IESL Part II Mechanical case studies

IESL Part II Mechanical · Put your knowledge to work in context.

The Institution of Engineers, Sri Lanka (IESL) is the apex body of engineering professionals in the country and awards credentials such as the Chartered Engineer - CEng (SL) and AMIE (SL), which enable a member to practise as a licensed engineer in Sri Lanka. IESL was incorporated in 1968 by Parliament Act No.17 and describes itself as the largest engineers' organisation in Sri Lanka with over 25,000 members. The IESL Part II Mechanical case studies are 5 cases and about 5,596 words.

Feed Pump Cavitation from a Deaerator with a Fouled Suction Strainer

A deaerator at a textile mill supplies boiler feedwater at 1.2 bar absolute, where the saturation temperature is 105 °C, to a centrifugal feed pump rated 120 m³/h at 1470 rpm. The manufacturer's curve gives a required NPSH of 4.5 m at the duty flow.

1,105 words, about 6 min 2

Boiler Efficiency Test and the Cold-End Limit on an Economiser

A textile plant runs a packaged three-pass fire-tube boiler rated at 10 t/h of saturated steam at 10.5 bar gauge. A four-hour test was carried out at steady load.

1,006 words, about 5 min 3

Shaft Fatigue Failure at a Shoulder Fillet Machined Under Size

A 45 mm diameter drive shaft at the input of a bucket-elevator gearbox transmits 900 N·m at 250 rpm. It carries steady torque and a fully reversed bending moment of 900 N·m at a shoulder where the diameter steps from 60 mm at the bearing seat to 45 mm.

1,172 words, about 6 min 4

Lube-Oil Cooler Fouling: Clean, Upsize or Increase Water Flow

A shell-and-tube lube-oil cooler on a 2 MW diesel generator set is designed to remove 150 kW from the oil: 5.0 kg/s of oil (cp 2.0 kJ/kg·K) entering at 80 °C and leaving at 65 °C, cooled by 3.0 kg/s of water (cp 4.18 kJ/kg·K) entering at 30 °C. The unit has 8.65 m² of area and a clean overall coefficient of 500 W/m²·K; the design fouling allowance is 0.0005 m²·K/W.

1,109 words, about 6 min 5

Air Receiver Wall Thinning and a Weld Defect Found at Inspection

An air receiver in a foundry is 1.2 m inside diameter and 3.6 m long, vertical, designed for 10 bar gauge at 60 °C in SA-516 Gr 70 plate with an allowable stress of 138 MPa. The longitudinal seam is a single-V butt weld with spot radiography (E = 0.85) and the vessel carries a 1.5 mm corrosion allowance.

1,204 words, about 6 min