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The use of RotaBolt load monitored fasteners at the BP complex at Grangemouth, Scotland is making a significant contribution to the company's programme of reducing leaks and fugitive emissions to the environment.
Since 1994, RotaBolt Ltd has worked alongside the company's gasket suppliers and leak sealing engineers to achieve reliable, long term solutions to the problems of leaks on heat exchangers.
In addition to the aims of its environmental policy, BP recognized the cost and downtime implications of persistent leaks and undertook a thorough investigative study and cost analysis of the problem. This revealed that the cost of rectifying leaking joints on a typical heat exchanger, over a two year period, could be as much as £12,000.
In 1996, the first heat exchanger at the Grangemouth Complex was fitted with RotaBolt tension monitored fasteners. The major advantage of RotaBolts is that tension can be guaranteed to +/- 5% and checked using a simple thumb and finger test. When the rota cap is 'locked' at the prescribed limit, the engineer knows that the correct tension is being maintained.
This feature provides enormous time savings in large petrochemical complexes and enable checks to be made instantly by the company's own engineers so that joint integrity can be regularly and accurately monitored.
Based on the success of the initial RotaBolt installations, BP Grangemouth went on to fit RotaBolt converted fasteners to other heat exchangers and by 1997 over 7,000 had been fitted throughout the plant.
By combining RotaBolts and improved gasket design, the refinery has established that leaking heat exchangers can be a thing of the past.
"RotaBolts have proved of particular value when combined with an improved design of gasket in heat exchangers which are subject to thermal cycling during operation", said Tony Smith, Pressure Vessel & Pipeline Design Authority at Grangemouth.
RotaBolt achieved similar success with a project at BP Chemicals' Salt End plant in Hull where they were able to achieve significant improvements in pipe flange and vessel integrity, where there had previously been problems due to the effects of thermal recycling.
This revealed the disadvantages of torque tightening methods which have the inherent limitation of only registering the condition of the mating surfaces on the joint, not the axial load on the fastener resulting inaccuracies in excess of 60%. Similarly, where hydraulic tensioners are used, the resultant axial load has been found to be unacceptably inaccurate. In contrast, RotaBolts provide extremely accurate and verifiable tension control on installation and in service.
"I think that the BP projects demonstrate our ability to work with customers in the long term. There is the need for continuos improvement in response to increasingly higher standards of environmental accountability and plant performance. The technical support provided by RotaBolt can make an important contribution to achieving these aims", said Rod Corbett, managing director of RotaBolt Ltd.
For more information on RotaBolt, click here
