Quality control efforts during

The number and severity of fabrication and installation deficiencies are also directly related to quality control efforts during construction phases of a project. For example, a review of contractor submittals, or shop drawings, usually helps assure comphance with contract documents before equipment is delivered to the job site. Site inspections during installation work may detect deficiencies in design or workmanship before they lead to operational problems and performance difficulties. In addition, specific operating and performance testing as a prerequisite to final accepfance is a key element in assuring that a system is installed properly. 

A complete lEC 61508 assessment includes a FMEDA, a study of Prior Use and adds an assessment of all fault avoidance and fault control measures during hardware and software development as well as detail study of the testing, modification, user documentation and manufacturing processes. The objective of all this effort is to provide a high level of assurance that an instrument has sufficient quality and integrity for a safety instrumented system application. This is clearly more important for products containing software as many end users have the strong opinion that software is "bad... 

Although many process variables are easily measured, lack of on-line sensors for key polymer properties renders quality control of polymer plants difficult. Process control schemes based on process variables p, T, flow-rate and feedstock compositions) alone are no longer sufficient, because these cannot reveal all material property variations. Significant efforts are being spent on improvements to process control systems, as exemplified by the numerous attempts to monitor polymer properties during processing, such as composition, density, viscosity and dispersion of a minor phase, etc., all of which are somehow difficult to measure. The development of an on-line inferential system for polymer property is a very active research area of polymerisation reactor control [1]. A schematic of inferential systems is illustrated in Fig. 7.1. For highest quality... 

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