Mechanical Engineering Practice
Mechanical Engineering Practice is the general-competence domain of the COREN Mechanical examination. It tests whether you can run a pressure system, rotating equipment, fabrication or maintenance scope lawfully, to recognised codes, and to a defensible professional standard in Nigeria.
Registration, ethics and statute
The Engineers (Registration, etc.) Act CAP E11 LFN 2004 establishes COREN and its register of Graduate, Registered and Professional Engineers; protected titles and the engineering seal are reserved for registered persons. Your seal certifies personal review - never seal calculations, materials or inspection records you have not checked, or work outside your competence. Under the Factories Act, boilers, air receivers and similar pressure equipment need statutory examination by an approved inspector at prescribed intervals, and the certificate must be current before operation.
Design basis and codes
Fix design pressure, design temperature, corrosion allowance, mill tolerance and load cases before sizing. Use ASME BPVC Section VIII for vessels, ASME B31.3 for process piping, ASME IX for welding procedure and welder qualification, and EN 10204 3.1/3.2 certificates for traceable material. Keep units consistent: the B31.3 and BPVC formulas work in SI or US units if P, D, S and t match.
Contracts and quality
Lump-sum contracts shift quantity risk to the contractor; measured contracts pay on re-measurement; cost-plus needs strict scope control. Tie payment to the inspection and test plan, hold points and closed non-conformance reports.
Worked example
A 200 mm outside-diameter pipe has design pressure 2.0 MPa, allowable stress 138 MPa, joint factor 1.0, Y = 0.4 and corrosion allowance 3 mm. B31.3: t = PD/[2(SE + PY)] + c = (2.0 × 200)/[2(138 × 1.0 + 2.0 × 0.4)] + 3 = 400/277.6 + 3 = 4.44 mm. A 5 mm nominal wall with 12.5% mill tolerance gives only 4.38 mm minimum, so select 6 mm - not the 1.44 mm calculated before allowances.
Traps
Using operating pressure instead of design pressure; omitting corrosion allowance or mill tolerance; applying a piping code to a vessel; accepting uncertified plate or electrodes; sealing unchecked drawings; missing an expired statutory certificate.