Learn the checks and communication needed to start a tanker cargo pump, establish initial flow, monitor manifold pressure and respond to abnormal conditions.
Starting a cargo pump is the point at which a prepared tanker discharge system becomes a live ship–shore transfer. The pump may be ready, but cargo should move only after the crew has confirmed the tank, suction route, discharge route, manifold connection and terminal readiness.
This guide follows the operation from the final pre-start checks to steady initial flow. It focuses on a centrifugal cargo pump. Pump controls, valve positions and start limits vary by installation, so the vessel’s discharge plan, piping diagram, pump-maker instructions and safety management procedures govern the actual sequence.
Before the start: one agreed operation
The chief officer directs the discharge plan. The cargo control room (CCR) operator monitors tank levels, valves, pressures and pump controls. Designated deck or pump-room personnel carry out local checks and report back. The terminal confirms that its receiving system is ready.
These are connected checks, not separate formalities. A pump can be correctly primed and still create a serious problem if its discharge path is shut, the wrong tank is selected or shore is unprepared. ISGOTT 6 places particular emphasis on communication and agreed procedures throughout the ship–shore transfer. Its checklist covers cargo handling limits, supervision, communications and emergency shutdown arrangements. www.ocimf.org
Step 1: Confirm the ship–shore discharge agreement
Before anyone requests a pump start, confirm the agreed:
- Tank and cargo grade to be discharged first
- Shore receiving line and manifold connection
- Initial and maximum transfer rates
- Maximum permitted manifold pressure
- Communication method and named contacts
- Procedure for changing rate or stopping transfer
- Emergency signals and shutdown actions
The ISGOTT ship–shore agreements include transfer rates, manifold pressure, pressure-surge controls and tank-switching protocols. Those limits should be available to the CCR operator during the start, not left solely in a completed checklist. www.ocimf.org
The terminal must know before the pump starts. Once flow is stable, the ship should report its observed rate and pressure and confirm that they match the terminal’s readings and the agreed plan.
Step 2: Trace the cargo route
Using the approved cargo piping diagram and discharge plan, trace the route from the selected tank to the receiving line ashore:
Selected tank → tank suction → suction line → cargo pump → discharge line → manifold → terminal
Confirm the required valve positions through the CCR indications and local checks specified by the vessel’s procedure. Check for unintended cross-connections to another tank, cargo grade, ballast system or unused manifold connection. The selected tank must have adequate liquid at its suction for the planned start.
A valve shown as open on a screen is useful information; where local verification is required, the team should confirm that the physical lineup agrees. Resolve conflicting indications before starting.
Step 3: Confirm pump priming and machinery readiness
A conventional non-self-priming centrifugal pump needs liquid in its suction path and casing before start. Gas trapped in the pump can prevent it from establishing flow, while dry running can damage pump components. Confirm priming by the means provided in the ship’s procedure, including any approved closed venting or priming arrangement. www.ksb.com
Then check the equipment applicable to that installation: drive readiness, lubrication, seals, bearings, alarms, temperature monitoring and any required support systems. Ensure that protective devices have not been bypassed without authorisation.
Do not briefly start an unprimed pump to test its rotation. If rotation direction is uncertain following maintenance, it requires an authorised machinery check under the applicable procedure.
Step 4: Check the discharge path and pressure controls
Confirm that cargo has a valid path to the terminal and that the intended start arrangement will protect the pump and piping. The correct position of a pump discharge valve at start depends on the pump, drive and control system. Some installations use an automatic discharge control valve or a recirculation arrangement; others require a different sequence.
Follow the specific pump-maker and vessel instructions. A universal rule to start with the discharge valve fully open or fully closed would be unreliable. In either case, avoid an uncontrolled change in flow or a rapid valve movement that could create a pressure surge. The ship and terminal should already have agreed the operating limits and surge-control arrangements. www.ocimf.org
Step 5: Give the start instruction and establish initial flow
When the chief officer or authorised officer confirms readiness with shore, the CCR operator can start the designated pump according to the vessel’s sequence. Increase output or open the controlled flow path as instructed, aiming first for the agreed initial rate.
