Ultrasonic Inspection Detects Pipeline Defect

Ultrasonic inspection involves transmitting sound waves of short wavelength at high frequencies to identify flaws, measure the thickness of materials or detect corrosion.
Conventional ultrasonic testing equipment sends a pulsed beam of high-ultrasound from a handheld transducer, which is placed upon the surface of the object being tested. This wave is disturbed and then partially returned from spots with internal imperfections or from the back of the material wall.

Capturing and analysing the return sound can show the amplitude of the pulse and the duration taken for return to the transducer. By measuring this sound, a skilled operator can identify the location and orientation of imperfections and the wall thickness. Acceptance criteria define whether or not the indication is a defect. Ultrasonic testing is now being used more often for inspection than the traditional balance between radiographic testing and ultrasonic testing - especially for pipelines.

SGS has good experience of failure mechanisms. SGS's network operates all NDT technologies in more than 30 countries. SGS offers an integrated NDT service pack, combining inspection, supply-chain services and asset-integrity management. SGS offers conventional ultrasonic testing as well as other NDT methods.

Its service varies from standard non-destructive testing services to advanced NDT techniques such as risk-based inspections, time of flight diffraction, Corroscan, positive material identification, magnetic flux leakage, leak testing, thermography, electromagnetic testing, RFEC, iris, digital radiography, radiation detection RVI and endoscopy inspections. SGS also provides relevant NDT training courses including NDT ultrasonic testing courses and examinations suitable for PCN certification.

Sound Dead Steel Reduces Gas Pipeline Noise

Sound Dead Steel (SDS) was contacted by the Industrial Noise and Vibration Centre (INVC) to assist with a noise reduction programme for Scottish Power. The power station's main gas pipe work is 400mm diameter, with a reduction to 150mm at the metering section Close microphone measurements indicated noise levels as high as 100 to 110dB(A) with the dominant energy at frequencies >500Hz. SDS clad the pipeline with Sonphonon sound dead steel, fabricated and fitted split boxes to encase the valves.

After the final snagging was completed, the attached noise survey was carried out to determine the overall noise reduction for this project. The average noise reduction achieved within the GRF compound was approximately 8dB(A). The maximum reduction achieved was 16dB(A); this was adjacent the metering flow meter area. INVC noted that noise from adjacent cooling fans masked the full noise reduction benefits.

Noise reductions on plain pipeline measured 19dB(A), which clearly shows the effectiveness of the SDS cladding on standard pipe sections. Reductions of 7 to 8dB(A) were measured mid, up and downstream of the metering section using close microphone measurements. The reductions would have been greater, but pipe joint flanges have to be left open in case leakage occurs resulting in explosive conditions.