Financial details for the deal were not disclosed, although a previous report by Reuters said the business could attract bids of between $700m and $800m.
The deal marks a quick turnaround for Rhone, which picked up 73-year-old oil and gas seal manufacturer Utex in December 2010.
KKR, First Reserve and Ares Management were all believed to be considering bids for the Texas-based business.
Riverstone said the offer, which is expected to close next month, was made in partnership with Utex management.
John Lancaster, a partner at Riverstone, said the investment was consistent with Riverstone’s prior investments in niche manufacturing companies providing engineered consumable products, with demand driven by increasing challenges of deeper, higher-pressure, and more service-intensive drilling and production operations.
The energy-focused private equity firm is planning an imminent close of its Global Energy & Power Fund V thanks to strong interest from investors such as CalPERS, which had about $242bn under management at the end of October 2012.
Altassets learned in December that Riverstone was preparing to break through its original $6bn target for the vehicle and planned to continue fundraising until mid-February.
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