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LPG carrier cargo pipeline & tank inspection/ test procedure
Cargo tanks are to be inspected internally during every dry-docking and in circumstances where a
particular tank is required to be gas freed for repairs. All other tanks, including ballast and void spaces
must be internally inspected on a 12-month cycle to establish the condition of steelwork, pipework,
fittings and coatings of anodes, as applicable.
In order to assist in this process and ensure a uniform
and objective framework of reporting, the publication “condition Evaluation & Maintenance of Tanker
Structures” is to be referred to before commencing an inspection. In addition, pocket-sized copies of the
LR publication “Tank Coatings Condition Guide” will also be provided onboard.
Defects must be reported as early as possible to allow repairs to be budgeted and scheduled. Wherever
possible, the report is to be supported with photographic evidence. However, only cameras that are
intrinsically safe are to be used. Where there is doubt as to the suitability of the camera, the
management office is to be advised.
Particular attention is to be paid to examine and remove any debris which may be left inside the cargo
tanks after a repair period. Such debris may cause damage to filters, pumps and valves on both ship
and shore installations. Any water accumulated should also be removed in order to avoid the formation
of hydrates.
It is appreciated that due to certain ship designs and/or trading patterns that the six-month cycle may
not be practical. In such cases, a suitable inspection cycle must be agreed to, in association with the
fleet cell and followed. Such an agreement must be documented.
Cargo pipeline inspection / test procedure
Cargo pipelines are to be inspected and tested on a regular basis with any defects immediately reported
to the management office. The condition of pipelines on semi-refrigerated LPG carriers is often difficult to
ascertain due to the presence of insulation material, however, the following procedures should be
followed:-
Checks During Loading / Discharging
- A complete visual check of all pipelines is to be carried out during cooling operations and
initial cargo transfer. Close attention is to be paid to areas where pipes are insulated. If a
leak is suspected, the insulation must be removed in the immediate area of the suspected
leak.
- Cool down of all pipes to be carried out in accordance with the established cool down
procedures onboard.
- Regular pipeline checks are to be carried out during the cargo operations.
Annual Checks
At least once in every 12 months period, ship staff should undertake a thorough visual examination
of the cargo and process pipelines, valves (including pressure relief valves and drainage
arrangements), piping anchor supports, fittings, liquid/vapour hoses and expansion bellows.
Furthermore, a pressure test should be carried out after a cargo change over, particularly if the
cargo system has been broken to alter tank segregation.
A pressure test to a minimum of the designed maximum working pressure for the pipeline is to be
carried out. The preferred medium for this test is cargo, as opposed to nitrogen, due to the quantity
of pressurising medium required on larger vessels. The system should be checked for leaks and if
there are any deficiencies noted, the management office is to be advised immediately. If a leak is
suspected, the insulation must be removed in the immediate area of the suspected leak.
Prior to carrying out this test, the settings for the line pressure safety valves are to be ascertained.
During the test, it is important that the maximum pressure does not exceed 85% of the safety valve
activation pressure.
The inspection and testing routine should be entered into the PMS onboard and records maintained
up-to-date.
Test Procedure in Dry-dock
During period of dry-docking, all cargo and process piping systems, including valves,
actuators and compensators, should be opened for examination as deemed necessary by the
Class surveyor, to ascertain the condition of the pipes. A recognised shore-based company
is to be employed to carry out this close-up inspection as insulation may need to be removed
and subsequently replaced.
Normally, if any doubt exists regarding the integrity of the piping, based upon visual
examination, , where deemed necessary by the Class Surveyor, a pressure test to 1.25 times
MARVS (Maximum Allowable Relief Valve Setting) for the pipeline is carried out on the
suspected section of pipe. After reassembly and any repairs, the complete piping system is
to be tested to a minimum of the designated working pressure and checks made for leaks.
Related Information:
- Various type LPG tanker - Design characteristics and usability
- LPG tanker cargo work equipments & product line system
- Carriage of LPG cargo at sea & safety guideline
- LPG reliquefaction plant safety guideline
- Preparations for LPG cargo discharging, pumping & stripping guideline
- Preparations for loading compatible cargo onboard LPG tanker
- Preparation for changing different grade cargo or drydocking -LPG tanker guideline
- Cargo tank inerting prior to gassing up - LPG tanker procedure
- LPG cargo tank purging & safety guideline
- LPG cargo tank cooling safety procedure
- LPG cargo loading special guideline
- Tackling fire onboard LNG & LPG ships
- Detail guideline for Ballast operation at sea by LPG carrier
- Handling cargo related documents for LPG carrier
- Cargo sampling procedure for liquefied gas cargo
- Cargo measurement and calculation guideline for LPG carriers
- Handling Propylene oxide, Ethylene oxide mixtures
- Special characteristics of Vinyl Chloride Monomer & Butadiene
- Various type LPG tanker - Design characteristics and usability
- LPG tanker cargo work equipments & product line system
- Carriage of LPG cargo at sea & safety guideline
- LPG reliquefaction plant safety guideline
- Preparations for LPG cargo discharging, pumping & stripping guideline
- Preparations for loading compatible cargo onboard LPG tanker
- Preparation for changing different grade cargo or drydocking -LPG tanker guideline
- Cargo tank inerting prior to gassing up - LPG tanker procedure
- LPG cargo tank purging & safety guideline
- LPG cargo tank cooling safety procedure
- LPG cargo loading special guideline
- Tackling fire onboard LNG & LPG ships
- Detail guideline for Ballast operation at sea by LPG carrier
- Handling cargo related documents for LPG carrier
- Cargo sampling procedure for liquefied gas cargo
- Cargo measurement and calculation guideline for LPG carriers
- Handling Propylene oxide, Ethylene oxide mixtures
- Special characteristics of Vinyl Chloride Monomer & Butadiene
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