bi-directional and self-reversible and operate in pipes and tubular conduits of irregular cross-sectional size or shape. They are able to negotiate bends down to 1.5D, mitred bends, vertically ascending or descending pipes.

UNPIGGABLE LINES

Pipelines can be unpiggable due to a variety of reasons: changes in diameter, presence of unsuitable valves, tight or mitred bends, low operating pressure, low flow or absence of flow, lack of launching and receiving facilities, dented or collapsed areas, excessive debris or scale build-up, short and dead-end sections, etc.

DPT pipeline crawlers can access many lines that are currently considered unpiggable and carry out cleaning and inspection activities as a cost-effective alternative to conventional pigging.

APPLICATIONS

DPT crawlers offer cost-effective alternatives to conventional pigging and inspection methods as well as new ways to assist flow maintenance programmes:

• CCTV inspection of pipelines, risers and pipework
• Regular and advanced cleaning
• De-waxing
• Metal loss detection
• Crack detection
• Deployment of calliper pigs
• Deployment of isolating plugs
• Buckling detection in new-built pipelines
• Recovering stuck pigs