Surge Analysis / Flow Assurance

Hydraulic Analysis Limited is a worldwide leader in surge analysis, flow assurance and dynamic simulation. The hydraulic computer modelling techniques utilised for the wide range of projects in the water, oil, gas, nuclear and petrochemical sectors have been developed in house over the last forty years (VariSim) and independently validated and verified against on site testing.

Surge pressures and the associated out of balance loads can be rapidly applied and hence need to be simulated by specialist hydraulic computer modelling techniques. Many dynamic simulators do not incorporate these methods and so are not suitable for surge analysis / flow assurance applications. Hydraulic Analysis Limited’s programs are specifically designed for the full range of surge analysis / flow assurance applications resulting in exceptional accuracy when compared to as built systems.

However, it is not just the quality and precision of the hydraulic computer modelling which has built up Hydraulic Analysis Limited’s reputation in the surge analysis / flow assurance field. Hydraulic Analysis Limited is also, in its own right, an integrated engineering consultancy offering clients the benefits of our highly experience consultants, who can draw upon the knowledge base of over forty years of previous projects.

It is this extensive engineering consultancy background combined with the acknowledged surge analysis / flow assurance capabilities that allows Hydraulic Analysis Limited to provide clients with an unprecedented level of service.

Surge pressures (or waterhammer as it is also known) are generated in a pipeline whenever there is a sudden change in flow, for example, as a result of a valve opening / closing, pump start up /shutdown or interaction between equipment on a system during normal or abnormal operation, which may cause problems such as:-

  • Unacceptable high and low pressures
  • Severe pipe loads
  • Unwanted trips and shutdowns
  • Pipe movement and vibration
  • Equipment damage
  • Operation of relief valves / bursting discs

A typical surge analysis would appraise the system, quantify the problems, identify the primary cause, select the preferred solution, prove recommendations and eliminate any secondary effects in consultation with the client in order to provide the optimum solution, both in terms of cost, timescales and practicality.

A Scope of Work along the lines of that detailed below would be agreed with the client prior to any surge analysis being undertaken.

  • Contract review and handover to assigned engineer in accordance with the latest Lloyds Register Quality Management Procedure.
  • Engineering familiarisation with the project and study objectives.
  • Client liaison, to discuss system philosophy and request additional data.
  • Review of the hydraulic design to evaluate compliance with current Codes of Practice and manufacturers’ recommendations.
  • Preparation of a mathematical model to be used for the steady state and transient analysis phases of the study which will incorporate HAL’s detailed surge analysis / flow assurance capabilities.
  • Computation of steady flow and pressures to determine achievable flowrates for extremes of static and friction conditions.
  • Execution of computer simulations of transient events to determine the maximum and minimum surge pressures which are then compared with the system rating.
  • Determination of maximum out of balance load forces between nodal locations throughout the computer simulation to be used by stress engineers as part of their separate stress analysis study.
  • If necessary, appropriate surge suppression / alleviation techniques are proposed and verified.
  • Provision of a report, including graphical results and full engineering recommendations.
  • A full record of the study and the mathematical model are retained in accordance with the requirements of our Quality Management System.