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Sizing a Restriction Orifice

A restriction orifice is a simple, inexpensive device used to limit the flow of fluids. Despite their simplicity they are often used in safety-critical situations, such as limiting the vapour flowrate to within the capacity of a relief valve or controlling the rate of an emergency depressurisation. Accurate sizing of the orifice is therefore critical but is often misunderstood. Whilst the Bernoulli-derived equations for flow through an orifice are well documented in literature, such as in Crane ...

Process Safety Time (PST) vs SIF Response Time (SRT)

Safety Instrumented Systems (SIS) need to ensure that the response time of a Safety Instrumented Function (SIF) protecting a specific hazard, responds in sufficient time to mitigate the hazard. The process safety time should be developed during process design. This value is documented in the Safety Requirements Specification (SRS). SIF design should include calculation of the SIF Response Time (SRT) taking sensing element, logic solver and actuation time into account. The rate of hazardous event...

From Idea to Investment: Rules of Thumb for Project Costing

Accurate cost estimates are critical for making informed investment decisions. The more defined a project’s design scope is, the more refined the financial assessment can be. However, a project begins its lifecycle as an initial idea with an undefined scope and the opportunity for broad deviation from basic concept; how do we ensure financial viability of a project during these early phases?This article will outline some rules-of-thumb for project economics in the oil and gas or specialty chem...