Pipework, Fittings, and Jointing
What you must know
Materials and sizing: copper, steel, and approved flexible connectors; correct pipe sizing for pressure drop and appliance demand; support spacing; protection from corrosion and mechanical damage; sleeving through walls and cavities; and the rules on concealed pipework (no joints in inaccessible locations unless approved methods). Know jointing methods - compression, soldered (lead-free), press-fit - and where each is permitted. Understand purge volumes, test pressures, and the requirement for accessible isolation valves. Recognise that gas pipework must be adequately sized and that undersizing causes pressure loss and poor appliance performance.
Traps in questions
- Assuming any joint is acceptable in a wall or floor - concealed joints are generally prohibited unless a specific approved method applies.
- Forgetting sleeving and sealing where a pipe passes through a cavity or external wall.
- Mixing up test pressure for tightness testing versus operating pressure.
- Overlooking support spacing and protection from vibration or corrosion.
Worked example / rule of thumb
Rule of thumb: Accessible, protected, sized, and sleeved. Before signing off pipework, check each: is every joint accessible? Is the pipe protected and supported? Is it sized for demand? Is it sleeved through structures? If any answer is no, it is not compliant.
Key exam behaviours
Stems often describe an installation detail and ask whether it is acceptable. Apply the four checks above and choose the compliant option; watch for "concealed joint" and "unsupported run" distractors.