Lancashire boiler construction detail Statement: In a Lancashire boiler, the internal flue tubes are reduced in diameter at the back (rear) end to provide access to the lower part of the boiler for cleaning and inspection.

Introduction / Context:
The Lancashire boiler is a large fire-tube boiler with two internal furnace/flue tubes running longitudinally through a water-filled shell. Practical design includes features for access, soot removal, scale cleaning, and inspection to maintain heat transfer and safety. One such feature is a reduction in the flue tube diameter near the rear end.

Given Data / Assumptions:

• Conventional Lancashire boiler with two furnace tubes and a brick-lined setting.
• Provision for manholes and handholes for maintenance access.
• Galloway cross-tubes may be present but are not essential to this feature.

Concept / Approach:
By slightly reducing the diameter of the internal flue tubes at the back end, space is created to access the lower regions of the shell and for cleaning pathways. This facilitates deslagging, scale removal, and inspection of the water side, which is crucial for efficiency and structural integrity.

Step-by-Step Solution:
Recognize the two large flue/furnace tubes act as gas passages through water.Near the rear, a diameter reduction (breeching region) provides clearance.This clearance enables maintenance access to the lower shell areas.Therefore, the statement is true.

Verification / Alternative check:
Standard sectional drawings and maintenance notes for Lancashire boilers show rear-end features including access routes and tube geometry changes to aid cleaning.

Why Other Options Are Wrong:
Galloway tubes are heat transfer enhancements and not prerequisites. Cornish boilers differ in having one flue; the feature in question pertains to Lancashire practice. A front-end reduction would not serve the stated access purpose.

Common Pitfalls:
Confusing Cornish and Lancashire layouts; assuming access is only via manholes without considering tube geometry adjustments.

Final Answer:
True