ISA CCST Level I case studies

ISA CCST Level I · Put your knowledge to work in context.

The Certified Control Systems Technician (CCST) - Level 1 is the first of the three certification levels ISA offers for control systems technicians. It is described as a non-biased, third-party, objective assessment and confirmation of a technician's skills: CCSTs calibrate, document, troubleshoot and repair or replace instrumentation for systems that measure and control level, temperature, pressure, flow and other process variables, working with pneumatic, mechanical and electronic instrumentation and with process control loops that include computer-based systems. The ISA CCST Level I case studies are 5 cases and about 4,536 words.

Zero-Shift Found on an In-Service Orifice DP Flow Loop

A 4-inch orifice meter on a natural-gas line uses a DP transmitter ranged 0-50 inH2O, 4-20 mA, with square-root extraction performed in the DCS (DCS flow span 0-12 MMSCFD). The instrument specification calls for accuracy of +/-0.25% of span.

826 words, about 4 min 2

Control Valve Reaches Only 88% Travel at Full Output

A 4-inch air-to-open globe valve (fail closed) controls flow to a column reboiler. Nameplate data: spring-and-diaphragm actuator with a bench set of 3-15 psi, electro-pneumatic positioner, 4-20 mA input, 0-100% travel.

960 words, about 5 min 3

Loop That Reads Low Only at High Output

A two-wire 4-20 mA pressure transmitter on a new fuel-gas line has a datasheet range of 0-100 psig and a minimum terminal voltage of 12 VDC. The cable run is 250 m of 1.5 mm2 copper, one way, with one field junction box mid-run, landed on a DCS analog input card with a 250 ohm sense resistor.

887 words, about 4 min 4

Ten Days to Feed: Dispositioning Walk-Down Findings

A 62-loop compressor seal-gas skid is 10 days from first feed. The mechanical completion certificate requires every safety-critical loop to be closed.

909 words, about 5 min 5

Level Loop Checks Out but Reads Low When the Tank Fills

During commissioning of open tank T-201, a DP transmitter measures level over a working range of 10 ft of water. Range is 0-120 inH2O = 0-100% of the DCS span.

954 words, about 5 min