Bahrain-based Investcorp has bought Hydrasun from Equistone in the latest sign of strong overseas interest in Scottish services businesses among firms that hope to cash in on boomimg activity in oil and gas markets.
The deal is part of Investcorp's strategy to back international firms that it can help to expand in the region's oil and gas industry.
The price of the deal was not disclosed.
However, the head of Investcorp's Gulf business, Mohammed al Shroogi, told reporters in Dubai it was in the middle-market range of $150m to $300m.
It is believed Investcorp paid more than $200m for Hydrasun.
The sale cements a dramatic increase in the valuation of Hydrasun, which supplies specialised hoses used to transport oil and other fluids, and related equipment and services.
The company has flourished amid the boom market conditions that have been driven by strong demand for energy in fast-growing countries like China in recent years.
Equistone said it made a return of more than 2.5 times on the £40m it invested in the business. The investment firm is owned and run by former executves of Barclays Private Equity, which backed a £75.5m buyout of the company led by Mr Drummond in 2007.
Members of the Hydrasun management team have a significant minority stake in the business. Companies House records show Mr Drummond had 18% of the Hydrasun Holdings shares in issue last August.
A veteran of giants like Wood Group and Maersk, Mr Drummond participated in a £20m takover of the business in 2001, since when the company has prospered helped by exporting expertise developed in the North Sea to overseas markets.
The 57-year-old Mr Drummond said: "We believe this transaction will enable us to continue to grow organically and pursue strategic acquisitions to further accelerate our international footprint."
Hazem Ben-Gacem, head of Investcorp's European corporate investments activities, said: "Hydrasun offers a unique and fully integrated range of products and services to the oil and gas sector. Given the continuing rapid
demand in the sector, we look forward to working with Hydrasun's experienced management team as it continues to diversify the range of products and services it offers and expand into new geographies."
Investcorp will probably follow the kind of buy-and-build strategy adopted by Equistone and Barclays Private Equity.
Equistone said it had transitioned the business from being a North Sea centric distributor of fluid transfer products, into an international provider of products and services to a global customer base.
The company has expanded into markets like Kazakhstan. Hydrasun acquired Aberdeen-based ATR Hydraulics in 2009 and IFP Systems of Rosyth in 2008). It bought Remaq, a Brazilian flexible hose assemblies provider in 2011.
It has 350 employees in Aberdeen, out of a global total of 608.
Rob Myers, managing director of Equistone Partners Europe, said the company continued to invest in positioning Hydrasrun for growth, even when the oil price slumped temporarily amid the credit crunch at the tail end of last decade.
Hydrasun is on course to achieve £105m revenues in the year to March compared with approximately £85m last time.
Hydrasun was founded by Bill Cameron and Stan Fraser in 1976.
The firm prospered in the niche supply and manufacture of hydraulic hoses and associated fittings to oil and gas firms. These use miles of hoses.