The deal - executed through Rothesay Life's target-based pricing mechanism - secures the benefits relating to approximately 1,800 of the engineering firm's pensioners.
Rothesay Life said this was the first time this mechanism - which monitored movements in the scheme assets and the insurer's premium requirement over three months - had been used over an extended period.
TI Group Pension Scheme secretary to the trustee Mike Abrams said: "The trustee has chosen to purchase annuities at a satisfactory price - working with Rothesay Life, we designed a process that allowed us to secure the policy when the value of our available assets was equal to the premium payable with no impact on the scheme's funding requirements."
The Rothesay Group already insures benefits payable to a separate group of 4,000 of the scheme's pensioners which were taken on by Paternoster - since acquired by Rothesay - three years ago.
The Paternoster deal was the second buy-in entered into by the scheme, following a £250m deal tied up with Legal & General earlier that year.
Rothesay Life chief executive Addy Loudiadis said the target-based mechanism used to implement the latest deal added real value to trustees looking to secure liabilities with an insurer.
"By working closely with the Trustee to finalise documentation, we were immediately ready to lock in the Trustee's target economics within hours of the target being hit," he explained.
Source: Professional Pensions