Oil and Gas Pipelines

Panoramic Pipleines Inspection

Panoramic Pipleines Inspection

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Computed Radiograhic inspection can be used to inspect panoramic pipewelds across cross country pipeline construction projects, with increased productivity in the form of higher throughput per shift and faster preparation of deliverables.

The latest Computed Digital Radiography (CDR) developments are establishing a higher Non Destructive Testing (NDT) production throughput than existing Automated Ultrasonic and conventional film radiography and a simplified production process is providing the results within as little as 4 minutes from start to finish.

In addition, the production process is environmentally green, with a lower carbon footprint, and is transportable without wet chemistry (as this has now been eliminated). The resulting radiographic images match radiographic film quality and the acceptance code of practice as stipulated by existing international standards.

CIT's Computed Radiography system allows a range of 12" to 48" OD pipeline circumferential welds inspection to be carried out successfully. Both normal and tie-in welds can be inspected, the digital images of which can then be archived safely for long life and electronic retrieval.

The computed image quality is assessed with radiographic sensitivity and qualified radiographic unsharpness for NDE inspection. CDR can make use of the gamma radiography or X-ray sources. Smaller focal spot sizes improve the image quality hence the acceptance quality can be defined in the radiographic techniques.

Radiographic repeatability of radiation sources positioning is now possible to verify by using "BAM Snail" (an acceptable German standard developed in 1996), enhancing the radiographic process for qualification criteria and acceptance standards. The BAM Snail tape shows the beam profile alignment and assists with the detection of the flaw defect for early rectification. While this method has not been in use to date in the oil and gas sector, it is something to consider for improved quality control.

Automatic defect recognition for radiographic welds is now emerging in the construction industry from the research and academic worlds. In the meantime, with CIT's CR technology, the flaw gauge template is a major aid to the radiographer, speeding up reporting and archiving. This allows paperless reporting and increases the speed of inspection reporting and decision-making.

Pipes of aluminum, carbon steel, Glass Reinforced Plastic (GRP) pipes and clad steel pipes can be inspected by CR. In addition the technology enables metallic and non-metallic material components to be inspected.

A CR pipeline inspection facility on site can consist of a laboratory/factory or portacabin. housing a CDR system. Such a system typically includes a high-end computer system (which may be a laptop), a high resolution display unit, scanners, NDT software and consumables like phosphorus re-useable imaging plates with protectors and storage media such as DVDs. There is also a Digital Imaging Plates (DIP) preparation and storage area, mains supply with UPS back-up power in case of electrical power interruptions. The DIP plates can be supplied in various sizes up to 1.5 meters and must be protected against water, rain, sand and dust.

The mobile unit can be conveniently located and does not need to be tagged along the pipeline as required with other inspection methods. The radiographic crew takes a batch of DIP plates along with the X-ray set-ups/crawlers and conducts the radiography. The exposed plates are then brought to the mobile CR facility where they are scanned, welds examined and report generated. The DIP plates are erased with the integrated erasure once scanned and reused again for the next exposure. The images can be analysed on- or offsite with a centralized NDE management System (CIT DR 4200). All NDE data can be integrated into an existing corporate database.

A typical CR production process consists of:

1. Radiographic set up time (the same as in conventional radiography)
2. Scanning/Interpreters' time
3. Preparation of the deliverable (electronic submission)

The above time-efficient and cost-effective solutions enable pipeline construction to move forward without current constraints. Thus computed radiography meets the current need for pipeline weld material inspection as well as handling dissimilar materials, and the use of upcoming clad pipes.

The end user's health and safety department can use this electronic NDE data submission for investigations into product integrity and thus plan predictive or preventative maintenance during the product pipeline life cycle. The information derived serves to enhance the operational knowledge database and contributes to knowledge engineering.