Pipeline inspection companies for every kind of line

In line inspection tools travel inside the pipe with the product flow, launched and received through pig traps. Magnetic flux leakage (MFL) tools saturate the wall with a magnetic field and detect metal loss from internal and external corrosion; axial MFL is the common workhorse, and circumferential designs respond better to narrow axial features. Ultrasonic wall measurement tools give direct thickness readings in liquid lines, ultrasonic and EMAT crack tools target stress corrosion cracking and seam defects, and caliper or geometry tools find dents, ovality and restrictions. Inertial mapping units add location and bending strain. Before a high resolution run, operators usually run cleaning pigs and a gauging or caliper tool to confirm the tool can pass.

• Metal loss from corrosion, internal and external
• Dents, ovality and geometry restrictions
• Cracks and crack like features, with crack detection tools
• Pipeline route and bending strain, with inertial mapping

Many lines were never built for pigs: tight bends, changes in diameter, plug valves, no launchers, or flow too low to push a tool. Robotic crawlers and tethered or self propelled tools carry ultrasonic, MFL, eddy current or laser and camera sensors through these lines, often from a single access point. Runs are shorter and slower than free swimming ILI, but they reach plant piping, station piping and short critical segments that otherwise get only spot checks.

Guided wave ultrasonic testing sends low frequency waves along the pipe wall from a ring of transducers clamped at one location and screens for changes in cross section, often tens of feet in each direction depending on coating, soil, fluid and features. It is a screening tool: it tells you where to look, and flagged areas are then measured with conventional or phased array ultrasonic testing. It is widely used at road crossings, wall penetrations, insulated lines and pipe racks. For welds in new construction, radiographic testing and automated UT remain standard.

For sewers, storm drains, water mains and process drains, a camera on a crawler or push rod records the inside of the pipe. Operators code what they see, such as cracks, root intrusion, offsets, deformation, deposits and infiltration, and many municipal programs require coding to the NASSCO PACP standard. CCTV shows the visible surface only; for wall loss in pressure pipe, a sensor based tool is needed.

Buried steel lines can also be assessed from the surface. External corrosion direct assessment (ECDA) follows a four step process (pre assessment, indirect inspection, direct examination at dig sites, post assessment) using surveys such as close interval potential surveys, DCVG and ACVG to find coating holidays and cathodic protection problems. Leak surveys, right of way patrols and drone or aerial surveys add surface and encroachment data, see drone inspection services.

Gas transmission and hazardous liquid pipelines in the United States are regulated by PHMSA under 49 CFR Parts 192 and 195, which include integrity management requirements for segments that could affect high consequence areas. Assessment methods recognized there include in line inspection, pressure testing and direct assessment, among others. Which method and interval apply to your line is a matter for your integrity management program and your compliance team; an inspection provider supplies data and reports, not regulatory sign off.

• Match the tool to the threat: metal loss, cracks, dents or coating condition
• Ask for tool specifications: probability of detection, sizing accuracy and confidence for each feature type
• Check whether the provider qualifies tools and analysis under API 1163 and personnel under ANSI/ASNT ILI-PQ
• Ask about run success history on lines like yours, cleaning and gauging requirements, and rerun terms
• Look at the deliverable: feature list format, dig sheets, integration with previous runs
• For CCTV, ask for PACP certified operators and coded reports
• Confirm safety programs, operator qualification for covered tasks and insurance

Cost depends on line length and diameter, tool technology, number of runs, cleaning and gauging runs, mobilization, analysis level and field support.

See oil and gas inspection services and NDT inspection cost for context.