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Subsea Expo
NSRI

The voice of the UK subsea industry

Hydratight Offers Hot Bolting Services Offshore in the UK

17 December 2013

The need to replace corroded or damaged bolts that are fitted to live pressurised flanges is a common problem for many operators. Hydratight, the market leading joint integrity and machining specialist now offers a solution for safe hot bolting services on all 4-bolt ASMEflanges, and those with eight or more bolts.

The patented design of the hot bolt clamp offers a robust solution, providing the highest mitigation of risk of flange or gasket damage or worse, a leak. Meeting these safety standards ensures these services are performed without any damage, leakages or interruptions in daily production.

Paul Holland, Global Technical Services Lead for Hydratight said: "Our hot bolting solution is designed to be simple – it does not require any pneumatics or hydraulics for clamp engagement, nor does it increase the load on the gasket, and it requires less bulky systems for a given flange size. The lightweight and compact design fits almost all flange space restrictions; it is easy to handle and fit, therefore enabling speedy bolt replacement. Furthermore it is designed and tested in accordance with ASME VIII Division 2. Added to this, hot bolt clamps can be specified to be fitted in advance, remaining in-situ until the flange bolting can be safely replaced at the next shutdown.”

The clamp consists of segments that are temporarily bolted around the flange, whilst patented backstops prevent the clamp pre-tensioning from being transferred directly to the flange and inter-alia the gasket. Clamps for 4-bolted flanges have an "open” design, enabling the use of a nut splitter and bolt cutting. Clamps for larger flanges with more than 4 bolts have an enclosed design with space for use of hydraulic socket wrench, spanner and twist socket.

Safe hot bolting on old flange connections mitigates many unknowns such as the condition of the bolts and gaskets; how the gasket will act under increased or decreased load; the remaining bolt tension after a long time in service and how much force is needed to remove old rusted bolts. Safe hot bolting also reduces many concerns including failure of bolts during hot bolting operation on adjacent bolt; changes in operating parameters like flow, temperature, or pressure and the occurrence of unpredictable situations which could cause personnel to leave the workplace.

Paul Holland continues: "Hydratight has continually invested to lead the industry in best service, products, software and techniques for safer and more effective joint integrity and we are pleased to add this novel approach to the thorny issue of hot bolting, while always maintaining the highest standards of safety.”