OTM-7.7	Oil Tanker Manual OTM Cargo Discharging	Doc No.: OTM 7.7 Revision: 01 Date: 15 Oct 2024 Issued by: DPA Approved by: MD

1. APPLICATION

This document applies to all tanker vessels managed by Company.

2. PURPOSE

The purpose of this document is to specify cargo discharging procedures.

3. RESPONSIBILITIES

• Master
  • Overall in-charge for arrival / departure / cargo documents.
  • Send at least one cargo plan per month to Marine Superintendent for review, when applicable.
• Chief Officer – Overall in-charge of discharging operation.
• Chief Engineer – Ensure operational readiness all machinery required for discharging.
• Deck Officers – Follow discharge plan instructions.
• Deck Crew – Assist in discharge operations and tend to moorings & gangway.

4. DISCHARGING

4.1 Discharging strategy

Prepare discharge sequence to have a good trim for effective stripping.

4.2 At discharge berth

• Get NOR acceptance endorsed by charterers representatives or terminal representatives or receivers.
• Different local regulations may apply for NOR acceptance time. Get clarifications from the local Agents.
• Cargo delivery
  • Get original Bill of Lading from receiver before allowing discharge, or
  • Get authorisation to discharge from company / Operators after they receive Letter of Indemnity from charterers.
  • If applicable, sign original Bill of Lading with the wording "Voyage Accomplished".
  • Forward signed original Bill of Lading to company / Operators by registered airmail together with other cargo documents.
• Pre-Transfer / Safety meeting – Carry out Safety Meeting with the Cargo / Terminal representatives.

Note:

• Use TNK 06B for Pre-Transfer / Safety Meeting
• Discharge Plan – Discuss with Terminal representative.

Note:

• Use TNK 010 for Discharge Plan
• Test high level and overfill alarms.
• Vessel and Terminal representative must complete Ship/Shore Safety Check-List before start of operations.

Note:

• Use TNK 06A – Ship Shore Safety Checklist
• Lining up Pipelines and Valves
  • Set deck and pump room lines before start of loading.
  • Ensure all the cargo lines are well drained as per ship specific procedures before commencing shore hose connections.
  • Firmly shut pump room / deck cargo-line valves not in use.
  • Keep offshore manifold valves closed & blanked, using all bolts.
  • Set gauges to ensure offshore valves are not passing.

  Note:

  • Chief Officer must supervise below, cross verified by another officer:
  • - Line / Valve setting for cargo, ballast, venting and heating system.
  • After confirmation of line-up and before start of operation, record in the Port Log as “Cargo valve line-up checked and confirmed.”
• Ullaging / sampling
  • Receiver / Terminal independent surveyors will gauge / sample cargo tanks prior discharging.
  • Refer OTM 7.14 – Cargo sampling procedures.

  Note:

  • Refer ISGOTT 6th Edition Chapter 12.8 for safety procedures to measure and sample inerted tanks.

  Coution:

  • Maintain cargo tank atmosphere integrity during ullaging / sampling.

4.3 Inert Gas / venting

• Comply with OTM 7.12 Inert Gas System.
• Refer OTM 7.4 – Setting of Venting system.

4.4 Operation of Cargo Pumps

• Starting
  • Start pumps as required in the Manufacturers Instruction Manual.
  • Carry out pre-operation checks.
  • Confirmation that pipeline system is set correctly.
  • Maintain minimum flow / pressure at start.
  • Inspect for any leaks form loading arm connection or from any blanks at both side manifolds.
  • Check over the side for any possible escape of oil through sea-valves, drain cocks and plugs.
  • For terminals employing line clearance techniques, check for initial pressure requirement.
  • Increase flow / pressure only on confirmation from the receiving terminal.
  • Check bending moments and sheer forces every hour to ensure that they are within harbor condition limits.
  • Monitor and record UKC periodically.

  Note:

  • Use NAV Form 002B – Under Keel Clearance – Monitoring during Cargo Operations
  • Include Bending Moment and Sheer Forces limits in Chief officer's written orders / cargo operations plan.
• Running at full nominal RPM
  • Run the centrifugal pumps at their full nominal rpm during bulk discharge.
  • On nearing stripping level, partially close the discharge valve to reduce flow.
  • Avoid reducing pump revolutions to reduce flow.
  • Cavitation occurs with high viscosity cargo when the pump tries to discharge more cargo than is able to enter the suction.

  Coution:

  • Cavitation can lead to:
  • -Danger of drawing gas or air into the pump,
  • -Pump operating in a partial vacuum instead of liquid.
  • -Reduced pump output.
  • -Vibration / damage of pump.
• During the pump operation
  • An officer or the pump man must be in cargo control room at all times.
  • Observe the tachometer and discharge pressure.
  • Standby to partially close ("throttle") the pump discharge valve if pressure drops.
  • Shut down the pump if it loses suction.
• Multi-pump operation
  • Run all pumps at same discharge pressure monitoring the Casing Temperature of all pumps.
  • If any pump's casing temperature is higher than the other, one of the following actions to be taken:
    • Increase speed of the said pump that has higher casing temperature.
    • Reduce speed of the other pumps in order to equalize the discharge pressures.
  • If one pump runs slower than another, it may stop pumping and heat up.
  • If there is high back pressure do not run all pumps.
• Shutting Down a Pump
  • Close pump discharge valve at the same time as reducing the pump rpm.
  • Close suction valve when the pump has stopped.

4.5 Rate of Discharging

• The Charter Party may contain a provision guaranteeing a certain rate of discharge.
• Normally the clause is for pressure of 100 PSI at the ship's rail or discharge of entire cargo within 24 hours.
• Deep well pumps are normally tested to operate at 10 bars.
• Laytime extends when installations are unable to receive at this rate.
• Issue Letter of Protest to terminal if installation cannot receive required rate.

5. REFERENCED FORMS AND CHECKLISTS

• NAV Form 002B – Under keel clearance – monitoring during cargo operations
• TNK 06B - Pre-transfer / Safety meeting
• TNK 10 - Discharge plan
• TNK 06A – Ship shore safety checklist