API STD 2560:2003 pdf download

API STD 2560:2003 pdf download.Reconciliation of Liquid Pipeline Quantities.
6.2 PRESENTATION OF DATA
6.2.1 Data may he presented in the form of Control Charts. Trending Charts or (‘umulatise Charts. Guidelines on such charts may indude control limits and trending lines.
6.2.2 Charts used for monitoring pipeline systems should he living documents arid should be updated whenever new data are available. Aecuinubhng data fw some period of tune and periodically updating charts (say. semiannually) “ICTWS no useful purpxse. Charts and monitoring procedures can he effective only if charts are current and used as constructive torus.
6.3 CONTROL CHARTS
6.3.1 measurement can he assured by continuously mcwutonng measurement results to determine if systems. or equipment and procedures, are performing in predictable ways and are operating within acceptable limits. This may be d4w1e by the use of Control Charts.
6.3.2 Control charts display a collection of data osr some period of time and include control limits shown as horuiontal lines on the charts. Control limits help define normal and abnormal system performance, and may indicate hen wnething in the system has changed and’or cornctise action(s) may he required.
6.3.3 limits are often determined by historical performance of the system. In other cases the control limits are set on an established arbitrary value, e.g.. contractual limits. Control charts are the most common method of ascertaining system loss/gain performance. Control charts di%play a collect ion of data over some period of time and include the control limits. Control charts help to define normal trends of a system and may indicate hcn something has changed. TSpical loss/gain charts as shown in Figure I. indicate a systems performance based on a percentage of throughputs over time. Typicaly. because accounting systems encompass a kIay period, monthly evaluations of a system are commonly used to evaluate performance. Control charts may he prepared for any time ‘pan (e.g., weekly or daily) if adequate data are avai laNe,
6.3.4 Control charts may he maintained for entire systems. or for individual egnlents 01 a system if adequate measurement and records are available at the junctures of segments.
6.3.5 The data on control charts tend to hover around a central (mean) value, which is the arithmetic average of the data and can he represented by a hori,ontal line on the chart The control chart also includes upper and lower control limits (UCL and LCL) which may be (I) defined as engineenng limits which are values based on experience or performance objectives.