The Pirates are installing 44 walk-through metal detectors at the gates to PNC Park to comply with a Major League Baseball directive requiring security screening at all stadiums starting this season.

The Pirates began screening fans with handheld metal detectors during the 2013 season. Team president Frank Coonelly, in a statement, said the change to walk-through detectors “will enhance fan safety, while also speeding up the screening process versus the use of metal detecting wands.”

Unlike at airport checkpoints, fans will not be asked to remove small metal objects like coins, keys and watches, the team said. They will be asked to place cell phones, cameras, tablets, laptops and other large metal objects into a tray that will be fixed alongside the detector and in clear sight, and to retrieve those items after going through the detector.

Michael Teevan, vice president of communications for MLB, said the screening requirement “resulted from a recent study of best security practices and MLB’s continuing work with the Department of Homeland Security.”

The league notified teams in 2013 that it would implement a screening program for all stadiums, either with walk-through or handheld detectors, and that they needed to have their programs in place by opening day this year, Mr. Teevan said.

MLB does not anticipate that the requirement will create airportlike delays for fans entering ballparks, he said.

“Our experiences in both 2013 and 2014, at many ballparks and during our jewel events, have been positive. When clubs roll this program out for the first time, fans may not first expect it or be prepared for it, and there may be some delays during the introductory phase. But we expect the measures to become routine,” Mr. Teevan said.

When the Pirates began screening in 2013, it coincided with the first major league start of pitching prospect Gerrit Cole, which drew a weeknight crowd of more than 30,000. Many fans were still in long lines outside PNC Park when the game started, bringing an apology from Mr. Coonelly.

“The experience was simply unacceptable, and we will ensure this does not happen again,” he said.

The Pirates open their home schedule with a 1:35 p.m. game against Detroit on April 13. Policies on what is and isn’t allowed to be taken into the ballpark are not changing, the team said.

Critics say screening at ballparks is a waste of time and money.

“Generally, security measures that defend specific targets are wasteful, because they can be avoided simply by switching targets. If we completely defend the World Series from attack, and the terrorists bomb a crowded shopping mall instead, little has been gained,” wrote Bruce Schneier, a Harvard University fellow who has written 12 books and hundreds of essays and academic papers and testified in Congress on security issues.

“What does work is people — smart security officials watching the crowds. It’s called ‘behavior recognition,’ and it requires trained personnel looking for suspicious behavior,” he said in an article on his blog in October.

Mr. Schneier, chief technology officer of Resilient Systems Inc., said in an email on Wednesday that the screening at stadiums was motivated by leagues’ desire to appear to be providing safety — he calls it “security theater” — and to protect concession sales.

Mr. Teevan said the MLB policy was not inspired by any particular incident or attack at a ballpark.

“The policy is motivated by the commissioner’s and all of our clubs’ concerns that ballparks be safe and comfortable places for all of our fans,” he said.

-The 16th China(Guangzhou)Int’l Metal &Metallurgy Exhibition