During these first moments, the CCR should check whether the indications tell a consistent story:
| Indication | Expected question |
|---|---|
| Suction pressure | Is the selected tank supplying liquid steadily? |
| Pump discharge pressure | Is the pump developing pressure without exceeding its limits? |
| Manifold pressure | Is it within the ship–shore agreement? |
| Flow rate | Is cargo flow established at the intended initial rate? |
| Tank level | Is the correct tank beginning to discharge? |
| Terminal confirmation | Is shore receiving the cargo at a matching rate? |
One reading alone cannot prove a successful start. For example, a pump running indication does not prove flow, and discharge pressure without a confirmed receiving path is a reason to investigate.
Step 6: Verify locally and settle at the planned rate
Once initial flow is established, designated personnel check accessible parts of the cargo system for leaks and abnormal conditions. Depending on the installation, they may monitor the manifold, deck lines, pump seals, noise and vibration. They should communicate observations to the CCR without approaching a leak or hazardous area unnecessarily.
If a local pump-room check is required, entry follows the vessel’s pump-room and enclosed-space safety procedures. Pump rooms can develop hazardous atmospheres; ventilation and a normal fixed-gas indication do not, by themselves, authorise entry. IMO guidance identifies pump rooms as spaces requiring careful assessment and controls. imo.org
When ship and shore have confirmed stable flow, increase the rate in planned stages. Watch manifold pressure and pump behaviour after each change. Keep the terminal informed of changes that affect its receiving system.
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What if the pump start is abnormal?
Stop or reduce the pump as the vessel’s procedure requires, and tell the cargo team and terminal promptly. Do not keep increasing speed to overcome an unexplained lack of flow.
| Observation | Possible issue to investigate |
|---|---|
| Pump runs but little or no cargo flows | Loss of prime, incorrect valve lineup, inadequate tank supply or blocked receiving path |
| Suction or flow fluctuates | Gas or vapour entering the suction, changing tank level or unstable suction conditions |
| Manifold pressure rises unexpectedly | Restricted or incorrect discharge path, shore-side issue or valve-control problem |
| Abnormal vibration or noise | Cavitation, loss of suction or a mechanical fault |
| Leak or rising pump-room alarm | Loss of containment or an unsafe pump-room condition |
The crew should diagnose the cause using the ship’s indications and safe inspection methods before any restart. Where a pump-room gas, bilge or temperature alarm is involved, apply the vessel’s emergency and access controls. SOLAS tanker provisions address monitoring of cargo pump-room gas concentration, bilge levels and relevant pump temperatures. imo.org
Preventing spills during pump start
The first flow through a pressurised cargo system is also a check of its containment. Verify manifold connections, unused connections, drip trays, scuppers and visible lines as required by the ship’s checklist. If cargo escapes, stop transfer, alert the terminal and follow the ship’s spill-response procedure.
MARPOL Annex I addresses prevention of pollution by oil from both operational and accidental discharges. Qualifying oil tankers must carry an approved Shipboard Oil Pollution Emergency Plan (SOPEP). These requirements support pollution prevention and response; they do not prescribe one universal sequence for opening cargo-pump valves. Prevention of Pollution by Oil
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Common questions
Should the terminal be informed before or after starting the pump?
Both. The terminal confirms readiness before the start. After initial flow is established, ship and shore compare the actual rate and pressure and agree on the next rate increase.
Is confirming priming enough to start?
No. Priming confirms a necessary pump condition for a conventional centrifugal installation. The tank selection, valve lineup, receiving path, machinery readiness and ship–shore agreement must also be confirmed.
Should the discharge valve always be closed at start?
No universal valve position applies to every tanker cargo pump. Use the vessel’s approved start sequence and pump-maker instructions, including any automatic valve or minimum-flow controls.
What is the most useful sign of a successful start?
A stable, agreed flow supported by consistent pump and manifold pressures, the expected change in the selected tank’s level, and confirmation from the terminal.
Final takeaway
A safe cargo-pump start is a controlled transition: confirm the route and receiving system, confirm pump readiness, establish a modest initial flow, then verify it from both ship and shore before increasing the rate. If pressures, flow or local observations disagree, pause the operation and resolve the cause before continuing.
Further reading: ISGOTT 6 and its ship–shore checklists · IMO tanker safety guidance · IMO MARPOL Annex I overview