JGC Technical Exam

What is the primary difference between a PFD (Process Flow Diagram) and a P&ID (Piping and Instrumentation Diagram)?

A P&ID includes detailed information about piping, instrumentation, and control loops, whereas a PFD shows only the main process flow and major equipment.

Which valve type is best suited for 'throttling' (regulating) flow?

Globe Valve.

What does the term 'Lump Sum Turn Key' (LSTK) mean in a JGC contract?

The contractor agrees to complete the project for a fixed price and hand over a fully operational facility to the client.

Convert 5 Bar to PSI (approximate).

72.5 PSI.

What is the purpose of a 'Check Valve'?

To prevent backflow in a piping system.

What is NPSH, and why is it important for pumps?

Net Positive Suction Head; it is required to prevent cavitation.

In Thermodynamics, what defines an 'Isentropic' process?

A process that is both adiabatic and reversible.

Which heat exchanger type is most commonly used in oil refineries?

Shell and Tube Heat Exchanger.

What happens to the viscosity of a liquid as temperature increases?

It decreases.

Define 'Schedule Number' in piping.

It relates to the wall thickness of the pipe.

What is the difference between a 'Fixed' support and a 'Pinned' support?

A fixed support resists rotation (moment), while a pinned support does not.

In reinforced concrete, what is the primary purpose of steel rebars?

To carry tensile loads.

What is 'Slump Test' used for in construction?

To measure the workability or consistency of fresh concrete.

Define 'Young’s Modulus'.

The ratio of tensile stress to tensile strain in the elastic region of a material.

What is the power factor, and why do plants want it close to 1.0?

The ratio of Real Power (kW) to Apparent Power (kVA); it indicates electrical efficiency.

What is the function of a Transformer?

To change the voltage level of an AC current.

What does 'IP65' rating signify for electrical enclosures?

It means the enclosure is dust-tight and protected against water jets.

If you are asked to design a pipe for a highly corrosive acid, which material is generally better: Carbon Steel or Stainless Steel?

Stainless Steel.

In a project, if the 'Critical Path' is delayed by 2 days, what happens to the project completion date?

The project completion date is delayed by 2 days.

Why is 'Stress Relieving' (PWHT) performed after welding heavy-wall pipes?

To reduce residual stresses caused by the high heat of welding.