Hatch cover testing

IACS Unified Requirement S26 and the International Convention on Load Lines 1966 (with the 1988 Protocol) require hatch covers to be weathertight and structurally sound. Three test methods are accepted by class — hose test, ultrasonic test, and chalk test. Each has different sensitivity and is used at different points in the survey cycle.

Hose test

• · Water jet directed at the joint between hatch cover and coaming, hatch panels, and side seams.
• · Minimum pressure 2 bar at the nozzle (pressure gauge required); 1.0–1.5 m distance from the joint; 100 mm nozzle diameter.
• · Inside person watches for water ingress at the rubber packing, locator pins, cleats, side cleats, and quick-acting closing devices.
• · Cannot be used at sub-zero temperatures (water freezes); ultrasonic test substitutes.

Ultrasonic test

• · Ultrasonic transmitter (~40 kHz) placed inside the closed hatch.
• · Receiver wand swept over every joint, packing rubber, and weather shield from outside.
• · Gap detection threshold typically 1-2 dB above ambient; equipment must be calibrated and the operator class-approved.
• · Quantitative leak-rate measurement; preferred method for grain, project cargo, and condition assessment.
• · Standards: ISO 17840 + class society approval scheme (e.g. DNV CMP, LR ShipRight).

Chalk test

• · Chalk applied to the packing rubber along its full circumference.
• · Hatch closed and locked under normal cleating force.
• · Re-opened; inspected for chalk transfer to the compression bar — a continuous transfer mark indicates correct compression; gaps indicate poor packing condition.
• · Qualitative only; used as a routine maintenance check by the deck crew rather than class evidence.
• · Performed at port stays before sensitive cargoes; recorded in the deck log.

Inspection points

• Packing rubber — set, hardness (target 70±5 Shore A), continuity, no gouges, no permanent deformation.
• Compression bar — straight, no corrosion, no bend; clean of paint or debris.
• Locator pins, cleats, quick-acting devices — operate freely, no seizure, lubricated, locking pins in place.
• Hatch panel structure — UTM gauging at intermediate/renewal survey; deflection ≤6 mm under load (IACS UR S21).
• Drain channels — clear, valves operate; non-return flap in place.
• Coaming — corrosion limit per IACS Common Structural Rules (CSR-BC), typically 25% original thickness.

Common findings

• · Packing rubber compressed flat (no rebound) — replace.
• · Cleats with seized threads, cannot reach correct torque — overhaul.
• · Deformed or wasted compression bar — straighten or renew.
• · Drain holes clogged or non-return flap missing — clear and replace.
• · Locator pins worn, hatch panel sits at angle — renew pins/bushings.
• · Coaming top wasting near scupper — class consultation required.

Sources: IACS Unified Requirement S26 (Strength and weathertightness of hatch covers and coamings of cargo holds and tanktops); International Convention on Load Lines 1966 (as modified by the 1988 Protocol); IMO Resolution A.714(17) (CSS Code); ISO 17840 (ultrasonic testing for hatch cover weathertightness). See also scantlings, Load Line Certificate, IACS classification.