Figure 14
A Typical 300,000 dwt VLCC, the Tateyama, Owned by NYK, Panama Flag, Built by NKK Japan in 2002
Figure 13
This Photograph Taken in October 2002 is Supplied by the European Commission and Shows Timber Awaiting Shipment to Finland, Sweden and
Norway from the Latvian port of Skulte. This is a Typical Cargo of Forest Products Carried on Relatively Small Vessels and its Loading and Stowage
Requires Careful Supervision
Types of Survey – Cargo-related Surveys Module 1
12.9.1 Oil and chemicals
1-486 The vast majority of vessels that fall into this category are oil tankers. These vessels carry cargoes of various grades of oil and its derivatives but with an occasional cargo of liquid chemicals. However the last quarter of a century, has seen a dramatic increase in the specialist chemical and liquid gas carriers which today comprise a significant part of the world’s tanker fleets.
1-487 The carriage of bulk chemicals has become a very specialised trade with the chemical tankers being purpose-built and operated by a small number of shipping companies which specialise in their carriage. These surveys vary in complexity and some of the precautions required depend upon the toxicity of the chemicals which are categorised by the US Coast Guard as:
(i) Practically non-toxic.
(ii) Slightly toxic.
(iii) Moderately toxic.
(iv) Highly toxic.
1-488 Surveys associated with the loading and discharging of products of the oil/petroleum industry and with the chemical industry are amongst the most demanding on surveyors. They require careful attention to detail.
1-489 In most cases the requirement is for dual attendance – that is, attendance on both the ship and the shore installation. This may be impractical for one surveyor and two may be required, one in each place. The surveyor(s) may be required to ascertain:
(i) The quantities loaded/discharged.
(ii) The quality of different samples. (This is largely a laboratory function but will involve the surveyor in sampling.)
(iii) That there is no avenue for cross contamination.
1-490 Attendance on board is usually the more demanding and will involve:
(a) Checking that overside and cargo tank valves are all closed except those actually required for and during the immediate cargo transfer.
(b) Sounding ballast and fuel tanks (and making allowances for quantities consumed by the ship).
(c) Pump and pipeline cleanliness and, before loading, tank cleanliness.
(d) Sampling of ballast water pumped out of cargo tanks.
Module 1 Types of Survey – Cargo-related Surveys
(e) Ascertaining the vessel’s experience factor (checking records of past cargo operations to determine the differences between ship and shore figures for quantities handled).
(f) Sampling the cargo loaded/discharged (and may involve the surveyor in witnessing the testing of the product).
(g) Measuring the tanks before and after pumping.
(h) Recording the trim and list.
(i) Checking and recording temperatures.
1-491 Ashore the survey will include where possible:
(a) Checking for water and sampling the content of the pumping lines.
(b) Checking the state of the valves in the holding and adjacent tanks and wit-nessing their operation.
(c) Sampling the holding tanks.
(d) Measuring the content of the holding tanks before and after pumping.
(e) Checking and recording temperatures.
1-492 Equipment required:
(a) Measuring tape conforming to ASST standards (free of kinks, legible, with a secure bob and checked regularly for accuracy).
(b) Thermometers (also checked regularly).
(c) Hydrometer conforming to American national standards or British standards.
(d) Containers for samples.
(e) Protective clothing (for chemicals).
1-493 Oil and chemical cargo sampling, unless the surveyor is instructed otherwise or has good reason to depart from standard practice, is best carried out as outlined in the Institute of Petroleum’s manuals on oil and chemical measuring techniques.
1-494 During loading operations, apart from sampling the cargo being shipped, the prudent surveyor will also obtain samples of the cargo, slops and ballast water on board at the commencement of loading.
1-495 Not all of the vast quantity of liquid bulk cargoes are carried in ships specially designed for them and small parcels are carried in general cargo ships and containerships. Deep tanks, often fitted with heating and pumping arrangements, are sometimes located in cargo ship holds and are used to carry small quantities of chemicals, oils and other liquid cargoes. The advent of the small parcel tanker has seen a reduction in the number of cargo ships with deep tanks.
Types of Survey – Cargo-related Surveys Module 1
1-496 Latex, coconut, sunflower seed, rape seed, linseed and other vegetable oils are commonly cargoes loaded in small quantities in eastern ports for discharge in Europe and the US and for which cargo ships’ deep tanks are often suitable, depending upon quantity. Tallow is also carried in deep tanks between countries having a significant animal products trade.
1-497 The surveyor’s role in connection with these is usually to take samples and to verify the cleanliness and fitness of tanks, pumps and lines to receive or discharge cargoes. They will often be required to confirm quantities shipped or received.
1-498 A word of warning concerning tank inspections. Toxic residues of cargo, but also little used tanks, can be lethal to unsuspecting surveyors. Each year a number of lives are lost by failure to check the vapour content of a tank before entry, and empty tanks which lack oxygen through the effects of rust generation are as responsible as any. Where there is any doubt surveyors must always check before entry and have a “buddy” to watch over them. The buddy must be fully conversant with the operation and whereabouts of breathing equipment which must be nearby and accessible.
1-499 Recommendations for entering enclosed spaces on board ships as provided under IMO resolution A864/20 warrants attention and includes a pre-entry checklist It is an essential document which should be carried on board all vessels and all seafarers should make themselves familiar with its contents if they are ever likely to have to enter cargo spaces or tanks. Refer to the Appendix 7 to this module for a list of its contents.
Figure 15
DNVPS Surveyors Preparing Fuel Samples May 2004
Module 1 Types of Survey – Cargo-related Surveys
1-500 Another highly specialised area for which ships have been designed in recent years is that of the carriage of liquid natural and other gases. Standards are, in some cases, still being evolved and outside of the few carriers operating these ships there is very limited knowledge and experience.
1-501 Most of these gases are vapours at ambient temperature and pressure. For carriage by sea they are liquefied by:
(i) refrigerating to drop the temperature but still at atmospheric pressure;
(ii) a combination of part refrigerating and part pressurising;
(iii) pressurising without refrigeration (the temperatures and pressures at which gases liquefy varies vary very considerably).
1-502 From the surveyor’s point of view the requirement is principally that of ullage and temperature recording followed by fairly extensive calculations to determine quantity. Both measurements are usually made with ship’s equipment. Accuracy is absolutely critical to correct results.