Private equity firm Advent International is set to purchase Distribution International Inc., a distributor and fabricator of mechanical insulation and related products

The deal marks an exit for Audax Group LP and CapStreet Group LLC, which jointly-owned DI since 2010.

Houston-based DI has 64 branch locations across North America with products and services across the commercial building, chemicals, energy, power, railcar and marine end markets.

Most of DI’s sales are derived from ongoing maintenance and repair spending in industrial installations and commercial buildings. The company has grown significantly over the past four years, having completed 11 acquisitions.

In October, the company acquired Mechanical Insulation Supply Inc., a Redford, Michigan-based wholesaler of industrial, commercial and residential insulation products. A month earlier, it picked up Pacific Insulation Co., a Los Angeles-based wholesaler of insulation products.

As part of the transaction, Boston-based Advent partners Wes Clark and Chip Hornsby are to be added to the DI board of directors.

Hornsby is the former CEO of Wolseley plc and current CEO of plumbing and HVAC company Morsco, which originally did business as Morris Supply Co., which Advent bought in November 2011.