Coffman Announces AC Interference Services Led by Industry Veterans

Andrew Onken Spearheads New Corrosion Control Capabilities

Andrew Onken, NACE

Coffman Engineers (Coffman), a national multidiscipline engineering firm, announced adding AC interference services to the company’s corrosion control capabilities. Coffman welcomes industry veterans Andrew Onken, NACE, Alex Ristow, NACE, and Eli Rassler, NACE. Onken is responsible for growing the firm’s AC interference services as part of Coffman’s corrosion control group. This new offering for oil and gas clients is a critical service that protects property and personnel and prevents costly disruptions.

Onken has over 12 years of experience as a corrosion engineer and integrity engineering supervisor. He holds bachelor’s and master’s degrees in chemical engineering and is a certified NACE Cathodic Protection Specialist and Internal Corrosion Technologist. He is also a Level 1 Certified CDEGS user by SES Technologies for AC interference modeling. His experience includes overseeing teams of engineers for cathodic protection and AC mitigation system designs and evaluations for new and existing pipeline projects.

Ristow and Rassler have worked with Onken for many years; their experience includes national client support and past experience working with Coffman. Onken, Ristow, and Rassler are based remotely in Duluth, Minnesota, and provide AC interference services companywide. 

“Andrew, Alex, and Eli are respected professionals in this highly technical field. Coffman is fortunate to welcome their wealth of experience and bolster our corrosion control services for our oil and gas clients,” said Tyler Doil, PE, NACE, Principal, Corrosion Control Engineering for Coffman.

AC interference is an adverse interaction that occurs between high-voltage powerlines co-located with buried pipelines. This can result in accelerated corrosion, affecting pipeline integrity and creating electrical safety hazards for pipeline personnel and the public. Using technical software, Coffman evaluates threats by computer modeling and designs AC mitigation systems to reduce risk to an acceptable level.

Coffman has provided corrosion control engineering services for national and international clients for more than 30 years. Today, the group consists of more than 35 engineers and technicians with multiple NACE certifications, including four Cathodic Protection specialists.

Learn more about Coffman’s corrosion control engineering services.

About Coffman Engineers

Coffman Engineers is a multidiscipline engineering consulting firm that offers clients local, personalized services by integrating many disciplines including civil, structural, mechanical, electrical, fire protection, and other specialties. Coffman has 800+ employees in 21 offices across the U.S. committed to the team effort it takes to build a better world. This year, Coffman is celebrating 45 years in business. Visit or connect with us on social media.

For more information about this topic, call Beth Shimogawa at 808.687.8884 or email

Source: Coffman Engineers, Inc.

About Coffman Engineers, Inc.

Coffman Engineers is a multidiscipline consulting engineering firm that has been serving clients in the U.S. and overseas since 1979. We have 780+ employees supporting clients from 21 office locations across the country.

Coffman Engineers, Inc.
745 Fort Street , #400
Honolulu, Hawaii


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