Two executive officers of Portland Pipe Line Corp., the company that owns the pipeline that runs from South Portland to Montreal, have retired.

Larry Wilson has retired as CEO of the South Portland-based company while David Cyr has retired as treasurer, according to a corporate statement.

Additionally, the company board selected Tom Hardinson to act as vice president of Portland Pipe Line, a subsidiary of Montreal Pipe Line Ltd. He will also serve as a vice president of Montreal Pipe Line Ltd. Before his April 1 appointments, Hardinson served 18 years as director of operations and maintenance at the company.

In addition, Chris Gillies was selected to become treasurer and secretary of both companies.

It was unclear on Tuesday how the hierarchy of the company has changed with Wilson’s departure. Several calls to a consultant who works for Portland Pipe Line and to Hardinson were not returned by deadline.

The company’s pipeline is at the center of the debate over the transporting of oil sand crude, commonly referred to as tar sands, from Canada to South Portland’s harbor for export. The company has pumped crude oil from South Portland harbor to refineries in the Montreal area since World War II. However, changes in global oil markets have raised the prospect of pumping tar sands from western Canada down to South Portland for export to refineries.

While the company entertained the idea of reversing the pipeline five years ago, Wilson has told the Portland Press Herald that it is not currently pursuing a reversal, although the company will keep its options open.

A collection of South Portland residents objects to the reversal idea. A draft ordinance committee in the city has proposed changes in local regulations that would prohibit the loading of crude oil onto ships in South Portland harbor.

Montreal Pipe Line Ltd. is owned by three oil companies: Suncor Energy in Calgary, Imperial Oil in Calgary and Houston, and Texas-based Shell Oil. According to documents filed with the U.S. Securities and Exchange Commission, Suncor owns 23.8 percent of the pipeline company. Of Portland Pipe Line Corp.’s nine-person board, representatives from Imperial occupy five seats, while representatives of Suncor and Shell each occupy two, according to the company’s 2014 annual report. The majority owner of Imperial Oil is ExxonMobil Corp.

Wilson had been on the company’s board, but it appears Hardinson has not assumed his seat.