Photo courtesy of Anadarko Petroleum Corp.

Oil and gas production in the Gulf of Mexico is carried out on huge production platforms. These production platforms are located many miles offshore into the Gulf. Due to the isolated location, all equipment and facilities needed for power, operations, safety, rescue and worker housing and comfort are necessary parts of the platform design. Although the production platforms are among the largest man-made constructions, the amount of equipment needed for self-contained operations means that space is at a premium and needs to be optimized. Further, all replacement equipment needed on the platform must be transported by water or air. Therefore, lighter tools and equipment are preferred so they can more easily be flown onto the platform.

Equally as important as optimizing space, it is critical that tools be replaced as soon as possible to minimize cost of operations and ensure the safety of the operators and the environment.

On these offshore production platforms, as in land pipelines and vessels, monitoring corrosion is a critical aspect of asset management and safety. Metal corrosion has the potential to cause catastrophic pipeline and assets failure, damaging the environment, injuring field operators, and causing costly downtime and waste in productivity.

Metal corrosion has the potential to cause catastrophic pipeline and assets failure, damaging the environment, injuring field operators, and causing costly downtime and waste in productivity.

To monitor corrosion, corrosion coupons are inserted into pressurized process equipment. A weighed sample (coupon) of the metal or alloy being measured is introduced into the pipeline and later removed after a set time interval. The coupon then is cleaned of all corrosion residue and reweighed. The weight loss is converted to a corrosion rate (CR) or metal loss (ML) rate. This process can help identify where, what kind, at what rate and why corrosion is occurring.

Challenge

A major oil and gas customer was facing a significant problem on one of their offshore platforms. The customer had determined that a valve revision was needed at a specific corrosion coupon insertion location. Unfortunately, the revision resulted in reduced operating clearances. The rod holding the coupon required a specific insertion length to place the coupon in the correct location.

However, the insertion tool the customer had been using prior to the valve change could not fit within the reduced operating clearance. The customer could no longer monitor corrosion at the location, placing the asset management program at risk for that piping branch. The customer required a custom solution, fast.

Solution

Our engineers evaluated the options available and determined that the existing coupon holder rod was still usable – only the insertion tool was impacted by the reduction in operating clearances. It was determined that the Sentry® HPTEXL insertion tool, which uses patented Saf-T-Vise™ collet technology, could be adapted to solve the customer’s problem. The existing tool design was modified to create a slightly smaller version that would fit into the new, reduced operation clearance – and that version was quickly manufactured to meet the customer’s needs.

The Sentry HPTEXL tool allows the user to insert and retract a coupon holder rod that is longer than the travel length of the HPTEXL tool. The Saf-T-Vise collet design allows the user to withdraw the rod a section at a time, with the collet safely securing the rod during travel. The collet on the holder itself is used to secure the rod, while the drawbar on the HPTEXL moves back for the next pull. This process can be repeated, allowing rod lengths of up to 20 feet.

The HPTEXL is ideal for hard-to-reach applications and locations such as offshore production platforms – no other product is available that offers this capability.

Because of these capabilities, the HPTEXL is ideal for hard-to-reach applications and locations such as offshore production platforms – no other product is available that offers this capability. Plus, the HPTEXL is simple to use, and because of its weight in comparison to other tools (which can weigh FOUR times as much), it was easy to transport to the production platform.

The tool was used in conjunction with a custom Sentry MM-50 corrosion coupon holder. The MM-50 lower body has a Class 2500 RTJ flange and was made of duplex stainless steel. The maximum allowable operating pressure (MAOP) rating is 6250 psi (430 bar) for extreme high pressure applications.

Learn more about our corrosion monitoring & chemical injection solutions for oil & gas markets here.