Practical Tools to Assist in Preventing or Reducing Dangers Associated with Flow Line Overpressure Events. Nuder Said

Transcription

1 Practical Tools to Assist in Preventing or Reducing Dangers Associated with Flow Line Overpressure Events Nuder Said

2 Dynamic Restraint Systems & Relief Valves General Guidelines

3 Presented by Said Nuder December 2-3, 2014

4 Introduction What is a dynamic restraint system? High strength synthetic loops with the ability to stretch under severe loads The synthetic loops are attached along the full length of the high pressure flow line The ends of the restraint system are attached to suitable robust anchor points In summary, it is a safety system that is intended to contain any projectiles that may occur in the event of a catastrophic line rupture. The purpose is to minimize the lethal zone. December 2-3, 2014

5 How does a dynamic restraint system work? During rupture of piping, the discharging fluid will create a reaction force on the failed component. The value of this force is a function of fluid velocity and fluid mass. The continuous discharge of fluid can cause the component to accelerate and gain additional energy. The purpose of the restraint system is to capture the ejecting components and dissipate their accumulated energy by converting to thermal energy. This is accomplished by the physical elongation of the primary restraint (spine) and the gradual dissipation of the energy. December 2-3, 2014

6 Applications What are the applications for a dynamic restraint system? Fraccing Cementing/Acidizing Fixed Manifolds Energized fluids (N2) Any application involving pressurized fluid December 2-3, 2014

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13 Critical Considerations Environmental considerations Chemical resistance The material for the restraint should be resistant to chemicals typical to a fraccing operation SPM material is resistant to all typical fraccing compounds Temperature The material should not exhibit reduction in breaking strength at typical low temperature applications (-30C) SPM restraints were tested at -50C December 2-3, 2014

14 Critical Considerations Inspection The restraint should be inspected on a periodic basis Should be conducted per published guidelines regarding recertification Must maintain serialization and traceability for the restraint December 2-3, 2014

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22 Relief Valve Provide over-pressure protection for the following: Reciprocating pumps Treating lines Pressure vessels Well Head December 2-3, 2014

23 Relief Valve Beneficial characteristics of Relief Valves High discharge capacity Adjustable pressure settings Auto reset Robust seal surfaces Reaction time Repeatability December 2-3, 2014

24 Relief Valve guidelines Discharge Capacity Valve should be sized based on the total flow rate through the system Incorrect sizing could result in over pressure even when the valve is sequenced If necessary multiple valves can be installed to meet the discharge capacity December 2-3, 2014

25 Relief Valve guidelines Valve Chatter Primary failure of mechanical relief valves Occurs when valve mechanically response to pressure pulsation from the pump. Solutions Pulsation dampeners Increase distance between valve and pump Maintain adequate pressure differential between set pressure and system pressure. December 2-3, 2014

26 Relief Valve guidelines Valve orientation Up right orientation will minimize sand accumulation around seal surface Discharge line visible to operator All seal failures are proceeded by visible discharge. Ability of operator to observe leaking will provide advance notice of seal failure. December 2-3, 2014

27 Relief Valve guidelines Auto reset Valve should reset after predetermined pressure value. Ability to continue pumping in an event of a pressure spike Maintenance Exposed to extremely challenging conditions. Typical operations may result in rapid wear of sealing components. Follow manufacturers guidelines regarding rekiting and maintenance recommendations. December 2-3, 2014

28 Relief Valve guidelines Summary Valves should be sized correctly. Take steps to manage the effects of chatter Consider proper valve orientation Follow manufacturer guidelines December 2-3, 2014

29 Questions December 2-3, 2014