3M Co. on Tuesday announced its largest acquisition — the $2.5 billion purchase of Bloomington-based Capital Safety, a maker of rugged harnesses and other safety equipment for workers in the construction, drilling and mining industries.

The deal is nearly twice the size of the previous record acquisition for 3M, the Maplewood-based conglomerate best known for Scotch tape, Post-it notes, sandpaper and health equipment.

3M executives signaled last year that the company would look for more deals with a price tag in excess of $1 billion. For years, most of 3M's purchases were so small that it didn't need to tell investors how much it was spending.

With about $430 million in annual revenue, Capital Safety will be a relatively small addition to 3M's overall $32 billion in annual revenue. But it is a significant addition to 3M's safety and graphics business unit, which did about $5.7 billion in sales last year.

While 3M is well known for respirators, safety goggles, ear protection and safety vests, it has more limited offerings in the area of harnesses and fall prevention ropes. This acquisition will change that; Capital Safety operates in 27 global facilities and is known for brands such as DBI-Sala and Protecta.

"Personal safety is a large and strategically important growth business in the 3M portfolio," 3M CEO Inge Thulin said in a statement. "The acquisition of Capital Safety bolsters our personal safety platform and will build on our fundamental strengths in technology, manufacturing, global capabilities and brand."

The purchase figure includes the assumption of $700 million in debt.

Capital Safety is currently owned by the New York investment firm Kohlberg Kravis Roberts, known as KKR, which bought the company in 2011 for $1.1 billion and moved its headquarters from London to Minnesota.

Capital Safety employs 1,500 people, including about 550 manufacturing and sales workers at its main production facility in Red Wing.

There, workers make harnesses, self-retracting lifelines, fall shock absorbers, anchors and other safety products for workers building skyscrapers, washing tower windows, or toiling on ships, oil rigs and in mines.

KKR Industrial head Pete Stavros praised Capital Safety's track record and "absolutely fantastic partnership with management. Over the past three years, the company has driven impressive top-line growth, broadened its geographic presence and further optimized its operations," he said in a statement. "3M is a perfect home for a company and team that is so deeply committed to safety."

Wall Street analysts ­welcomed the deal and said it's a smart move for 3M.

Edward Jones equity research analyst Matt Arnold said that 3M "made it clear that their ambitions to make some sizable acquisitions has risen and they are starting to put some capital to work. So [the acquisition] is not surprising. More importantly, we think it's a good thing. 3M has done a ton to get their house in order and to improve the margin structure of the company."

Capital Safety supports that, he said. "You are talking about a business that is growing double digits and should have high margins and some 'value add' in terms of its self-retracting lifeline [products]," Arnold said.

The deal, expected to close in the third quarter, marks 3M's second major acquisition this year.

In February, 3M announced it would pay $1 billion to buy the assets of Polypore International Incorporated's ultrafiltration business. That deal gave 3M an additional $210 million in annual sales and ended an eight-year period in which 3M shied away from large deals.

Of the 40 companies 3M bought in the past decade, only 12 were large enough to require price disclosures. Of those 12, only three scratched $1 billion. 3M made no major acquisitions during the last two years.

In 2007, 3M bought eye and hearing protection firm Aearo Technologies for $1.2 billion to expand its safety business. 3M also bought Cuno Inc., a water filtration firm, in 2005 for $1.3 billion so it could expand beyond its ­air-filtration capabilities. In 2012, 3M purchased high-strength-ceramics maker Ceradyne for $860 million.

3M said the Capital Safety deal will reduce its earnings by 4 cents a share during the first 12 months, but will add about 12 cents per share after integration costs are finalized.

3M's stock price closed up 16 cents a share to $159.84.

Dee DePass • 612-673-7725