Causes of magnetism in pipelines
Pipelines are susceptible to magnetization, which can result in costly delays when welding is necessary to be performed. The causes of magnetization include:
- Use of lower grades of steel
- poor manufacturing
- residual magnetism from regular manufacturing processes
- electro-magnetic crane lifting pipes during transportation
- orientation with the earth’s magnetic poles (pipes traveling around the equator on a ship)
- proximity to iron in the ground
- proximity to overhead wires
- galvanic protection system
- poor welding techniques, and
- lightning strikes
- the increased use of magnetic flux inspection tools (or pipeline inspection gauges – “PIGs”) as part of Pipeline Integrity Management programs
The government is increasing the frequency of required inspections on pipelines across the country due to the aging infrastructure and the danger of a damaged pipeline. Pipeline faults can be dangerous to the environment (see Yellowstone spill) or can even be catastrophic (CA pipeline explosion). The nature of the magnetic flux inspection tools subjects the pipeline walls to a magnetic field. When a section is deemed necessary for replacement, the magnetic field that remains from the PIG will affect the weld.
Due to the pipeline magnetism, welding can become difficult and slow, which often leads to failed x-ray inspections and delays, or welding could be impossible, which would result in major delays. Above 50 gauss, problems will occur in welding.
Demagnetizing Solutions can help overcome the issues of pipeline magnetism and prevent costly delays.