The Shaw Group, a Baton Rouge-based Fortune 500 company, will become part of CB&I under a cash and stock deal valued at $3 billion.

Under the agreement, CB&I will pay Shaw shareholders $46 per share in cash and stock, $41 in cash and $5 in CB&I shares. The deal is expected to close in early 2013.

Shaw shares closed Friday at $26.69.

The acquisition will create one of the most complete energy-focused technology, engineering, procurement, fabrication, construction, maintenance and associated services companies in the world, according to CB&I (formerly known as Chicago Bridge & Iron). The combined company will have nearly 50,000 employees worldwide and be capable of executing the largest infrastructure projects.

“This is a highly compelling transaction that we believe will create significant value for our shareholders,” CB&I President and Chief Executive Officer Philip K. Asherman said in a news release. “Shaw is a great company with tremendously talented employees. By adding them into the CB&I family, we will become fully diversified across the entire energy sector, from Power Generation to LNG, from Refining to Gas Processing, from Offshore to Oil Sands, and beyond. We will have the capabilities and the expertise to provide our clients with the full range of solutions, wherever they are in the world. Most important, we will have the experience and relationships necessary to successfully meet and exceed our clients’ expectations.”

In the same news release, Shaw Chairman, President and Chief Executive Officer J.M. Bernhard Jr. said he was extremely proud of the company “we have built and operated for the last 25 years.”

“While Shaw has been growing in our business and has many opportunities ahead of us, we believe this transaction is in the best interest of and creates significant value for our shareholders, our employees and our customers,” Bernhard said.

CB&I plans to operate Shaw as a business sector under the brand name CB&I Shaw.