Five Tips to Keep in Mind This Survey Season
By Jarret Brelsford, Bass Engineering
Every year, not long after New Year’s celebrations end, cathodic protection technicians start working on a fresh batch of annual surveys. For many technicians, this means surveying hundreds or even thousands of miles of pipe in a short time.
With so much work ahead, it can be easy to lose sight of the ultimate objective. Use these tips as a reminder to take a breather and make sure you’re staying focused on conducting accurate, complete surveys that will help keep your pipelines safe and compliant.
Tip #1: Research Your Survey Site
If you attended our 2016 Users Group, you heard a lot of talk about being prepared for situations that can arise in the field. This is especially important during survey season, when heavy workloads and tight schedules leave little room for error.
Once you determine where you’ll be surveying, here are some specific things you should research to make sure you’re adequately prepared:
- Survey location
- The survey prompts that should be included on your form or Allegro
- GPS coordinates
- Alignment sheets, if applicable
- The tools and equipment you’ll need
- Whether your cables and connections are functioning properly
- Equipment calibration due dates if applicable
- Recommendations or comments from previous surveys
- Any applicable inspection requirements, particularly those from the Department of Transportation
- OQ requirements
You should also read through historical survey data such as rectifier readings, pipe-to-soil potentials (native, on, and polarized), applicable close interval survey results, and failure history. As you’re doing this, keep in mind that it can be useful to look at every data point that’s available.
For example, it’s common to consider rectifier output voltage and amperage, but you may also want to think about calculated circuit resistance, rectifier efficiency and tap settings, which can help you diagnose a change in pipe-to-soil potential while conducting the survey. Using Allegro Field Data PCs and PCS allows you to quickly and easily review this data in the field and add new measurements.
For an example of the variety of data that can be collected with the Allegro and managed or reported on using PCS, take a look at these sample reports.
Tip #2: Remember Maintenance
When researching your site and planning your surveys, don’t forget that cathodic protection systems and other pipeline protection mechanisms need to be maintained. For an example of a successful cathodic protection program accompanied by an unsuccessful maintenance program, see this chart.
The chart shows dramatic decrease in failures after cathodic protection systems were installed. The slight uptick in failures in 2006 and 2007 were caused by inoperable rectifiers that were disabled by electrical surges. These failures could have been easily avoided by implementing a routine maintenance schedule or using remote monitors to enable constant oversight.
For regulated pipelines, CFR 192.465 specifies the following maintenance intervals for an external corrosion control system:
- Annual CP surveys: Once per calendar year / not to exceed 15 months
- Rectifier inspections: 6 times per calendar year / not to exceed 2.5 months (however, if your rectifier is equipped with a remote monitor, you only need to physically inspect the rectifier once per calendar year provided that the monitor is functioning and reporting volts and amps)
- Critical bond inspections: 6 times per calendar year / not to exceed 2.5 months
- Other bonds: Once per calendar year / not to exceed 15 months
Tip #3: Consider Regulatory Activity
In addition to CP system maintenance requirements, you may also want to consider proposed or pending regulatory requirements. Of course, the biggest of these is the PHMSA’s proposed regulation to update critical safety requirements for natural gas transmission pipelines.
Another lesser-known example is the NACE standard SP0169-2007 (Formerly RP0169-2002): Control of External Corrosion on Underground or Submerged Metallic Piping Systems. This is the cathodic protection standard that’s referenced in federal regulations CFR 192 and 195, and it only specifies that IR drop must be considered. In 2013, it was updated to include detailed instructions on how to consider IR drop (see Section 6.2) – but CFR 192 and 195 have not yet been updated to reference the latest revision.
It’s only a matter of time before the federal regulations are updated, so you should make sure that your surveys are following the best practices for taking IR drop into consideration. For more information about the specific sections of SP0169-2007 that were updated, contact us.
Tip #4: Use the Right Tool for the Job
A good way to make sure you’re appropriately accounting for IR drop is to question whether you’re using the right survey method for the location in question. For example, if you’re planning to survey a pipeline system that has an extensive AC mitigation system in place, an off-potential survey may yield results that don’t accurately account for IR drop.
This is because most of these systems include direct current de-coupling devices. When rectifier current is interrupted, the resulting potential measurements are likely to be influenced by the capacitive discharge of these decoupling devices. Pipelines with direct-buried galvanic anodes will experience similar issues, as the galvanic anodes will continue to provide cathodic protection current when the rectifier is interrupted.
In these cases, taking readings at a coupon test station is a practical way to ensure that your survey results account for IR drop. Most AC mitigation system designs include test stations with 1cm2 coupons: the industry-standard coupon size for measuring AC current density.
For cathodic protection purposes, it’s necessary to ensure that you’re simulating the largest coating holiday that might be present in that area. For most pipelines, a 100 cm2 coupon is sufficient. There are many coupon test stations commercially available, but only the Triton® Triple-Coupon Test Station comes standard with a 1 cm2 coupon for taking AC measurements as well as 100 cm2 test and native coupons for cathodic protection testing.
Tip #5: Avoid Common Mistakes
Because we’re all human, mistakes can happen no matter how much preparation and planning you do. This is especially true when you’re tired, stressed or distracted. Below are some of the most common mistakes found in annual survey data. Understanding them will help make you more likely to catch them when they occur.
- Transposing numbers while writing or typing
- Recording data for the wrong location (misidentifying test point)
- Not setting up interrupters correctly
- Electrical shocks from touching a facility before checking it for current
- Adjusting rectifiers mid-survey
- Unintentionally bumping a switch while working inside a rectifier
- Skipping locations that are difficult to access or far away
- Not recording current direction in a bond or other electrical jumper
- Not testing electrical isolation during survey
- Skipping steps in an established process to save time
To avoid mistakes like these, follow your company processes, use the best available technology, get enough rest, take breaks when you need them, eat regular meals, don’t forget to hydrate, and consider enlisting contract services if you’re pressed for time to complete your surveys properly.Learn more about services from AI Learn more about services from Bass Engineering