Cathodic Protection in the Houston Area

Gulf Coast soil and water

At the Sweeny plant site, layer resistivities in the top 5 feet averaged 819 ohm-cm, with a low of 662, and the geotechnical borings showed clays and sandy clays above pipe depth. That ranks the soil as highly corrosive to steel. The design protects seven buried piping systems with galvanic magnesium anodes, with test stations on each system.

On the water side, the Freeport wharves are steel sheet piling in Gulf seawater. We measured the current the piling needed by energizing an existing deep well from a portable source near high tide, then recommended a replacement impressed current system with rectifiers sized so that storm surges would not trip them.

Plants and buildings

Much of the Houston-area work is inside plant fences. At the La Porte chemical plant a single rectifier protects the buried gas piping, and we have surveyed it from 2019 through 2026 at 21 riser test points against the NACE SP0169 criteria. In Baytown a new fuel gas line read far short of protection at start-up until the missing insulating flange kit at its tie-in was installed. The next day it met the criteria.

Buildings bring different problems. At an office complex in Houston the buried water piping between buildings is not isolated from structural steel and copper grounding, three rectifiers had been wired for the wrong input voltage, and the high-rise buildings blocked the satellite signal our GPS-synchronized interrupters need, so off readings were taken by switching rectifiers by hand.

How we work here

Our corrosion engineers test the soil, design galvanic and impressed current systems, train installation crews, commission new systems and come back for annual surveys. On the Sweeny job we watched the crew make test brazes on scrap pipe before they worked on the plant piping, because a cathodic protection system is only as good as its connections.