Phast/safeti 8.1 Workshop: User Conference 2018

Phast/Safeti 8.1 Workshop User Conference 2018

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Objective and Learning outcomes Objectives – Highlight and demonstrate new features that are available in Phast/Safeti 8.1 via: – Case studies – Practical applications – Demonstrations – Highlight what resources are available related to the new features Learning Outcomes – Become familiar with the selected new features in Phast/Safeti 8.1 and how to access/use them – Know where to find resources related to the new features

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Practicalities All delegates will need to have Phast/Safeti 8.1 preinstalled and licensed on their computers Familiarity/experience with Phast/Safeti is needed as this is not a full software training course Please ask questions as we go along. We will try and take quick ones, but “park” “others” for later

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Workshop Agenda Topic Introduction

15 min

Safety System modelling for time varying releases

60 min

Lunch

60 min

Consequence Data Export

15 min

Greying out on the tree

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Duration

15 min

Parallel running

15 min

Coffee Break

15 min

Population database

15 min

Export workspace

15 min

Email support case

15 min

AOB/Questions/Feedback/Wrap up/Close

45 min

Time Slot 11:15 – 11:30

11:30 – 12:30 12:30 – 13:30 13:30 – 13:45 13:45 – 14:00 14:00 – 14:15 14:15 – 14:30 14:30 – 14:45 14:45 – 15:00

15:00 – 15:15 15:15 – 16:00

Safety Systems: Introduction Safety Systems consists of: – Isolation – “isolate the inventory so as to minimise the amount available to be released” – Blowdown – “dump” the inventory to a safe location for controlled disposal e.g. to the flare” Implemented on a “consequence” basis – what does this mean? – No Probability of Failure on Demand (PfD) inputs are required – If you want this to be reflected in the risk calculations, you need to manually adjust your input frequencies to reflect each branch outcome

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Safety Systems: Benefits Enables users to quantify the benefit safety systems can offer Leverages the full time varying discharge and consequence modelling introduced in version 8.0 (using the “observer” concept) – This means the full TV discharge curve can be captured – No need to approximate release rates

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Safety systems – Set up (1)

Note that Safety system modelling is only available for time varying releases!!! Note also that the Long Pipe scenario has included shutdown capability since v 6.54 7

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Safety systems – Set up (2)

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Safety systems – Set up (3) Terminology – Isolation success – All ESDs shutdown – Isolation failure – Partial failure. Inventory of neighbouring vessel considered – Blowdown success – Blowdown modelled as being present – Blowdown failure – Not modelled

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Safety systems – Set up (4): Parameters

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Safety system modelling: some considerations…(1) We are working in a “time” dimension – Discharge takes place over a certain duration – Isolation/blowdown systems are initiated at certain times – The cloud disperses and develops in size/concentration in time

So… – If isolation is set to occur at 30s and the duration of release is only 20s – nothing will happen

Recommendation – Always look at the discharge results first to understand what impact (if any) the systems have

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Think about how “real life” blowdown systems work… – E.g. API guidance indicates: "…provide depressurising on all equipment that process light hydrocarbons and set the depressured rate to achieve 100 psig (690kPag) or 50% of the vessel design pressure, which ever is lower in 15 minutes.“ – This would suggest that blowdown systems are not of much value for systems at low pressure

Safety system modelling: some considerations…(2) Understand the “underlying approach/assumptions” and what impact it can have on the results…

E.g. “Isolation success”: – the discharge calculations will assume that the conditions at the start of the release are maintained until isolation occurs, i.e. the discharge rate will be constant until Time to isolation is reached

Observed differences can be due to: – Base modelling assumptions – Erroneous inputs – Actual physical differences Always check to be sure you are confident in your results!!!

– E.g. Blowdown is to atmospheric pressure (fixed)

E.g. Time averaging – Default setting is “Average between 2 times”, typically over the first 20s – This effectively overrides the time varying result with a single value. Use “Up to 10 rates”

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Longer duration with Isolation?

Safety Systems: Case Study Input *Case Inputs for Isolatable Section (Pressure Vessel in Phast) – Material: Ethylene – Inventory: 500kg – Pressure: 15barg – Temperature: 100°C

Challenge? – The predicted dispersion hazard ranges are considered intolerable – Assess the impact of adding an isolation and blowdown system to the section on the predicted hazard ranges Safety system assumptions

Scenario Type – Time Varying Leak – Hole size of 10in

– Both successful – Assume diameter of BD valve is 275 mm – Isolation and BD delay = 0s

Weather – Wind speed of 1.5m/s, D Stability * Note that the inputs here are designed to showcase the functionality and might not be reflective of real life

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