It took a 40-pitch bullpen session from Aaron Harang on Friday for manager Eric Wedge and pitching coach Carl Willis to determine he’s ready to join the starting rotation.

Wedge announced before the game that Harang, whom the Mariners acquired in a trade from the Rockies on Thursday, will replace Blake Beavan in the rotation and start on Tuesday against the Detroit Tigers.

Beavan will assume the role of long reliever in the bullpen, something the Mariners haven’t had this season

“He (Harang) looked good today,” Wedge said. “We felt like that was the right thing for him to do. Moving Beavan to the bullpen will give us some length there. Hopefully, it’s a win-win.”

Harang, 34, went 10-10 with a 3.61 earned run average in 31 starts with the Dodgers. He pitched 1792/3 innings, striking out 131 batters.

The 6-foot-7, 260-pound right-hander has pitched in 12 big league seasons with a career record of 105-104 with a 4.19 ERA.

“He’s a veteran guy,” Wedge said. “He knows what he has to do to go out there and be successful.”

For Harang, he’s just happy to be out of the baseball limbo he’d been trapped in for the last week. After failing to make the Dodgers’ starting rotation out of spring training, he was traded to the Colorado Rockies for catcher Ramon Hernandez. The Rockies actually had no intention of keeping Harang and designated him for assignment after making the trade.

“They (the Rockies) said, ‘We are going to wait around and we are definitely going to try to move you, so just stay ready,’” Harang said. “It was a little nerve-wracking.”

He spent the time at home in San Diego with his family and kept up his throwing regimen at his alma mater – San Diego State.

Still, the waiting wasn’t easy.

“It was just finally nice to have a resolution and repack and get ready to go,” Harang said.

As for Beavan’s psyche, Wedge said the young right-hander handled the change like a professional.

“We had a good conversation with him and he understands,” Wedge said. “As with all these guys, their mindset is do what’s best for this ballclub. That’s what you have to love about this team and the individuals on it.”

Beavan hasn’t been exactly crisp in his first two starts this season, giving up 10 runs on 16 hits in 102/3 innings. The changes he’s made to his mechanics and delivery have not yielded great results and also have made his breaking stuff a little ineffective.

“Blake won 11 games for us last year, but he’s still a young pitcher figuring it out,” Wedge said. “… Sometimes when you move a guy to the bullpen, they get a different look and a different feel.”

There was some thought rookie Brandon Maurer might be replaced in the rotation by Harang after rough outings in his first two major league starts, but the Mariners are reluctant to stunt his growth with a move to the bullpen.